stealtht/a

iTrader: (1)

hello,
im using a 10 bolt from a 91 formula that had posi and 3.42 gears. I prefer the truetracs reliability so im swapping it in while replacing all bearings and seals. reusing stock gears. using a yukon install kit with timkin bearings.
i thought i would start with stock shims and see if i get lucky.
stock pinion shim is .015, preload set to 22 inlbs
stock carriers shims created zero backlash, so adjusted carrier shims until i got .009 backlash. heres the pattern resulting:

stealtht/a

iTrader: (1)

im thinking the pinion is not close enough to the ring, so i checked to see if decreasing backlash would help. heres the result at .006 backlash:

stealtht/a

iTrader: (1)

still seems to be out on the heel, so i think i need thicker pinion shim. Im thinking try a .030 next. only problem is i havent bought a pinion bearing puller yet, i cut the old one up enought to press it off with plates. i think i will invest in one of the clamshell style as this wont be my last gear set up. anyone use this one? its about $150 cheaper than the yukon one.
http://www.ebay.com/itm/151072660286...84.m1438.l2649
what do you think?

big gear head

I think you need to go to about .018 pinion shim and set the backlash back to .009 and try again.

I'll say this again, if you are going to use a gear again then check the backlash and do a pattern check BEFORE you disassemble it and take pictures of the pattern so that you will know what it is suppose to look like when you put it back together.

stealtht/a

iTrader: (1)

Good advice that I heard many times AFTER I took it apart
Yes, the .009 backlash seemed better.
Are you saying ADD .018 or just add .003 to get to .018 total? .003 will make enough difference?
Thanks for the help!

big gear head

Just add .003. It will make a big difference.

stealtht/a

iTrader: (1)

Great! Thanks!Big Gear Head, what kind of puller do you use? The clamshell style like the Yukon is the only type that will pull the bearing without damaging it, right? I guess the other way is to cut this one off again and buy a new one, costs a lot less, but I'm probably going to do many more gear set ups. Is there any tool I can use with my big shop press that won't kill the bearing?

big gear head

I've been using a Harbor Freight bearing seperator in my press for many years and I have damaged very few bearings with it.

jmd

iTrader: (4)

Good job checking your pattern on here with pics.

I'd be interested to hear feedback on how you like the new truetrac also.

stealtht/a

iTrader: (1)

Well, it's unlikely this car will be on the road before winter, this axle is going under my 85 TA project that is just becoming a roller again after a full frame off resto. I will be sure to let everyone know how awesome it is in the spring!
I have used truetracs in a couple of my jeeps and have been very happy with them. The most relevant would be my 2wd comanche street pick up. The 4.0 i6 has as much low end torque as the v8s in most third gens and it put the power down nicely. They are very smooth, never clunk or grab. Really noticed the difference putting on power coming out of the turns. I never took it to the strip, but I never had a problem with hooking up from a standing start. It is true that in very low traction conditions like snow can make one wheel spin, but just modulating the throttle brings them together, you don't usually even need to fool it with the brakes. I also put thousands of miles on and off road on them and zero problems. When I scrapped the comanche, I pulled the truetrac and sold it after 30k miles of hard use and it looked like new.
For a street driver or all around car, truetracs are the way to go.

stealtht/a

iTrader: (1)

Ok, wasn't able to get back to this project until now.
I was incorrect about my pinion shim, it was .028 on my last pattern, not .015
So using the smallest increment of pinion shim I reset the pinion depth to .032
I knew this would result in too little backlash, so moved the carrier over smallest increment as well. I'm not sure I have enough carrier preload now, seems light even though It still takes a little force to get carrier in and out. I'm getting conflicting info on the pinion preload as well so I went with the Yukon install manual at 15 in/lbs

So current specs are .007 backlash with .032 pinion shim. Pinion preload is 15 in/lbs

I'm thinking I need to maybe increase backlash again, I could add another shim to the carrier so it would also increase carrier preload.
All input welcome!

stealtht/a

iTrader: (1)

ok, i added .010 to the carrier shim away from ring gear. this see to be better carrier preload and now backlash is .010 and i like the pattern.
I'm thinking this is about as good as i can get. keep in mind this is a used gear set with all new bearings and new truetrac carrier.
am i ready for the crush sleeve? any tips on that would be appreciated as well.

stealtht/a

iTrader: (1)

Looking at guides again, now I'm not sure this is good enough.
Maybe I should increase pinion shim slightly again? Drive side looks perfect, but coast side seems to be maybe to far up towards the face?

big gear head

I think I would run it like it is.

stealtht/a

iTrader: (1)

Great, I think I will. I'll do the final install tomorrow. Took it all back apart so it's all ready for the crush sleeve. I'll be sure to post results when it's driving, should be a month or so.

stealtht/a

iTrader: (1)

just some final update on this
got everything put back together and installed axles with no problem. double checked backlash, still .010.
crush sleeve was interesting. I think everything went fine but a couple notes.
first, I didn't realize the crush sleeve would bottom out before zero preload so it takes a lot of small increments of torque to get to the final preload.
second, takes a LOT of torque to crush it! using the write ups advice i went just a 16th of a turn at a time, used a big breaker bar. I think it helped that i had made my own yoke holder wrench that is a bit longer than a pipe wrench.
here are some pics buttoned up. everything seems to be rolling smoothly and quietly, true trac working as expected. Just need a car to put it under now! Almost ready to roll!

Ron U.S.M.C.

That's got to be a nice thing to be able to do and
hopefully you nailed it first time out on the road.

What about a cover ?
When you decide its where you want it will you invest in a support cover ?
You cant tell from the photo but its close to an inch thick.

stealtht/a

iTrader: (1)

I wasn't planning on a support cover for this guy. I'm only running a slightly modded 305 tpi and high school was a long time ago so I don't think I will be stressing this rear too much.
I just got a new stock cover and painted it to go with the rest of the cars black and silver theme. I will certainly be looking into a cover like that if I decide to put a bigger motor in.

I hope I got it right too! But I'm pretty confident in building gears now so if it whines, I can do it again pretty quick. Having all the right tools helps!

It also gives a lot more confidence to have such good help here on the forum, thanks Big Gear Head!

big gear head

Glad to help. I hope it does well.