Rear end's posi is over.. [Archive] - LS1 Performance Information

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AKIRA

01-05-2007, 11:27 AM

A pinion bearing is pretty much gone in my rear end and my "clutch pack" is no longer giving me posi traction. This is all German to me. The only thing I know about a rear end is what gear ratio to get and maybe which rear end cover to keep the 10-bolt as strong as it can.

The mechanic said the cheapest route would be to get new "clutch packs." I asked if the gears couldve been screwed up from the pinion bearing and he said he wouldnt know until he opened it up. He explained how he knew it was a pinion bearing that was screwed cuz the car makes a noise the second it takes off, in other words, this is a diagnosis without going in there.

BUT!

Since I am going in, I am worried that other things might be messed up and theres no point in paying for an installation twice (seeing as how I cant be without the car for a long period of time), I was thinking of what to do...

After a recent thread I figured I had an Auburn rear(?) and I didnt know if I could just replace these clutch packs (where the fuck can I get these????) or if I should get an Eaton or a Torsen. Again, this is all new to me.

I need some reccomendations here. I dont race the car too much anymore. I havent been to the track in over a year. :(

9t8z28

01-05-2007, 11:42 AM

Is the pinion seal leaking?
As far as wether to keep the Auburn, I don't know. I bought my car when the clutch packs were allready gone. So I don't know the reliability of that setup.
With the pinion being loose, sometimes you could just retorque or reset the tolerances if you wanted to make it last longer. I have done this to many 4 wheel drive vehicles and in some cases, iy stopped howling!
If it helps at all: I have a torsen setup with 135,000 miles of hard driving!! Never had a problem with it!!!!!

AKIRA

01-05-2007, 04:40 PM

Apparently there are no leaks. FIRST TIME EVER. The "clutch packs" lasted until I guess 90k?

Wesman

01-05-2007, 07:15 PM

I'd invest in an Eaton Powertrax locker. Its got the benefits of a fully locking diff, without the ratcheting and squealing around turns that lockers tend to have. Both wheels spin, unlike the torsen, that "senses torque" and tries to distribute power to the wheel with more traction.

It can also be installed without removing or altering the ring and pinion, so you could even do it yourself. However, if your pinion bearings are shot, you will have to get that addressed by a mechanic separately.

01Z28M6

01-06-2007, 05:24 AM

Dillard99

01-06-2007, 10:29 AM

hey check out this web site at www.thirdgen.org/beefinguprear
this guy gives you step by step on how to beef up your 10bolt
good info I will be starting my step up soon.

AKIRA

01-06-2007, 01:00 PM

To my knowledge your 99 TransAm has a Zexel Torsen from the factory unless it has been changed out. It has no clutches in the differential so it can't be rebuilt in that regard. Your mechanic should know that so take care as you allow him to start work on your car.

He installed the 373s a couple of years ago, so Id say he rememebers what was in there.

In any case, where are these "clutch packs" to buy anyway? Ive never heard of them.

volleybill

01-06-2007, 02:10 PM

Eatons have clutches, Auburns have cone clutches, Torsens don't- You can get new Eaton clutches, I don't think the factory Auburn stuff is re-buildable. If you went Eaton, you can change the spring bias on the Eaton, make the pressure locking the clutch plates together higher.

AFAIK, you have a torsen, which is a load-sensing diff- the wheels may spin easily on the lift, but they should lock together under a good torque load. Have you done a couple burn-outs to see if it is is working?

AKIRA

01-06-2007, 02:33 PM

No I havent burned out in a long time. Years. And I beleive he said I had cone clutches...

Doesnt seem to be a cheap way around this one huh? My mechanic explained to me about all this stuff, though it was too technical for my full understanding, he did say that products like a Detroit Locker could be dangerous the rain if the tires cut loose.

9t8z28

01-07-2007, 08:35 AM

01Z28M6

01-08-2007, 08:36 AM

Factory Auburn's are rebuildable!

http://www.auburngear.com/aftermarket/drex/

9t8z28

01-08-2007, 08:40 AM

http://www.auburngear.com/aftermarket/drex/

Nice work! I didn't realize that. Why the hell would they not make it rebuildable? $100 ain't bad!
How long have you guys had these things last?

AKIRA

01-08-2007, 07:22 PM

Ok so to go to an Eaton...what is everything that I would need? Looking at a Summit catalog for example, what would I get to make this job over and done with?

AKIRA

01-08-2007, 07:24 PM

http://www.auburngear.com/aftermarket/drex/

Or could I just buy this? I didnt know if I should buy an installation kit or SOMETHING else to complete the job.

01Z28M6

01-09-2007, 07:37 AM

The D-Rex offer is pretty time limited. I think 3 years or maybe 5. I know mine was way past the replacement limit so I bought one out of a 2000 Z28 with just a few thousand miles on it for $75. If you want to save money that is one way to go.

I'm pretty certain you have a 3 series carrier (differential) because of your 3.73 gears. There is a chance that you have a 2 series carrier with special thickness ring gear or a spacer. But if you do have the expected 3 series then all you will need is a new or good used 3 series differential, 10 new bolts, a new gasket for the gear cover or just use ATV and some loctite if you want to use it on the new bolts. All your side shims should work if you don't mix them up when you pull the bearing caps off but then again a different carrier might change things. Mine didn't and I went from an Auburn to a Zexel.

Those are the parts you will need but if you are going to do the work yourself, all you need is basic hand tools a torque wrench AND an indicator to check for proper lash and that the ring gear is running within a few thousandths concentric. It's only a check because you aren't changing pinion depth and using the same ring gear. These 1 inch travel indicators with a magnetic base can be bought for under $30.

volleybill

01-09-2007, 04:13 PM

Don't forget the pinion bearing, the reason you are going in there in the first place- actually, if you are going in with new parts, and going to go through the trouble of installing new parts, it would be a good idea to do all the bearings- for a few bucks more in parts, no more in labor or time, have all new moving parts. If the pinion bearing wore out, how much life is left in the other bearings?
DOn't forget a mild break in for a few hundred miles, heat cycling a few things- then change the fluid. And use the limit slip additive in there, or run synthetic gear oil- BTDT

AKIRA

01-09-2007, 05:31 PM

Can these be bought in a kit? Say a Ratech installation kit?

AKIRA

01-30-2007, 11:43 AM

Wesman

01-30-2007, 07:42 PM

Ok heres an update..and if I fucked up :( I guess let me know. :cry:

I went ahead and purchased an Eaton Posi Performance differential from Summit ETN-19599-010

And a Ratech Install Kit
RAT-308TK.

I hope this will all fit.. What do you guys say?

As long as its for a GM 7.5 inch 10 bolt, then it should work fine.

Eaton makes good differentials, so don't worry about it :)

AKIRA

01-30-2007, 07:52 PM

As long as its for a GM 7.5 inch 10 bolt, then it should work fine.

Eaton makes good differentials, so don't worry about it :)

Goodie!

I wonder if Ill notice a difference in drivability..? It would be nice to not hear that fucking howling anymore! :love:

Firebirdjones

02-02-2007, 07:57 AM

Eatons are what I recommend when rebuilding rearends for people. It's what Gm used throughout the muscle car days of the 60's and 70's. A clutch style unit that is very easy to rebuild, and in the process you can change the type of clutch material and the preload spring pressures around,,,and make it as tight as you like with virtually no slippage.
Out of the box brand new ones are pretty tight. Especially if you go with a pro series, with heat treated gears etc...

Pinion seal can be a little tricky. It really depends on why it started leaking, sometimes the seal is at fault but more times than not,,,if the seal is leaking it's due to the pinion bearing possibly starting to go south. You can simply grab the yoke and see if you can move it in and out, up and down, etc...if you feel ANYTHING at all,,,the bearing preload has changed, which means the bearing is probably going out, and if the pinion is moving around at all the seal cannot do it's job.

Requires complete disassembly. How complete is the setup kit you purchased. You are going to need a new crush sleeve and both pinion bearings. Some setup kits are partials that only come with shims for the carrier to setup backlash.
The setup kits I use come complete with carrier bearings, axle bearings and seals, as well as pinion bearings and seal, crush sleeve, pinion nut, cover gasket, and in some cases, new ring gear bolts.

If the pinion bearing was bad,,,,not only does that pass alot of trash throughout the rearend and cause havick on the other bearings,,,it also means the pinion gear was moving around,,,and if the car was driven for any length of time it's possible it ruined the ring gear pattern as well.
In most cases you can reuse the ring gear, but if the pattern has been altered you may get some ring gear noise when it's all done. Only way to fix that is a new ring and pinion set.
I don't mean to scare you with all this,,,,just giving you a heads up on some things that you might run into.

Setting up the rearend from scratch with new gears is time consuming and takes a few special tools. Pinion depth measuring device is one major tool used,,,that can be picked up for as cheap as $100 or so. Better ones cost quite a bit more. A magnetic base dial indicator is also a big help for setting backlash. An inch pound wrench is also needed to set proper bearing preload on the pinion bearings, usually around 25-30 inch lbs. for new bearings. Also you will need proper preload on the carrier bearings while setting up backlash.
If you are reusing the original gears, you may be able to reinstall the pinion with the original shims and be ok. Once you set the back lash check the gear pattern and make sure all is well. Adjust if necessary.

Sometimes people get lucky on the first try,,,and there are people out there that claim they install new gears with the old shims and throw it together without any of the special tools with no problems. Thats all well and good if your that lucky,,,but I prefer to set things up meticulously with everything to spec, maybe a little on the tight side to compensate for wear. Enough babble,,,,hope it all works out for you,,,Larry.

9t8z28

02-02-2007, 12:16 PM

Very nice write-up!

AKIRA

02-02-2007, 01:30 PM

I purchased an installation kit that had everything you listed except "wheel bearings."

Firebirdjones

02-02-2007, 04:41 PM

Sounds good,,,,thanks for the kudos, I just hope it is helpfull. Larry.

02z28ls1

02-02-2007, 05:03 PM

In 99 they did change over all F-bodies to the Torsen-Zexel type. Maybe an early production model with the earlier rear end?
I had a 98 with a posi-clutch type. Different driveability and what not. The torque sensing type (in my 02) is fun on road course sports car type driving where you can steer the rear end around with the gas pedal. Drawbacks are if one wheel has no traction at all (like ice or dirt)it will spin like an open type. Had a couple of incidence where this was a problem. Still-I like the torque sensing type fine, it really locks up when it's needed.
The clutch type is more predictable as it is always doing the same thing, however it can slip. Setting the clutch packs up tighter would cure this, but may cause driveabilty problems in the rain or snow.