paul_huryk

Actually CTW wheels are 9.5" in width. The wheels do increase the rear track - adding about 1.5" in width (obviously the wheels are much wider than stock outside edge to outside edge).

One thing I have noticed in a street application moving up to the 275-40-17 from the 245-50-16 is a huge increase in rear stability and confidence in the corners, even with a stock suspension. And there is only about 2lbs in weight difference between the wheels - not enough to notice on the street.

I've had the discussion of unsprung weight vs. wider tires with a few CMC racers in the last week or two - all of them are concerned with the additional 4lb minimum weight increase of a 275-40-17 over the 255-50-17 spec tire (plus the rules about wheel weights) - but they all concede that the cars should be faster due to the increased tire grip in the cornering, braking, and corner exit power application. How much is to be seen - they are not allowed to change the suspension much under the series rules.

TEDSgrad

iTrader: (4)

Paul, what wheel are they using for 255 - 8.5"?
Ryan, I readily agree with you on race car/courses. I think Paul & Dean (sounds like a 60's duo) were right in pointing at 275 as a good balance for street - but someone will always say they're running 315's and it's comfortable. For most of us, we go from street to HPDE. Separate rolling stock could accomplish this, though. 20-30% difference would definitely tilt in favor. Also agree that rear RC is easier to adjust, but again street considerations don't allow for great adjust (unless I'm wrong, here).
I don't want to sacrifice street comfort/drive-ability/longevity for two track events/year. But I'm building to be able to transition between both (I know one foot in each means halfway in both). I can't justify all my expense on just a hobby - need to get some transportation value out, too. My local venue is very high speed which would favor a skinnier (emphasis on er) tire width.
I could get my hands a wheel right and see if an 8.5" would fit without hitting the tie rod, or with some massaging. A 255x4 (w/drop spindle) would definitely challenge the 275x4 (ext bj), but the weight increase for just 10 increase seems not worth the effort.
Like to hear all this stuff!! As long as my choices are informed choices, I'll drive happy.

SlickTrackGod

Paul & Dean sound more like some big lady on the Food Network (Paula Dean)

Yes the rear RC adjustment is easier with the pandhard relocator-its what is done on the fly in NASCAR pits,etc (track bar adjuistment)

Yes it brings the roll axis more level by lowering the rear...

BUT, it brings the roll axis greater in distance form the lateral cg in increases the need for heavier sway bars to resist roll. Those heavier swaybars will lift the weight off the inside tire contact patches like previously described when the positive body roll weight rolls the chassis. Getting the front roll center up reduces the positive roll weight (a far better way to go.)

SlickTrackGod

Hopefully this visual will help explain things better than words to alot of people who do not understand the roll centers and overall roll axis. You are looking at the car from the front and lets just pretend for ease of discussion that the front rc (roll center) ahd rear rc are exactly the same height off the ground. Thus the roll axis that is an imaginary line that connects the two is what the chassis rolls upon. The purple represents the lateral cg (center of gravity) of the chassis. The verticle purple line is like a breaker bar in leverage length whether above (positive) or below (negative) of the(red) rc (most all cars ar positive, and thus the need for a larger swaybar the more positive it is.)

Note that the more weight is underneath the rc, the more the lower weight resists the heavier upper roll weight when lateral centrifical force is applied+ thus smaller swaybars needed. As grip increases, the sway bars size goes up to control roll degree- it is all relative. So on a car with race tires, you need larger swaybars than a car with street tires because the overall roll will be greater even when the ra (roll axis) is not changed in height- UNLESS it is completely neutral or negative. Alot of open wheel cars do not run sway bars because they are so close to neutral. A little roll is good to promote suspesnion articlulation for camber gain.

paul_huryk

Most of the racers are running the 255 on the TA mesh 8" wide wheels, which are right at the 16lb per wheel minimum. I know of one racer on custom made 9.5" wide 16" wheels, which come in at 16.5lbs and give a more stable footprint. The Toyo RA1 in 255 measure out at 265mm (per the dimensions on their site), not a true 255 like you would expect. The 275 version comes in at a true 275 width and coupled with a 9.5" wheel will give an improvement, but not as big as say a true 245 street tire to a 275 width version of the same pattern. Although racers on the 8" wide wheels will definitely pick up sidewall stability with the slightly wider tire on a much wider wheel. Waiting for some data on this...

I really like the idea of a 275/315 stagger in 17" - although wheels are hard to come by in the right BS and the lack of tires in both sizes. Essentially you are sticking as much rubber in 17" all around as you can with minor modifications. That would add up to 200mm more rubber on the car! Even better would be the 295/315 combo in 18" - 240mm more.

Not many folks run 255 tires on the street, majority have the 245 width. Replacing them with a 275 all around adds another 12.2% width. And if you compare CTW wheels with a 275 to say a 245 on a 92 Z28 wheel, they actually weigh 3lbs less each, a win-win for both tire patch and weight - not to mention more brake clearance than 99% of people with ever use.

SlickTrackGod

I can also show everyone a great example of a vehicle with both types of roll characteristics in one vehicle. the front half resembels the greater roll and less percentage of insde contact patch than the rear of the vehicle does. This is very very rare and is an inherent problem that can not be fixed due to the body shape, size, and weights difference front and rear as it rolls.

https://www.thirdgen.org/forums/memb...on-5000lb.html

Lets take my Vetruck- alot can bee seen and learned in this picture. you can see how the front half is tall. It is lifting the inside and rolling over "and out" on the outside front tires.... while the rear stays more level and centered over the two rear tires. I did a scketchof both independant front weight movement over the rc, and then rear movement over the rear rc in roll. Lastly I put them together so you can see the roll couple and the chassis twist rear to front as it leans into a corner. note the inside wheel is still lifting and not flat/ The rear inside wheel is much more flat.

I have already cut the entire OEM front suspension off this and entirely re-engineered a one of a kind new front suspension with new suspension mount points raing the frotn RC higher than possible with the OEM configuration w/ aftermarker adjustments ever could. But it is limited because the rc leverage to the front half chassis CG is so high compared to the rear half. Wider tires are the only way to further increase grip at this point, at a price of more body roll up front also. If I get the front rc up any higfher then I would not be able to rotate the truck into a corner. It is at its best. The only way to make it better would be to cut the roof off and lower the front chasiss cg.

Also note on the layover how the front (green) migrtes to the right more as it rolls as does the rear half (yellow) does. This is what makes the weird twist in the chassis flex- Snce I added about 400lbs in safety cage up top, I also added about 300lbs of metal inside the frame rails down underneath in chassis bracing so a total of about 700lbs is added to it. THis is still a truck and needs to function as one. just something I custom built over the years as things broke- so it was never built to be a race car. It was built to be a reliable truck first and foremmost that just happens to run extremely well on a racetrack for what it is- but this example showws the limit of chassis loading on the inside tires when weight and heiight of that weight(cg height over axles) is a problem.

If you focues on understanding and limiting weight transfer to the outside wheels, evenyou wider tires will work better on inside tire traction.

This post is about grip- not just the outside wheel, but about best grip possible is using all 4 wheels to their best.

paul_huryk

As some of the readers of this thread may have trouble translating what you are elaborating on into actionable concepts, can you specify what parts in general (or settings) would help one get closer to the optimal setup in a street car. Stiffer springs? More or less sway bar rate? Minimizing deflection through aftermarket suspension components? Things like that.

TEDSgrad

iTrader: (4)

For starters:

Lower Car - springs;drop spindle Or ext bj; rear coil-overs - this lowers CG & RC
Bring up Fr RC with ext bj OR drop spindle
Lower rear RC with Jegster - axle side PHB bracket

Generally, Bigger Bar - softer spring

TEDSgrad

iTrader: (4)

I'll attempt the theory part in layman's terms:
The stuff above helps lessen/control weight movement or roll. It shortens the leverage bar so to speak and smooths weight movement. Weight control is grip.
Then you reduce weight and seek better weight distribution: lighten weight above the center of gravity (Cg), lighten/move weight in front of fr wheels & behind rr wheels, and in some cases add weight between wheels but below Cg (there is an optimal ratio between unsprung and sprung weight, but not sure how that's quantified) -->Dean calls all this polar weight; especially look for unsprung weight savings.
Then optimize suspension components to best keep weight distributed during weight roll movement = optimize all four tire patches. This is more critical than just a wider tire - more grip over four tires, smooth movement, better tire management/longevity, easier to drive, etc.

Not complete, but short/concise.

Component list could large. Firm but softer range of spring - want to allow articulation to absorb, Del-a-lum bushings on a-arms, swivel cup weight jacks (raise for street - lower at track), tallest spring you can use (better ride) at the height you want (#850 fr 9.5", #200 rr coil-over set on 4th click), koni strut (soft for street), jegster bracket & adj PHB (poly bushing ok) to lower rear RC slightly, LCA needs articulation on those bushings, quality strut towers (added coil-over plate underneath to strengthen fender/tower); 3 pt STB, wonder bar, & SFC to stiffen chassis.
Unsprung weight: alum hubs, light 6pot calipers, 2 pc rotors, drop or modified spindles (w/ext bj) for lowering (and raising fr RC) and weight savings, and light wheels & tires.
Matching dampers with springs is critical and I'm a newbie.
Street sees more bumps, holes, jarring impacts, and more straight line driving (camber). Softer springs & settings with medium bars (36 fr 24 rr). Low unsprung weight really helps on rough surface. Hopefully, a street driver is not at the edge of grip very often - or not around me, anyway.

SlickTrackGod

Very good- but to further clarify Polar weight. we will look down at the car from above. The pole is the cg of the car from above. it will be slightly towards the drivers side since the driver makes the car heavier on that side, and it is slgihtly forward from center since most 3rd gens are aprox 57% front weight and 43% rear weight. Stab a pole right through that part of the roof right down to the floor. You now want to stab another pole right down in teh smack dab center of the axles and exact center of the car and try to move weigth to the right and rear of the cockpit to counteract the drivers weight.

From here, the further you get for the polar, the heavier an object beciomes to move in a wpinning rotation when veiwed from above. Also the further out avawy from the pole the harder it is to stop that weigth momentum form turning to become stable, Not that turning a car from straight line takes force. that force is then converted into momentum that needs to be stopped when entering steady state of the corner- it then needs to be started again and then stopped when moved back to stright line travel. The more weight at each bumper of the car, the harder force needed to start rotation, and the harder the force to stop the momentum. You try and stop the stop.
example- you turn the wheels 25* to enter a 20* corner (consider slip angle of the tread)from 0* travel. Then when the car is about 18* aprox, you turn the whell back to about 15* for a moment to slow the rotation so the car turns 20*. momentum car take it to 22* and you jiggle the wheel even lowere for a quick second to correct and stabilise the 20* turn then hokd it back percisely at 20* to maintain the 20* turn. This is force needed to stop the momentum into a turn. lower polar weight at the extremities of the cars bumpers will make it easier to start and stop this rotation.

The best example to try at home is stand with youer feet at shoulders wdth- and arms streched out parallel to the ground to both sides. Now rotate with the arms strecthed out to your left 45* and stop and imediately reverse the direction to the right past 0 tp 45* and stop again- then quickly going backj to zero and stopping. Now do it with your arms ad hands touching your side- much lighter polar weight and much quicker response with more percision.

Thats polar movement.

More to come- give me a several minutes

SlickTrackGod

To make it easy, I just searched for a McPherson strut roll center diagram rather that drawing one. This shows how the rc is calculated off the strut top at a 90* angle. You can visualize how more negative camber 9more inward lean of the strut angle) will lower the front rc. More angle of the a-arm will also lower the front rc.

Loock at pics, then move to next post for corrections via extended ball joints.

SlickTrackGod

Now we will show how the geometry will change the front rc - the pivot point as which the front chassis weight rolls around. Weight above and below this counter act easchother. Morechassis weight above will increase roll (positive roll as explained in the graph several posts back).

I will re draw the A-arm angle on how it will change with an extended ball joint. Note that the car will lower the exact same distance of the extended ball joint (ie- a 1/2" longer ball joint will lower the front chassis 1/2", 1/4 will lower 1/4", etc.) This lowers the cg, but raises the rc and brings them both closer. rc is red, cg is purple.

SlickTrackGod

To further give some answer to Pauls request for what to do with chassis tricks- Brian (tedsgrad) talked already of the phb lowering to lower the rear RC a little...

but to more importantly get into lateral position of the rear rc (I won;t bother talking about front lateral position of the rc- I left that in centerline of the chassis for ease of illustation and learning purposes) but the rear I will discuss the migration of the rc off the cnterline of the vehicle.

When different spring rates arte used on a solid axle panhard rod rearend (meaning lets use an example of 100lb left spring and 200 lb right spring- why would we do this? NASCAR circle track cars do it all the time for left hand cornering) ... the rear rc will migrate off center toward the higher spring rate side. Thus the imaginary line of the roll axis front fornt rc to rear rc which the car pivots on will yaw towards the outside rear of the car when viewed from above.

Ill show an example-

SlickTrackGod

So how do we do this on a car that has equal rear sping rates and turns both left AND right? it will automatically do it a little when one spring unloads with rll and the other compresses (outside srping) Lets say stic spring rates are 200 lbs each with linear springs. One can go to 225 on the right, and decrease with chassis weight lifting off it on the left to 175lbs. even astock 3rd gen will have the rear rc migrate a little off center towards the outside wheel. We use thi feature to ourr advantage and increase the effect using progressive rate rear springs. Why? because under the smae senerio, lets say a porgessive spring set 1 inch compression is at 175lbs static- but once the outside is compressed more in roll it builds to 250, and the inide decreases to 135- the gap widens much more rapidly and THUS, the roll center migrates right alot further than the example in the above post. Note how the left rear of the car now becomes a heavier teeter totter and will weight more onto the LR tire keeping that section of chassis down. Greater leverage is more weight... chassis trick, we love em

SlickTrackGod

Noiw the next chassis trick we will steal the attachment from post 54 above and show how adding weight to it will change things for the better in roll weight bias.

Note how the simple addition of 70 lbs of Dynamat sould and heat absorbing material lined to the floorboard of the cockpit (keep it inside the axles for less polar weight)- so just the cockpit floorbard and under the rear seats-I put mine up the rear backrest also to add just a few more pounds of rear bias to the chassis weight- every little bit here and there all add up to help wih a 50/50 bias load on the front and rear axles. note the change in upper and lower roll weight percentages. Works towards a more neutral roll rate.

Note that the cg will come down very slightly- too little to show since 70 lbs of weigth added to a 2000 lbs chassis (sprung weight) is small in visual but the polar placement of the Dynamat from the CG is what is important to get it llow from the cg so it helps counter act the heavier upper positive roll weight. the chassis stays more flat in a corner- THUS keeping more weight on the inside tires.

SlickTrackGod

15 years on TGO and I am finally giving up all my old secrets. I do not own a 3rd gen anymore but love them- so I guess its time to share.

Dean

TEDSgrad

iTrader: (4)

The RC migration really clicked with me! It would also aid LCA's to help steering.

SlickTrackGod

Even alot of so called chassis pros do not understand the importance of rc migration and how the roll axis yaws.

Most of the NASCAR supertruck teams had no idea why they ran different rear spring rates- the old monkey see monkey do. At Irwindale Speedway- the premier asphalt half mile oval in the country, most teams would take their turcks to the local "Race Car Factory" owned by Kenny Schrader and pay to have track setups done for them. Then those teams would do a little experimenting from there but generally would havbe no clue what was going on.

The important of it on that track- on a banked oval, you get "compression bank effect from the banks turns. Instead of the chassis just rolling over and down like on a flat corner, the car is set into chassis rake favoring the inside lean already ( for starters) and then when the car enters into the bank the compression force of the bank holds down the entire car including the inside rear. THe MORE we yaw this roll axis, the more force the compression weights that inside rear chassis and keep it force down from lifting and rolling over to the right- its keep massive weight on the inside rear tire which is the hardest to keep heat into otherwise on only left hand turns.

Pablo

iTrader: (1)

I wasn't going to address this but I changed my mind. I'm not sure why you keep bringing me up dean. You are making more predictions. I'm not sure why. It almost seems as though you are searching for reasons to explain why my car is fast in spite of not being built to your specifications, or, that it's only fast in x,y,z format since it's not built to your specs.
In the other thread it was about my brakes being all wrong. Now I all of the sudden have A6s (which is essentially the stickiest autoX tire you can get.. I must have had them to run so well right? They have always been USED R6s) and the car would be a mess on a road course.
Originally, when I posted about adding the large tire and wheel package you said it would be no good for the small track but good for a large track. Those posts are on TGO unless you deleted them already. Now since I put down some decent numbers on small tracks, you reverse your position. Which is it?

Then you go throw out words like ackerman and scrub radius which might seem like legitimate concerns on a road course (to the uninformed), except that they have a much greater effect on a small course than on a road course. And with that statement, I am not trying to convince any of your fans of that. Please by all means believe otherwise if you want, it only affects your setup so I don't mind

And what's this about me using 200 tw tires on the street but wearing them out quickly? What is different about my car than any other car in this regard? My alignment? Do you even know what my alignment is?

Finally, about the CCWs... they are nice wheels but aren't quite top shelf. Have you priced a set of HREs vs CCWs? Heck, there's a guy on here with HREs. Maybe he can tell you. The price of these CCWs might buy you an HRE decal.
Anyway, the wheels aren't unobtanium. I got them from craigslist, and I paid less than what most people pay for new wheels with pizza cutter 275s. Moral of the story? Anyone can do the same thing, especially if you have the money to throw at all the powdercoated BS people are selling.

Oh and I got the 315s reference earlier from the other guy. I'm not trying to tell you what you should run, it's just advice -it's not even that.. it's just my experience. You can take it or leave it. Run the skinnies if you think that will work for you. Maybe you'll build a helluva fast car. Lots of ways to skin a cat

SlickTrackGod

1) I know why your car is fast- I bring you up becasue you do have a fast car. Your car is fast because it is stripped down, very wide race rubber (so I missed the tw by 20, big deal) and some decent power. I have been told by several people that know you that there in not a stock cam in that car either as you claim. So lets keep talking about predctions?

I said you tires would serve better on a larger course that would not turn as tight wherre you can keep the footprints more stable. That Ackerman and Scrub are tearing the crap out of your front tires. You have to get hard onto the throttle in mid corner andplow the crap out of them all the way off corner exit until they are almost straight again. On a long track you do not need to turn as tight, so they would wear a litle better, but compared to a thinner tire on a long track, they will still wear out fast and be heavy rotational mass. Pablo- what yo have witht hose extra wide tires on that car ore an expensive high that will wear down fast. You can not drive that car on the street if you put the sam size street tires on it- it would cost you a FORTUNE...period- if that is what you mean by predictions? Go try if anyou will 100% see I am correct.

Go race a season in autox in modified class with your scrub and ackerman the way it is wit those tires. You will last half a season- prediction? yes

You have built a very fast track car- that is its sole purpoese and you have done a very good job wit it. It FITS YOUR WANTS AND NEEDS- However, if you went further than that with your race desires, or driving or miles on street use, I use you as an example that it s not a setup that can be dual purpose like mst peopel here are building. It is simply your garage queen tack toy.

I will make one comment that eally sucks I can not back it anymore. I had a car that was "OnARail" on street tires that would trun circles on that big pig of truck I have that does wonders for its size. That Camaro was proven and was proven on both track and street without touching the alignemnt special for either- same ca, same alignment, track or street ift did not matter it worked xtremely well and beat anything it came across on street tires. I even paced a vintage GT40 through a high speed sweeper and most of the infield course DOCUMENTED on street tires and he was on his racing slicks. I have not seen another 4rd gen alive that would do that on street tires never the less 245-50-16 sized ones...period. What made that car special? I am sharing that....my comment- I wish to god I had my Camaro out at the track that day you and I were running your car and my truck together on the track.... and Mike said the same thing. On street tires I would have hung with you, not beat you, but I would have hung with you...with that little V6 to boot. I can not back that anymore sadly because that car is gone and it was a very frustrating day for me being as competitive as I am to be stuck in that heavy truck and not have a 3rd gen with you guys at a 3rd gen event.- but **** happens in life and life goes on. We will never be abe to run both cars together to ever find out the truth. I know what my car would do- especially compared to my truck, I owned both of them together for a very long time.


The skinny of it Pavblo is that I could build a car on the same budget you did on 8" wide wheels and race tires that would beat your car -AND the tires would last a long time. and that is a fact.


Now that is not toi take away from what you built. If you were to take my advice- and you an I know you spent many nights on the phone and internet picking my brain in the past and that youw ere also doing a budget build with what you had. You were not going out wpending lots of cash becasue the car was working well enough you would beat anyone you needed to when you went out there with those wide sticky tires. Fact is, the car could be better if the chassis was weghted better- but you chasiss is also weighted much better than most being stripped down race car

Roostmeyer

iTrader: (3)

More camber should decrease the length of the Front View Instant Center (FVIC). This moves the tire patch intersection line inboard with it and will actually slightly raise the roll center assuming the lower control arm is at the same angle.

The dynamat idea would be okay if you needed ballast, but for a street/track car w/o a minimum weight the higher weight will hurt more than help. You may have less % weight transfer with the weight down low, but the overall weight on the tires, both inside and outside will be higher, and with that lower grip. Even if the 70lbs of dynomat is at ground level, having no effect on overall weight transfer, you've put an estimated 20lbs more on each front tire, and 15 more each rear, regardless of lateral acceleration in a turn.

Horizontal RC migration with the more uneven roll shouldn't be a big issue. I think I've posted this link before, the roll center is nice statically, but in roll there are some myths: http://www.neohio-scca.org/comp_clin...namics2007.pdf

I'm not saying it's right or wrong, but its a different perspective written by one of the suspension "pros".

And Pablo, yes there are tons of different ways to build a race car. My car is different from about any I've seen. Goals are to meet 2800lb (5.1L CP) minimum weight with 52% or lower front weight distribution. Running 18" wheels costs me 50lbs in CP, but I shouldn't need as radical flares up front, scrub radius is kept to a sane level and overall width should be about 4" less over similar width 16" wheels. Not running oil coolers, larger radiator, big cage etc. for track days will help keep overall weight down and hopefully let me meet minimum weight while keeping the car street legal. Its certainly not the right way for many people but I hope its damn fast for a rowdy "street" autocross car running in a class with trailered race cars. We'll see how it PAX's compared to a few fast SS Z06 drivers locally when I get it going.

rlewi771

Not to stir the pot, but Dean, you always claim your car is so proven. You paced a GT40, etc etc etc (i dont remember the whole list)

Every single summer I beat porsche GT3's, 911's, Corvettes, etc. on the road course I race at. At our last race of the season a guy in a 2006 Lamborghini Diablo seemed as if he was almost willing to trade cars he was so blown away at how much faster I was than him. Sure, the first few times out on track that you accomplish these feats you think you've really done something special. Are all the drivers of these other vehicles you've paced or whatever professional or accomplished drivers? Do they have the same amount or more experience on the track that you have? I have beaten these other cars because I am the better driver, not because my car is better, or my setup is brilliant, I beat them because I push my car harder and feel more comfortable doing it than the other drivers do. I've beat modified corvettes on better tire compounds than I run and the drivers have way more experience at the track than I do, but it's because i'm the better driver, not because my car is better.

The driver is everything. I dont think it helps to bolster how fast your car is when you say you beat this or that or paced this or that. It might impress the new guys that have never been on a track before, but if you have, you know that some people are just plain wuss's behind the wheel of their cars.

I'm not saying your car wasn't fast as I dont know, I never saw it or raced it. All i'm saying is, telling people you beat this or that doesn't do anything to justify the realities of your car.

Dreambird

Will the roll center be the same with drop spindles like racecrafts as you state here with extended ball joints? Thanks for sharing your expertise I am learning alot about how to setup 3d gens properly.

Pablo

iTrader: (1)

Sorry to hijack this one guys but I need to clear this up.

There you go again. I've posted about this freely, several times on this forum. I don't know who you talked to but if they told you I didn't have a stock cam, then I would like to ask them what cam I have since I bought the car that way. Actually, when I picked it up it had about 50 horsepower, a million problems including a corroded injector wiring junction that was very hard to diagnose. It probably had not run right in years. It looks like a parts store rebuilt 305 and has swirl port heads, yes, the heads from a TBI engine. Whatever cam those cheapy rebuilds come with is what is in there. It has headers and exhaust and that is it.

So you've driven my car at some point? You've seen what my tires look like?
Ackerman is an issue on all thirdgens. On mine more so because of the shortened wheel base and wider track width. I'd rather fix the ackerman than run pizza cutter tires, and even with it being less than optimal the car still does ok But if you want to limit yourself and others to stock ackerman and wheel widths be my guest. As far as scrub.. I don't see the skinny tire as a "fix" that outweighs the benefit of a wider tire, but hey, go run some drag race skinnies and get yourself minimal scrub if you think it's faster that way . Fixing the ackerman by relocating the tie rod end will allow reduced scrub too so win win.

Actually, the ccws and hoosiers are as light as my 17x9 SS wheels with V700s. The 315s might actually be lighter IIRC. So there goes that one.

Just more predictions, you haven't provided a valid reason why simply having wider tires would cause worse wear than any other thirdgen. Sounds like you think they are changing my alignment somehow. They don't appreciably toe any more or any less than my skinnies, and the camber is still the same. Whatever ackerman and scrub are doing on the track, it hardly matters on the street when you are driving straight for looong periods of time. BTW I drove the car on the street quite a bit with those wheels. They lasted me a good long time for used tires. They wore out like any other tire would with that camber setting and compound, no matter the width.


Actually it would be in prepared, and "I" would last? Or do you mean the tires? If they lasted half a season I'd say that's about right. I must have had a solid hour of pure adams track time on that set, not to mention hours of street driving before I corded an inside edge, although heat cycles are what matters, and these tires were used when I got them. At the end of the day, these are indeed just more predictions without any hard facts to back them up.

Well then I guess none of what I've done is applicable to street cars. I'll post my modlist so that everyone can avoid doing any of it

They aren't facts if you can't back them up.

The car can always be better, that's why it's never done..

Pablo

iTrader: (1)

Sounds like a great game plan and is similar to what I have done. Do you have a build thread anywhere?

SlickTrackGod

Roostmeyer- yes in my haste to quickly find graphs rather than draw things I did make a mistake and typed the wrong thing. Was putting up a bunch of info quick cuz I was ina hurry and I should not do that witho9ut double checking for errors.- for example my terrible typing and spelling errors (wireless keyboards- I usually try to go back and edit my posts for grammar and punctuation errors) Yes the more negative Cmaber the higher the roll center.

Next the link you listed. I did not want to get into the migration of the front roll center since it is something you really can not change. It will generally always migrate towards the inside wheel on front suspensions. The front suspension links become nonsymetrical so the actual rc changes in dynamic form. Thatis too complex to start talking to everyone about so I left it alone. The rear can be changed in effect with the type of spring rate and the suspenion link type- not so much the front so I left the subject alone in static state.

@rlewi771- yes you are absolutely correct on driver ability in most cases. On the GT40 subject, It is hardly the case though that a guy buys a half million dollars vintage race car and is oout running it on test days at 170mph down the straights without having some kind of ability. I have actually footage of him catching and leaving me on the striaghts, but I was hanging in the corners with him. It is quite imporessive footage I will boast. As for other accounts, I have documented this car on a skid pad test of 1.07g's, and a documented 60-0 brake test of 102ft at the police test facility in Devore Calif. I have also documented footage of it taking down 11 of the local 3rd gen SC3G cars in a friendly autox grudge match. There was a 3.9 second margine to the 2nd fastest car and so on as the margin climbed into double digits. I would think a few of those 11 would know how to drive. One of them I have drivien his car on a track many times and we run the same time in the same car- I think that is enough examples to give creditility to the car.

SlickTrackGod

For a short answer- yes. Drop spindles are even better for geometry because they give you 2" of drop in CG without even changing the factory geometry. Then when you start lowering more in spring height, the car will go low enough without inverting the A-arm like happens without extended ball joints. Extended ball joints give you 1/2". spindles give you muich more with 2". Better way to go but more expensive and alot of guys are reporting problems with tierod clearance issues on the Racecraft spindles. I have not touched a set in person so that from me is second hand knowledge.

SlickTrackGod

Pablo- where do I start? You've ansered alot of your own statements. You have Ackerman and srcub issues. You can not run that wide of a tireon a 3rd gen for prolonged periods.. that is an undebatable fact that you continue to debate- yet you also make my same sstatements- whichh is it? you are confused.

As for cording tires, I ran my 540 rwhp Vette in Autocross 2 years on every set of R1's I had(most of you have seen video of that car in action- fact s it would eat your car for lunch and the tires would last 4 times as long). I have used more sets of race tires both in personal use as well as NASCAR that you will probably look at in a lifetimes (yes I am being facetious, but you do not hold a candle to my experience and resume) I know tires, I know alignments, I know chassis setups. I have done quite a few in my day and I have quite the winning resume to go with those experiences.

The rotation mass subject is about using even 8" ccw's compared to 11" ccw's/ You are better off running a wheel size made for the car it would last you longer and not wear unevenly like yours did- would it be as fast? No, it would give a little in performance- That is why I stated what you choose to do fits your needs and if you are happy with the cost of replacing times 4 times as quick then hey, its your choice and it fits what you want to do. You have not logged enough miles on those R6's on the street to even shake a stick at. Put a 220DOT tire on those wheels and drive it just how it is on the street- to the grocery store etc- those tires would be gone in 10,000 miles because of the scrub and lack of ackeramn.

THis is not a put down to you, it is simply an analysis of chassis dynamics and grip and I used your car ( you should be flattered) as an example of a fast car on wide tires- but I am also talking truth to anyone curious that buyer beware of cost and longivity. If you are fine with that then do what Pablo did.

No hard feelings Pablo. Peace out. Maybe when you get back into town we can get together at the track again.

SlickTrackGod

And to anyone else reading this- The purpose of me coming into here and helping is becasue I know 3rd gen suspensions like the back of my hand. I love the cars, unfortunately I do not own one anymore due to a now ex wife that took the car upon separation and had the car unsecured where she took it. The car was stolen form her prior to the settlement of my divorce- its is gone and was probably stripped. (that was several years ago now- aprox 2008-9)

I have too many other things going in life to start building another car that I have already done in life. I have other loves too and I am doing those. Maybe someday I will come across one and have the room for it but it does not look that way for the next few years. SO I come into here and share what I know because I have alot of friends that still own them and I help alot of them regularly still. It would be ashame for me to not pass on what I have learned of these car s over the years- even if it is just my opinions.

Good day

Dean

TEDSgrad

iTrader: (4)

RC differences between the two would greatly favor the drop spindle. The tie rod problem is with wheels wider than 8".
The choice between 275 w/ext bj and the 245 w/ drop spindle is very close. Going past 275 in width would tip the scales for sure, but I don't think that practical for street- my opinion.
As you have read, opinions are passionately held - wouldn't give two cents for an opinion that is not. For only 30 Xtra width, I think the benefits of drop spindle is worth it, but you also have to consider a build philosophy as well.

BumpaD82

If I PMed (or posted here if you'd prefer) would you tell me what YOU would change on my setup ? .. My car works well ... (FOR ME), but maybe I'm missing something obvious ?

~DaVe

SlickTrackGod

I PMed you, but will answer here also. You can make a new thread if you want and we can do it publically or jut private- up to you. I help alot of people in pm's and over the phone even

paul_huryk

How about a stock height car with a 245-50-16 and also with a 275-40-17? That is one thing that hasn't been pondered - exact same static front suspension geometry...

TEDSgrad

iTrader: (4)

If the only change from stock is wider tire, then it's easy to see that wider tire has more grip. For customers who don't mess with ride height, this is a no-brainer. Lowering Cg & raising fr RC give more grip for less cost (new wheels/tires vs spindle/spring). But the issue of grip selection in 16" makes the purchase of new wheels necessary. Who knows, manufacturers could come back into the 16" size (or they move up to 18" and leave 17"). It's hard enough to make good choices with manufacturers changing the landscape.
But, weight control is grip.
Lowering Cg and raising fr RC will help more than wider tires (street/track discussion), and unsprung weight comes in, too. All the chassis dynamics come into discussion for grip.
Drop spindle is best way to lower Cg and raise fr RC - but it limits wheel size
Ext Ball-joint doesn't lower Cg as much neither do they come close to raising fr RC as much - but they are a viable option and they allow for wider tire. If you're going to go 295 or above, then this is the option - . You get more grip, but at the cost of more roll movement, unsprung weight, cost, & longevity (ride comfort on street - pretty much track only at this width or above, IMO). But you come out ahead at this width.

If the choice is 275 or 245 (with better roll movement), then I have chosen the drop spindle. My local venue is a 4 mile lap and fast. It fits what I am trying to do. Since my brake pkg fits the 16x8, I can put used r rubber on those and run the 17's on the street.

SlickTrackGod

Given the same brand of tire used in both sizes, the 17 will of course do better.

It is my opinion that if the 245-50-16 is used on the stock rim with a 2" drop spindle, and nothing else is changed- that it will have better lateral grip then the stock height car with the 275-40-17. (with the rear of the car lowered 2" in spring)

Why? it has a lower cg witht he same height rc. The roll couple is 2" lower on the front RC with the drop spindle and yeilds a far better roll axis. THe lower cg will also make the inside tires weight more, and less on the outsides in percentages thn the stock height car (this also applies to front and rear)

Its a better bang for the buck. One this is done, then putting the wider wheels on will make it even better (if the suspension is properly tuned by someone who knows what they are doing)

TEDSgrad

iTrader: (4)

Racecraft says the drops save #4.2 per side. I don't think modded spindles would quite match that. Combine those weight saving with lighter wheel pkg, and it gets into significant territory.

SlickTrackGod

If that is true per side then that is scary. I cleaned mine down a alot and did not even take a half pound off each spindle. I would be afraid to take any more mass off of them. I bet that 4.2 is a combined total, not each.

87350IROC

iTrader: (2)

Has anyone weighed one yet? I would like to compare it to a modified OEM spindle.

The material removed in modifying the spindles is probably 1-1.5lbs.

SlickTrackGod

WOW- I just looked at Racecrafts page-...


..."NOT INTENDED FOR STREET OR ROAD RACE USE"

Guess that answers if they've had rumored trouble with one failing. I heard of something on Corner Carvers of this happening but never confirmed it.

TEDSgrad

iTrader: (4)

The design has changed. There was a gusset along the curved arm for added strength/support - I purchased the roadrace version.
I cut our a section so as to not interfere with end link (position was changed on Spohn's a-arm). I added material on the inside to re-enforce that gusset. I made sure to tightly fit the added material before the weld, then slopped POR-15 all over it.

InfernalVortex

iTrader: (4)

So they're just intended for .... car show use? Seems like you'd be better off just dropping it onto the bump stops lol.

TEDSgrad

iTrader: (4)

Here's Racecraft (a little blurry) & stock

rlewi771

racecraft told me over the phone that they are not intended for street use and especially not intended for road race / auto cross, so that leaves car shows and drag racing.

Seems odd that they told TEDSgrad that they were up to the task. I know for a fact that they are not

TEDSgrad

iTrader: (4)

Wow, that is a change from when I purchased mine. We discussed Road America on the phone. Those disclaimers were not up on their website, either. Wonder what changed?

TEDSgrad

iTrader: (4)

Pulled out the sales receipt:
No Warranties expressed or implied.
"ALL PRODUCTS ARE INTENDED FOR RACING AND OFF-ROAD USE AND MAY NOT BE LEGALLY USED ON THE HIGHWAY. These products are offered for sale as true racecar components and in all cases require some fabrication skill. NO PRODUCT OR SERVICE IS DESIGNED OR INTENDED TO PREVENT INJURY OR DEATH."

TEDSgrad

iTrader: (4)

click the link for detailed write-up (Mustang drop spindles, though):
http://corner-carvers.com/forums/showthread.php?t=34665

paul_huryk

Unfortunately the selection of 245-50-16 sized tires is dwindling and there are no signs of it going back in our favor. Actually the two manufacturers I talking to at last year's PRI mentioned that the 245-50-16 and 255-50-16 are two oddball sizes that will be phased out by every manufacturer in the next 2 to 4 years. 225-55-16 will work on 8" wheels, but gives up tread on the ground - there are just as many choices in that size as the 275-40-17.

You mention the 295, which is a good option in an 18" - it easily fits with the right BS all around. I did find that the 295-35-18 BFG KDW has the exact same tread width as a 275-40-17 Falken 615K, although that is just one comparison. Manufacturers are looking to get rid of the weirdo sizes and focus on the ones that either sell a lot or are on a lot of different cars. 18" wheels with a stock height 25.7" tire has too little sidewall for the people in the northern parts of the county with cratered roads and is probably going to be slower than the same width 17" equivalent around an autocross or road course.

87350IROC

iTrader: (2)

Perhaps it was rlewi771's experience with them that change their mind.

This is the big reason I haven't played with these spindles, with regards to brake kits. I don't want to supply these kits to someone then have them break.

TEDSgrad

iTrader: (4)

Condensing the thread ('08 - early '10):
2 failures
1 tester found cracks

Tester repaired the cracks and uses the spindle.
One of the track failure guys got updated version, is happy, and ordered a set for his camaro - "VERY satisfied response."
Brave for Racecraft to do all this on-line. Have not heard of failure with f-body spindle - these were all with fox.
I purchased mine 10/5/2010

rlewi771

I started a separate thread so that people researching can find easily. Have a look here, this should explain the new disclaimers on Racecrafts website : https://www.thirdgen.org/forums/susp...e-failure.html