Driveshaft/ Rear Suspension Question

[combatcamera]

Hi all..

 

I've got an '89 Comanche that has been lifted. The truck has a 4.5 inch lift to it, using an add-a-leaf  in the rear. In addition to that, the rear has a spring-over-axle conversion. The end result is the rear is about four inches higher than the front.

The issue is the truck keeps chewing up U-joints in the driveshaft. A result, I've been told, of the angle of the driveshaft. 

 

I'd prefer not to keep replacing U-joints. My inclination is to either remove the add-a-leaf in the rear or simply replace the springs with stock replacements, keeping the spring-over-axle.

The question I have is, would this correct the angle issue with the driveshaft?

 

Thanks.

 

Jon 

[gogmorgo]

What do your driveshaft angles look like? The two should be the same (i.e. your tcase output and pinion shafts should be parallel), and there is a maximum angle on the u-joint. What's you're pinion angle at? Also what u-joints are you using?

[Pete M]

I would start with removing the AAL.  SOA gives around 5" by itself.

[desbennett004]

I got 6" of lift with my SOA, because I put in a chrysler 8.25. You will have about 5" without the AAL. You can get pinion angle shims to change your angle, if you want to keep your ride height.

 

Sent from my SM-N900W8 using Tapatalk

[HOrnbrod]

The reason you are smoking u-joints is because the u-joint operating angle is beyond 11* or so, about the max you can run them. Like Pete said, remove your AAL then measure your pinion angle with an angle finder. You can look up how to do this on the Tom Wood driveshaft site. Right now your rear axle pinion snout  is pointing too high because of your lift. As stated you can lower the axle snout back down with axle shims between the leafs and axle spring plate. The shims are steel wedges and come in varying degree sizes. So to know which size you need you'll need to measure the angles. Since you are SOA, the "fat" side of the wedge will be facing forward to lower the axle snout. All this info is on this site:

 

  http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml#OperatingAngle

[combatcamera]

Thanks for the replies everybody. Just wanted to double check things before getting into it.

 

Hornbrod...

 

Thanks for the link. That's more info about driveshaft geometry specs than I ever knew before. The info from everybody is greatly appreciated.

[mikekaz1]

just curious, why do you want the rear 4" higher than the front to begin with?

[combatcamera]

just curious, why do you want the rear 4" higher than the front to begin with?

 

I don't. Never did. It was just sort of a comedy of errors it ended up that way.