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Intermittent clunking sound from rear


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17 replies to this topic

#1 Tom63050

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Posted 22 July 2007 - 09:34 PM

Got a question about a puzzling situation with my Loyale. Sometimes, not always, when I'm driving straight there is a clunking sound from the rear of the car, that changes with speed. Slow speed, slow clunk; speeds up when the car does. If I turn left or right, it goes away then comes back when I straighten out.

When I had a left wheel bearing go in my VW van, the noise went away only when I turned left, i.e. took the weight off the left axle as the body rolled right. That noise sounded like an aircraft propellor, though, a constant noise, not a clunk clunk clunk.

Looked under the car and didn't see anything loose. Any ideas? BTW it does have a lift kit on it.

#2 nipper

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Posted 22 July 2007 - 09:36 PM

Check the universal joints in the driveshaft.


nipper

#3 Tom63050

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Posted 22 July 2007 - 09:53 PM

Check the universal joints in the driveshaft.

nipper


Thanks, good thought.

#4 zyewdall

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Posted 22 July 2007 - 11:07 PM

Check the universal joints in the driveshaft.


nipper


Second that. On mine it was a light vibration vaguely from back there, and then one day it became a very very loud clunk at speeds under 5mph, that I thought was a loose wheel or something -- when the center carrier bearing completely died, and at low speeds the driveshaft was sagging and flopping. At higher speeds it would straighten itself out from gyroscopic force.

I'd also check all the parts of the lift kit for looseness. Rear diff hanger etc. You might have to jack it up so the rear end is hanging to get a good check for loose stuff, as some might appear tight when weight is on it.

Z

#5 Tom63050

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Posted 23 July 2007 - 09:47 AM

Second that. On mine it was a light vibration vaguely from back there, and then one day it became a very very loud clunk at speeds under 5mph, that I thought was a loose wheel or something -- when the center carrier bearing completely died, and at low speeds the driveshaft was sagging and flopping. At higher speeds it would straighten itself out from gyroscopic force.

I'd also check all the parts of the lift kit for looseness. Rear diff hanger etc. You might have to jack it up so the rear end is hanging to get a good check for loose stuff, as some might appear tight when weight is on it.

Z


More good ideas! I think it may well be the driveshaft carrier bearing. I got under there and rotated the driveshaft about 1/8 - 1/4 turn or so, but didn't notice any unusual play, like side play, in the u-joints themselves. But I'm not sure what to look for. Any tips?

Regarding the lift kit, later I will jack it up and see if anything's loose. But I doubt that's it, because it seems to me that you wouldn't get the clunking from a loose lifting block or shock extension while just going down a smooth road, because weight is on it. Especially since the clunking increases or decreases directly in relation to vehicle speed. But I'll check.

A temporary fix would be to just remove one rear halfshaft, to prevent the driveshaft from rotating. Or to remove the rear half of the driveshaft itself, leaving the front half and the carrier bearing. That way I could test to see that it was really there that the noise is coming from. But if I do need to eventually replace the carrier bearing or u-joints, how do I go about it? I can remove the driveshaft of course and take it someplace, but can I reasonably do the bearing and/or u-joints myself? And what is the typical lifespan range for the carrier bearing/u-joints?

Also, I have a spare driveshaft that came with the D/R 5-speed I bought off a guy. IIRC it would be an exact replacement for my stock Loyale S/R 5-speed driveshaft. True or false?

#6 Tom63050

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Posted 23 July 2007 - 04:30 PM

Bump.

#7 nipper

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Posted 23 July 2007 - 04:35 PM

no bumping, i just got notice the thread updated :-p

I cant tell from re reading the posts, is this 4wd (press a button) or awd.
Auto or manual?

Is the clunk hollow or solid sounding.

Do you have a LSD?

Yes you checked the uni's properly. You look for movement in the x and y axis. There should be none.

What kind of brakes are on the back of the car and how old.

If you lightly apply the parking brake, does the noise go away?


nipper

#8 Tom63050

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Posted 23 July 2007 - 05:23 PM

no bumping, i just got notice the thread updated :-p

I cant tell from re reading the posts, is this 4wd (press a button) or awd.
Auto or manual?

Is the clunk hollow or solid sounding.

Do you have a LSD?

Yes you checked the uni's properly. You look for movement in the x and y axis. There should be none.

What kind of brakes are on the back of the car and how old.

If you lightly apply the parking brake, does the noise go away?


nipper


It's manual 4WD, pushbutton. Sounds solid (I think). No LSD. Drum brakes, about 12K miles on 'em. Braking with foot has no effect, probably parking brake doesn't either, but I never tried.

There's also a squeaky-rubber sound to it, at lower speeds. I wonder if it's a rear halfshaft? Thinking about removing the rear half of the driveshaft and driving it that way, to see if the sounds go away. Do you think this could cause a problem, with only the front half of the driveshaft in place, held in place by the carrier bearing?

#9 nipper

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Posted 23 July 2007 - 05:29 PM

How is the carrier bearing and transmission mount?

Is your 4wd working, meaning disengaged.

nipper

#10 Tom63050

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Posted 23 July 2007 - 05:42 PM

How is the carrier bearing and transmission mount?

Is your 4wd working, meaning disengaged.

nipper


The carrier bearing is my best guess as to the problem. Transmission mount is OK I think, no reason to think otherwise. 4WD is disengaged.

#11 86BRATMAN

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Posted 23 July 2007 - 06:09 PM

I'll go ahead and say that the e-brake will have no bearing at all on the clunk as it works the front wheels. Check the bushings on the mustache bar, and the one on the front mount for the rear diff as well. It might not be a bad idea to check the rear halfshafts for excessive play as well.

#12 nipper

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Posted 23 July 2007 - 06:11 PM

I'll go ahead and say that the e-brake will have no bearing at all on the clunk as it works the front wheels. Check the bushings on the mustache bar, and the one on the front mount for the rear diff as well. It might not be a bad idea to check the rear halfshafts for excessive play as well.


I thought on a loyale it was on the rear.

nipper

#13 86BRATMAN

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Posted 23 July 2007 - 06:13 PM

They still use the same design as the ea81 and other ea82 stuff.

#14 Tom63050

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Posted 23 July 2007 - 07:29 PM

They still use the same design as the ea81 and other ea82 stuff.


Yeah, when it was suggested I didn't even think about the fact that the e-brake operates the front brakes.

I just removed the driver's rear halfshaft, which removes it and the driveshaft from the equation (open diff). Took it for a spin, the noise is still there. That's good news in a way--no driveshaft work. I thought 171K was too soon for driveshaft problems anyway. I had an 86 wagon with 220K when I sold it, never a driveshaft problem. Since it no longer seems drivetrain-related I'm not so worried.

Next (maybe tomorrow) I'll get under there and check the tightness of every bolt. But what still gets me is that the clunking rate of speed is in direct proportion to vehicle speed. Nor does it matter whether I'm in gear or coasting in neutral. Maybe I'll pull off the passenger side rear halfshaft too, but I really doubt that's the issue.

#15 nipper

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Posted 23 July 2007 - 07:42 PM

rear bushings or a broken strut?


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#16 Tom63050

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Posted 23 July 2007 - 07:51 PM

rear bushings or a broken strut?

nipper


My left rear strut is broken, but I doubt that's the problem here because of how the noise occurs. And when I rocked the car up and down right over that strut, it didn't produce any noise other than a sucking-shock noise. No clunks.

#17 nipper

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Posted 23 July 2007 - 08:01 PM

My left rear strut is broken, but I doubt that's the problem here because of how the noise occurs. And when I rocked the car up and down right over that strut, it didn't produce any noise other than a sucking-shock noise. No clunks.


Jack the car up on that wheel and physically shake the strut. It can be the strut or the tophat.

I hate noises. They are so hard to diagnose over the net.

nipper

#18 Tom63050

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Posted 23 July 2007 - 08:15 PM

Jack the car up on that wheel and physically shake the strut. It can be the strut or the tophat.

I hate noises. They are so hard to diagnose over the net.

nipper


OK, I'll get to it tomorrow. No tophat though, it's two bolts. They're tight.




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