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ESTRADA
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727 Posts
Man, I have yet to break vintage 31 spline shafts with 38.5's. I couldn't imagine what these could hold up to.
 

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GL 4x4 Vendors
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3,146 Posts
35-spline is 1.5"

40-spline is 1.708"

Set 20 bearings are 1.562" ID. (OD is 3.15")

Therefore, stock bearings won't fit a 40-spline axle shaft unless the shaft is machined down to 35-spline diameter (but then why run 40-spline?).

So to use a 40-spline shaft you'll need a 3.25" bearing case, big bearing ends (3.15") and you'll have to use a ball-type bearing instead of the tapered roller bearing (like Set 20). The drawback to the ball-type bearing is that it's great for the straight line guys, but bad for anything that takes a side load.
 

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GL 4x4 Vendors
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3,146 Posts
Do your ends look like this?
http://www.evilmonkeymedia.com/jeep/609/reartruss1.jpg

Mine are big bearing, and I was under the impression they were the Torino style, but these have .5 holes instead of .375. I ordered late style big bearing retainers and they do not fit :confused:
There are 3 different bearing retainers available.

The small bearing retainer is 2" x 3.375" w/ 3/8" holes.

The medium bearing is 2" x 3.562" w 3/8" holes

The big bearing is 2.375" x 3.5" w/ 1/2" holes

Most of the Torinos used the medium bearing 88128-RA. While the trucks usually used the big bearing Set 20. The medium bearing is considered the first type of "big bearing" and the big bearing is considered the second type of "big bearing".
 

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i like jungle gym's.
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10,920 Posts
some good info guys!! tony what ya doin? guess me and joel need to take a run to your house.
 

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Low Range Drifter
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8,519 Posts
The drawback to the ball-type bearing is that it's great for the straight line guys, but bad for anything that takes a side load.
I've been running my axle for almost 5 years now on 39.5 Iroks and I'm not very nice to the jeep and the bearings are holding up fine. That is longer than the bearings on my stock D44 lasted.

If they were to blow out on my next trip, I woudln't feel that they owed me anything.
 

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Premium Member
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9,000 Posts
There are 3 different bearing retainers available.

The small bearing retainer is 2" x 3.375" w/ 3/8" holes.

The medium bearing is 2" x 3.562" w 3/8" holes

The big bearing is 2.375" x 3.5" w/ 1/2" holes

Most of the Torinos used the medium bearing 88128-RA. While the trucks usually used the big bearing Set 20. The medium bearing is considered the first type of "big bearing" and the big bearing is considered the second type of "big bearing".
Sweet, thanks for the info.
 

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Rock Rebel
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575 Posts
Discussion Starter · #12 ·
There are 3 different bearing retainers available.

The small bearing retainer is 2" x 3.375" w/ 3/8" holes.

The medium bearing is 2" x 3.562" w 3/8" holes

The big bearing is 2.375" x 3.5" w/ 1/2" holes

Most of the Torinos used the medium bearing 88128-RA. While the trucks usually used the big bearing Set 20. The medium bearing is considered the first type of "big bearing" and the big bearing is considered the second type of "big bearing".
I got a bunch of parts from a 1/4 mile guy, and it looks like he gave me the wrong bearing ends. I'll call strange monday. thanks for the info.
 

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I'm not old, honest...
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30,551 Posts
Not exactly the same comparison but I ran the early Bronco axle for a while that had the small bearing ends. I upgraded to 31 spline so I had to use the ball bearing style bearings. I blew out at least one a year because of side loading.

John, yours isn't a 9" is it?
 

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GL 4x4 Vendors
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3,146 Posts
I've been running my axle for almost 5 years now on 39.5 Iroks and I'm not very nice to the jeep and the bearings are holding up fine. That is longer than the bearings on my stock D44 lasted.

If they were to blow out on my next trip, I woudln't feel that they owed me anything.
There's an exception to every rule.

Also, you have to take into consideration that the ball bearings in your unit would be smaller than the ball bearings in a 31-spline (1.3" axle) so there can be more movement between the inner and outer race.
 
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