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///M LIFEŠ
02-24-2005, 11:42 AM
I just noticed a strange tapping noise which I believe is coming from the rear of the car. Here is whats happening.
I am cruising around 20-30 Mph and I let go of the gas, the tapping, thumping noise (sounds like a chopper) starts when I begin to decelerate.

When I pull the clutch in it, the sound stops, while decelerating

I dont hear it when I am accelerating.

I also notice my exhaust is a bit sounds louder then usual.
Please advice
///M LIFEŠ
02-24-2005, 11:50 AM
It almost sounds like I have a flat tire,which even if I did should have a continuous noise. I have a very small clipping of the noise, Ill post it up as soon as I get a host.
LWRNCE
02-24-2005, 11:53 AM
hmmmm.... your exhaust hitting? or you axles clicking. :dunno
///M LIFEŠ
02-24-2005, 11:55 AM
One theory I thought of could be my exhaust hangers being shot (its a 97) therefore the exhaust swinging side to side. But wouldnt that also happen upon acceleration?
LWRNCE
02-24-2005, 12:02 PM
Yeah.. My exhaust hangers are doing the same thing and its hitting against my M diffuser. You wont notice it when you are accelerating because of all of the other noises coming. when you decelerate everything quiets down letting you listen for all the bad things haha... When you car is all cool'd down go to your exhaust and grap and move it side to side. You will then get to figure out where and what is making that noise. You also get to find out if it is the exhaust or not.

SO when you exhaust hangers are bad they sway side to side?
///M LIFEŠ
02-24-2005, 12:06 PM
I am almost positive it does not happen when accelerating, but very evident upon deceleration.

I have a 1.5mb clip if someone can host it I can show you guys what im talking about.
///M LIFEŠ
02-24-2005, 01:03 PM
Here I have attached a little clip. It starts of in first gear, shifting into second, then letting go of the gas. same in the second section.
LWRNCE
02-24-2005, 01:05 PM
shit I dont know what that is....
///M LIFEŠ
02-24-2005, 09:46 PM
it seems to get louder with time
HellBilly
02-24-2005, 09:53 PM
thats messed up

things that come to mind when i hear it:

CV Joints
Somthing hitting your tires
loose lug nuts
AntiHero
02-24-2005, 09:54 PM
Thats a very strange sound indeed. If you get time take off the wheels and check around the brakes or see if something is hitting or rubbing. Other then that you got me stumped, it doesnt sound very good tho. Maybe your car wants to be a helicopter now :dunno:
tEckniks
02-24-2005, 09:58 PM
damn thats one scary noise
///M LIFEŠ
02-24-2005, 11:30 PM
Somthing hitting your tires
loose lug nuts

If that were the case wouldnt it sound on acceleration as well? As soon as I hit the gas the sound is gone.
sardil
02-25-2005, 12:14 AM
Its a problem with your transmission. Throwout bearing maybe?
HellBilly
02-25-2005, 01:20 AM
Its a problem with your transmission. Throwout bearing maybe?
when that goes doesnt your clutch make a squeeking noise?
///M LIFEŠ
02-25-2005, 08:52 AM
Its a problem with your transmission. Throwout bearing maybe?

I just recently had a new clutch and T/O bearing installed...
giterdone
02-25-2005, 09:07 AM
hmmmm......strange indeed. I have no clue, but interested to find out..........bump :)
ss109
02-25-2005, 09:16 AM
Yeah it has almost got to be something with your tranny. All other variables are eliminated because they would do the same thing on acceleration. Very bad sound indeed.
sardil
02-25-2005, 09:23 AM
I just recently had a new clutch and T/O bearing installed...
Hmm..maybe faulty install maybe?

Also, double check your CV joints & driveshaft veerrry carefully (particularly the center splines).
///M LIFEŠ
02-25-2005, 09:38 AM
I am going to have it checked out at my local shop. Hopefully it is not anything too bad
///M LIFEŠ
06-09-2005, 03:46 PM
My differential was shot. I just got a used one off a member here and im going to pick it up today all repaired.
jason033
06-09-2005, 04:11 PM
i had the same exact thing happing to my 96' M about a week ago. when i would hit the gass the car would be smooth, but when i let off teh gas it would make that floping sound . i took my car to get aligned and it was all out of wack. so after simple alightment the car was fine and it as smooth as glass now. could be the same prob with you? also check you wheel weights make sure they havent fallen off.
///M LIFEŠ
06-09-2005, 04:14 PM
They guy at the shop told me the car is running smoothly now. If you think about it, if it was the alignment, shouldnt the knocking sound come on borh acceleration and deceleration?
///M LIFEŠ
06-17-2005, 03:33 AM
Picked up the car with the new (used) diff and now it runs like a charm.

My guess is that it was all those burnouts :devillook :nono
black318i
12-21-2005, 11:25 PM
My differential was shot. I just got a used one off a member here and im going to pick it up today all repaired.

My car make the same sound, but not as loud. It sounds like it's from the rear of the car but when I jacked up the rear of my car and let it idle in 1st it sounded like it was the trans. Where were your sounds coming from and what parts on the diff were shot?
thejlevie
12-22-2005, 12:21 AM
I think I'd be concentrating on the driveshaft, differential or axles. I don't think it is driveshaft speed and it sounds more like a wheel speed noise. That could be from the axles or diff.
black318i
12-22-2005, 02:21 AM
My car make the same sound, but not as loud. It sounds like it's from the rear of the car but when I jacked up the rear of my car and let it idle in 1st it sounded like it was the trans. Where were your sounds coming from and what parts on the diff were shot?

Does anyone bother to read at least the first and last post?
///M LIFEŠ
12-22-2005, 04:10 AM
Yea it was the differential that needed to be replaced. Thanks to BFC I got a good deal.