BlackFormula01

When I get on the gas (85%-100%) in my 01 3.23 Formula, there is this poping/ thumping sound from what seems to be coming from under the drivers side area. Does anyone know if this is just normal noise or is this really, really bad? I've only ever been on the car for a few seconds 3-4 and usually it "thumps" 2-3 times. It only does it from low speeds also 5-15 (I've never done it from standstill). Any information regarding this would be appreciated.
Thanks in advance.
Ed

Cal

iTrader: (1)

Could your Y pipe be hitting the floor pan? That's the side that always hits.

trackbird

iTrader: (4)

Make sure the transmission mount is not broken or loose.

BlackFormula01

Thanks for the Ideas guys...I am sure it is not the y pipe...I checked it and its extremely sturdy. I am not sure about he Transmission brace until I get the car in the air, but I don't think its this either. Does anyone else have any other Ideas?
Thanks,
Ed

BlackFormula01

TTT I know now that its not the transmission brace...any other ideas?

Slowhawk

iTrader: (12)

I would second the Y-pipe for the first check.Right under the driver seat on the crossbrace is where it ussually hits.Just look for marks on that brace and the Y-pipe.Second would be check the bolt's on the torque arm and LCA's.

BlackFormula01

For you second, where are each of those located...and pardon my ignorance, but what is an LCA?

Thanks Slowhawk.
Ed

Proud2bSS

iTrader: (2)

LCA = Lower Control Arm; attaches the rear end (near the wheels) to the frame via two 'arms'.

Should the bolts that are at the pivot points of the LCAs be loose, then you will have slippage. Under shock load, these will make a 'clunk' noise or feel.

Since you say the noise appears to be coming from under neath you, most times it is the y-pipe. Just because you can grab it and it seems firm, does not eliminate that as the problem. Remember that your engine wants to twist when you accelerate; the harder you accel the more the engine/tranny want to twist (or flex). The exhaust system flexes with them, thus the y-pipe may hit the car.

Should the y-pipe not be causing this, my vote is for the torque arm where it attaches to the tranmission. I replced the stock 'marshmellow' bushing with a prothane type. My 'clunk' went away.......

roy

Id third that the y pipe, that is what it was for me when I switched it out

01Z0H6

iTrader: (63)

Ditto...... Y pipe.
Does not take much for it to hit the undercarriage.
see if you can fit a finger between the y & the body.
if so you might try some heater hose in between! i'll bet that will remedy your problem.

RevGTO

iTrader: (12)

On my 94 Formula the Y pipe would bang against the crossbrace - you could see the mark. You could tell the sound was coming right from underneath the console. I worked the brace a little and shimmed it to create more clearance. End of clunk.

BlackFormula01

Thanks guys...I'll look for scrapes on the Y and on the heatplate....
Just to not put up another post....
I found out today that my Formula is on it's third rear end...
I am the second owner and it came from Detroit over an auction...I don't think its been draged, or if it has not often...anyways the 10bolt was replaced a 5k and then again at 14K...does anyone have any idea to why a rearend would need to be replaced like that? Thanks again guys...I hope it is the y and not the rear going out for the fourth.
Ed

Proud2bSS

iTrader: (2)

It is the weak link in the 4th gens.....probably too many hard launches by the prior owner.

z98

If its an M6 I have a good idea why it would have to be

BlackFormula01

Nah...its an A4...But I seriously don't think the car has been beat. There were no mods done to it before I got it, I checked everything I could think of, from old exhaust welds to holes for a n20 bottle.