mystery noise

[rge748]

I have a noise coming from behind the seats on my 2.8, possibly from the roll hoop-subwoofer-seat belt tensioner enclosure. Its a dull 'thunk', not necessarily something loose but two things too close to each other. On rough roads I get a stuttering "thunk-thunk-thunk, thunk-thunk" corresponding to the road surface. When the car hits a major bump, there is a single "THUNK!", considerably louder than the stuttering thunks. Just to make it more interesting, this seems to happen only when the top is up. I've done a cursory inspection of the top frame and found nothing loose, but I could be wrong. Anyone have a similar gremlin or able to offer a fix? Thanks

[@ MinnMark]

Check your upper strut mounts. You can do some inspection from the bottom in the wheel well, but you should also pull the liner in the well behind the seats and look at them there. You likely won't see anything, because most of the time when they are shot it's the internal bushings.

So, while you're at it, just replace them with Meyles or some other heavy duty mount! That's the best thing to do!


MinnMark
'00 2.3 Oxford Green/Tan/Tan
And yes, I drive my car in the snowy winter!

[rge748]

While peeling back the carpet in the top well, I reached underneath and felt something loose. I pulled it out: a lead weight, about the size of a hockey puck with a slot up the middle of about 1/2 inch. Thought it might be some sort of counterweight for the top. Went for a drive and...no more 'thunk'. I've looked at parts diagrams for this area and can find nothing that resembles this thing. Huh?

[scottpettit]

If he has pulled out the object that he described, it doesn't sound like it is the RSM and, if it was, the shock would no longer be attached to the car.

Also, as far as I know (which most folks will say is not much) the top does not have a counter weight. At least, mine doesn't.

Could it be a dead magnet from a speaker?

By the way, if you are in Northern California, I'd be happy to let you use my lift to check out the shocks.

Scott Pettit

[@ MinnMark]

No parts back there that I know of that resemble that at all!

I wish all clunks and rattles were that easy to find and eliminate....


MinnMark
'00 2.3 Oxford Green/Tan/Tan
And yes, I drive my car in the snowy winter!

[Giznaz]

of the Captain's stateroom in the Coast Guard. Drove him NUTS.

[Bob S.]

u-joints are shot. I had the same sound and chased it for over a year before I found it. The u-joints wear out and then they intermittently lock up [thunk]. Now if you have very low mileage I would just consider this the ramblings of a silly old man.

[s-retire]

in the fire house

[st-pete-z3]

There is a charcoal canister behind the seat between the trunk & driver’s seat. Not sure what it is for. One time had work done and they forgot to reattach it after removing it to get to something. Possibly it is a strap that holds it and yours broke. Just a thought. Honestly I looked, but I couldn’t see it, but the dealer said so.

[rge748]

xx xxxx xx
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x xx x x xx x
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x xx x x xx x
x x x x
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x x x x

Here's a crude drawing of the object. Diameter = 4 in., thickness= 1 in., slot extends 3 inches from the edge radially and is 1/2 in. wide. Seems to be made of lead, weighs about 5-7lbs and looks like its been bounced around a bit -- several circular indentations of various sizes on both sides of the object, no more than 1/16 in. deep. One other clue: previous owner had the top replaced immediately before I bought the car. Maybe whomever installed the top wanted to have a little fun with her...Last night I drove over a particularly rough road nearby; no "thunks", nothing fell off the car, smooth and quiet as the day it left the Werkstaat.

[rge748]

Sorry -- the drawing didn't work; dimensions are correct, though.

[stluciez3]

Not having installed a top (not wanting to, also) I don't know what sort of tools are involved, but a piece of lead is handy for use as either a backing anvil or for striking in a restricted space.

How about stopping by the shop that did the top and see if they claim it?

[rge748]

Judging from the indentations and general appearance and weight of the object your theory makes perfect sense. Its not a BMW part -- unless they're going for the "distressed" look now. I'll see if I can track down the installer...