problem installing gm diff

thrashperformance · Post by **thrashperformance** » Tue Oct 14, 2008 8:58 am

i am un able to wiggle the gm posi diff into the carrier housing. did i need to cut out the inside of the housing to get it slid into place? am i missing some other step? i can get it so close to wanting to drop into place, but my bearings hit the side of the case and no matter how i move, i cant get it to clear.

xrattiracer · Post by **xrattiracer** » Tue Oct 14, 2008 9:18 am

yes, anytime ive seen people talk about they mentioned having to shave the inside of the case.

Post by **DPDISXR4Ti** » Tue Oct 14, 2008 10:20 am

It depends on which unit you're using, but it seems that many of the GM-spec LSD's require some grinding to fit into the case, much like the Quaife. I believe Grayson is planning on documenting the install of the Eaton soon, so perhaps we'll finally have a set of good instructions with pics for this installation, some 10+ years after it was first "discovered".

deathbypsi · Post by **deathbypsi** » Tue Oct 14, 2008 2:03 pm

Mine had to be clearanced also

CV12Steve · Post by **CV12Steve** » Tue Oct 14, 2008 2:18 pm

DPDISXR4Ti wrote:It depends on which unit you're using, but it seems that many of the GM-spec LSD's require some grinding to fit into the case, much like the Quaife. I believe Grayson is planning on documenting the install of the Eaton soon, so perhaps we'll finally have a set of good instructions with pics for this installation, some 10+ years after it was first "discovered".

I thought both sizes of GM-spec LSDs needed clearancing.

thrashperformance · Post by **thrashperformance** » Tue Oct 14, 2008 2:24 pm

guess i should have read moe befor beginning the assembly. now i have to take out the pinion and hopefully not wreck the seal.

Post by **DPDISXR4Ti** » Tue Oct 14, 2008 3:06 pm

CV12Steve wrote:I thought both sizes of GM-spec LSDs needed clearancing.

Both? There's more than two... Eaton, Auburn, Detroit, etc. Plus, there's different varieties for the same manufacturer - we've seen that just recently with the Eaton stuff. Oh, but maybe you're talking about the series II vs. series III (+/- 3.23) difference? That just doubles the number for each of the aforementioned manufacturers.

Any way, some may not clearancing, but apparently, most will.

Post by **Grayson** » Tue Oct 14, 2008 4:40 pm

I "clearanced" my case during my Quaife install without removing the pinion. Clean out the case very, very, very well so that metal bits won't cling to it. Then, just tape off the pinion area, or cover the pinion area with rags, or whatever - just make sure chips don't get near the pinion. When you're done, flip the case over and clean everything out, and remove the tape/rags/whatever. If you work from underneath then chips can't fall toward the pinion when you remove the protective material. Honestly, I didn't even work from underneath and I still didn't get any chips anywhere near the pinion. It's not hard.

Ben Martinez installed his 3.23 and up Eaton LSD without grinding his case. I'll speak further on this when I start the write-ups. The group purchase diffs will be in either Friday or early next week.

CV12Steve · Post by **CV12Steve** » Tue Oct 14, 2008 8:49 pm

DPDISXR4Ti wrote:
CV12Steve wrote:I thought both sizes of GM-spec LSDs needed clearancing.
Both? There's more than two... Eaton, Auburn, Detroit, etc. Plus, there's different varieties for the same manufacturer - we've seen that just recently with the Eaton stuff. Oh, but maybe you're talking about the series II vs. series III (+/- 3.23) difference? That just doubles the number for each of the aforementioned manufacturers.

Any way, some may not clearancing, but apparently, most will.

That's what I meant.
Ben also had to clearance for the pinion; is that a factor of using the "+"?

DSPXR4ti · Post by **DSPXR4ti** » Thu Oct 16, 2008 5:21 pm

CV12Steve wrote:
DPDISXR4Ti wrote:
CV12Steve wrote:I thought both sizes of GM-spec LSDs needed clearancing.
Both? There's more than two... Eaton, Auburn, Detroit, etc. Plus, there's different varieties for the same manufacturer - we've seen that just recently with the Eaton stuff. Oh, but maybe you're talking about the series II vs. series III (+/- 3.23) difference? That just doubles the number for each of the aforementioned manufacturers.

Any way, some may not clearancing, but apparently, most will.
That's what I meant.
Ben also had to clearance for the pinion; is that a factor of using the "+"?

No clearance problems for the pinion or for the Case, if I reading it right you install your side/LSD bearing before you installed it in your Case, I found that pressing the bearings on after you install the LSD unit in your Case is the only way so you don't have to mod. the Case, Grayson may find a better way to install the LSD units in the case, we will see but if you would like to install it in this weekend make sure that the LSD unit on the pinion side does not stick up pass the bearing or you will not be able to install your E-clip your stub shaft and install your bearings after you put the LSD uint in your Case.

Ben

CV12Steve · Post by **CV12Steve** » Fri Oct 17, 2008 10:50 am

DSPXR4ti wrote:
CV12Steve wrote:
DPDISXR4Ti wrote: Both? There's more than two... Eaton, Auburn, Detroit, etc. Plus, there's different varieties for the same manufacturer - we've seen that just recently with the Eaton stuff. Oh, but maybe you're talking about the series II vs. series III (+/- 3.23) difference? That just doubles the number for each of the aforementioned manufacturers.

Any way, some may not clearancing, but apparently, most will.
That's what I meant.
Ben also had to clearance for the pinion; is that a factor of using the "+"?

No clearance problems for the pinion or for the Case, if I reading it right you install your side/LSD bearing before you installed it in your Case, I found that pressing the bearings on after you install the LSD unit in your Case is the only way so you don't have to mod. the Case, Grayson may find a better way to install the LSD units in the case, we will see but if you would like to install it in this weekend make sure that the LSD unit on the pinion side does not stick up pass the bearing or you will not be able to install your E-clip your stub shaft and install your bearings after you put the LSD uint in your Case.

Ben

Sorry Ben, I thought it was you that had to turn down the middle of the LSD to clear the pinion. There are picture of that install around here somewhere.

DSPXR4ti · Post by **DSPXR4ti** » Fri Oct 17, 2008 11:36 am

Hey Stephen,

I know which one your talking about, The biggest problem with the unit that he put in is Xr's rear Diff., his ring gear shim that was it about 2" thick. You only have about .600 to play with because if you look at the Pic's of Ray's (demonfire) on an LSD unit you will see the landing that I'm talking about (see it here "Differential Destruction"), that's the part were the ring gear centers up on the Diff unit on any carrier, you take that away and the whole thing is weaker, and then the ring shim need to be harden steel. So the ring gear shim that I used was .150 thick so I had some landing left, that was a big deal for me because of how I was going to use it.

Ben

Post by **DPDISXR4Ti** » Fri Oct 17, 2008 12:37 pm

DSPXR4ti wrote:his ring gear shim that was it about 2" thick. You only have about .600 to play with because if you look at the Pic's of Ray's (demonfire) on an LSD unit you will see the landing that I'm talking about (see it here "Differential Destruction"), that's the part were the ring gear centers up on the Diff unit on any carrier, you take that away and the whole thing is weaker, and then the ring shim need to be harden steel. So the ring gear shim that I used was .150 thick so I had some landing left, that was a big deal for me because of how I was going to use it.

If I'm understanding this correctly, by going with a 2" spacer, the ring gear was no longer hub-centric - it was centered and secured by the bolts alone?

Is there enough play in how the bearings are set to allow what seems to be a significant variance in the height of these spacers? Or is that more related to the multitude of different GM diffs that we seem to be dealing with here?

DSPXR4ti · Post by **DSPXR4ti** » Fri Oct 17, 2008 2:33 pm

DPDISXR4Ti wrote:
DSPXR4ti wrote:his ring gear shim that was it about 2" thick. You only have about .600 to play with because if you look at the Pic's of Ray's (demonfire) on an LSD unit you will see the landing that I'm talking about (see it here "Differential Destruction"), that's the part were the ring gear centers up on the Diff unit on any carrier, you take that away and the whole thing is weaker, and then the ring shim need to be harden steel. So the ring gear shim that I used was .150 thick so I had some landing left, that was a big deal for me because of how I was going to use it.
If I'm understanding this correctly, by going with a 2" spacer, the ring gear was no longer hub-centric - it was centered and secured by the bolts alone?

Is there enough play in how the bearings are set to allow what seems to be a significant variance in the height of these spacers? Or is that more related to the multitude of different GM diffs that we seem to be dealing with here?

Hub-centric is one way to look at it, the bolts don't center as much as the landing does, Have you ever taking a ring gear off the carrier and had to use a hammer? The best thing to do is call your local Diff. shop and ask him about the ring gear surface and the landing and what would happen with a big ring gear shim, he going to say " it won't last".

Ben