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vibration & humming when on the gas

wgregt

NAXJA Forum User
Location
SoCal
1988 XJ. 300k+ miles. OEM tires, shocks, lift height, etc (I know...what fun is that?)

Last few days I've got a moderate vibration thru the steering wheel and body when on the gas. Coasting: doesn't do it. Braking: doesn't do it. Sounds like it's coming from the rear of the vehicle when the window down, but only when I'm on the gas. Also, heard some pretty loud squealing a few times when starting to move, which gradually progressed and got louder until I got up to speed.

Tires still have plenty tread, but the birth date on them is apparently beyond what Firestone accepts in order to honor my free rotation/balance/alignment agreement. I guess it COULD be one of those things, but I haven't hit any potholes or curbs, and usually when I go in to have the rotation/balance/alignment done nothing is out of place anyhow.

Logic tells me that it's not braking or shocks (brand new...about 500 miles on them maybe) since I'd have the vibes all the time it those things were going bad. Thought I'd ask for ideas. Transmission? 4WD case?

Thanks gang.
 
Anyone got a tranny shop they like in SoCal? Looks like my bushing on the transfer case has some play in it & needs to be swapped out too.
 
Hmmm....I was told it was the bushing where the drive shaft goes into the transfer case, but I suspect I'd replace the one on the rear of the transfer case as well.
 
Oh really? I was under the impression there are two seals leading out of the transfer case...one @ the front, one @ the back, each where a little short section of drive shaft joins the case. The front one has some play in it (I saw the tech move it by hand a bit) and he says it's leaking some as well.

I figured I'd have the front & the rear swapped out since I'm in there if it's not too expensive.

The front seal is only under torque/load when I'm in 4WD though, right? I had the rear u-joints swapped out yesterday, and it drives lots smoother now (no vibes), but I'm thinking I'll only notice improvement in the front bearing swap if I'm driving in 4WD, that sound correct?
 
I'm confused. Are you wanting to swap the bearings or seals?

The seals are simple to swap out and should only take YOU 30 minutes or so.

The seals are never under "load". And yes, the front shaft spins when you're in 2wd it's just not pulling because it is disconnected inside the transfer case while it's in 2wd.

If he moved the output shaft up and down by hand then you need to have the bearings and seals replaced. Might as well have him rebuild the case and make it new again.
 
My mistake. The bearings need to be swapped out. I guess I'm getting mixed up between bearings, bushings, and seals. The tech used all 3 terms mostly interchangeably.

In any case, would the transfer case need to come out completely in order to swap these @ each end? I talked to 3 shops today.

One said $500 to take it out, plus parts (seals, bearings, etc) to prevent the play and the leaking.

One said $150 total to swap the bearings, and the transfer case did not need to come out.

One said having play @ the shaft was normal and to leave it alone.
 
lol You need to find a 4th shop.

The guy that used bearings, bushings and seals interchangebly... Don't go to him.

To have the bearings replaced, if you insist on a shop, I would go with the second guy. The first one is extremely over priced and the third one obviously doesn't know what he's doing and didn't want to take the job.

You do not have to remove the case just to swap out the bearings. You can split the case in half with it still mounted. You can replace the bearings there.

I'm just curious. Are you not mechanically inclined at all? No time to work on stuff? Handicap?

This would be easy for you to do and a learning process. Take the whole thing out, spend your money on a complete rebuild kit and fix it. Take your time, read and do it.
 
LOL!!!

"Logic tells me that it's not braking or shocks (brand new...about 500 miles on them maybe) since I'd have the vibes all the time it those things were going bad."

Toss logic out the door when diagnosing an XJ!!!! XJ gremlins are too smart for that to work!!!!
 
lol You need to find a 4th shop.

The guy that used bearings, bushings and seals interchangebly... Don't go to him.

To have the bearings replaced, if you insist on a shop, I would go with the second guy. The first one is extremely over priced and the third one obviously doesn't know what he's doing and didn't want to take the job.

You do not have to remove the case just to swap out the bearings. You can split the case in half with it still mounted. You can replace the bearings there.

I'm just curious. Are you not mechanically inclined at all? No time to work on stuff? Handicap?

This would be easy for you to do and a learning process. Take the whole thing out, spend your money on a complete rebuild kit and fix it. Take your time, read and do it.

Interesting, I would think that it would take a full pull of the TC in order to use a bearing press to R&R bearings? But I have never torn a TC apart, yet.

Also, if the bearings are far enough gone to need R&R, there might be other issues about to cause problems in the case itself?
 
I'm just curious. Are you not mechanically inclined at all? No time to work on stuff? Handicap?

This would be easy for you to do and a learning process. Take the whole thing out, spend your money on a complete rebuild kit and fix it. Take your time, read and do it.


No, I'm very mechanically inclined. I'm a motorcyclist (5 japanese sportbikes) and I do all the work on them myself: valve adjustments, carb rebuilds, even a full engine tear down, head work, piston swap, big bore kit, tranny work, etc. I've got a full garage of tools too.

I do not however have a way to get the jeep up in the air in order to do any of the TC work.
 
Interesting, I would think that it would take a full pull of the TC in order to use a bearing press to R&R bearings? But I have never torn a TC apart, yet.

Also, if the bearings are far enough gone to need R&R, there might be other issues about to cause problems in the case itself?

I'd certainly WANT the whole thing down but I think I was leaning more towards him doing it without having to take it down. I was assuming he'd have to use a hammer and a center punch by the way he was talking about taking it somewhere. :shrug:


Naaahhhh...I'm stock on the lift, so I'd need something

How do you think all of us did stuff to the underside of their Jeeps? lol I WISH I had a full garage. I have a spot in the yard that has no grass from working on the Jeep. I don't even have a damn shade tree! I got plenty tools tho. If out Jeeps can go from stock to crawler in the middle of a dirt hole you can fix your t-case, Mr. Cycleman. :)

I hope you didn't take me as being an ass in the post you quoted. I just can't figure out how a perfectly capable man can't fix his own car.

Working at a parts store seeing grown men coming thru asking how to change a tire created that peev of mine.

Ramps, jack stands and jacks will do juuuust fine. Climb under the Jeep already and do something.
 
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