PDA

View Full Version : Front Drivehshaft Vibrations - What am I missing?



dondandd
01-05-2006, 01:34 PM
Just as and FYI, my Jeep is sitting at about 4.5-5" of lift, 231TC, HP30 front end, and the stock double-cardon front driveshaft. 4.56 gears were installed a year ago, so pinion bearings are in good shape. TC front output shaft bearing was replaced over the summer... although it didn't have a lot of slop, it had a little and I replaced it anyway.

I have narrowed my vibrations down to the front driveshaft. Without the front shaft, the thing drives perfectly smooth at any speed. As soon as I throw the front driveshaft back in, vibes start at about 65 MPH. Usually under 60-65, I don't notice anything. The vibes do seem to oscillate, as in they get loud, soft, loud, soft, all while holding a steady speed. They also seem to get worse while accelerating (even in 2wd).

I've had this problem for a while, which I think eventually led to the slip joint on the front shaft wearing out. I replaced the driveshaft with a junkyard shaft. The joints all felt good, and the slip joint was tight. I had a shop check the shaft and they said it was true and balanced. I have custom long arms in the front, so the pinion angle is easily adjustable, and it is within 1 degree or less of being zero. I tried indexing the driveshaft (rotating each end of the driveshaft 180 degrees, 4 combinations) and still no luck.

Finally, after driving with vibes for long enough on this shaft, the slip joint is worn out again! I have another shaft waiting (used again, but seems in good shape, though haven't had the balance check yet), but I don't want to install it and destroy another one.

Is there something I'm missing? Am I running at too much of an angle for the stock double-cardon joint? Is it possible to have a bad yoke? Is there another angle I need to measure?

Sorry for the long post, but I'd appreciate any help and suggestions!
Thanks very much!
Don.

Kraqa
01-05-2006, 05:45 PM
weird. i don't know what to say. this happend to a guy on the local board and it turned out to be the drive shaft. he went through three of them. all three were supposed to be balanced. the third one finally gave him not vibs.

instead of buying more junk yard shafts why not send your truck in and have a custom front one built. they will garuntee no vibes and it will be the last shaft you ever have to deal with.

dondandd
01-06-2006, 04:27 AM
Hmm, three different driveshafts, yeah that is sounding familar to me too! I guess since I already have it, I could try my thrid driveshaft and see if it works or not. If that doesn't work, getting a custom built one is sounding better and better. During the summer I can deal with taking it out and putting it in when needed, but in the winter, snow can strike anytime and I'm getting tired of having to put it on in the snow, and then deal with the vibes!

Thanks for the reply!

Anyone else had any experiences? Problems with stock driveshafts?

Don.

K2
01-06-2006, 05:51 AM
This will sound stupid but this was very similar to me. 4.0 swapped in 242 and a u-joint ds. I had a vibe in the ds. I had it ballanced it soon was out again, I had it re-balanced. It was ok then same thing. I would take it out and I was driving fine in 2wd. Has to be the ds. I was getting bad wear on the front tires so I checked the toe, it was way off. I fixed it and my "ds vibe" went away. I cant explain it as it doesn't make sense. Call me a noob moron whatever, this is the truth. Check that out could be similar. good luck.

K2

dondandd
01-06-2006, 12:58 PM
Thanks K2, I'll double check my toe in case its something wierd like that. I've acutally been meaning to check my axle alignment under the Jeep, just to be sure its sitting square, although I don't know why it wouldn't be.

Don.

nate
01-08-2006, 05:19 PM
Is the front output on the T Case tight? I'm assuming it is, put it's just an idea.

I had the same problem with my rear driveshaft, and it ended up being the Hack and Tap SYE.

Krash80
01-09-2006, 02:52 AM
I've never heard of any custom d/s builder "guaranteeing" that your vibrations will go away if you buy one of their shafts.

Regardless, some vehicles just simply can't get rid of d/s vibes no matter what you do to them. If you've checked/replaced/balanced/etc everything connected to that shaft and you still have vibes, I'd start looking for a manual hub kit or a whole new front axle w/ manual hubs.

-Ron-

PhilZJ
01-10-2006, 04:59 PM
I have exactly the same problem although I haven't gone to the double CV DS yet.
The vibe is exactly like you said - nothing at all until 55 or so. But by 65 - 75 full deep, cycling, low harmonic vibration smears the mirrors. Disconnect the front DS and totally goes away.
I've had my front DS shortened, balanced, new u-joint. Adj control arms tinkered with to set pinion angle.
Still there.
Options:
1. Go to a Tom Woods Double CV shaft. - expensive, no guarantee
2. Longer UCAs. - custom, expensive, no guarantee
3. Warn Hubs - locking - guaranteed to work, loose ABS - could care less but NJ inspection might think otherwise. My driver side wheel bearing is beginning to go anyway.
4. Disconnect front driveshaft on trips. - Nuisance but works!
5. Lower ACOS reduce pinion angle. - no guarantee, loose clearance but I can change it back if it doesn't work, won't fit 33s.
6. Front Long Arms - didn't work for you!

So checking out Tom Woods DS but strongly considering hubs.

Phil

nathaniel
01-11-2006, 01:39 AM
Vibes like that could also come from the gear setup or gears themselves.

dondandd
01-11-2006, 09:01 PM
Thanks very much for all of the suggestions.... I appologise for taking so long to get back to this post to respond.

Nate, I'm am almost 100% positive the yoke is tight, as I had vibrations before and after replacing the front output shaft bearing on the TCase, and I know I had that nut cranked on there when I reinstalled it. Never the less, I'll double check to be sure that something hasn't changed.

Krash - The manual hub kit has crossed my mind. Although the 30 is holding up for me now, maybe it is time to start looking at a D44 upgrade. I would much rather get out of the Jeep to lock the hubs, than have to reinstall the driveshaft!

Phil, thanks for the list of ideas! The warn hubs wouldn't bother me, since I don't have ABS anyway after my 8.8 install (plus the ABS system was about dead anyway), I just can't swallow that $1000 price tag yet! It definitly sounds like you have the same problem I do. Its frustrating, but I guess I've gotten lucky and never had to deal with death wobble either, so this is payback. Like Krash had mentioned, which sounds like a good idea for me, is to upgrade the front axle to something that already has lockouts, like a D44. It sounds like a good excuse to upgrade!

Nathaniel, I'd hope it wouldn't be the gears, as they were redone (new gears and bearings) less than a year ago. Although, trying to think back, I'm pretty sure I had vibes before doing the gears, but I can't remember how bad they were. Is there anyway to really isolate the problem to the gears themselves?

Although this "new" driveshaft looks good, I think I will tear apart the double cardon joint to make sure it's really in top shape. Previous shafts, I've just "felt" the joint to make sure it was free, but maybe just refreshing the joint will help anyway. Otherwise I'll just have to keep removing the shaft until I can either get lockouts on the D30, or upgrade to a D44.

Thanks for all the suggestions! Phil, hope you can figure something out with yours.... I understand the frustration with this.

Don.

nate
01-11-2006, 09:21 PM
Bring the driveshaft to a driveline shop and have them balance it. It's normally only $20-30.