brendon

I just installed my new cam and at low rpms the car surges or bucks a little bit (1100-1500 rpm's) when I am giving very little throttle. But my concern is when the car is slightly bucking, something sounds as though the driveshaft or rearend is very loose and makes a clunking type noise, it lny does it when the car begins to surge or buck back and forth, the noise from underneath doesn't sound normal. Does anyone know what this is? I also have 4.10s in the stock rear end but I don't think that would affect it.

ShooterSS

iTrader: (3)

Is this an A4 or M6 car?

I know an A4 with a loose converter will do this at that RPM range right around 30 MPH.

<img src="gr_stretch.gif" border="0">

Magnus

iTrader: (4)

My 3.8 A4 with 3200+ stall converter and 3.42 gear does this. <img src="gr_sad.gif" border="0">

Seems like its coming from the rear end when the drive changes from coast to accel... or when the car surges. <img src="gr_sad.gif" border="0">

It's a terrible terrible sound. <img src="gr_sad.gif" border="0">

brendon

My car is an M6, it only does it at low rpms when there is no load on the motor or when no power is being put to the wheels. It sounds like something is loose and clunking around back there. I mainly started to notice it when I put my cam in because it surges/bucks a little bit and causes the clunking noise underneath in the rear.

99WhiteSS

Some cams do this, it's intrinsic to the valve pattern and the bucking that results (especially at low loads and low RPMs) is totally normal. It's part of the price you pay for a big cam and a powerful engine. My 382 does this too, my advice is to learn to live with it.

-Kris

brendon

I understand that the surging is normal but is the clunking noise in the driveshaft/rear end normal?

3GROC

if you have an aftermarket panhard it might be loose. an asustable one. if not and you have aftermarket LCAs they might need ot be regreased and tightened. or your torgue arm is loose. Or your E-Brake cable is hittin and you dont knw it


Chris

LS1x2

iTrader: (11)

My '01 formula does it, my 94 m6 did it, my friend's 94 m6 did it, etc. I've probably driven 12 f-bodies and I have felt that clunk on almost all of them. Must be the design. I think it's the rearend making the clunk. I always get it when i am going slow in parking lots barely giving it any gas at all and then when i let off....clunk. Annoying as hell, but one of thsoe things i put up with on these cars.

brendon

that is pretty much the noise that I am talking about, I think that my car just makes it more pronounced because it surges all the time at low rpm's. Does it usually get worse or will it stay the same?

farhawk

I was having similar problems with my Firehawk with just 1k miles on it. It also vibrated at speed like a tire was out of balance.
I added the weld in BMR sub frame connectors and it quit doing both! GM should have stiffened the T-Top cars a little better from the factory.