Brutal Driveline Vibrations

Karl

TJ Enthusiast
Joined
Mar 4, 2019
Messages
168
Location
Vancouver Canada
Notes:
97 TJ
Everything adjustable (8 control arms, front track bar, even sway bars)
4" lift
Transfer Case drop installed.
New tires with less than 1000km on them. Balanced with beads.

I've had all the tires balanced and had a full alignment done. I was in the shop when the alignment was all greened out to 0 degrees, however there is still a minor pull to the left (it's quite minor).

I am convinced it's from the driveline somewhere. Here's my symptoms:

Vibrates at high RPM's right before it goes into the next gear. This happens going into 2nd and 3rd. The mirror is fuzzy to look through and the steering wheel vibrates like mad. I even have to readjust my side mirrors some times. Smooths out once it changes gear.
Then at 80kph (50mph), it's just a wall of vibrations. Foot on the gas =constant growling vibrations at 50mph and above without going away. The second I release my foot from the throttle (during any vibrations at any speed), the vibrations go away and it coasts smooth. This is the main symptom that tells me it's drivetrain.

I suppose I need to remove the front driveline and and see if this gets rid of it. I already bought a SYE and rear CV driveshaft but now I'm sitting here thinking it's the front driveshaft. Do I need a motor mount lift if I get a new front driveshaft? Or is a motor mount lift redundant if I'm buying a front driveshaft?

Simply looking for a quick opinion on this being the driveline or some other thing I'm not thinking about.
 
Can you take pictures of your driveshaft angles? Both front and rear.

Even better, buy a digital angle finder and measure the angle between the differential pinion and the driveshaft both front and rear. For a CV driveshaft, this needs to be as small as possible, ideally 1 degree at the rear and less than 3 degrees at the front. In addition, you’ll need to measure the caster angle to ensure you don’t get unstable steering.
 
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With your caster "in the green" and a 4" lift you may have put too much angle in the front shaft. Steering wheel vibe would lead me that direction too. I'm sure the whole steering system has been gone through, including ball joints if you are getting an alignment to fine a vibe. Tire balance and swap front to rear has been done too?
 
Yes I’m 90% sure they went through it all. There is a Jeep guy who works at the shop and he was doing everything in his power. They had it for 3 days and charged me 3 hours of work. Pretty great treatment just because he’s into jeeps.
I had the balance done (again with beads) at Kal tire.

I’m sure the caster angle is fine as they just “zero’d” everything out but I agree, It makes sense that this has put strain on the driveshaft. Honestly if I can just buy a new driveshaft and put it in and be done with it, I’d do it. But I don’t want to spend the dough and find it unsolved.

Based on it happening right before it changes gear and when I release the throttle, must be driveline.
 
Vibrates at high RPM's right before it goes into the next gear. This happens going into 2nd and 3rd. The mirror is fuzzy to look through and the steering wheel vibrates like mad. I even have to readjust my side mirrors some times. Smooths out once it changes gear.
Almost sounds like you busted your harmonic balancer.

Edit: but I guess that wouldn't really be load dependent like you said
 
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Drivelines do not know what gear you are in. They only spin faster the faster you go. So if it vibrates at 3k rpm in second and goes away into 3rd gear that sounds engine related. The constant vibration above 50 sounds like a driveline issue. You have a tcase drop? At 4” lift I would suggest a SYE. Sound like a couple different issues going on.
 
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Other than something simple like u-joint is it possible your rear axle is rotating under load more than it should causing a big change in pinion angle. Loose control arm bolt or something like that?
 
Notes:
97 TJ
Everything adjustable (8 control arms, front track bar, even sway bars)
4" lift
Transfer Case drop installed.
A TC drop is seldom enough to eliminate the vibrations a 4" suspension lift causes. 4" is the height where a SYE kit should be installed into the tcase and the rear driveshaft replaced with a CV driveshaft from someone like Tom Wood's Custom Driveshafts at www.4xshaft.com. They also sell the SYE and CV together as a kit.

In the mean time we still need to see photos taken from the side of your rear driveshaft also showing the rear axle. We need to be able to see the angular relationship between the axle housing and driveshaft. With 8 adjustable length control arms I would be surprised if no one screwed up the pinion angles, especially in the rear.
 
A TC drop is seldom enough to eliminate the vibrations a 4" suspension lift causes. 4" is the height where a SYE kit should be installed into the tcase and the rear driveshaft replaced with a CV driveshaft from someone like Tom Wood's Custom Driveshafts at www.4xshaft.com. They also sell the SYE and CV together as a kit.

In the mean time we still need to see photos taken from the side of your rear driveshaft also showing the rear axle. We need to be able to see the angular relationship between the axle housing and driveshaft. With 8 adjustable length control arms I would be surprised if no one screwed up the pinion angles, especially in the rear.
Well Jerry, I will take that claim to fame. Did my Zone Offroad 8 arm adjustable kit. 3" lift, sye, Tom Woods driveshaft, removed tcase drop, moved rear axle back 1", front axle forward1/2", rebuilt front driveline. I used a digital angle finder and took my time setting driveline angle front and rear. I'm off .08 in the front and .03 rear. No vibration at any speed. Hell of alot better than when I bought it. Plus one handed driving at highway speeds.😉
 
The video here of going 1st to 2nd gear makes the vibration seem far gentler than it is. I never mentioned it’s an automatic (right hand drives only come automatic I believe).

Pagrey
I never even considered a harmonic balancer. That would typically make more noise than it would vibrations though I think? I’ll check it out.

Jerry
I have already ordered a SYE and rear CV driveshaft. My concern once it’s all here and installed is it will be the front driveshaft having issues. Should I bother with a motor mount lift if I get a front cv driftshaft?

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I have already ordered a SYE and rear CV driveshaft. My concern once it’s all here and installed is it will be the front driveshaft having issues.
You can remove the rear driveshaft and drive around in 4wd to see if anything changes. You can also remove the front driveshaft to see if anything changes.
 
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Wit your having a CV driveshaft I thought the transfer and diff are supposed to be as close to parallel as possible. It looks like your diff is rotated up as if you had a CV shaft which you don't. Those Ujoints are way out of phase. Willing to be wrong here. Someone with a bit more driveshaft experience can correct me.
 
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I believe all Wranglers have DC driveshafts. A MML is not needed IMO unless you are doing a tummy tuck. You could do it and it would slightly reduce the working angle of the new rear driveshaft.
 
All TJs have a DC front drive shaft. I think they all have regular shafts in the rear. Even my 06 Rubicon has a single joint at the transfer case and a single joint at the rear pinion. So does the OP. Difference being his slides in and out of the transfer case, mine is bolted to the TC output flange. This is why people switch to a Slip Yoke Eliminater. And then buy a DC driveshaft. If they already came that way stock we wouldn't see so many vibration problems.
 
DC driveshafts can work at higher angles. I switched to DC because the stock type DS was binding at droop. I had no vibration, but I had spacers on the t-case skid, aka shovel. I was able to get rid of the spacers and I plan on raising the t-case more and have a 2" drop Barnes skid for it, but not installed yet. LJs can get away with a little more because of the longer DS. Another advantage to a DC is it rotates the pinion up and is less likely to take hits in the rocks.
 
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Wit your having a CV driveshaft I thought the transfer and diff are supposed to be as close to parallel as possible. It looks like your diff is rotated up as if you had a CV shaft which you don't. Those Ujoints are way out of phase. Willing to be wrong here. Someone with a bit more driveshaft experience can correct me.
Hi sorry I should have been more clear. I have already PURCHASED a rear CV drive shaft and SYE. They have not been installed, the photos are factory. So they should be parallel currently.
 
So I was just at a buddies shop. I figured I’d ask him before pulling the rear drive shaft. He said he’s not sure I can do that with an automatic.

So can I pull the rear drive shaft and roll around in 4 high with an automatic?

Cheers