Rear diff vibe?

Hello all,

I'm having an issue with vibes 65+ and really bad in the 75-80 range. It feels like the rear diff. Here is the specs.

89 XJ 4.0 aw4 242 D30 front D35 trac-lok non c-clip rear TW sye 3.5 RE super ride 4 degree rear shims ~1 degree DS pinion angle for axle wrap. And no front DS at the moment. Also have stock gold spokelike wheels.

It's smooth as silk up to 65 then gets worse. I've replaced just about everything suspension related. The rear shackles are the only originals left. Also I have road force balanced all the tires. When I first got the jeep I pulled the rear diff cover to change the fluid and found one of the trac lok clips at the bottom. I had to replace the bearings, carrier and clutch pack. The ring/pinion and spiders looked fine as far as wear. I also have done all the eng/Trans mounts and cat back exhaust.

So the problem- at highway speeds it starts with a vibe in the back and I can start to see the spare tire vibrate. Then It travels through the body. The weird part is that it changes after a long corner on the highway, it gets better after a corner then gets worse on the next. It will also change once I get off a particular highway and get on another.

My thoughts-

The spider gears in the rear are worn at certain spots so that when the tires rotate on a turn it gets to the "sweet" spot. I didn't change them when I fixed the rear. Other than that maybe the shackles are causing the issue.

Just wondering if anyone else has had this type of thing.

Consider swapping the drive shaft to the front and drive it and see if it changes, or run a stock or other drive shaft. Just because it's TW D-shaft doesn't mean that it's perfect. If it is the shaft, I am sure they will take care of you.
Also, rotate tires and such?

Ultimately, anyone else will tell you to get rid of the Turdy5. I do agree, but aside from that there could be something else wrong.

With it not being all the time I would think its not the DS, it was the same before I did the SYE and Tom woods And it's not an accel or decel type of vibe.

What's the fluid look like? Ring gear bolts tight?

I know I need to pull it and look, everything was fine about an oil change or 2 ago and that's with it still doing the same thing. I had torqued all the ring bolts down when I put in the new carrier.

I would try swapping the driveshaft first. It could also be the axle setup or wheel bearings. Going around corners has an affect on the angles that the drivetrain runs at. I have a TW driveshaft on the shelf because I got tired of dealing with it. His customer service was excellent, he rebuilt and changed parts in it once at no cost to me but it was still not as smooth as a Spicer. I also noticed the corners thing. If a driveshaft is out of balance good enough it will vibrate the front doors, if its got less severe issues it can act like other problems.

Well, maybe replacing the axle with something better for a low price should be an option. No reason to spend money on a Turdy5.

Yeah I know I should swap it for a differ setup but I want to be sure of my issue before I do that. Just a piece of mind. Also I don't have as much of an issue in the corners, it's just after a corner it changes frequency and intensity till the next corner.

I just am not sure of how to measure the spider gear play or anything else that may be in play in there. I can do lash and what not but that's about as far as I go on axles besides bearings.

If the spiders or side gears look worn you could replace them. There are thrust washers behind the spiders. With the Track Lok in there everything will be tight if the clutches are good. I have had "liquid metal" come out of my differential from carrier bearing failure and the spiders and thrust washers looked fine and were reused. I would look elsewhere for your problem, consider the wheel bearings or driveshaft. Sounds like you already have a driveshaft to try, so its free. Wheel bearings and seals aren't expensive either. Keep in mind the wheel bearings are lubricated with the same oil as the differential so if you changed all that stuff because of contaminated oil then it'd be a good idea to change the wheel bearings too.

Bent rim or bad wheel bearing or something bad in the diff

md21722 said:

I would try swapping the driveshaft first. It could also be the axle setup or wheel bearings. Going around corners has an affect on the angles that the drivetrain runs at. I have a TW driveshaft on the shelf because I got tired of dealing with it. His customer service was excellent, he rebuilt and changed parts in it once at no cost to me but it was still not as smooth as a Spicer. I also noticed the corners thing. If a driveshaft is out of balance good enough it will vibrate the front doors, if its got less severe issues it can act like other problems.

Click to expand...

I too have a Tom Woods drive shaft in the rear of my XJ. I installed it at the same time as I lifted the XJ and did a lot more work to both front and rear suspension including re-gearing. I have been chasing my tail for years since then for the cause of a vibration that get worse as speed increases. I adjusted an re-adjusted everything except the drive shaft. After all, it is a Tom Woods it is perfect. Recently, I removed the driveshaft and laid it on the floor and noticed the 'U' joints were out of phase front to rear. I took it to a drive shaft shop and had them work on it and re-balanced it. That was about 6 months ago. I have not taken the XJ out since then so I do not know if that solved the problem.

I said all of that to say, Just because it is a TM drive shaft do not assume it is vibration free.

I am hoping that's not the case, but before and after the sye the problem never changed. Got slightly better even after the sye install but that was more in the low speed range. Also the speed of the vibration feels like wheel speed and not shaft speed. And honestly I would love toss this 35 in the trash but I've already put 400 into it just so I could drive it, this of course before I knew of the things it's been called. And I just want to figure it out really. I drive it 160 miles a day and it's beginning to beat me down every time I drive it. But then there is that 15-20 minutes of mostly vibration free unadulterated awesomeness that makes me remember why I love this thing. I also am trying to accept the fact that it's 25yrs old and it ain't gonna be perfect.

Anyway, I was just wanting to pick yalls brains and see if I was missing something. Thanks everyone for the input. I'll start digging into it next week when it gets some down time.

First things first spider gears don't move or turn in the carrier going straight down the road. They only turn in the curves. If you had a bent axle flange, that would be make the wheel and tire wobble all the time. If the rear axle was causing the vibration either the carrier or the pinion gear would have to be loose. I see this a lot with pinion gears. Either the bearings come apart or the pinion nut starts to back off.

Yeah it's a wierd deal, I know that the axle goes into the spider and I thought maybe it was worn in the carrier at certain positions that would allow the axle to wobble on the spider side. I really need to pull it apart again. But I am beginning to think otherwise as it would have detonated by now or gotten worse. But it's been the same for about 15k. I am going to give it the once over this week. I've also swapped axles shafts with no change.

I just rotated the tires and the rear vibe has seemed to have died down. It must be a wheel. I've balanced all of them myself and looked them over but can't see any obvious problems. But gives me an excuse for new wheels which I've been wanting anyway.

Well I've had a few observations over the past few drives. The problem seems to be temperature dependent. When I drive to work with the temps in the 80s I get the dancing spare tire. On my way home when it's in the low 70s it's mostly solid as a rock. I do have a front vibe but I attribute that to a tire. I swapped the rim in the front for the spare and that had seemed to help.

Any ideas?

Got my new wheels on and replaced the sway bar bushings. I found the bushings were sloppy when I was working on it last and was hoping that was something. But I still get the vibe. Still trying to figure this thing out. Also replaced the calipers because of some rust in the fluid that was coming from the inside of one of them. I thought that maybe one might be hanging at times. But no real change with that either.

Pressing on.

Replaced the tires finally!, I'd say it got 75% better. I'm still amazed that the old tires still looked good but were wreaking havoc. I still have a slight vibe going at high speed but I think that may be the drive shaft. I'll play with that some more to see if it helps. As of right now the front is fine and just a small but annoying amount from the body/rear. I think they were all playing together to create a mega vibe.

Could happen, front and rear vibes can combine to make a real problem...