Todays lesson
Todays lesson I recently swapped in an LQ4 in to my 02 Trans Am. As expected, it went well, no real issues. I installed poly motor mounts and tranny mount during the swap. Naturally I had the PCM reprogrammed for the new engine and I had the tranny shift points stiffened up, but not real stiff, the car will probably never see the drag strip. Anyway, after startup, I noticed some annoying exhaust rumbling that echoed thru the body. Wasnt expected since I stayed with the original stock exhaust system. Rechecked all the mounts/hangers, no help. Also, I had a heavy clunk in the front of the tranny, sounded like the torque converter. Spent a lot of time checking things, no improvement. Today I swapped out the poly tranny mount with stock style rubber mount and the heavy clunk is gone as well as most of the exhaust noise. So I guess the message is if you arent racing or heavy use driving, poly mounts are not required and in the long run, probably not the best choice. Now I have to decide if I want to bother replacing the poly engine mounts with new stock rubber mounts, over the winter.
Interesting, I had the complete opposite experience. Clutch chatter is almost non existent now and motor hardly torques over. Next time I swap out my poly motor/trans mounts i may even go solid.
Hope your problem is solved and not just masked by the softer mount.
Hope your problem is solved and not just masked by the softer mount.
I still dont really understand how this change made the noise go away, but it could be that the drivetrain ( differential) clunk is echoing down the driveshaft and doesnt stop until it reaches the torque converter. Not knowing much about auto tranny's it may be the first place there is a hard bolt together for the driveshaft/tranny mainshaft/ engine block. I will drive it some more to see how long this fix lasts. In your case, I can see how the stiffer mounts improve performance depending on how aggressive your clutch is. The harder mounts prevent the engine/drivetrain from chattering/bouncing. Anyway, for now the clunk is greatly reduced and I can live with that while I work on the rear differential ( new crush collar for starters).
