Front driveshaft issues

I put my new gears in and was worried because my jeep developed a rumble vibration coming from the front at 70 mph. The more I thought about it though, the less it seemed like something caused by the gears. I realized that while the driveshaft hasn't changed and there wasn't any vibrations before (why I didn't suspect it before now), it is now spinning like 30% faster than it did before. When I checked out the shaft, it seems there is some play at the slip joint. I figured it was either this or just poor factory balancing that was causing the problem (without it my car was buttery smooth).

Is this play normal? If not, can it be fixed? Would it be worth having it balanced before I fixed the play? Any advice welcome.

Thanks a ton,
Marcus

Pull it first and make sure that's the problem. You shouldn't have much play, but I've ran them with a fair amount with no problems.

If the vibes or noise goes away then take it to a shop and let them look it over.

Later,
Lincoln

I agree with Lincoln. Pull it first and drive it. Do you have a Locrite or Detroit in front? The front shaft shouldn't be spinnig if you don't. (NP 231) The rear shaft might be the problem. How much lift? SYE? How many miles on the u-joints? The stock shaft will still vibrate at 2" lift. My old Rancho kit did. Good luck, Chris

it is now spinning like 30% faster than it did before

Click to expand...

how do you figure?

just curious.....

what was the old tire/gear combo and what is the new one?

chances are, the driveshaft is spinning about the same compared to vehicle speed.

which driveshaft is spinning faster?

a. 28"-3.55 or b. 33"-4.11


answer: both ratios almost perfectly the same....

don't know if you've done something different, just wanted to throw that out there.

XJCHRIS said:

Do you have a Locrite or Detroit in front? The front shaft shouldn't be spinnig if you don't.

Click to expand...

Of course it spins. He has a '99. DaimlerChrysler stopped using front axle disconnects on the XJ in 1991.

I already pulled it, I put that near the end of the first post, but I realize now it wasn't clear.

Beez- This is how I figured:

For the last year: 3.55, 32s
now: 4.56, 32s

I think it comes out to like 28% faster or something like that, please correct me, my math isn't the best.

I guess I'll just take it to a shop and have them look it over, thanks for the advice guys.

Marcus

It could also be your angles, and the lower gearing puts it over the edge in the vibration category. I had terrible front vibes on my '97, and it was angles. Look at that first...your '99 front shaft shouldn't be worn out. Anything more than three degrees is going to vibrate.

Nay

I was thinking that the ratio between gear and tire remianed close to the same, but I guess if you look at it, when you put on those 32's and DIDN'T gear right away, your driveshaft was spinning a little less relative to ground speed.....meaning, you kinda' temporarily slowed it down a wee bit

basically, what its doing now is fairly close to what it was doinf when your rig was stock......I know I'm pointing out the obvious, just was trying to say that ya really can't blame your driveshaft problems on revolutions per se, its gotta be something else

Nay-
What did you do to correct your front DL vibe/angle issues on the '97?

beezil-

Ya, that's a good point. I really hadn't even given much thought about the cherokee when stock, because it wasn't lifted and therefor the situation was different (where as, when the vib started, all that had changed was the gears). But ya, it is spinning much like when stock, and if it didn't vib then, so it might be something else like angles. EXCEPT that with the skyjacker subframe and mid-length arms I'm using, the driveshaft is to short. As the front droops, it maxes out the shaft, which limits the travel... so I wonder if that is what has caused the extra play.

The angles really aren't bad though. I run less front caster in order to keep the shaft lined up and it is pretty close to have no angle at the u-joint.

marcus