GM LSD Underway

Post by **DPDISXR4Ti** » Sun Sep 14, 2008 12:42 pm

DSPXR4ti wrote: This is the shims That I installed, no Pic's yet but I will building a spare.

Ben, did you ever get a chance to take any pics? Also, did you verify that the spline angle was indeed a match? This topic just came up on the XR4-Xtreme list as a possible concern - makes me wonder if perhaps GM used two different spline angles.

DSPXR4ti · Post by **DSPXR4ti** » Sun Sep 14, 2008 1:25 pm

Hey Brad,

I saw that post and I tried to reply to Dan and you All to give him my input but it kick back to me, so I was going to email him today about my install/set up.

Ok..Spline angle? not sure what your asking here but here is what I did, took an input shaft from a spare diff. and put input shaft in the Eaton for a test fit, it had very little play, when I put the input shaft in the stock diff. it also had very little play at that point I found the LSD diff. for me.

I'm going to make a spare Eaton LSD diff. and I will take pic of the install, now that I have done this a time or two it go's a lot faster so keep your eye's open for my "Eaton LSD install" Thanks.

Ben

deathbypsi · Post by **deathbypsi** » Sun Sep 14, 2008 7:48 pm

Mine blew up last weds. At the drag strip it wheel hopped just a tad outa the hole and then BOOM. Its dead.

Wanna build another?

Post by **DPDISXR4Ti** » Mon Sep 15, 2008 10:37 am

DSPXR4ti wrote:Ok..Spline angle? not sure what your asking here

Ben, I'm referring to the angle at which the splines are machined into the stub-shaft and matching receivers in the differential. If you look back in this thread you'll see that JV raised this as a potential concern as did Harry on XR4-Xtreme. Luke understood the question and tried to take some pics documenting that they do match.

Bear in mind, it's possible that the splines could match (both are 26), and appear to be a proper fit, but you need to look close and see that the interface is flat and thorough in the "V" of the groove.

I'm wondering if perhaps some of the GM stuff was cut at 45 degrees and others cut at 30 (matching the Ford spec)? I'm sure someone who really knows GM rear-ends would know for sure.

deathbypsi · Post by **deathbypsi** » Sun Sep 21, 2008 10:55 pm

Here is what I found inside today. Anyone have a set of the small spider gears for one of these?

DSPXR4ti · Post by **DSPXR4ti** » Sun Sep 21, 2008 11:20 pm

I'll look I'm sure I do and if I do you can have them you just have to pay for shipping

Ben

deathbypsi · Post by **deathbypsi** » Sun Sep 21, 2008 11:32 pm

Thanks Ben! what about any of the springs and that plate?

John V · Post by **John V** » Mon Sep 22, 2008 12:20 am

DPDISXR4Ti wrote:
DSPXR4ti wrote:Ok..Spline angle? not sure what your asking here
I'm wondering if perhaps some of the GM stuff was cut at 45 degrees and others cut at 30 (matching the Ford spec)? I'm sure someone who really knows GM rear-ends would know for sure.

Ford is 45*PA. (Pressure angle---fancy schmantzy talk for the spline angle)

It's easy as pie to check.
Use the corner of a piece of ordinary paper, it's a nice 90* and should fill the spline. Best done on a OD, but with some scissors and some tape you could make a simple jig to hold the "gauge" to check IDs

Post by **DPDISXR4Ti** » Mon Sep 22, 2008 9:59 am

John V wrote:Ford is 45*PA. (Pressure angle---fancy schmantzy talk for the spline angle)

Damn it, that's what I get for taking someone's else word as fact rather than checking it myself.

John V wrote:It's easy as pie to check.
Use the corner of a piece of ordinary paper, it's a nice 90* and should fill the spline.

Yep, just recently had to do this when a part was incorrectly machined with a 82* counter-sink and the metric bolt just wasn't sitting right (Metric flat-heads have a 90* seat). Dropped the corner of my business card in the hole and saw daylight and confirmed it was wrong.

Post by **DPDISXR4Ti** » Mon Sep 22, 2008 10:01 am

deathbypsi wrote:Here is what I found inside today.

Was this a stock GM Eaton you had in there?

DSPXR4ti · Post by **DSPXR4ti** » Mon Sep 22, 2008 10:07 am

DPDISXR4Ti wrote:
deathbypsi wrote:Here is what I found inside today.
Was this a stock GM Eaton you had in there?

That was my next question?

Ben

deathbypsi · Post by **deathbypsi** » Mon Sep 22, 2008 10:08 am

DPDISXR4Ti wrote:
deathbypsi wrote:Here is what I found inside today.
Was this a stock GM Eaton you had in there?

Auburn I thought.

deathbypsi · Post by **deathbypsi** » Mon Sep 22, 2008 10:13 am

This one...

I thought a while back it was decided this was the Auburn . Eaton I'm not so sure of.I will go outside and check for some numbers on it.

John V · Post by **John V** » Mon Sep 22, 2008 11:38 am

DPDISXR4Ti wrote:
John V wrote:Ford is 45*PA. (Pressure angle---fancy schmantzy talk for the spline angle)
Damn it, that's what I get for taking someone's else word as fact rather than checking it myself.

Well you coulda just asked me

I think, I can't recall exactly but I believe it was this spline thing that caused be to reject the GM thing way back in like 1988, just as the plunging tri-bearings was my reason to reject the Ford 8.8" IRS diff.

As second strike against both the GM and the Ford USA diff is the weaker "2 planet gear design which I won't use unless I have no other choice.

The Supra diff I prefer is of course a 4 planet design, and you needn't buy axles and adaptors costing HUNDREDS of dollars.