When im at WOT and my car is above say 3,700 rpms i get a very hard vibration from the gear box. It sounds kinda like grinding, but it never does it when im only gradually pressing the gas? Does it in the 1-2 shift and the 2-3 shift, it'll rattle the change in the cup holder it's so bad. Any ideas on what could be happening?

posted this in the transmission section anfd didnt get any replies thought i'd try my luck here,

 

more info... I can hold the gas 3/4 down and bring the car up to 5-6k with no grinding, the only time it grinds is when im at WOT, any clues?

 

What is your car? Sounds like misfire to me... No SES light?

 

Maybe an out of balance Driveshaft.

 

it's a 94 trans am, i dont think it's a misfire, it a like grinding from under the shifter.

 

This may sound dumb, but check your tranny mount. If its broken, or on the way out, when under WOT its allowing the tailshaft of the tranny to lift higher than normal and can cause clunks, bumps, and all kinds of strange noises. I just replaced mine and it was the last thing I would have thought to check and my car runs like a champ again.

 

anybody have a pic of the tranny mount so i know what to look for?

 

Yep, it's possible to be a tranny mount. Can't find any picture, but it's pretty easy to locate it - look under a car from driver side and locate a place where tranny is supported. But it's not easy to say whether it's good or bad from that point of view Reference for changing it you can find here http://www.fbody.com/tech/details.cgi?id=38 If you decide to change it, consider poly mount.

 

I cant find any pics of a mount under the car, but get underneath your car and its right in the middle (where your console is) and bolts to the tailshaft of the transmission. You'll see the crossmemeber which runs door to door and the tailshaft rest on the mount which is in the middle of the crossmember. I included a picture of what the mount looks like and if its broken you will be able to easily manually push the tailshaft of the tranny up when under the car. http://www.zmydust.com/images/crossandmount/mount2.jpg

 

any body have a direct link to where to buy this part. im having trouble finding it

 

I got mine from AutoZone with a lifetime warranty for about $18. They also have the Poly mounts, which I bought a few weeks ago, but I hated it a swapped it back with a rubber mount after 2 days of driving with the poly one. It made my car vibrate so bad and the noise was awful, and basically made my car feel as if it were going to blow up. With the rubber mount it runs smooth and drives great again.

 

Tranny mount from gmpartsdirect.com, part# 22201140. I personally went with Energy Suspension Poly mount - car feels much better right now, no vibrations. But I have 1LE alum DS in perfect balance.

 

went under the car today, the trailshaft moved but not easily.

 

Well I shouldnt have said easily,but if you see the mount strectch alot while lifting it its broken.

 

i did however notice the tranny is indeed hitting the floor, i could tell this because there was a piece of like grinded metal on floor above the tranny.