Gears & Axles - Concerned




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BlackFormula01
11-06-2003, 06:29 PM
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 :usa:


Cal
11-06-2003, 09:16 PM
Could your Y pipe be hitting the floor pan? That's the side that always hits.

trackbird
11-06-2003, 11:20 PM
Make sure the transmission mount is not broken or loose.


BlackFormula01
11-08-2003, 03:52 PM
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
11-23-2003, 07:05 PM
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
TTT I know now that its not the transmission brace...any other ideas?

Slowhawk
11-23-2003, 07:33 PM
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
11-24-2003, 11:27 AM
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.

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

Thanks Slowhawk.
Ed

Proud2bSS
11-24-2003, 08:02 PM
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
11-24-2003, 09:34 PM
Id third that the y pipe, that is what it was for me when I switched it out

01Z0H6
11-26-2003, 08:18 PM
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
11-26-2003, 08:46 PM
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
11-28-2003, 03:44 PM
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
11-28-2003, 05:54 PM
does anyone have any idea to why a rearend would need to be replaced like that?
Ed

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

z98
11-28-2003, 07:24 PM
If its an M6 I have a good idea why it would have to be :)

BlackFormula01
11-29-2003, 09:57 AM
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.