more driveshaft fun

[89bigblue]

Among others, I have an '89 with a 4" skyjacker and 35s. Since I've gotten this one about 2 years ago I have been going through u-joints. About 6 months ago I actually replaced the rear differential yoke, it was adding to the problem but replacing that did not solve the problem. If I get on the gas hard, there is a big vibration somewhere that feels like it is coming from back there. I still don't have the confidence to stomp on the gas because it feels like it will just snap yet another u-joint.

I am stuck at looking at new driveshafts, maybe a custom one or one with the CV, or one of those "indestructable" driveshafts I think CTM makes them, they're like $200. The problem is, I don't want to throw down either 200$ for the u-joint if thats just something just being caused by the bigger problem, especially if its not all it is cracked up to be... and I don't want to spend the ~$300 on the driveshaft if that doesnt completely fix it. I am definitely willing to put down the money if the part is worth it though because as we all know, stomping on the gas is one of the funnest and most important parts of driving.

Anybody have experience with this?

 

[Hogback Fabrication]

First, check to see if there is any side to side play in your pinion shaft. Its likely that when you replaced the pinion yoke you didn't replace it correctly (yes, there is a lot more to it than just removing/reinstalling the pinion nut ). If there's any play, your rear end is toast and that is causing your problems.

If there isn't any play in the pinion yoke, its probably because your driveshaft angles are pretty steep because of your lift. Are there any shims on your rear axle to change the pinion angle?

If your angles are right and the pinion bearings are fine, your only options are to either deal with replacing your u-joints all the time or go to a double cardan (CV) shaft. If you decide to stick with your current situation, spicer u-joints will last longer than any of the others.

CTM makes really strong u-joints, but they don't last very long due to their bushing (rather than roller bearing) design. They don't make them in driveshaft u-joint sizes either.

 

[JEBSR]

With no more lift than you have you shouldn't be eating u-joints so easily. My guess it that when you are accelerating you are getting bad axle wrap and killing them. That would explain the vibration while accelerating hard but not when driving normal.

DO you have blocks in the rear or is it an all spring lift?

If blocks, are they aluminum?

 

[Pvt. Maggot]

I'd say you need to shim the rear end, I did not, but had no noticable vibes. but I know I need shims, yours might be worse. if blocks, then it might be the axle wrap. you def should not need a new driveshaft for such a small lift.

 

[Chaddy]

I had the same prob when I first lifted my blaze.

I had to add 1 inch to the drivelines and put Spicer u-joints in them, then drop the t-case about 1 inch. Problem solved.