Feel vibration when holding brakes on a hill.

**Street Fighter** · 07-07-2017, 04:43 AM

I have noticed that my trans am started vibrating when in drive on a hill sitting still. I just noticed it about two months ago. it is not missing runs great but it fells as if the engine or exhaust is touching something. I have looked, but I don't see anything touching. what could it be ? NEED HELP. Could it be a motor mount?

**pajeff02** · 07-08-2017, 02:03 AM

Trans or motor mount would be my first thought, followed by the exhaust beneath the driver side floor pan or up over the rear axle.

***SMWS6TA*** · 07-10-2017, 01:28 PM

Motor mount would show on hard rev or acceleration. Trans maybe but it could be a worn out exhaust hanger.

Is there a metallic sound in vibration or just a shutter?

**cammed goat** · 07-11-2017, 04:07 PM

Also agree with the motor/trans mount.

**Street Fighter** · 07-15-2017, 05:00 AM

Needed muffler, replaced it, but I believe its the motor mounts ,holding the brake and raising the engine in drive the engine raises up about 1inch and the same in reverse. I was thinking about getting new mounts and going with Energy poly mount inserts,will they be too harsh for a daily driver? The car is a 99 ta with 47,000 miles I would think the mounts would have last a little longer,but the trans mount gave out at about 45,000.

***SMWS6TA*** · 07-15-2017, 02:10 PM

Poly mounts are ok for a daily, hell I almost daily mine with a 403. I have those exact poly mounts. Been pretty good so far.

**pajeff02** · 07-16-2017, 04:12 AM

I couldn't really feel any difference after installing poly engine mounts, but I made a bunch of changes all at the same time too. My only issue was the poly trans mount. Seemed to transmit a bunch of vibration into the driver compartment, so I swapped the stocker back in and it immediately went away.