"thump thump thump" under acceleration

[KooLaid]

When i accelerate moderately, not lightly, not hard, just sorta under medium acceleration I get this thud thud thud or thump thump thump sound. It's very similiar to the sound of patting your hand hard against the fender of the car. It only does it under acceleration, and most noticeable in 2nd gear when the motor is quiet and road/wind noise is minimal, accelerating in 2nd from 2,000 rpm or so. I can't tell for sure if it's from front or back but I'm guessing it's back. Since it's only under acceleration. There is no vibration or shake, just noise. All I can figure is it's someplace from flywheel to one of the rear hubs. My grease boots are intact. There is no play in the wheel bearings. Any ideas?

 

[jeffchai]

motor mount may be?

 

[KooLaid]

Maybe, I didn't look at those. I've broken a motor mount in my truck before and it basically slams down. This doesn't slam. I'd say it'd be like having a rock stuck in your tire only it doesn't click it goes thump thump thump and only occurs under the right acceleration.

makes me worried hoping it's not the tranny or diff............


also there's no "squeal, woosh, click, bang, clank, screetch, etc". Just a sound similiar to patting your hand on the car's fender. There's nothing on the tire hitting the fender either. Not brake pads or rotors. Not tires.

 

[nsxot1c]

try jacking up the car, and letting it run in gear and sort it out. Possibly even remove the rear wheels and take a look in there... that's what I had to do.

 

[Synthesis]

got me...
i hope you find it soon....

 

[KooLaid]

Did a little experiment. In any gear it makes the sound apparently, but in 1st gear I'd press down on the brake pedal to put pressure on the drivetrain and the noise gets louder as I press down the brake and gas harder while the car rolls along. It's most noticable from 1500-2500 rpm. Can't tell which side it's from but definitely from the rear.

Is there any way to distinguish a bad CV joint/shaft?

It only makes the noise when the car is driven and in gear, not in neutral rolling along or constant throttle.

 

[KooLaid]

I have found these and will go through them now... sounds like it might be it...

http://www.nsxprime.com/forums/showthread.php?t=53550&highlight=cv*+joint
http://www.nsxprime.com/forums/showpost.php?p=242624&postcount=3
http://www.nsxprime.com/forums/showthread.php?t=68902&highlight=cv*+joint

 

[synergy004]

I had this same issue with mine about 2 years ago. It turned out the CV shafts were so dry in the boot. I went to acura bought there cv boot kit etc and ordered 2 new shafts for piece of mind. Same symptoms you have I had. CV shafts from the dealer are KILLER PRICED (NOT CHEAP) I ended up spending a little under 2g's for the cv boot grease which the inner and outer had two different types and the new shafts which ran a little at about 900.00 a piece. The cv boot kit was 140.00 bucks or so give or take.

Any questions PM me.

gil

 

[KooLaid]

I can't seem to distinguish which side it is. Any easy way to figure that out? When I try to stick my head out the door to hear it, all I hear is exhaust

 

[KooLaid]

Is there any reason why an entire shaft would need to be purchased instead of just the 3 bearings per ends if the bearings have gone bad? I've read that the bearings can be purchased separately from the cv joints.

 

[alverman]

I don't think you can buy the bearings(rollers) seperately. Not here anyway,
and mostly Honda service works in the same way (only much more expensive in Euro :frown: - envy ... ENVY ). You should be able to buy the joints, together with spider and rollers seperately I guess, instead of the complete axle.

 

[synergy004]

Big possibility your cv joints just need to be repacked with Hondas grease. My old cv shafts thump went away after. Also noticed since it was so old, the grease inside had deminished, along with the boots they were changed also. I too didn't know which side because of the exhaust and I just ended up doing both sides for piece of mind I just bought new shafts just in case. I didn't have to buy them but I kept them just in case. As for the other pcs. mentioned, they can too order them.

While your at it since everything was off I had repacked my wheel bearings since that also was bare with no grease. The back seem to be worse than the front.

Anyways I hope you remedy your thumping issue.

Happy Holidays
Gil

 

[KooLaid]

Does the grease sitting in the CV cavity lubricate all the little roller bearings inside? I was wondering because I had an idea of using a grease gun that uses a small thin needle to inject plenty of grease to fill the cavity. I was thinking that it would self lubricate everything and I wouldn't need to disassemble. Then silicone the small puncture hole closed.