Knocking/thumping under car

[GSX26]

Hey Guys,

I've just been driving around and yesterday noticed a thump under the car. It seems to come from right under me or my legs. It only does it when you let off the gas and not all the time. I was wondering if anyone else has had this problem, or is it just a loose part or something? Thanks.

 

[blackGSX2g]

Check your motor mounts. When they go bad, you can often feel bad vibrations and clunking during engine movements.

If it really is coming from underneath you, check your driveshaft bushings. If the rubber in them goes bad the shaft can clunk when rapid torque is applied.

I would assume motor mounts first.

 

[sphinx0nine]

does it feel like its comming from right under the center console?
if so the problem are the carrier bearings of the driveshaft.
they are rubber and after a while they just wear and let the driveshaft run off center, hence the bumping.
There are two things you can do, iether get it off and replace them. keeping the same driveshaft.
Or do what i did, just got my hands on a used driveshaft and replaced the whole thing.

theres an article at vfaq
Vfaq article here

 

[GSX26]

Thanks for the responses guys. The noise is coming from right under the center console, I think. So you are probably right. What causes this wear and tear on it? Also, it sounds kind of like a pop noise. Is this accurate with this problem? And it'll only do it when I am accelerating and then let off the gas, either to shift or to slow down. How much are the replacements and how hard is it? Thanks again! Rep Point!

 

[GSX26]

I've been thinking about what else it could be/ or what caused it and I have a detail that might add to the scenario. I went into a ditch last Friday. It's all snow here and I'm still on bald summer tires (lack of funds ) It was a ditch that angled down and it was pretty deep. I ended up having to dig out the whole car about 2 feet around and then drove it out. Reverseing, going forward, rocking, using sand under tires, everything. I finally got out. Thinking about it, maybe I knocked something loose or broke something on the underbody? Could I have broke the carrier bearings or bushings (can't remember what they're called, sorry) by possibly bottoming out my car (even though I don't think I did). Thanks again guys! ALso, I know it's not the tranny, STage 3 shep tranny went in 3 weeks ago

 

[wingzgsx]

It could be your exhaust system might have shifted or "loose/broken hanger(s)" allowing the system to move more freely therefore rubbing up against the driveshaft during acceleration/deceleration.

 

[GSX26]

Thanks for the idea. I was also thinking it might be a loose exhaust. Would I feel it through the pedals or would the car jerk if it was those bearings? Because I'll look out for that next time I drive. It didn't seem like i could feel it, just hear it. I guess I'll jack it up this weekend, just trying to avoid it cause it's so damn cold!

 

[GSX26]

So if it is the bearings, is the only thing to do replace them? Or is there other solutions?