Do I need a ring gear spacer

[81cutlass]

I bought a new, installed, never ran auburn posi carrier about a year ago for my 7.5" rear. Bought it from a guy that had a 4th gen F body but it was a 26spline unit and needed 28 and he couldnt return it since he pressed bearings on it.

I was told it was a series III carier but I put my 3.42's in and the backlash is over .5". Shoved all the shims right and put a ton of pinion shims in and the pinion hit the carrier before I got the pattern right.

Im assuming its actually a series II and I just need a spacer but Im not sure. Im 95% sure but dont want to blow the money if its in the gears or somthing stupid. Just need reasurance. Its sitting next to the open GM carrier that came out of the car with 2.41's.

Why the hell would somebody manage to not only order the wront spline count, but also the wrong carrier series? And why would auburn build a series II posi carrier? Frustrated......

 

[jrm81bu]

Yep, looks like you need a spacer.

 

[bill]

the spacer is to make up for difference in the ring gear, not the carrier. So, without the OEM ring gear for comparision, its not a sure bet yet. Lay the old gear on the old carrier, then take a pic. you should see a big difference in the thickness, or you have the right ring gear and dont need a spacer. just my .02

 

[jrm81bu]

You can see in the pics that the carriers are the same series. He knows the original was a 2 series, so that means that the new one is as well. GM never made a "thick" 3.42 gear, so it's definetely for a 3 series carrier. Now he never said it was an oem 3.42 gear set, but i can tell from the picture it is not a "thick" gear, meaining whatever brand it is, it is a 3 series gear. Therefore a spacer will be needed, no question about it.

 

[pontiacgp]

I bought a new, installed, never ran auburn posi carrier about a year ago for my 7.5" rear. Bought it from a guy that had a 4th gen F body but it was a 26spline unit and needed 28 and he couldnt return it since he pressed bearings on it.

I was told it was a series III carier but I put my 3.42's in and the backlash is over .5". Shoved all the shims right and put a ton of pinion shims in and the pinion hit the carrier before I got the pattern right.

Im assuming its actually a series II and I just need a spacer but Im not sure. Im 95% sure but dont want to blow the money if its in the gears or somthing stupid. Just need reasurance. Its sitting next to the open GM carrier that came out of the car with 2.41's.

Why the hell would somebody manage to not only order the wront spline count, but also the wrong carrier series? And why would auburn build a series II posi carrier? Frustrated......

if you just changed the carrier and used your crown gear there was no need to adjust the shims on the pinion. The backlash for a 7.5 is .006 - .010 and adjusting the backlash shims you would have achieved that setting. If I were you I'd put the original shim back on the pinion and adjust the backlash until you get the right setting. If the posi was a series 2 carrier the flange that the crown gear sits on would be lower than the series 3 that you took out. 3.08 and up have larger diameter pinions.

 

[81cutlass]

The 2.41 with series 2 carier was factory GM, never removed.

The 3.42 set was a lightly used set that has an M stamped on. Dont know if its a moser or what but its not GM.

I set it up with the 3.42's on the new carier using the stock backlash shims out of the housing and pinion shim that came with the 3.42's and the pinion had literally no engangement into the ring gear.

The pinion diameter on the 3.42 is smaller than the 2.41 by quite a bit so I can see why I need a spacer. Its a series 3 3.42 and a series 2 carrier.

 

[pontiacgp]

The 2.41 with series 2 carier was factory GM, never removed.

The 3.42 set was a lightly used set that has an M stamped on. Dont know if its a moser or what but its not GM.

I set it up with the 3.42's on the new carier using the stock backlash shims out of the housing and pinion shim that came with the 3.42's and the pinion had literally no engangement into the ring gear.

The pinion diameter on the 3.42 is smaller than the 2.41 by quite a bit so I can see why I need a spacer. Its a series 3 3.42 and a series 2 carrier.

after reading that I suggest you bring to a shop to have it done or do some reading so you understand the components and how to set up a rear end...if the unit you took out was a series 2 then the posi is also a series 2 but you made it sound like you had 3.42 gears in your rear end and was just switching out the carrier..."I was told it was a series III carier but I put my 3.42's in"

 

[pontiacgp]

but on the other side of the coin I appreciate your ambition. There are many who would not have attempted to do that job. Rear ends are not hard to do when you have done a few but to start off blind isn't a good choice. I was taught by a rear end expert and you get to know what flies and doesn't. There isn't much to it.

 

[bill]

You can see in the pics that the carriers are the same series. He knows the original was a 2 series, so that means that the new one is as well. GM never made a "thick" 3.42 gear, so it's definetely for a 3 series carrier. Now he never said it was an oem 3.42 gear set, but i can tell from the picture it is not a "thick" gear, meaining whatever brand it is, it is a 3 series gear. Therefore a spacer will be needed, no question about it.

I stand corrected....so its because of the smaller pinion size that it requires the spacer, correct?

 

[jrm81bu]

You can see in the pics that the carriers are the same series. He knows the original was a 2 series, so that means that the new one is as well. GM never made a "thick" 3.42 gear, so it's definetely for a 3 series carrier. Now he never said it was an oem 3.42 gear set, but i can tell from the picture it is not a "thick" gear, meaining whatever brand it is, it is a 3 series gear. Therefore a spacer will be needed, no question about it.

I stand corrected....so its because of the smaller pinion size that it requires the spacer, correct?

Yep. As the ratio went down(numerically higher), the pinion gear got smaller(diameter). So at the 3.08-3.23 split they moved the mounting surface of the carrier over a bit to compensate(3 series), so they would have to have really thick ring gears. However the aftermarket does make thick gears and when you see one compared to a regular gear it's pretty noticeable.