RedWS6 00

I purchased an Eaton Posi and 3.08 gear, I've just been looking at the specs of the Eaton Posi http://www.eaton.com/ecm/groups/publ.../ct_128302.pdf I would have been supplied the 3.23&Up differential.
What would stop a 3.08 ring gear fitting the differential? I havn't tried it yet, still sitting in the box and will be going on the car time soon.

FirstYrLS1Z

iTrader: (4)

If the posi # is 19599-010,no it won't work. A 3.08 gearset will only work with a 2 series carrier. A 3.08 gearset has too large of a dimension from the pinion shaft centerline to ring gear surface that mounts to the carrier flange.

RedWS6 00

humm, thats a pain. I've checked the number on the order, and its a 19559-010, I'm hoping this is a typo, as it looks like that's for an earlier model (1988-96). I'm hoping its just me in a muddle and not messed up on the order.

FirstYrLS1Z

iTrader: (4)

19559-010 is a 2series posi for GM 8.5" 10 bolt. If you're car has the OEM GM 7.5/7.625 10 bolt,IT IS THE TOTALLY WRONG CARRIER.
What is the manufacturer and part number of the 3.08 gearset.
The car in question is the 2000 Red TA WS6 M6,right ?

RedWS6 00

Yes car in question is the 2000 T/A.

The rear end is totally stock. I just wanted lower gears to bring down the rpm's on the freeway. Ordered it all at once from the same place, I gave the company my VIN number as I didn't know what was fitted to the car. The Gears that arrived are 'Motive Gear Ring and Pinion 3.08's GM7.5-308'

Perhaps some wires got crossed during ordering. I'll give them a call when they are open after 5pm UK time, which is about 9am their time.

The next problem is that they noted me down for 4 channel ABS for the axles, but when I was under the car last night, I found a sensor on top of the diff housing, making it 3 channel.

Looks like the parts I have will not work together

I had to get a new rear diff anyway, as my old one is a bit kaput...

FirstYrLS1Z

iTrader: (4)

Your 2000 stock rear (M6) has a Torsen 'posi' differential with 3.42 gears. You really shouldn't be thinking about 3.08s in an M6.
If your rpm,in 6th, is 1350 at 60mph,it would only drop to about 1220rpm. Being that the drivetrain is looseing the mechanical advantage it HAD,it'll cause more wear & tear on the clutch and the engine will always be under more of a 'load' compared to the 'load' it was under with the 3.42s'. You'll probably gain 1mpg.
Eaton doesn't have a 'posi' for 2.73/3.08 gearsets,you'd have to acquire a Torsen 'posi' carrier from an 99-02 f-bod LS1 automatic that had the GU2 (2.73) standard rearend OR an Auburn 'posi' from a 98 or earlier f-bod LS1/LT1 automatic that had the GU2 (2.73) standard rearend.

RedWS6 00

Thanks for the fast responses and your help. It would appear I have a mismatch of items.

The other reason for the gear change is wanting a ratio between 1st and 2nd. Trying out 0-60mph on the highway, pulling away carefully in 1st and then into 2nd take a similar time to pulling away in just second to reach 60mph. So with the 3.08's it could get to between 55mph and 60mph in one gear.

Perhaps I should have done some research on the Eaton posi and gear ratios before I ordered. I'm starting to think I should have stuck with 3.42's.

I'm hoping I have the 19599-010 on the box as at least I can use it with my old gears.

FirstYrLS1Z

iTrader: (4)

your picture in post 5 is starting to show up as one of the ways a Torsen will break.

It would have great if you posted your intentions and accurate details of your car before you started buying.

RedWS6 00

The picture in post 5 was damaged, probably caused by a small accident, had a little side impact on the rear wheel with a concrete block, which may not have helped.

Perhaps I shouldn't have chosen the 3.08's I chose them not knowing they wouldn't work with that diff. Your right I should have posted on here for advice first.

The diff I have is #19599-010, so it is the right one for the 2000 T/A. I may stick with my stock gears. Change all the bearings and I'm good to go again. If ordered some Limited slip diff additive. Having trouble getting hold of GU5 75W-90, but can get GU5 80W-90, is it okay to use this slightly different thickness of oil?

FirstYrLS1Z

iTrader: (4)

couple questions;
Did you remove the pinion also,no need to remove pinion for a carrier change.
Did you 'mark' the carrier bearing caps,they're not interchangeable.
Did you mark the carrier shims as far as which side they came out of. There's a good chance that the 'lash' will be good with the new carrier.
The 3 channel reluctor ring has to removed off the old carrier carefully and put on the new carrier carefully as they are no longer available and rare.
Are the bearing surfaces on the axles good/servicable. If you replace axle bearings,DO NOT USE axle bearing savers assemblies.
The ring gear bolts are LEFT HAND.
Concerning your broken Torsen carrier,the 4 bolts that hold the internals in are sometimes looked for as some of them have been loosening and breaking and those bolts are sellable. The Torsen 'paddle',the block you had to remove to get at the axle c-clips,is also sellable as it is often lost and there are many threads looking for one.

RedWS6 00

wow, thanks for all the info. You are very helpful.

The pinion hasn't been removed yet, was going to do that with the new gears, but I may run with stock gears for a while longer just to get my daily runner back on the road. so I'll leave this in place.

Yes the carrier bearing caps have been marked left and right, I had a feeling they would be different, however looking as the castings they have the same number. I will put them back in the position they came out.

Well, most of the shim was in the oil. I'll get a photo of that one, there was soo much movement in there the shims have been destroyed. However I do have a shim kit I ordered with the new gears.

The reluctor ring look good and intact. I'll make sure i take care of that when removing. One axle is around 70k miles old, the other is 150k miles old. The surfaces look good on the younger one, the other looks a little pitted on the outer bearing area, not real bad. I do have new axels on order that should be on their way soon. I have new bearings for every part. I will check to see if old axle is straight and may reuse it in view to change axels/outer bearings when new ones arrive.

Thats handy to know. I could see myself struggling with that one. In the shim kit, I have bolts and thread sealer, I have some instructions with torque numbers, so I have something to go by when doing this.

Good though. I may pop that in the for sale section. The block 'paddle' is in good condition, and I have no use for the old Torsen carrier. So if anyone is after this, make me an offer.

As we were taking the axles out, we took off the diff cover, the bolts near the wheels are all off, only need to pop out the paddle and c clips to remove the axel. We took this video. Now remember all bearings and shims are still in place. No wonder I heard noises from the back end....
http://www.youtube.com/watch?v=AXZnY...layer_embedded
The video was taken while getting another chap to wobble the axle. Look at the movement of the diff, its certainly not right. Turns out the inner bearing was shot away along with the shims.

RedWS6 00

I will do what I should have done 3 months ago before the original choice of gears.

What gears would best suit my car, it may visit the drag strip, but not often, it wants to be a fast road car. Good 0-60, and 0-100. The 1/4mile times is currently 12.8seconds @ 114mph on a regular road.

The car has heads and cam, dyno plot of flywheel HP/TQ here:-

I've attached the photos in case it helps select the gearing knowing where the power is in the rev range. I lost power after 5700 rpm due to the fuel getting very rich, around 10:1, I have leaned it off since to about 12.5:1, so I'd say the cam is still making power past 6000rpm, my limiter is 6200.


The car will do many miles on the freeway, but we probably wont exceed 70mph as many other cars in the convoy to shows will be going slower. So keeping below 2000rpm at 70mph sounds fine to me.

Looking at the gear calculator from here:- http://xse.com/leres/bin/gearratio?t...rofile=&wheel=
I currently do 70mph in second gear. and a the 1/4 mile in 4th gear doing over 110mph. So thats 3 gear changes costing about 0.5seconds each.

I have been looking at 3.90 gear ratios. My 0-60 may be able to be done by pulling away in 2nd gear (earlier trys on the road with current gears, using 1st and 2nd is about the same time as pulling away in 2nd to reach 60mph). If that's the case then only 2 gears changes until I reach my old trap speed.

I guess by changing the rear gears it makes every gear shorter, and by staying in the power band it gives better acceleration than before?

I was considering 4.10's, that's almost 2000 rpm at 70mph. I know a few people have had positive results. I'm not sure if I should make the jump from 3.42's to 4.10's, maybe something in between? Whats the pro's and cons.?

I know worst mpg for 4.1's, most of the time I will be doing round town driving, so things wont change too much, as it would be just the same as selecting a different gear on the MM6. Fuel is around 1.30 GBP per litre here, thats $2.145 for a litre, 3.8litres to a gallon. $8.15 for a gallon of gas. But I'm not winging about fuel, driving the car far outweighs the cost and I'm enjoying it, and have been for almost 9 years.

FirstYrLS1Z

iTrader: (4)

During the OEM building of the rearend,the caps are bolted to the housing and then the bores for the carrier bearings are machined in,which then makes for the situation that the caps should be put back in their original position.
Confused about your original post about 3.08s' and now mentioning 3.90s' & 4.10s'.
Why so concerned about having less shifts to reach a certain speed ?
Increase of torque to pavement
3.42 to 3.73 = 9 %
3.42 to 3.90 = 14 %
3.42 to 4.10 = 20 %
4.10s' with M6 is what most everybody goes to.
At the power levels from the graph,keeping the little 10 bolt with a M6 intact will prove difficult,I'm sure others will chime in on this.

RedWS6 00

I think i was confused on the 3.08's which is why I think gearing the other way would be better. I was thinking along the lines of longer gears in the power band may increase the acceleration, and less gear changes. The reason I was aiming for less gear changes is my friend has a '78 supercharged Camaro, looks like a nice bit of kit, pushing out more power than me, heavier and an auto. I loose acceleration time when changing gear. Its been a bit of banter for many years about going in for a race.

I wanted to change gears while I had the rear end apart. They are getting old, and probably tired, so I thought why not go for a different ratio. After reading many posts something like 3.73's 3.90's or 4.10's is the direction I want to go. I will be driving on the road, and not launching with slicks at the dragstip, so I'm hoping the rear end will stay intact. I'm hoping too someone will chime in with results.

The above graph was FW power taking into account gear loses.
This graph was measured in 4th gear doing a pull up to 138mph.

FirstYrLS1Z

iTrader: (4)

How much power is the 78 putting out,what's his rearend ratio, a 78 came with a 8.5" 10 bolt,but he's probably upgraded to 12 bolt or 9" for his power levels.

RedWS6 00

Around 650hp on an engine dyno. Its a 383ci. I think he has changed the rear end. Certainly looks larger than mine, he has put some extra bars under the car to strengthen it as it kept twisting. One thing I know on the road he cant get the traction. which give me the advantage, but if he grips I'm buggered.
Here it is...

FirstYrLS1Z

iTrader: (4)

Even the stock 78 8.5" 10 bolt is gonna look bigger than yours.
Gears will help match,or at least get closer to, his torque to the pavement,but he simply outpowers you.
Have you added LCA re-location brackets to help your traction and reduce 'wheel hop'.
You're always gonna be limited by the little 10 bolt.

RedWS6 00

The 4.10's wern't in stock, so I've gone for 3.90's, maybe a better ratio for my car. I spoke to the chap who owned the '78 camaro, he was thinking 4.10's may be too high. He did have a 8.5" 10bolt in there.

Looking forward to getting them in the car and back on the road.