Which Limited Slip Carrier To Go With?

[camaro71/holland]

Remember also to get the conversion carrier bearing. ID of the bearing is bigger than for 28 spline due to increased thickness of the axle and the carrier flange. OD of the bearing and cup remains the same.

Do a search on here, there are several threads with the correct part numbers as BGH knows them by heart...

 

[big gear head]

The reason that Summit doesn't list the 30 spline Truetrac for the Camaro is because the Camaro never came with 30 spline axles. It will still fit as long as you use 30 spline axles. When you get an installation kit you will need to get one that has the correct bearings for the after market differential. As far as I know all of the after market 8.5 differentials use these special bearings, whether it's a 28 or 30 spline unit.

 

[evilWS6]

Did a search but didn't find any part numbers to verify. Here's what I found, tell me if these sound right to you guys:

"Eaton differentials require special bearings. For 1999 and prior- bearing LM102949 and race LM102911 are required. (2.89 O.D. race) For applications 1999 and newer with race O.D. of 3.06 in. bearing LM603049 and race LM603012 are required."

1999 & Prior:
LM102949 Bearing:
Cup Bore: 1.7812 (Stock is 1.6250)
Cup Length: 0.7800
Cup Radius: 0.1400

LM102911 Race:
Cup Bore: 2.8910
Cup Length: 0.6937
Cup Radius: 0.0300

1999 & Newer:
LM603049 Bearing:
Cup Bore: 1.7812
Cup Length: 0.7812
Cup Radius: 0.1400

LM603012 Race:
Cup Bore: 3.0625
Cup Length: 0.6562
Cup Radius: 0.0310

Does using 30 spline axles effect which setup I need? Or is the "99 and prior" 2.8910 race configuration still the correct one?

I'm sure Tom's Differentials knows exactly what I need, but I like to know *why* for myself. If I decide to go this route, I'll do a quick write-up with all the part numbers so BGH can stop repeating himself lol.

Thanks again!

 

[big gear head]

In '89 GM upgraded the 8.5 to 30 spline axles, but they didn't increase the size of the bearing journal on the differential. The 30 spline axles required a larger hole in the differential, which made the bearing journal thin. They had problems with the bearing journal breaking off of the left side of the differential. In '99 they made the journal the same size as the 12 bolt bearing journal. The after market companies beat GM to it and made their differentials with the larger journals. To keep things simple they make their 28 and 30 spline differentials with the same size journals so that they all take the same bearings. So if you use a after market differential you need the special bearings, whether you use 28 or 30 spline axles. You need the LM102949 and LM102911 bearings. They will come in the HD installation kits.

 

[evilWS6]

In '89 GM upgraded the 8.5 to 30 spline axles, but they didn't increase the size of the bearing journal on the differential. The 30 spline axles required a larger hole in the differential, which made the bearing journal thin. They had problems with the bearing journal breaking off of the left side of the differential. In '99 they made the journal the same size as the 12 bolt bearing journal. The after market companies beat GM to it and made their differentials with the larger journals. To keep things simple they make their 28 and 30 spline differentials with the same size journals so that they all take the same bearings. So if you use a after market differential you need the special bearings, whether you use 28 or 30 spline axles. You need the LM102949 and LM102911 bearings. They will come in the HD installation kits.

Awesome, thanks bgh! I appreciate everyone's help here. I'm going to pull the axles out of my rear probably today. I'll post pics just to see what you guys think of their condition. This is my first time doing rear end work and I'd like to learn the spots to check and stuff. Thanks again!

 

[big gear head]

Look at the area where the axle bearing runs on it. If it's pitted or worn then they need to be replaced.

 

[evilWS6]

Look at the area where the axle bearing runs on it. If it's pitted or worn then they need to be replaced.

Yep, one of them was in pretty rough shape where they ride in the carrier bearing. Should I get an extra of the two bearings that go on the pinion, so I can grind out the center a little for test fitting the shim stack?

 

[big gear head]

That's not the way that I do it, but if you don't have a press then it might be easier. Just be sure to check the pattern again when you install the good bearing because it might change.

 

[evilWS6]

That's not the way that I do it, but if you don't have a press then it might be easier. Just be sure to check the pattern again when you install the good bearing because it might change.

How do you do it? Press the bearings on with a “base line” shim, install, check depth, and press it back off if necessary? I do have a press, but thought it might be easier with the extra bearings. If it’s simple to press them on and off, I could do that too.

Do you even measure pinion depth or do you just check the pattern?

Thanks for all your help so far bgh

 

[big gear head]

Exactly like you said. Press it on with about .032 shim and check the pattern. Make adjustments by what the pattern says.