After racing a harley devidson truck i noticed my tranny would "Thump" everytime it shifter mostly frrom 1-2. Now everytime it shifts i can feel a Thump as if the tranny would jump. the higher the Rpms the louder the thump. Could it be the tranny mounts?

what happens when the tranny is "Slipping"?

 

I'll bet the bank on your tranny mount being broken Quick, cheap and easy fix. Just buy a new mount.

The trannys basically bumping on your floorboards when the engine torques up...

 

get a poly mount and dont worry about it again.

 

Thanks for the info, you made me feel better, just dumped in alot of money in another engine and wasnt looking foward to spend more on rebuilding the tranny. ill take it to a mechanic 2morrow.

 

What he said

 

Yeah but somepoly mounts will make your drive shaft vibrate like a ****!!! i made some 1/8 inch aluminum shims to lower the poly mount and set the pinion angle correctly because b4 I did that my car vibrated like crazy at 60+ mph. it was VERY aggravating!!

so check your DS angle b4 and shim it accordingly, and the you can forget about your poblem and enjoy your ride!