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D35 to 8.25 axle change out


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Finally changed out the old D35 in the 87 MJ. THe '35 was moaning under acceleration and appeared to need a new pinion bearing and race...and I just wasnt in the mood for trying to rebuild it.

 

The 8.25 came from a 98 XJ with 154K on the clock. I used JEGS spring perches and U-bolts (but got the 10 inch bolts which was way overkill - had to cut them so a deep socket would fit!). The driveshaft did not need to be cut, and from the pictures the angles were almost straight on, with no vibrations when driving.

 

The only two wierd things were the drums on the D35 appeared bigger then the ones on the 8.25 (even though they both took 9" brake shoes), and the pinion yoke was tapped for 5/16 - 18 TPI (threads per inch) strap bolts instead of the 5/16 24 TPI that came on the D35. I had to re-tap the yoke for the correct TPI.

 

Anyway - Pictures:

 

Drum comparison: (8.25 drum on left)

 

U-bolt length before cutting:

 

Axle installed:

 

 

Poor old D35:

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Axle installed:

 

Ummm, for a stock style drive shaft (single u joint on each end) that angle is completely wrong and I'm surprised you have no vibrations. The pinion should run parallel to the transfer case output.

 

If you run a double cardan CV style drive shaft (like the front drive shaft), that angle would be correct.

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Axle installed:

 

Ummm, for a stock style drive shaft (single u joint on each end) that angle is completely wrong and I'm surprised you have no vibrations. The pinion should run parallel to the transfer case output.

 

If you run a double cardan CV style drive shaft (like the front drive shaft), that angle would be correct.

 

Not sure I understand...the truck is 2WD. Standard drive shaft with the U-joint on each end. In the pictures the drive shaft was straight and had no vibrations.

 

The guy who did the welding stated he felt the pinion end would 'dip' slightly under acceleration and recommended it be raised by 1 inch, which I agreed with (after putting the truck on stands and running it). Still no vibrations, but I've yet to drive it on the freeway.

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the pinion yoke was tapped for 5/16 - 18 TPI (threads per inch) strap bolts instead of the 5/16 24 TPI that came on the D35. I had to re-tap the yoke for the correct TPI.

 

I'm curious as to why you tapped the holes instead of using 5/16-18 bolts?

 

Dunno. I suppose I was being hard headed and wanted to use what I had.. :yes:

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um, the pinion will raise slightly upon acceleration, not dip. :yes:

He's in reverse? :D

 

LOL Jim

 

I was relating what the person who did the welding stated. If he was incorrect, then when I floor it on the highway this afternoon the results should be interesting...

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Pete is correct. With a load on the axle (in a forward gear) the pinion will turn up, making the angle even more incorrect.

 

The pinion should be parallel to the output of the transfer case, or about 2 to 3 degrees lower to account for it turning up. That would be pretty much parallel to the ground.

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