Rear Driveshaft Question

[92XJ85]

Planning on doing a springover in the rear? Will a front XJ driveshaft work with a slip yoke eliminator? Or would I have to get the original rear shaft lengthened or get one custom made? Thanks.

[Pete M]

MJs have a foot more wheelbase than an XJ, so the front driveshaft trick doesn't work. The stock shaft will work ok, but it really should be about an inch longer. :thumbsup: If you have a 4.0/auto, a 4.0/stick rear shaft will be one inch longer.

[mvusse]

After my SOA swap I fully compressed, and completely unloaded the suspension, measuring the travel of the slip yoke to find out what I needed. I now have a drive shaft 1" longer than my stock shaft, but that's on top of a D35->8.25" swap (8.25" has 1" longer nose) and a YJ yoke, which is 1/2" longer.

 

So with my original axle and yoke a perfect length shaft (as much spline engagement as possible without bottoming out) would have been 2.5" longer. Because of this, when I ran my D35 spring over and my old shaft, I used another set of holes in the spring perches to move the axle forward 1".

[92XJ85]

I am putting a 8.25 in, so what your sayin is i can use the stock shaft because i will gain the extra inch with the 8.25 yoke?

[mvusse]

Yes you should be able to, but it's also quite possible you could still use more length. I drove around with a drive shaft 1" shorter than I have now until I bent it by parking my truck with the drive shaft on a rock and the rear wheels off the ground.

 

Only way to find out what length is optimal is to do the SOA swap, install the drive shaft, and cycle the rear suspension from extreme to extreme while watching the slip yoke and measure left over travel when engaged most. There are many variables including the shape of your rear spring, length of shackles (not everyone uses the stock ones) and pinion angle.