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Old 09-23-2007, 06:33 PM   #1
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Default Odd thump under car

For awhile now the wife has complained that every so often she hears and feels a thump under the car.
I've looked underneath but can't see anything obvious. Today I heard and felt it myself, it'* just as if someone hit the floorboards with a rubber hammer.
Any ideas as to what I should be looking for?
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Old 09-23-2007, 06:39 PM   #2
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Look for any small animals near the road on the way to work.

'94 Bonnevilles have been known for this issue.
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Old 09-23-2007, 07:00 PM   #3
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Check the cradle mounts.
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Old 09-23-2007, 07:55 PM   #4
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Yeah, the first thing I'd check is the subframe mounts. I looked under my '96 a couple of weeks ago, and one of the big washers was just hanging there!

Further inspection revealed that another one was missing altogether. The bolts were there, but the washers had rusted out. Scary. All fixed now though.

Otherwise, the small animal theory seems reasonable. In this case, there is often evidence left behind in the form of fur, or sticky liquid residue, on the underside of the car. Sometimes the "Thump" is also accompanied by a "yelp", or "squeak".
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Old 09-23-2007, 08:02 PM   #5
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I've pretty well ruled out small animals. As for the wifes complaints, I can't be sure but when it happened to me it was in town, I was making a slow left turn, no animals visible except one ricer in the lane next to me.

I looked at the sub frome mounts a few days ago, all looked good, No rust anwhere on the car actually.

What and where are the cradle mounts?
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Old 09-23-2007, 08:10 PM   #6
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That'* creepy. I heard a rather loud bang while making a slow left turn, just before I found my busted washer. Did you look hard? The rubber part was still there on mine, so it looked like the washer was there.

Otherwise, could it possibly be a strut bearing? Sometimes those get worn out and clunk while making a sharp turn.

Cradle mount/subframe mounts are the same thing, different name. Sorry to confuse.


EDIT: Oh, another thing that comes to mind, since it thumped while turning: Check your sway bar mounts and end links. Those will clunk too if they are broken or even loose.
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Old 09-23-2007, 08:19 PM   #7
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Just ran the car up on ramps and crawled around underneath with a pry bar. All the mounts are tight, rubbers are in one piece and where they should be. End links and sway bar mounts appear to be in good condition also.


I'm thinking it'* time to find a hoist and have a real good look under there and find out what'* going on, this crawling around in the dirt is for the younger guys.
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Old 09-23-2007, 08:59 PM   #8
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Hang the front suspension and check your ball joints. Also check your tie rod ends and your strut mounts for wear.
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