I took my firebird to get the front-end aligned yesterday and when I fired up the car in the parking lot it started knocking in the transmission tunnel! The knocking seems somehow tied to my power steering as it starts more as I turn the steering wheel. and strangely enough it goes away after about 10-15 seconds. Scanners not picking up any knock from it as near as I can tell so it doesn't appear to be in the engine and oil pressure is great. Transmissions not throwing any faults and doesnt appear to be slipping. My current theory is that since their parking lot was limestone gravel somehow a peice of the limestone is in between my tranny and the tranny mount. and as the tranny heats up the mount gets software and thus stops the knock.

 

id pop the trans mount off and take a peek at it. They are fairly cheap and easy to install if thats the case. I went through 2 stock ones, and then put an energy suspension trans mount on there and have had no problems since.

 

Yup I would check the transmission mounts, I also with through 2 OEM ones before switching the a poly mount and have had no problems since then

 

tranny/engine mounts

or take the hammer away from the midget

 

Tranny and engine mounts are both brand new, less than 3k miles on tranny mounts less than 1k miles on engine mount, tranny mount is stock style engine mounts are poly. The strange thing is it goes away a few mins after starting up, it doesn't appear to be heat related though. I'm beginning to worry they may have left a wrench in there somewhere, il'l put her up on jackstands this weekend (gotta fix an exhaust leak anyway) and check around, run her while shes on stands and see what i see. and dammit! i like my midget with the hammer!

 

Could be your exhaust system is too close to the tunnel support bracket.

 

I went through an oem rubber tranny mount really quick, less then 3k miles I say, the poly one in there now is holding up like a champ though.