Eaton LSD

XR4Ti / Sierra / Sierra Cosworth Discussions - Questions, problem resolution, general talk, technical tips and modifications.
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whitelx
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Post by whitelx » Sun May 27, 2007 6:13 pm

DPDISXR4Ti wrote:
whitelx wrote:I'm going to have to do some JY searching. I'd like to experiment first with a JY part then order up the Detroit Tru-Trac sometime later (after I figure out trans and rear gear ratios).
I seem to recall that there's a way to decipher the ratio and LSD or not via the VIN sticker or maybe some sort of ID badge in the glove-box? Maybe search around the 'net and you'll find the info. S10's and Blazers were the most likely candidates. A lot of RWD car GM products had ratios in the 2.7x neighborhood, and those won't be right (see comment above re: 3.23 or higher).

Pretty sure you'd be blazing new ground with trying to fit a GM 7.5 Tru-Trac. I know that generally speaking, Tru-Tracs are physically bigger, so you may have an issue with needing to grind too much of the case to be able to get it in there.
Yes, GM was kind enough to put the rear gear ratio and differential codes (along with many other codes) on a sheet in the glovebox (or center console on F-bodies). These are known as RPOs. The gov-lock differential is known as RPO G80. This is an Eaton differential that appearently operates as a limited slip and a locker and was originally developed for the government trucks.

I found a G80 in the yard this past weekend, but I wasn't really wanting to roll around in the dirt. I'll have to get some cardboard and make sure I have all the correct tools when I go back next time.


I really want to do the tru-trac at some point. I have a spare auto diff that I can put on the bench and it will make working on it much easier. I don't care if I have to grind a lot, a torsen-style diff is so much better for the road courses. I like the auto diff a little better since I am using an 89 2.3L Mustang T-5. I want 1st gear to be somewhat useable and lower RPMs on the freeway.
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apedavid
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Post by apedavid » Sat Jun 16, 2007 12:49 pm

Does the GM 7.5 Ring and Pinon gear set fit in the Merkur axle case ?


I beleive our driveshaft flange is 24 tooth.

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Post by DSPXR4ti » Sat Jun 16, 2007 1:42 pm

Hello,

All I can say is what I used, the ring & pinion from the xr4 fit the Eaton LSD, any of the others just not sure, I'm sure what your looking for is the best gearing but because of the SCCA rules I could not change the gears, so I didn't try.

Ben DSP XR4ti

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Post by DPDISXR4Ti » Sat Jun 16, 2007 1:59 pm

apedavid wrote:Does the GM 7.5 Ring and Pinon gear set fit in the Merkur axle case ?
That seems HIGHLY unlikely. There would have to be a whole bunch of dimensions that would match, and that seems so unlikely that I'll just say, "No, no way that's gonna work."
Brad

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Post by vcallaway » Thu Jun 21, 2007 2:04 pm

One last question.

Did you use a 5-spd or auto diff?
Vince Callaway

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Post by DSPXR4ti » Thu Jun 21, 2007 3:15 pm

5 speed Diff had the 3:64 gears

Ben DSP XR4ti

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Ray
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Post by Ray » Mon Oct 06, 2008 7:28 pm

I am bringing this back "from the dead" as my diff went yesterday during autoX. I have the 7" euro LSD, and since i killed one, i'd rather go with something a bit more robust.

Ben - if i am reading this right, the following is needed for the GM eaton swap:
  • *GM diff part number part number GM7/P426 from www.reiderracing.com
    *0.150 ring gear shim
    *10 25mm 100x10 bolts (what is that size exactly, and do you know the torque spec?)
    *0.250 bearing race shim for the non ring gear side
    *grind the GM diff a little where the bearings fit
sounds like a very good, cost effective option. and now i'm looking into it.
-Ray
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Post by BeefFajitas » Mon Oct 06, 2008 7:33 pm

Ray,

I'm not sure if you saw it, but someone else exploded their's drag racing. Just an FYI on something that's going to take a lot of work.
-Nate
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Post by hEaT » Mon Oct 06, 2008 8:36 pm

My roommate is selling his 3rd gen rear from his Iroc. I don't know if it's a Auburn or Eaton unit, but the whole rear end is out of the car already so it wouldn't be too hard to look. Let me know if you do want it. I can at least open it up and see what posi unit is inside.
Joe
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Post by DSPXR4ti » Mon Oct 06, 2008 10:40 pm

BeefFajitas wrote:Ray,

I'm not sure if you saw it, but someone else exploded their's drag racing. Just an FYI on something that's going to take a lot of work.
I think you need to read that post again, it was an Auburn that the drag racer exploded not an Eaton, there is a difference.

Ben
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Post by DSPXR4ti » Mon Oct 06, 2008 10:42 pm

hEaT wrote:My roommate is selling his 3rd gen rear from his Iroc. I don't know if it's a Auburn or Eaton unit, but the whole rear end is out of the car already so it wouldn't be too hard to look. Let me know if you do want it. I can at least open it up and see what posi unit is inside.
What year is the IROC?

Ben
85 DSP XR4ti, 2009 Solo 2 National Champion, burns muffler, 3in exhaust, Mc2 Full suspension, 325 hps & 328tqr, GMR Intake, Wilwood brakes, Eaton LSD, stand alone ECU. Working on being SM National Champion.

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Post by merkurmaniac » Tue Oct 07, 2008 8:22 am

From SNL....

Chris Farley dressed as a nerdy street reporter, David Spade, safely back in the anchor booth.

David Spade says "Go ask those guys if they know what IROC stands for"

Chris Farley says "umm, o.k......wait what does it stand for ?"

Spade says "Italian Retards Out Cruising."

Farley "O.K., I'll be right back" as he runs off towards some tuff looking dudes in a Camaro.
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Post by hEaT » Tue Oct 07, 2008 11:23 am

DSPXR4ti wrote:
hEaT wrote:My roommate is selling his 3rd gen rear from his Iroc. I don't know if it's a Auburn or Eaton unit, but the whole rear end is out of the car already so it wouldn't be too hard to look. Let me know if you do want it. I can at least open it up and see what posi unit is inside.
What year is the IROC?

Ben
1988.
Joe
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Post by Mike McCreight » Tue Oct 07, 2008 11:40 am

merkurmaniac wrote:From SNL....

Chris Farley dressed as a nerdy street reporter, David Spade, safely back in the anchor booth.

David Spade says "Go ask those guys if they know what IROC stands for"

Chris Farley says "umm, o.k......wait what does it stand for ?"

Spade says "Italian Retards Out Cruising."

Farley "O.K., I'll be right back" as he runs off towards some tuff looking dudes in a Camaro.
:haha :cheers :haha
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Ray
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Post by Ray » Thu Oct 09, 2008 2:02 pm

picked up my eaton yesterday. still looking for a place to get the spacers.
-Ray
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1985 Merkur XR4Ti -#141 CP "Miss Daisy"
2005 Subaru LGT
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