M body 7.25 to xj 8.25 swap

Gearhed

Well-Known Member
Joined
Jul 2, 2020
Messages
73
Reaction score
33
Location
Salem, NY
My 85 5th Ave has a 7.25 rear in it right now, and from what I understand some ungodly high ratio.

I just picked up a 8.25 Chrysler rear out of a 98 XJ Cherokee. It's a 3.55 open ratio, measures about 60" WMS to WMS (fmj is like 59ish I think?), and uses the same lug pattern and wheel hub bore as our cars. Should be 29 spline. Anyone else ever do this swap? I saw a thread using a KJ Liberty disc brake 8.25, but never an XJ drum brake axle

Obviously I have to cut off the existing spring perches, as they are for spring over, and install new ones, as well as ditching the shock mounts. That part should be easy. I'll be doing an iso clamp delete at the same time.

Looking at my parts book at work (the actual paper book lol) I'll need a Moog 319 u joint, which is a conversion joint from a Detroit 7260 series (our cars) to a Spicer 1310 (most jeeps from before the JKU 4 door era)

I'm guessing I'll have to shorten the driveshaft, can someone confirm/deny?

Drum brakes are very similar in size, and e brake cables look like they'll be pretty straightforward.
 

80mirada

Well-Known Member
Joined
Sep 3, 2012
Messages
1,575
Reaction score
627
Location
Wisconsin, Fort Atkinson
You will have to shorten the driveshaft. The drums should be an easy one to hoof up. I would see if you could just swap the M-body cable into the Jeep brakes
 

Gearhed

Well-Known Member
Joined
Jul 2, 2020
Messages
73
Reaction score
33
Location
Salem, NY
That's what I figured. Anyone have an idea of how much shorter the driveshaft will have to be? I've got the 904 trans by the look of it
 

Gearhed

Well-Known Member
Joined
Jul 2, 2020
Messages
73
Reaction score
33
Location
Salem, NY
Since threads without pics are awful, here's a pic of the rear end that will be going in. Hopefully will start working on it in the next week or so
IMG_20200904_103119_172.jpg
 
Back
Top