Byllz

Sometimes when I hit the accelerator hard and the transmission downshifts, there is a loud bang under my car. It sounds like something is hitting the floor just behind the front seats directly in the middle. I had my mechanic check out my transmission mount and he said it was fine. He suggested that it may be the cat hitting the underside. The next day I went and had my cat cut out and replaced with pipe. This seems to have lessened the occurence of the problem but it still does it occasionally. There is also another sound that may or may not be related. Usually when I turn a corner there is a dull clank that sounds like its coming from under the trunk. Does anyone have any ideas on what to check for? Could it still be some part of the exhaust hitting, or possibly some part of the suspension? If anyone does have an idea on what to check, please let me know how I go go about checking it. Thanks!

TraceZ

broken transmission mount. Did you check it yourself? I never trust a mechanic.

The other noise could be the spare tire / jack / tire iron.

Dave89IROC

also check the torque arm bushing, it is commonly overlooked by mechanics not familiar with f-bodys

Byllz

I just took a look at the transmision mount and it appears to be intact. I don't really know how else to check it to be honest. I'm not really familiar with working on cars so I don't know how else to go about checking it. I've checked to see if it is the spare doing it before and I was able to rule that out. How do I go about checking the torque arm bushings to see if they are the source of the problem?

BTW, I was wiggling different things to see if they would move enough to thunk under the car and I noticed that the drivers side exhaust hanger appears not to be attached the the bracket that holds the pipe. The pipe is able to slide in the hanger pretty easily whereas the passenger side doesnt move at all. I'm going to try to get this fixed and see if that'll get rid of the thunk. Should I go with a stock exhaust hanger or can I go with some sort of universal one?

Pandamonkey

I had the same thing, it sounded like a midget under my car with a hammer, banging on it.




So I took his hammer away. Little bastard....

Byllz

ROFL
What was causing your problem?


Ok I just pulled my drivers side exhaust hanger off and I put it right back on... apparently its meant to move like that lol. I told you guys I'm not that good with cars heheh... still trying to learn. I checked the torque arm by trying to move it with my hand and it wouldn't budge. I'm hoping that means that the torque arm bushing is good.

1997formula

when my tranny mount broke, you could'nt tell it was broke until I took it off the car.

sabre81

Same for me. Take out the transmission mount, dont just peek under the car.

Byllz

Will I need to support the transmission with anything when removing the mount? Also when I remove the mount how do I determine if its broken?

sabre81

You will need to support the transmission with a jack or something when you remove the cross member/mount. When you get the mount off look for a tear. I was able to pull mine apart and i was able to see where it actually tore on a seam.

Dave89IROC

to check the trans mount, you need to lift the trans, use a long pry bar and pry up on the trans or use a floor jack with a piece of wood on it to do the same, the rubber of the mount should strech only, if you see a crack or the mount seperate, replace it

Byllz

Ok just got the crossmember off and it looks like the mount has been torn almost all the way apart. Thank you guys for all the help and patience. I think this problem is about licked.

TraceZ

And that is exactly why I never trust mechanics. You said they checked it?? Incompetence at its finest! Did they charge you to check it? If they did, you should take them the broken mount and demand your money back!
They shoud put your cat back too free of charge. The resale value of your car is lowered if it is non-compliant for emissions. If you put the car on Ebay there are several states in which buyers will not be able to register it, so they wont bid, thus lowering the potential value of the car.

What did they do to check it? Maybe they just looked at it and said "looks good to me" LOL.

Byllz

Nah it wasnt like that at all. The mechanic didn't charge me a dime to check it out. He watched the transmission from underneath while I shifted it into and out of gear to see if there was excessive play in the transmission. The cat actually did need to come off though as it was making a rattling sound sound while driving. Somebody had apparently done a poor job when they hollowed it out. Still... I will probably start inspecting my own car from now on when a problem comes up heheh.

Byllz

Ok, Ive been driving the car a few days now since replacing the transmission mount. The loud bang under the floor is gone. There is still the matter of the softer clank that sounds like its coming from the trunk area (sounds like its coming from the driver side, but it's hard to tell for sure) when I hit bumps in the road or turn a downhill corner. I'm thinking that it might have something to do with the rear suspension. Anyone have any ideas? Can anyone explain how to check the rear suspension to see if that might be the culprit?