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-   -   Driveline Vibration Help (http://www.jeepforum.com/forum/f96/driveline-vibration-help-1555327/)

brianjw 07-29-2013 05:05 PM

Driveline Vibration Help
 
Ok I know there are enough vibration threads but hear me out. It's kind of long but I'm seeking advice on rear driveshaft replacement and pinion angle adjustment.

I installed my 3.5" AEV lift and 35s with about 700 miles on my jkru. Got a slight high frequency vibration at 65-70mph. The rear factory shaft angles look pretty good to me (factory control arms), angle out of the transfer case is straight (eye balling it) and the pinion angle is nearly straight, maybe pointed up ever so slightly.

So at that time I ordered a Tom woods front driveshaft (dual cardan 1310). I did notice a little bit of play on the output shaft on the front of the transfer case, but I compared it to other 2012s on the lot and about half of them felt the same. Anyway I pulled the front driveshaft, drove on the freeway and the vibration was still there. Installed the Tom woods front shaft, no change. So the front driveshaft was mainly replaced due to the angle after the lift anyway.

I rotated and balanced the tires, tried to eliminate other things. Didn't find anything, but the dealer told me that lots of people complained about similar vibrations on the new JKs so I just let it be as it was minor.

Now about 15k miles later the vibration seems pretty heavy when I was passing cars at 70mph this weekend. Enough to make me concerned about an upcoming drive from Portland Oregon to Reno Nevada. I do not believe it is coming from the front driveshaft. I have greased and re-torqued and check for play and haven't felt anything. The slight vibration really hadn't changed until it just recently got a lot worse. If I wasn't about to leave the state for two weeks for work I'd pull the driveshaft again to verify. But the bolts on the yoke end (TC side) are a major pain to remove and my neck problems were not allowing me to work on it when I tried this morning.

On the rear driveshaft, I do notice that the CV (rzeppa or whatever) joints do plunge in and out a little, but have no horizontal play that I can feel. I can easily slide the driveshaft back and forth a small amount due to this, and I can compress and extend the slip yoke a small amount with everything bolted in. Is this normal for these driveshafts? The whole thing feels a little loose to me, maybe I'll run to the dealer and compare...

Has anyone else had issues with vibrations from the stock rear on a four door with 3.5" lift? Did you install adjustable arms and the problem went away?

I'm not at all opposed to buying adjustable upper arms, but the angle is so near straight by looking at it, I wonder if 1-2 degrees will really make a difference with this style of joint? Anyone care to elaborate? What's the chance that the stock rear driveshaft is hosed?

I don't have a problem buying an aftermarket rear drive shaft either, but I suppose I will need adjustable control arms anyway to take out the very small amount of pinion angle that may be there. If so I'm looking at about $1k for a 1350 dual cardan and quality control arms. Which is okay if I can be certain this will fix it.

I'm hoping to hear some personal experience with this. Once I come home next time, I have 12 days at home to fix it, order a new driveshaft or do whatever it needs, then I'm back to work. When I come home the next time I'm packing and leaving for Reno immediately. I don't have much time for trial and error. I called six states in Portland to see if they could put it on a rack and diagnose it but they are booked a week out.

Thanks for any help.

brianjw 07-29-2013 05:50 PM

http://i462.photobucket.com/albums/q...r/null-543.jpg

Butterbuddha 07-29-2013 06:00 PM

I have just brought my jeep home today after 2.5 weeks at the dealer for a similar prob. I have Tom Woods front and rear, with a similar "pleasing to the eye" driveline angle. In my case, I got a rattle at about 45mph and up. As soon as I got off the gas it disappeared, and reappeared with accelerator pressure (even if I didn't speed up). Up on a rack, both driveshafts could be jiggled vertically a bit.


Turns out I got mud in my axle housings. Destroyed my crush sleeves, seals, and pinion bearings. Once the pinion bearing went, the ring and pinion started to follow. (Enough to require replacement)

I think I'm a more extreme case, but hey you never know.


EDIT:Your angle looks great to me, and I expect no less with an AEV lift kit.

brianjw 07-29-2013 06:22 PM

Thanks for the reply. I don't have any noticeable play at either of the pinions. No leaks. I recently changed gear oil in both axles and both ends were clean.

I took some video of the driveshafts driving around a bit and I do see some some pinion angle changes during acceleration but that's normal with the control arm bushings at certainly nothing that seems excessive. Although maybe it could be partially to blame if I'm heavy on the throttle trying to pass, with the pinion pointed up at a higher angle... I just don't know, I don't know what is normal for this style of driveshaft.
Bah. I'm not really sure what the answer is yet and I hate to just throw parts at it. I want to replace the control arms eventually, as well as the rear driveshaft, but due to a recent death in the family and taking extra time off work, changing plane tickets etc I don't have as much cash to spare as I normally would.

aznjeep 07-29-2013 06:23 PM

This vibration.. do you feel it more in the steering wheel, or in your seat? I use this to determine if something is coming from the front or rear. I see you have a pic of the rear pinion angle. Do you have a pic of the front pinion angle? I recall (on our 2010) that I had to point the pinion up a bit with the Tom Woods driveshaft to ensure the pinion was in line with the double cardan joint.

brianjw 07-29-2013 06:41 PM

Quote:

Originally Posted by aznjeep
This vibration.. do you feel it more in the steering wheel, or in your seat? I use this to determine if something is coming from the front or rear. I see you have a pic of the rear pinion angle. Do you have a pic of the front pinion angle? I recall (on our 2010) that I had to point the pinion up a bit with the Tom Woods driveshaft to ensure the pinion was in line with the double cardan joint.

Vibrations is in the seat/floor, high frequency.
The front end has the AEV brackets and caster is 4.2 degrees. The pinion angle isn't perfect but running no front driveshaft at all felt the same as running the dual cardan on it. The last time I had the front driveshaft out, the vibration was exactly the same so that's why I don't believe it's up front. Wish my damn neck and back weren't giving me such a hard time right now.

I really just don't want want to order either new controls arms OR a driveshaft and find out that I needed the other, or both. Lol. The metalcloak website says the control arms ship in a couple of weeks, so if I bought a driveshaft and needed them I'd be out of time. Maybe I can find someone to measure the pinion angle tomorrow before I leave...

aznjeep 07-29-2013 07:05 PM

Ah.. I may have missed that. Removing the front shaft is a good way of eliminating that as the culprit. I'm out of ideas... our 2013 has almost 1200 miles on it, and I just hit 75mph the other day. No vibrations, granted it's still stock at this point in time. The only vibration I get is coming to a stop and taking off (low speed vibration from the tire treads).

brianjw 07-30-2013 12:37 AM

Thanks for your input anyway man. That damn jeep is the most finicky vehicle I've ever had. Had so many other trucks that I lifted, ran bigger tires, locked, geared, whatever and were trouble free. This rig, brand new, has cost me so much money to keep it driving straight and running correctly. The stock setup just doesn't handle any mods without causing a problem somewhere else, very frustrating!

I'm going to make a few calls tomorrow and decide what to do. If I can find someone to check the balance on the rear shaft tomorrow I will but I hate to spend money on it. I will compare the factory front driveshaft I have in the basement. I may order a new rear shaft anyway since I knew how weak the stock one is, but I really want to know where it originates or why. Hard to imagine the problem is coming from a driveshaft with nearly straight angles and cv style joints on both ends. I don't see any missing weights but I did feel a veeeery small amount of lateral play in the slip yoke. Almost imperceivable but I do hear and feel a small click from the slip yoke when I push or pull in the center. I just wish there was a "smoking gun" like grease flying out from something.

I have had a minor tire balance issue I've tried to correct over and over but it moves when I rotate tires, and occurs at 55-60 rather than the 65-75 that I'm feeling, and at a different frequency. The tire balance is an obvious low frequency vibe and the drive line issue is clearly a high freq. It is very similar to a tail rotor vibration in a helicopter (spinning 2500-3000 rpm normally) which is right in line with drive shaft speeds for this rig around 70. I'm sure part of my problem is being very sensitive to these vibrations (I have to be to know what's going on with my aircraft), my wife doesn't notice it or feel a difference between this and the tire balance/round issue.

mello 07-30-2013 05:26 AM

Take it to someone with vibration analyzer. The tool/software combo is amazing. Will have to pay some diagnostic fee, but it is magic. I have used this tool a few times and it is very slick.

brianjw 07-30-2013 03:52 PM

I just ordered a new Tom woods rear driveshaft to match the front.

My pinion angle looks good so I'm not going to sweat it yet. If I get vibrations with it, I'll get adjustable control arms.

73azbronco 07-30-2013 07:10 PM

Watching.

Just lifted my new JKR 2dr with Teraflex 3 inch and 35 KMII's. Drives straight and true, Noticed no vibration until 69MPH, then audible low freq thrum/buzz which can be felt in floor between 69 and 74mph. No difference on accel steady or decal. I suspect tires are balanced, suspension is square. Only other suspect is driveline/driveshaft? Thoughts?

brianjw 07-30-2013 09:40 PM

Quote:

Originally Posted by 73azbronco
Watching.

Just lifted my new JKR 2dr with Teraflex 3 inch and 35 KMII's. Drives straight and true, Noticed no vibration until 69MPH, then audible low freq thrum/buzz which can be felt in floor between 69 and 74mph. No difference on accel steady or decal. I suspect tires are balanced, suspension is square. Only other suspect is driveline/driveshaft? Thoughts?

With a 2 door I would expect the rear driveshaft is on borrowed time. The front too, for that matter. The steep angles on the factory rzeppa joints on the driveshafts puts them in a bit of a bind. This in itself doesn't always create noise and vibration, but eventually the rubber boots rip and the grease flings out. Once that happens, the Rzeppa joints burn up in a hurry.

The easy place to start is to balance and rotate the tires again and see if anything moves or changes. If you have stock wheels and tires, run them again and see if it smooths out.

From there, remove the front driveshaft which is easy to do with the stock shaft. Mark the orientation first so it is reinstalled in the correct position for balance. If the vibration goes away with no front driveshaft, there's your problem. If it is still there, I'd suspect the rear.

But again with a 2 door, you'll probably need an aftermarket rear driveshaft before too long. You will need adjustable control arms to get the pinion angle correct on a 2 door with a dual cardan driveshaft.

I won't be home for another 17-18 days, but I'll report back and let you know if I just wasted $450 or not.

73azbronco 07-30-2013 10:16 PM

Thanks for info, since this is a dealer added lift via a local well known shop, I'll be taking it back to let them do the work. I know the front links are adjustable, not sure about rear ones, I'll find out. Either way, I'd expect it to not vibrate out the door from a dealer installed setup.

My view of the rear diff to driveshaft shows a significantly larger angle between diff and shaft. My lift is a three inch lift so do I really need to ask if a better driveshaft is in order? This has been a pretty standard dealer add on here for years, odd I would be one to find a vibration, then again, like you I'm picky about vibes. I ruled out tires because it only happens at one speed range, which in my experience points to driveshafts. Out of balance Tires tend to have bands of vibration?

4wdjeepguy 07-31-2013 07:30 AM

If the vibration is coming from under the driver's seat, it's your front shaft. Could be out of balance. Caster could be off...

73azbronco 07-31-2013 06:43 PM

Interesting day, on driving back to,shop, the speed the vibe occurs increased ten mph, so i figure I have a tire issue. Tires had 39psi, I lowered that to about 37 and most of the vibration has subsided. I also think the new tire nibs on the treads are causing some of this strangeness of vibes changing speed as more miles added. Shop wanted to take a look but was willing to let me keep it a week more before they dig into it if it doesn't get better. Ill,report back, thanks for help.


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