IROCZman15

iTrader: (25)

Luttrell, cool, thanks. I looked into the vac canisters back in the spring actually. Most people seemed to have the same results that you described having. Some people can get it to work pretty good, and some have bit the bullet and installed a vac pump instead. Some people even use both a vac pump and a vac can tank! I know Manolis (here on TGO) who goes by Klowny1969 (on youtube) did a video about vac canisters not too long ago. It is cheap enough to try, but I think I might feel more confident autocrossing with a vac pump. Now, nothing says that the vac pump couldn't just fail mid autocross lap!!! but I am not sure that I would get the repeatability I would need from just having a tank. thoughts? I'm hoping to have this issue solved and not have to worry about if my power brakes will be there or not for years to come.


Also, if anyone else has more feedback, feel free to chime on in. Would 3.91s be too non-street friendly? I kinda don't think so. I mean I used to run the 3.73 gears with the old TPI engine (and 700r4) from 2004-2019. The 3.73 ratio was never bad on the highway, and I was never looking to blast across the interstate at 90-100 mph anyways. I think anything in the 4.11, 4.xx range might be a little too much, but a 3.91 coupled with the 700r4 overdrive plus locking up t he converter would be just fine.


As for the 3.91 gear with nitrous, I am struggling at how to mathematically determine how my current 3.55s would work with nitrous too. If I were running a 100 shot I would probably be at the very top of 3rd gear crossing the finish line. However if I were to run the 200 or more shot I planned on running, I am pretty sure I would have to shift into 4th gear (overdrive is a 0.70 ratio) before the line so that is not optimal. If I ran the 3.91s I'd hope to be able to stay at the top of 3rd gear while crossing the line when running no nitrous (current setup), and on a small shot I'd be into 4th gear, but on a bigger shot I would be into the meat of 4th gear. Since I have no idea how to use math to figure this out, I am just doing my best guess.

Basically, I want the car for feel more alive and woken-up not only on the dragstrip, but especially on the street. I want to take people for rides and have that killer instant acceleration. It is pretty good now, but thinking the 3.91s would really deliver the "pinned in the seat" experience.

MSgt Luttrell

I believe if I were to autocross in my IROC I would want to know I was going to get the same results from the brakes in every turn and I'm not sure that just a vacuum canister alone can provide that.

IROCZman15

iTrader: (25)

correct, and I certainly do autocross the car and will continue to do so, and perhaps even more short-course road course racing is in the future too, but its been a few years since I was on a road course track. So, thats why I kinda quickly looked past the idea of just having a canister... and began exploring having an actual vacuum pump. however, some people are suggesting that I go full manual brakes.

MSgt Luttrell

Vacuum pump is cheaper and less work in the long run.

QwkTrip

iTrader: (22)

When you say your brakes are sketchy during autocross, what's the behavior that you're feeling? You have gobs and gobs of vacuum when you let off throttle with engine revving.

skinny z

I was going to ask that same question with the same observation.

IROCZman15

iTrader: (25)

I've noticed that I have to be heavier on the pedal if I am going into a turn/brake coming off of a lighter/moderate throttle. sounds silly to say that I am not at heavy throttle during a race, but some times I've had to be at low/moderate throttle and I "think" I have then had to use more forceful foot on the brake pedal. At times this has become unpredictable and I have gone too much and locked up the brakes, therefore sliding the car/tires and skidding. Also, my 6 year old nitto 555 street tires don't help with the skidding. Also, remember back in the summertime, i suffered from a failed brake power booster and at that time I simply replaced it with an oem style booster just to get through the rest of the year and do proper research on how to avoid potentially replacing brake boosters frequently. that's where I am at now.

thoughts on "manual brakes" ?

qwk and skinny, you guys are super knowledgeable too and I was wondering your thoughts on the gear swap to 3.91 ratio?

skinny z

Manual brakes, when done properly, at the very least will give you the repeatability that you're after. We did our share of installations in the many hotrods that passed through the old chassis shop. Street rods and drag racing stuff mostly but there was never a complaint about the lack of power assist. Check out the DSE-Z from Detroit Speed. Full manual.
Still, I'd like to see data logs of the manifold vacuum while you're in autocross mode. Something doesn't seem right in that your engine package, I would think, would develop sufficient vacuum for your needs. As a starting point, what's the idle vacuum and RPM in gear?

As for the gear swap, this is something we're considering at this moment with a friends 69 C10 LS3 powered truck. With a lower numerical 1st gear (2.48 new vs 3.06 old), a big heavy converter (the first thought was for towing the RV) and a 28" tall tire, the 3.73 rear gear led to a drag strip performance that was sub par. The 60' was terrible. With a new converter on the way (a 10" triple disc Yank) and a change to 26" tall slicks, we'll be able to see the need for a gear swap. If the improvement is significant and the traction is there with the 26" tire, then a permanent gear swap is in the works and the 28" tire can go back on.
So along those lines is what my decision tree for the Camaro will be based as well. A gear change to me is what's needed to get the car to RPM at the stripe. That RPM being, in a best planned scenario, where peak HP is. But not at the expense of overpowering the rear tires. There's that traction thing again. With a 3.06 1st gear, my effective overall gear ratio is 11.41:1 with the 3.73 rear gear. That's pretty steep already. Move along to a 3.91 and the overall ratio is now 11.96. Is that too much for the tires? At the other end, at a target speed of 115 MPH, a 3.73 gear gets me to 5822 while the 3.91 goes to 6100. That is approaching ideal territory for my package.
Do you have the ceiling at the stripe for more gear?
And are you dedicated enough to the drag racing platform to refine the car in that direction at the expense (possibly) of performance in another? How will it help or hinder your autocross efforts?
Then of course there's that bottle of nitrous...

IROCZman15

iTrader: (25)

I am definitely not opposed to manual brakes. I think I am either making one of three choices
A: leave it as it is
B. A simple self-contained electric vacum pump that I can use to have full power brakes on the street and on the autoX, but for drag racing I can run the vac pump to the valve cover and pull some vac on the engine to gain some more hp) and simply run the oem brake booster off the sniper vac port (like it currently is)
C. manual brakes. still researching those though. I would hate to have to redo all my nice and cleanly bent/mounted Ni-Cop brake lines under the master and I really don't feel that I am a master at setting up a brake system. My brakes are good, I don't want to start re-vamping a setup that is working. I just want the power booster to work properly, all the time. one of the NJ fbody club guys sent me this link : https://www.manualbrakes.com/3rd-gen--82--92.html
here is the guy's TGO link/tutorial https://www.thirdgen.org/forums/brak...-pictures.html
manual brakes would result in me shedding weight (booster) instead of adding weight with a vac pump. it would clean up the components underhood, but I'd still have to redo lines and such. also on that guys website he specifies "non low-drag" calipers are required. not sure what my Corvette C4 Ed miller PBR calipers are considered?

I'm searching for a datalog to match a video for you guys to see. I wish I took better notes that day at UMI, because I can't remember my brake pedal action all these months later.
edit: fixed video link: I am pretty sure that here at 0:33 seconds into the video I was pressing on the brake pedal immediately after coming off the throttle and the brakes weren't there for an instant, and they they were there too much, causing me to slide. Now, unless I am mistakenly reading the datalog, I was at 82% throttle and climbing to 6,180 rpm with the kPA at 92 (5.33 inHg) ..closed the throttle completely while hitting the brake pedal.. and tps, rpms all obviously dropped. MAP kPa went to 20 (23.69 inHg).. so this seems to be exactly what SHOULD be happening in a properly working system. right? I can't remember for sure, but I thought this instant was one where my power brake booster was "iffy" apparently not. apparently it is correct??



maybe I am just overthinking all this? still, I did blow out a brake booster this year, and I still don't know why that happened!

option A is fine with me, but if I need to make changes...
option B makes the most sense to me. I can hide away the unsightly vac pump and plumb a single hose to the booster. when drag racing I can move the hose from the brake booster to the valve cover and run a hose from booster to intake vacuum. simple, clean, electric.

as for my current vacuum. with a warmed up engine it pulls 7.5" of vac at a 920 rpm idle with ignition timing at 19 deg advanced.

I would indeed rather spend the money on tires or rear gears for the car instead of a vac pump... but as we all know it is super imperative that my brakes work .

IROCZman15

iTrader: (25)

As for the gears, I much appreciate the tech advice skinny. your experience is super helpful because real world tested/used setups are what I am after. I was certain that I could find someone online that has used a similar sbc, 700r4, 3.91, 26" tire for quarter mile drag racing as well as street use. google wasn't too helpful finding that, so i asked here. As mentioned, I used to have a 10 bolt setup with 3.73s with the same size tire, trans, and the tpi engine. they were pretty good. I picked 3.55s when moser built the rear just to be safe. If I put in the 3.91 gears and its too much low end "snot" or problematic for the nitrous, I can take a day and put the 3.55s back in. Not sure that I will open up the transmission ever and replace the 1st gear though, thats unlikely. I would like to try a 28" tire one day, but maybe borrowing s set from someone for a day, before buying the wheel/tire and finding out that they don't safely fit.

I am kinda curious to find out what are some realistic 60' numbers people see using the 26" tall MT ET Street SS tire? Google doesn't understand what I am looking for. are these ties capable of a 1.55, 1.50, or even a 1.4x sixty foot .. or where do these tires stop working and the need for drag slicks become necessary. any realistic chance of a nitrous launch with a 3.91 on these street drag radials?

I'd like to cross the stripe at 6,200 rpm, even if I have to hold back a little on the pedal if I am going to run out of gear just before the stripe. I'd rather have a wicked launch and get myself into 3rd gear asap. and for the street, this would just be much more exciting for zipping around and giving people thrill rides. Autocross might suffer a bit because I would have to be more tender on the pedal control, but that is a sacrifice I am willing to make and adjust to handle. I know I will have to re-learn my autocross driving all-together anyways when I finally get a proper set of better tires. I've been leaving a lot on the table with my old hard nitto 555 street tires, so those need to be replaced, perhaps this year if the budget allows. For me, autocross is more fun ad less competitive, where I am more competitive (with myself) in drag racing goals...also the drag strip is only 25 minutes away and autocross is less frequent and more of a travel.

skinny z

I'd start there.
Or more accurately stated, continue from there. A couple of autocross events won't give you nearly enough seat time to make a solid determination. That's my take on it anyway.
You're thinking on the booster vs manifold vacuum relationship is correct. Back off the throttle, create low pressure which is stored in the booster and there's your power assist. I would think you have enough throttle to brake transitions to keep that booster satisfied. Unless something is fundamentally wrong.

As for the manual brakes, you made an interesting observation and that's "designing" a brake system. With a manual MC, you could very well find yourself with a mix of primary and secondary piston diameters that will mess up any semblance of balance you have now. This is where a shop that does that sort of thing as a specialty would pay dividends. You may or may not want to venture down that path.
What do your comrades in the other third gens have for brakes? I'm thinking specifically of the UMI event that had a few representatives.

I'm still in the plan "A" camp.

skinny z

The choice in tire has everything to do with the effectiveness of the suspension.
We've seen that a slick, or more accurately, a slicks construction, has generally better traction than an equally sized radial when used with a slightly tweaked OEM setup.
There was a significant chassis and shock absorber revolution that came about with the newer drag radial classes. And I'm talking maybe ten years back (maybe more, maybe less). Times have changed from my early days.
The point is, yes, your SS radials are more than capable of excellent 60' times. Your suspension on the other hand may not be.
More gear might exacerbate an already troubling problem. Not saying that you have one though as your 60's are pretty good aren't they? What I am saying is that with more rear gear, (and I'm solidly on the side of more gear so as to target that optimum stripe RPM), you may introduce significant traction issues.
Here's comes the suspension. Double adjustable shocks and 4-link rear ends are part of the recipe to get those radials to hook. At power levels beyond my own anyway. I'm not saying that's what you have to do, I'm just pointing out what's been done and has proven effective.
An anecdote for you. 1967 Chevelle. 650 HP LSX 454. 4L60E (with 3.06 1st gear). 3.73 rear gear. Leaves off idle. It takes a big fat slick to get that thing to hook and pull a wheel (modestly) but there's no suspension work done. Adjustable shocks at most but no changes made at the track (lazy ***). Drive there. Bolt on the bias ply slicks. Race. Change tires and drive home. Still, it's a 1.5x/1.6x 60' but there's way more if the suspension was tuned. Maybe even get to leave at the converter stall ! Yes, that's a slick compared to a radial but the effect, or lack of it really, is similar.
Same applies to my Camaro. And it's probably fair to say, to yours as well. If I want to improve on my PB 1.7 flat 60' time, I'd better have a way to tune it to the track. Radial or otherwise. Weight transfer via of very biased front shock. All extension. Little rebound. Rear shocks that resist the weight transfer and don't allow the axle to migrate up into the wheel house. (Extension is what it's called although it's a fairly trick thing to pull off in a stock 3rd gen rear end arrangement).
And therein lies the rub Mr. IROCZman. You might have to choose between performance platforms. Although strictly from a time slip point of view, nitrous would take care of that and the suspension and 60' can be less of a focal point as far as the drag strip is concerned.
Anyway, I'm not saying do this or do that but rather trying to spill out some of what I've learned. Not all of it is from practical experience as a lot comes from observation, asking questions, gaining insights.
Exactly what you're doing now.

skinny z

While I don't have any personal hard data for you regarding your drag radials and their potential 60' (although in my previous post it was more less to say the sky's the limit) you may something useful here.

IROCZman15

iTrader: (25)

Brakes:
yea, I wish I had taken note of what some of the other 3rd gen cars run for power/manual brake systems when I was at UMI, but maybe I can dig around on here and online to find out. I wonder what Val does in the dragonlady car. The DSEZ is very well sorted and the manual brake system works for them, but again, they are a leading automotive performance kingpin, and I am just a guy in a 1 car garage with a car hobby. maybe I'll keep doing the research a while longer and do more testing of the brakes system in the springtime. I did email the guy who created the manual brakes kit for thirdgens and he had some interesting things to say, mostly that his 7/8" bore size master cylinder would be the one to use, and my current calipers/rotors/pads would work. Yet, I would have to redo brake lines, and I am not trying to re-do my engine bay after I just welded/smoothed it last year and painted it. I'll stick with plan A for now while I do more research. The last thing I want to do is take this brake system that is working pretty-good pretty-often and throw in new variables and have it work worse and become expensive. Maybe I can find a parking lot and do an array of brake testing and driving situations while datalogging and video recording. Not now, its snowing here in NJ today.

-edit another thing I forgot to mention, is that when i want to line-lock the front brakes for a burnout (either at teh track or secret street location), the line-lock works, but the booster doesn't have enough vacuum in it to really hold the car back for more than a few seconds. how would manual brakes work with this line-lock issue... for a vac pump, the vacuum would be there (22" of vac compared to my 7.5" of vac) so in theory, the line lock should be useful because the booster is getting proper vac for full power-assist. right? do manual brakes even work with a line-lock?.. I will ask the guy who builds the kits

Gears:
you are exactly right about the gear/traction/tire situation. I know my suspension setup is street based and its currently doing a good job on the dragstrip with many sixty foot times in the 1.64-1.66 range. Like ya said, more gear might push the suspension past the point of it "working good enough" to be "not-working" and so forth. Again, that blue bottle of nitrous will none-the less add more variables to the launch, but if I could keep the current suspension working properly after the 3.55-to-3.91 gear swap, maybe I would just spray nitrous in 2nd and 3rd gear past the 60foot...possibly no nitrous at the launch.

Good to know that these ET Street SS street radials can work well. I have read that post you posted, and lots of people will say "drag radial" but that's not clear if it is the treaded ET street SS like I have, or the other ones.. the ET street R tire..... mine are: https://www.summitracing.com/parts/mtt-3453 and if they are capable of a sixty foot in the mid 1.5x range, that would be great. Again, my suspension/car will probably be the weaker point compared to the tires. If the koni yellows become a problem at the track, i could maybe save up some money for a drag-race oriented shock for the rear. Changing shocks out on these cars is truly a 10 minute job. I could leave the koni yellows in the car most of the time, but if I knew I was going to have a drag strip day, I could swap out the rear shocks for the event....and heck, if the shocks are out, i could have a set of extra coil springs tht I could slip intop place (2 minute job) in order to raise the rear ride height a bit SO that a 28" tall tire might fit properly. (I'm getting nutty, I agree!, but a rear shock spring change could be done in 15 minutes for the day of drag racing, and then switched back easily. I would certainly not do this with the front struts because that's more work and would screw up the front end alignment. Food for though; not at that point yet.



As you mentioned, this fact-finding and question/answer research phase is important. Glad I can ask advice from people who have been-there-done-that even if it was some years ago. I'd rather make a well informed decision, instead of just impulse buying parts that won't work well.


Aside from that, I am waiting a few more weeks, but I think I am going to probably go ahead with the 3.91 gears. If I can test fit a 28" tire off of a fellow drag racing 3rd gen next year, that taller tire will eventually be the route I will go for drag racing.. but not for 2021. Money budget being extra tight this year I want to look for the most "bang for the buck" modifications. Knowing my Nitto 555 tires are not the best for the street or autocross, I might have to put money towards 4 tires for better street/autoX driving. Not going to do exhaust this year that is for sure. Hopefully the roll bar and possibly hopefully plumb the nitrous. Will probably do the gears here at my house since my neighbor has the tools and he has done some gear projects in his day. I have only helped on a 9" for rear before and back in 2003 I "helped" put in my richmond 3.73's with a mechanic. It will be a new thing for me to learn and do ... I am pretty sure that the MT Et Street SS street radial is up to the task of a better launch, but my street car suspension is the unknown variable..as to how well it will handle things. Perhaps I can bring my 1.64-1.66 sixty foot into the 1.5x zone and yank a small wheelie in the process....while coming close to crossing the finish line at 6,200 rpms.


edit: on that 60 foot TGo page ( https://www.thirdgen.org/forums/orga...uspension.html ) the following setups would be somewhat similar to mine.. but with some variation. weight, gear, trans, horsepower.... same general neighborhood .. but again my tires are the street SS, not the street R
- Post 3: Orr
- Post 7: Joeblue
- Post 46: 87 TA
- Post 52: Ttop89
- Post 58: PhoneixFirebird
- Post 89: Z28Fast1
-Post 97: Vaggota

QwkTrip

iTrader: (22)

Sorry, I'll confess to not reading everything. What brakes, pads, and fluid are you using?

QwkTrip

iTrader: (22)

And do you still have the stock metering valve in the brake lines? I remember at one time you were running a gutted stock valve with a prop valve at the back near the fuel filter.

IROCZman15

iTrader: (25)

calipers up front are the Ed Miller Fly-n-bye C4HD setup, PBR caliper with a 13" rotor
Hawks HPS HB111 F.610 brake pads up front
rear calipers are the C4 PBR caliper on a 12" rotor
Powerstop Extreme Z26 - 413 Street Warrior carbon fiber brake pads in the rear
Prestone DOT 3 fluid
Wilwood in-line adjustable prop valve mounted under the car
3/16" copper nickle tube and stainless steel braided flex lines
oem master
oem replacement booster
oem pedal
SLP line lock
no metering valve at all



not really looking to change any of the stuff that is listed above, was really just looking to maximize what I have and get a better pedal via the vacuum booster and really assumed the electric vac pump would be the best option. The guy who builds the kit that I linked above agreed that the electric vac pump would indeed be the least intrusive. he provided me with the directions and specs for his kit too. It would certainly require me redoing all of my brake lines in the engine bay and re-mounting them, thus having to make a mess out of my clean/smoothed engine bay in the process. he mentioned that if I did use his kit, i could get a fancy wilwood master cylinder and also route the brake lines to come out of the other side so they are not near the engine heat as much. It would shed 9 pounds. At this point in time, I am still doing research, so anyone who has any input, please feel free to chime in.

QwkTrip

iTrader: (22)

Photos on their facebook. Looks like they use a stock booster & master cylinder, with a Wilwood 5 port prop valve, and they have some kind of Wilwood brakes.

QwkTrip

iTrader: (22)

What brake calipers do you have?

IROCZman15

iTrader: (25)

sorry, i was editing my post as you were posting ! whoops, they are the C4 setup PBR calipers, I put/edited this into the post just above yours so all that info is together for future readers
dumb question.... is the C4HD PBR caliper and C4 PBR caliper the same as the coveted "1LE" package ? I bought it all from Ed years ago, and the stuff looks the same, but I don't want to sound like a doof and say I have 1LE brakes when they are C4 brakes.

QwkTrip

iTrader: (22)

The booster is not in play when line lock is active. The line lock closes a valve to isolate the lines between it and the front brakes. Whatever pressure is in that line should stay there until you open the valve. Either the line lock is leaking back to the master cylinder, or the front calipers are misbehaving. (I'm assuming you don't have any external leaks.)

IROCZman15

iTrader: (25)

correct, zero external leaks. I am going to have to test this. for years the line lock worked perfectly, after the new engine install, it felt weaker. i could push through it somewhat easily. I can't test it now (has already snowed here in Nj), but I am thinking that I'll line-lock it in the springtime and just sit there with the car in gear and see if it starts to "bleed pressure down" and allow the car to roll after a few seconds, or minutes, or whatever. If not, maybe its just a figment of my imagination, or I wasn't always putting my foot to the floor before locking it, or the brakes were too cold, or the rear tires started to hook. Will check

Qwk:
what was your consensus about my above brake combination and manual brakes vs vacuum pump vs leaving everything alone.
any thoughts on changing to the 3.91 gear ratio vs my current 3.55 on the 12 bolt?


Also:
I was thinking, if I have difficulty in the future fitting a 28" tall tire, I can easily remedy this by putting the oem rear rubber spring isolators in place to gain some more body height too. I currently do the heater-hose on the rear spring trick.. which are also cut 3/4 of a coil to get the body-drop I like. OR have a set of springs that are the proper height that I just swap into place in a few minutes of time during my track prep. but thats at least a year away. I am on 26" tall MT Et street SS tires for this year, that is for sure.

MDDAWG

Hi, the 1le calipers are not the same as the c4 hd calipers I am in the process of doing the C4 HD conversion right now , did the rears to the 12 inch C4 last year . I hope the fronts end up being worth doing, what pads would you recommend, I have the Stillen pads on there now and they work really good when they get some heat in them, not so great when they are cold. I have the same booster , M/cyl as you and run about 8 inches of vacuum at idle , gets a little shaky in stop and go traffic but seem to apply good when on and off the throttle where vacuum has a chance to build. Guess I'll find out when I Autocross this summer. Just put the Koni yellows on the rear , gonna do the yellow struts when I do the C4 hd brakes . What settings do you use on your shocks/ struts for street and autocross, if you don't mind ,Thanks ,Mike

IROCZman15

iTrader: (25)

ok, good to know. I was never for sure about 1LE brakes being the same as C4HD brakes or C4 brakes. gotcha I really like the powerstop pads that I put on the back brakes. The current front pads are Hawks HPS (listed above) and they seem to be pretty good, but next time I am due for pads, I will probably go with the same powerstop style pad that is now on the rear. our master/booster/vacuum situation sounds exactly the same. right, like you mentioned, at times its a little bit unsettling. thats what I am trying to correct; and my initial thought was a simple electric vac pump install, but during my research process, some other variables came about. what are you thinking about doing.. or leaving it as is?

I actually has best luck with the shocks medium-soft on the autocross. I started out stiffer and then worked my way down softer. I think i go into detail about it a few pages back during the August UMI event, it is post #118 on page 3 of this thread.


also, MDDAWG.. I see you have a 700r4 with a 3.73 rear gear , not sure if you have made any track passes with that setup and your engine ? if so, about what rpm are you coming through the trap at and do you use a 26" tall tire? do you foot brake launch and how is the 60 foot? how is the 3.73 on the street driving, and on the highway? it might help me make my decision on the gear ratio I decide to pick if I do a gear swap this year. its between 3.73 and 3.91 I'm still thinking I'll be disappointed with 3.73 so I am leaning towards 3.91 gears.. but any real-life experience and feedback is helpful, especially from someone with a very similar car setup to mine.

MDDAWG

Yes ,there is just alot of this stuff that is just a compromise leaning to the most frequent use and driving style. I think I'm going to try a vacuum reservoir first for the brake situation. Like you if that's not satisfactory I'll go with the electric vacuum pump. As far as track time ,no not yet , here in Montana they are a ways away. We have 1/8th mile within 100 miles so I'll probably go there next spring, kind of a bummer as I moved here from a bigger city in Washington, where we had 2 major facilities within 50 miles, plus road courses , and autocross every weekend if you wanted to. But anyway I run a 25.7 inch rear tire Firestone Indy 500 Firehawks , the 3.73 gear I like for the street, , highway 2400 rpm is 70 mph, from a dead stop leave at idle about 950 rpm it's hard to hook up ,spins pretty good. The 700r4 I bought Dana's street strip complete kit as he would build it and did it with help from a friend with a trans shop, works great, the converter is an Edge 9.5 inch with 2800 stall aprox., but I just feel it bogs a little too much on the 1-2 shift , about 2100-2201 best I can tell from the datalog, anyway , stuff to work on over the winter. lol

ploegi

Have you considered going hydraboost??

QwkTrip

iTrader: (22)

I can't be of much help to you. I'm not a great troubleshooter and that's what you really need right now. Gut feel is you should inspect and service the calipers and see where that leads you. Pretty much got to get hands on hardware or problems don't get solved.

Never had a 700R4 transmission, so can't share experience there either.

IROCZman15

iTrader: (25)

pleogi: I really have not. I know that I for sure do not want an ugly hydro-boost unit under the hood. all the extra fluid lines and the ugly housing would not be worth the benefit for me when i open the hood at a car show or even in the garage. Some people have luck with it. I dont really have serious brake issues, I am just simply looking to improve on what I have and I know that my brake booster is generally underpowered and unhappy because the lack of engine vacuum at idle. I killed a booster mid way through this year due to it.


QWk: gotcha thanks. I dont mind getting hands on, just figured I would do my research online and ask questions first to guide me along the way.


I think I am probably going to end up buying the 3.91 gearset from Moser and the install kit in January. I have been selling some parts inthe classifieds (here and ebay and racingjunk) and I almost made enough to pay for the gears, kit, and fluid.

-I am also going to buy a "fixed orifice" PCV valve to re[place the one I currently use. People with the holley sniper recommend a fixed orifice unit.
-one of my valve cover gaskets is leaking, so I will get a new set of cork valve covers
- will be sending the radiator back to Champion for a FREE replacement . very small pinhole leak, but it is covered under the lifetime warranty
- looking to move my 2-step rev limiter and might try to figure out a way to have two mounting locations for it. one possible choice is on the side of the brake pedal...so that when i release the brake pedal launching the track, I also come off the 2-step button . saw some guys who have done it this way on the racing websites
-

ploegi

I actually liked hydraboost better...... With good lines, the system works great, gives better access to the drivers side of the engine, especially at the back.... and has MUCH better pedal feel...... (my van has hydraboost, simply because of space/packaging issues.) Firmer pedal, less pedal travel, and better braking power with less effort....

Granted, I wasn't nearly so concerned about aesthetic value of it all.

IROCZman15

iTrader: (25)

gotcha, gotcha yup. I have indeed heard some good things about that system. If the car was more of a race/performance car, I would probably go that route. But its also something I like to bring to car shows and have a very streamlined/minimalist layout of everything under the hood (see engine bay photos on previous pages of this thread). I try to hide as much wiring and hoses as I possibly can and keep things neat.


Just sold the MSD digital 6 box today, and sold the MSD Pro Billet Distributor, so the $ from selling those will pay for the 3.91 gear project. awesome!

skinny z

I think you'll find the new gear to your liking. That is of course if you can get it to stick. There wasn't much feedback from the 60' thread here. Did you learn anything anyplace else? I know that your new radials are capable of the times you're after. What I don't know is how much suspension it'll take. Chances are I'll be looking to you for that advice once I'm back on the track.

IROCZman15

iTrader: (25)

Well, I emailed Mickey Thompson about my setup and was given a basic/blanket reply, which makes sense. As we all know, they can not give well formed advice on a vehicle/combination with so many variables. They won't say yes or no that it will work. I understand this. I did some other digging on yellow-bullet, forums, and some other drag race websites. I don't have facebook or instagram so I can't dig into anything there, and I would rather read tech articles or tech forums anyways. articles like this one: https://www.racingjunk.com/news/rota...-tires-part-1/ and so forth.

I'm pretty confident that these MT ET Street SS Dot treaded tires will be capable of an eventual low 1.5x launch.. I didn't find any similar cars to mine that were running sixty-foots in the 1.4 range, but maybe they are out there? but as we have discussed, my suspension might not be up for it. If I can get it to work, I'd be thrilled. I'm hoping it works perfectly N/A with the new gears.. and then it will be a true test of it with the nitrous. I could even setup the nitrous as a progressive hit, so I could not constantly ruin the launch with such a hard hit. It will be interesting to find out by trial and error, but I'll be super happy come springtime if the 3.91 gear swap can net me a 1.59 sixty and maybe a 11.5x quarter mile with a higher mph and going through the traps closer to my peak hp or a little beyond it.

vorteciroc

The project is looking good!

What were you thinking about doing with the ring and pinion ratio/ differential?

IROCZman15

iTrader: (25)

welp, I discussed it a bit int he above posts here... so most of it is detailed above. I want more snot and acceleration from my car. the horsepower and torque is great, but I think I played it too safe with a 3.55 gear ratio when i had moser build the 12 bolt . I called them last month and I can get a 3.91 ring and pinion and the install kit for under $400 and i will do the install here at my house. Really looking for more brutal acceleration on the street and strip. i don't want to change the converter. the car will get nitrous soon, but I want to really find its potential naturally aspirated first. I have a toggle switch setup to activate torque converter lockup for highway cruising. better 60 foot, possibly a wheelie at the strip if my suspension is up to it, and generally just more seat of the pants awesomeness. details above.

vorteciroc

Awesome!

So I can see that you are considering a ring-and-pinion gear-ratio change, from 3.55:1 to either 3.73:1 or 3.91:1.
I have read upward from your last post for about 10 minutes... but I am not going to read through 230+ posts to try and offer you some help. LOL

Most likely the gear-ratio change will be a positive for you.
But there are many factors that I consider when determining Power-Train configurations and/ or changes:

-Vehicle weight
-Engine displacement
-Compression ratio
-Camshaft specs
-Dynomometer results/ or aprox. power output
-Transmission type (i know it is a THM700-R4)
-Torque-Converter type, diameter, and specs
-Transmission modifications
-Differential type (i know it is a 12-Bolt)
-Differential specs and carrier type
-Current gear-ratio (i know it is 3.55:1)
-Rear suspension configuration
-Wheel dimentions
-Tire height
-Use of slick or not, and any traction issues currently

vorteciroc

Also any Drag-Racing time-slip information would be helpful!

Do have any concerns about losing some MPH in terms of maximum attainable velocity?
It seems that an acceleration improvement is your main concern.

We need to do some calculations so that we can actually increase your rate of acceleration...
and not just make the tires go up in smoke; making you actually accelerate slower (IE a worse ET at the drag-strip).

I specialize (meaning at my shop/ business) in building GM power-train for vehicles in the 1,000 - 3,000 HP range...
Most are "Track-Only" vehicles; a good amount of "Street" vehicles that are a "Drag-Week" style vehicle, and some "Pure-Street" vehicles that do not have to meet state/ federal emissions compliance.

IROCZman15

iTrader: (25)

Hey, thanks! I know for sure I have all the info you are looking for in previous pages, but I know it can be daunting for someone else to scroll through pages and pages of posts to find. So I will briefly recap what you need here. However... to prevent me double posting photos or timeslips and cluttering up the pages with more(redundant) timeslip photos, I would ask that ya just scrolll back a page and you will see MANY of my timeslips, datalogs, gopro racing videos of each run, and a chart I keep of to compare the timeslip info and my car's setup for each run. It is all there; I promise. I just don't want to re-post those photos.



-Vehicle weight: 3,320 drag race weight 3,440 pounds street weight WITHOUT me, and I weigh 190 pounds
-Engine displacement: 406 cubic inches gen 1 style small block chevy
-Compression ratio: 10.5:1
-Camshaft specs: Comp cams (cam card is located on page#1 of this thread) 245/254 duration @.050 110 Lobe seperation, .600 gross lift
-Dynomometer results/or aprox. power output: engine was dynoed at 531 hp crank and 513 torque at the crank in february of last year
-Transmission type (i know it is a THM700-R4): ProBuilt Autmoatics ProStreet Elite (the highest level power setup)
-Torque-Converter type: diameter, and specs 9.5" Edge Racing 3,400 street"STR" built by Andre anti balooning plates for nitrous
-Transmission modifications: See Dana's ProStreet Elite specs. Mike (in georgia) built it
-Differential type (i know it is a 12-Bolt): TruTrack setup with 33 spline axles Built at Moser
-Differential specs and carrier type: Moser 12 bolt housing, 3" tubes, ford big bearings,
-Current gear-ratio (i know it is 3.55:1): currently 3.55 US Gears
-Rear suspension: configuration Stock style. coil springs, Koni yellow shocks, adjustable UMi LCA and panhard bar, poly and roto-joints
-Wheel dimensions: 18x8 up front and 18x10 in the rear (for street) (for drag race skinnies up front and the old iroc-z wheels 16x8"
-Tire height: 26" on the Micket Thompson ET Street SS DOT style drag radial
-Use of slick or not, and any traction issues: currently nope, no traction problems 99% of the time with the drag radials on the track. only when I fiddled (incorrectly) with the suspension settings did I cause it to slightly spin the tires


additionally, I created a thread a few months ago based more on science/math and looking for expert advice on how to better improve my 60 foot and 1/4 mile by shift points. this might be of some enjoyment and use to you. (this thread is not that long):
https://www.thirdgen.org/forums/theo...nch-shift.html


Thanks in advance for the help !

vorteciroc

Thank you for all the information.

I spent a few hours today reading through the entire thread. I LOVED it!
My shop rate is $215/ hour... so that will be $430.00 +Tax... Sorry I could not help myself! LOL!

I actually like the car and the work that you did, so much that I would throw you some kind of freebie if I had seen your car at my shop.
Honestly the metal-work and the paint for the engine compartment ALONE blew me away! Truly great work!

Now... Sadly... after going through everything... I am very unhappy with the camshaft that was installed in your engine.
Honestly everything else seems great! However I really feel that the camshaft is far from ideal for both the engine and vehicle.

I know that you were not looking for an opinion on the camshaft, and I am sorry, but...
It is a major factor for selecting a ring and pinion ratio; and I could not keep my mouth shut.

Since I feel that the engine is Over-Cammed/ has the wrong valve events for your combination...
I suspect that you are going to want the most substantial increase in acceleration that you can get (being the 3.91:1 ratio).
With your engine the way it is; I would also go with the 3.91:1 gear set.
With a camshaft that was better suited for your combination, I would go to the 3.73:1...
With constant Nitrous use I would stay with the 3.55:1 gear set (but I would also disassemble the engine and open up the ring-gap from only 0.020".

No matter what you chose to do; enjoy that car! You did an Amazing job on it!!!

IROCZman15

iTrader: (25)

HaHa ! The $ check is in the mail to you! Kidding, funny though.
Thanks for reading through it all. I know I type a lot, but I try to put as much info out there to give the "most complete picture" for anyone who is interested. Datalogs, photos, videos, timeslips, I am willing to share it so that others are able to provide helpful feedback, which has always been awesome on this site.

As you mentioned, the cam is quite a bit big; one of the local NJ guys I talk to had the same opinion back in the spring when I was running mid-low 12's and was getting confused as to why. We discussed the details and he also mentioned the engine is over cammed. You are right, and I appreciate your honesty.
-I just talked to Dana Wilkes of ProBuilt Automatics on the phone for a bit last night. We have chatted before and he was mentioning to me that I should probably look into a different intake manifold (specifically the Performer RPM) based on my engines powerband and torque. So, in the event that I do decide to get a bit more rambunctious with the quest for speed by changing engine components, I am going to keep the camshaft and the intake manifold on the short-list of upgrades. For this 2021 year, I do not have any intentions (or big budget) to spend on engine components.

Since I plan on keeping the engine "as is" for this year, that keeps me in the mindset that I have been remaining in (and you agreeing with) that a gear swap to 3.91 will be the best idea. Since I have no short-term timeline for getting the nitrous system plumbed up yet (and a full blown bigger exhaust system to match it) I will be happy to do the gear swap, and hopefully get a better 60foot, 8th mile, and 1/4 mile times while learning what the limits of my suspension are. If I do cross that 11.50 number and need a roll bar, I will spend the money there first; and then do exhaust, nitrous, etc the winter of 2021-2022. Also, even though I will have the nitrous, I probably will race more N/A passes than nitrous passes just for the health and longevity of the engine.. so a 3.91 would make sense. The nitrous would mostly be there to make a few "personal best" type glory passes and hang a 10 second timeslip up in the garage. This car definitely won't ever be a purpose built nitrous-hog type drag car, so I don't want to install rear gears in it for that style setup.

-Dana also mentioned that If I go with a 28" tall rear tire, I should look into a 4.33 gear ratio; which is much more than I ever considered.. but again, that is with a taller tire.. which I will not have in 2021. I am staying with my 26" tires until they are totally used up. In fact he enlightened me with some old school knowledge that a pinion with an odd # of teeth on it is better to have than a pinion with an even # of teeth. cool little factoid! The 3.91 gear has an 11 tooth pinion gear, so that's awesome.

Thanks for the compliments too. Much appreciated.
I have a lot left to learn about this hobby, but i enjoy learning and seeing tangible results from the work.



So, I will probably order the gears in a week or so.
but
https://www.usgear.com/about/super-finishing
Anyone know if the "lightning finish" is worth spending the money on? looks to be about $160 for the lightning treatment.

vorteciroc

I am not familiar with "Lightning Finish"...
However I am very familiar with other "Super-Finishing" processes.

I very much like "Super-Finishing" processes, and I frequently use them on components of differentials, transmissions, and engines.

IROCZman15

iTrader: (25)

I am still waiting for my 3.91 gearset to arrive from amazon, it has been a nightmare. I ordered it on Jan 4th when they had 2 left in stock. over those two weeks, it did not ship, then it was out of stock for a few days, then I was told it will arrive jan 17, then this morning I was told they canceled my order altogether and don't have any. The past 5 consecutive days on the phone with amazon and many half-answers later, it looks like I will have to find the 3.91 gearset elsewhere. This is not a popular ratio and US gear won't sell me one directly as they don't have any to sell?!? US gear was also recently bought out by a bigger company (that works on excavating equipment) who now handles their customer service and they were of little help. When I talked to Moser on Jan 4th they told me they had 1 remaining 3.91 gearset left in stock, but it was not treated with the Iso-micro finish and if I wanted to get that upgrade, I would have to wait 3-4 weeks for them to send it out and get it back, prior to sending it to me and it would also be pretty costly. Thats why I looked elsewhere and saw that 2 were available on amazon on Jan 4th; and these exact US gear ones were already ISO treated and were a cheaper price.. No luck finding one on Summit or Jegs or anywhere. Places like Mark Williams say they have it on their website, but I am wondering if they just list it as for sale and it ships from elsewhere. So, today, after amazon told me it was hopeless for amazon to fulfill my order, I placed an online order for it on Mosers website, hoping that they still have that one gearset left in stock. I already ordered the 12 bolt install kit (shims, gasket, bearings) from Moser and it is here at my house. I also have the 80-90 NON-synthetic Lucas gear oil that they recommend. I really just need the ring and pinion so I can get to work. Fingers crossed!


I had wired up the 2-step rev limiter in October real quick and just put it on a push-hold on/off button in the ashtray with the nitrous controls. I only had 1 day at the track to test it, but I found that it was a bit non-user friendly for me to hold my foot on the throttle, another on the brake, AND hold the 2-step button while staging.... and trying to release the button at the exact moment that I release the brake pedal. I did well on my first attempt but on pass #2 and #3 I didn't get an even/clean release. I didn't want the 2-step on the steering wheel or on the shifter, so I thought, hmm what about putting it on the brake pedal, and also include a master toggle switch so I don't accidentally bump it. So thats what I did.






So, in order for the 2-step rev limiter to work I have to (1)have it ENABLED in the sniper tune(handheld) and this is also where I set the rpm I want it to be at. (2)I also have to have the master arming switch (in ashtray) flipped to ON, ... and (3) I have to push down the momentary release style button on the brake pedal using my foot. It works! I also made the button's head removable, so that I could simply pluck it out and put it in my center console storage if it seems to catch on my shoe. Without the button head on the brake pedal I can NOT accidentally push the button in. I know the brake pedal pad is clunky and ugly, but to me it is better than the skinny little oem brake pedal.

Now, all I have to do while staging is hold the brake pedal (and the incorporated button) to the floor while also holding the throttle to the floor and as soon as my left leg lifts off the brake, the 2-step button releases at the exact same time. If I am ever worried about knocking the button downs track, I will probably just click the manual on/off toggle switch to OFF after I shift from 2nd-3rd gear while at halftrack.








I finally got some time to install my new Dash camera system and so far it is working great. I need to play with the settings and experiment on sunny days, but so far so good. I might move the rear camera 1" lower so that the lines across the glass are less in-view, but time will tell.
I will type up the details in this other thread:
https://www.thirdgen.org/forums/elec...ns-racing.html



fingers crossed I can get this 3.91 gearset.
soon!!!!

IROCZman15

iTrader: (25)

Spoke to Moser on Monday and they said they had a 3.91 gearset still in stock. It was not treated with the micro-finishing process, but they may not even be offering that anymore. US gear and other places are stretched thin with staffing and production of extra stuff is at a standstill. US gear got bought out too, so things are in a transition phase, but my gear was made prior to the takeover and all seems good to go.

So, today the UPS package arrived with my new gearset from Moser/US Gear.
Amazon gave me a $50 gift card for their error, (see above story)

Anyways, If I get some time Friday I plan to remove the rear from the car and hopefully get the new 3.91 gearset installed on Sunday.

IROCZman15

iTrader: (25)

Had a few hours this afternoon to remove the rear from the car. All went just fine, no issues except the driveshaft's u-joint nuts were more stubborn than they needed to be; locktite red I used last time. everything else came out/apart real easy.










that white foam/liquid is just spray-degreaser I sprayed on there





Hoping to do the ring/pinion removal and install on sunday afternoon. It will be my first time.

IROCZman15

iTrader: (25)

Today I got pretty far, and I think I am super close to being able to button up the housing and get it back under the car.

existing 3.55 gearset removal:








3.91 install:

Starting with the pinion's rotational drag, I have it set somewhere between the 14-18 inch pounds range. not break away torque, but rotational. this is what moser and US gears calls for.

see video (sorry, hard to film and turn at the same time) the photo below was not taken at desired/proper drag, but its the only photo I had that was not blurry. video is kinda better...








reused the pinion races and pinion bearings. Moser said i could and should do this since my 3.55 gearset was so new and only had 6,000 miles on it since March 2018. If something went wrong, I had new bearings to use, but all went well and the new bearings are in a box still. I used a 3shim combination to get a total of 0.0425" on top of the solid pinion spacer. I did put in a new pinion seal.











Used the existing carrier bearings and races also. Adjusted the sim packs on each side, and the carrier is SNUG in the housing. Can not be pulled out by hand, need a pry bar to gently coax it out. Main caps are torqued down, but not lock-tited yet just in case anyone sees something that I need to adjust.

Backlash is right around 0.0090 and 0.010. This is in spec, but the only thing I notice is a "knock/thunk" from the teeth contacting eachother. I am ASSUMING this is normal on a bone-dry set of new gears. You can hear the noise in the video. Is this normal for a dry gearset?



desired pattern chart:


current COAST tooth pattern:


current DRIVE tooth pattern:


It took me about 4 times taking the carrier in and re-shimming it to get the current backlash and pattern. Might have initially used too much yellow paste, as it got everywhere so I had to do a cleanup of stuff and re-try it.


So, thats where I am at. if the pattern is as good as it needs to be, GREAT. and, if that clunk noise while checking backlash is normal for a new set of unlubricated gears, then that is also good.

NoEmissions84TA

iTrader: (1)

Looks good to me. Button it up.
The only thing I might do different is more side shims so it fits even tighter in the case.

vorteciroc

Wait...
Was the entire differential assembly removed from the vehicle, just to change the ring and pinion set?

IROCZman15

iTrader: (25)

Thanks noemissions, I have those carrier shims in there pretty tight currently. I have to use some force to drive them in and a pry bar to pull the carrier out. I’ll check it again tomorrow


vortech, yup. I have never done a gear set install before a d wanted to work on the whole project in a more professional/comfortable manner. I was afraid that if I tried to do it in the car while working lying on my back on the garage floor, I’d run into problems that would frustrate me... and I’d make a mistake or a bad measurement. It only took about 70 minutes or me to remove the whole axle and have it on Jack stands in my garage’s side room. I was able to sit there and work on it with proper lighting and work angles. Again, first time for this project for me as a hobby. So I’m learning.

how does the gear contact pattern look ?

IROCZman15

iTrader: (25)

Pretty much almost finished...









Got everything buttoned up after making one small shim adjustment to the pinion's solid spacer. It was just a bit too tight, now it is perfect for rotational drag. Put the housing cover on, added the recommended NON-SYNTHETIC Lucas 80-90 gear oil and tightened up the main cap support bolts in the cover. Hung the axle back in the car and got everything back into place.
- I am seriously debating removing the emergency/parking brake cables and assembly from the rear discs. I never use the brake, and they are always a pain in the butt when I go to get the calipers mounted. Always a hassle. Might remove them and leave the handle inside the car (for aesthetics).





Did a very brief test after bolting on the wheels and bleeding the brakes. This was NOT to break the rear in, but just to make sure I didn't hear or see any odd noises from the rear, driveshaft, brakes, or anything.
Short video:


I will get the car out soon to do a road test and break in the gears according to what Moser and US Gear recommends:




Then I will get under the car, wipe everything down clean, lube the suspension, and check the torque on all the bolts/fasteners. i also want to check/adjust my driveline angle too. That should do it!

skinny z

I'll be curious as to your methodology and what others might have to say about pinion angle and a 3rd Gen torque arm suspension.

IROCZman15

iTrader: (25)

yea, I have done it a few times. I never bought a magnetic angle finder (yet), and I just use the TREMEC app on my phone. It has a built in angle finder that you just click a phone button while holding the phone on 3 known driveline points. It has always served me pretty well. I did not want to go doing it yet because I wanted to do a test drive and get the suspension bounced around and settled before checking it or making any adjustments.

...and I went for that test drive yesterday. After I did the proper jackstand procedure for breaking in the gears, I did a 10 mile cruise at moderate speeds to put some heat to the gears. Let it cool down, but before putting the car away I went out for a couple quick blips of the throttle. I can certainly notice a more aggressive acceleration. I know the roads are cold, my tires were cold, and there is some salt dust on the road surface, but it instantly just zipped the tires loose in 1st gear, 2nd gear, and even in 3rd gear. that was fun!

And I did not notice any odd noise or activity from the gear install. So far so good. So next step will be to do a full bolt-check underneath, grease all the suspension points, wipe clean the chassis and underside, and check/set the driveline angle. Then I guess I will wait patiently for April when the dragstrip opens. Car definitely feels rowdy with acceleration now. cool.