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Suspension thump


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#1 Phoenix1

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Posted 2 weeks ago

Not sure if this is the right board...

 

Recently on my 00' 3.8 Firebird, I've been hearing a single thump or knock when I'm accelerating from a stop, or after coasting. The sound seems to be coming from under the cabin or rear end? (I'm not the best at hearing) The thump can also be heard when the transmission shifts. Could it be engine/trans mounts, bushings? I'd appreciate your opinions about this.

 

Thanks



#2 ZumpTA

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Posted 2 weeks ago

I'd definitely inspect the mounts.  I'd check the engines too.  Then I'd move on to the other potentials.


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#3 sea dog

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Posted 2 weeks ago

Like tony said, check motor & trans mounts first. And this check involves actually  trying to pry up the motor & trans. This is because a visual inspection alone won't show a broken mount.

 

While your under there, inspect the torque arm mounting at rear of trans. It's mounted in rubber also. If rubber mount is shot, torque arm will bounce around. Rear attachment of torque arm is solidly bolted to rear end.

 

If exhaust system rubber mounts are bad, exhaust can bounce around causing thumps & clunks.



#4 Phoenix1

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Posted A week ago

I inspected the engine/transmission/torque arm mounts and found that they are okay. I went under and wiggled around the exhaust and checked the hangers and they were also fine. I now found out that I can replicate the noise by shifting to reverse from drive or park. The knock is definitely coming from the rear end. This confuses me, because isn't noise from the rear end normal for a RWD car? Then again, this thump manifests itself during shifts at a standstill or moving. Even gently accelerating creates the noise. I went under and wiggled around the exhaust and checked the hangers and they were also fine. I don't mean to nitpick, but the thump is worrysome. I appreciate the tips given to me. Can yall offer more? I hope this narrows it down some..



#5 Injuneer

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Posted A week ago

By “shifts at a standstill” do you mean you hear the clunk when you put the trans in gear and when you take it out of gear, as stated in the earlier part of the paragraph?  That sounds like excessive play in the u-joints or excessive backlash in the ring and pinion gears.

 

How many miles on the car?

 

And no, noise from the rear end is not normal in a RWD car.  From your description, it wasn’t making this noise previously.


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#6 Phoenix1

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Posted A week ago

By “shifts at a standstill” do you mean you hear the clunk when you put the trans in gear and when you take it out of gear, as stated in the earlier part of the paragraph?  That sounds like excessive play in the u-joints or excessive backlash in the ring and pinion gears.

 

How many miles on the car?

 

And no, noise from the rear end is not normal in a RWD car.  From your description, it wasn’t making this noise previously.

The car has 130,000 miles. I have noticed that the thump manifests when I put the car into gear, but not out of it. The thumping is the loudest when put in reverse, but out of reverse, nothing. Sorry, I forgot to include that I change the transmission fluid and filter about a month ago now.






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