Sound/clunk during forward weight transfer

Hi all, I recently posted about my engine mount troubles caused by my attempt to track down and remove a unwelcome clunk in the engine compartment when the weight of the car shifts forward (think braking and downshifting). I finished the engine mounts, but it remains. To help with diagnosis I can tell you that within the last year I have swapped out my sway bar bushs, links, LCA's w BJ's and Bushes, new steering rack w new inner tie rods (not out), and front struts with their respective mounts. I have come to the end of my amateur attempts to find and vanquish the noise, any help would be appreciated, I'll take it to a professional monday if it persists.

Can you produce the noise if you make the car jump in reverse? Just wondering whether the CV joints might not have been swapped from side to side.

Other things:

Down pipe.

Brakes.

UhOh said:

Can you produce the noise if you make the car jump in reverse? Just wondering whether the CV joints might not have been swapped from side to side.

Other things:

Down pipe.

Brakes.

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Forgot to add that I did my pads, rotors, and soft lines last weekend. Sound was occuring before and since the work. I honestly havent tried to produce the noise in reverse (usually don't go over 5), but on the rearward weight shift (accel) I can feel a slight "thud", but its not audible, and not as bad as forward. I'll try reverse tomorrow, and what should I look for on the downpipe? The flex adapter is known good with no popped wires but aside from cursory glances I don't really inspect my exahust regularly.

You'd mentioned engine mounts, did that include the trans mount and dogbone mount?

Exhaust is a matter of any rub marks. Something is being pushed past its intended travel.

What trans?

Manual Trans, 5-spd. Both main mounts (engine and trans) were replaced along with their respctive TTY bolts. I didnt replace the dogbone but it was removed and inspected. Rubber was slightly cracked but it didnt move around when played with. I'll look for rub marks definitely. Been reading up on the CV joints you mentioned, do you think a rebuild or axle swap is smarter?

I'm not sure if a visual can rule out a bad dogbone or not: others have more experience on this.

On the CV joints, wait until you know you've got a bad one. What I was going with when bringing up CV joints is that sometimes folks swap the joints (only) from side to side, which effectively turns the joints around and thereby presents what should be a non-galled surface for the balls to press against when going forward: the galled surfaces are now only apparent when going in reverse (something that folks don't do a lot of, and not at high speed!).

Can you reproduce the sound with the trans in neutral (or clutch pushed in)?

Oh yea, rolling neutral I can gently tap the brakes and clunk along at a merry speed. I'll ask my parts guy about new dogbone bushes.

reildawg said:

Oh yea, rolling neutral I can gently tap the brakes and clunk along at a merry speed. I'll ask my parts guy about new dogbone bushes.

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Just so I'm understanding correctly, with no load on the drivetrain you can make the same noise? If this is the case then it has to be suspension (or brakes).

Is there any chance that the sound could actually be coming from the rear?

I recently diagnosed bad LCA bushings on my car. Early on I was trying to ignore the sounds, afraid that they were CV-related. About the time I'm figuring I need to make up my mind on how to deal with bad CV joints I discover that letting off the go-pedal and or hitting the brakes would also make the noise. A kind of grinding noise. LCA bushings!

Someone recently posted a problem that occurred after installing new LCA bushings. One of the rears pushed itself through the control arm! An issue with the hole or the way the bushing was pressed.

Roger, I have an extra set of febi LCA bushes, so maybe I'll install those and recheck before worrying too much.

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Is there any way you can tape a phone or camera down there and see whats going on. Refreshing suspension parts if they were worn out is one thing, but it sounds like you need to pinpoint it.

I technically could, but I dont have a go pro and dont want to risk my only cell phone. I took it to a friend who happens to be a professional today for a diagnosis and he also thinks it in the shafts. I'll pull the one from my spare jetta and see what happens.

Looking forward to hearing how the shafts can contribute to making noises when the drivetrain is essentially free-running. Love reading here, learn new stuff every day!

I just recently replaced my LCA bushings to the audi TT bushings and am now experiencing the same "poppish" noise when weight is transferred (hard acceleration or quick braking). I did a quick check and all bolts are still tight and did not notice any play when prying on LCA or tie rods. I am throwing this out there because the only thing I just changed was the Control arm bushings and the tie rods. This makes me think its not your shaft. Let me know your findings as I, too am at a loss for this new noise.

1998TDIMonster said:

I just recently replaced my LCA bushings to the audi TT bushings and am now experiencing the same "poppish" noise when weight is transferred (hard acceleration or quick braking). I did a quick check and all bolts are still tight and did not notice any play when prying on LCA or tie rods. I am throwing this out there because the only thing I just changed was the Control arm bushings and the tie rods. This makes me think its not your shaft. Let me know your findings as I, too am at a loss for this new noise.

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UPDATE: to wohoever runs into this issue of a clunking noise during weight shifting, make sure the front and rear LCA bushing bolts arr torqued down properly and the three triangle patterned bolts on the control arm are tightened fully as well. This cured my fromt end clunk.

UhOh said:

Looking forward to hearing how the shafts can contribute to making noises when the drivetrain is essentially free-running. Love reading here, learn new stuff every day!

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Its the CV joints getting flat spots.