We have been chasing a driveline vibration for 3 months now. The driveshaft guy is confident that he has done all that can be done with getting angles right and the shaft is correctly balanced. However the annoying vibration is still there and he says it seems to be in the box/torque convertor. I recently installed a 4L60E and torque convertor, fully reconditioned. He says that even with the car stationery and bringing up the revs to say 1500 the vibration starts through to 3000rpm. He calls it a harmonic vibration. So anyone here with some clues please. I really don't want to have to pull the box out again but maybe that has to happen.
Had this problem with one of my past car projects. Took my driveshaft out and took it back to the shop that put it together for me. Picked it up and they said it was fine. Spent 6 months chasing every other possible option to no avail. Took the driveshaft out again and took it to another driveline shop who told me it was the worst balancing job they'd ever seen. End of problem. Many other projects over the years and that first driveline shop never saw any of my business again.
What engine and does it need an externally balanced flex plate or not. Was the flex plate changed when the new trans was installed and was it right for the engine.
LS1 5.7 litre. Originally running a 700R4 behind it that was behind the big block I had in the car and then when the 700 crapped out we replaced it with the correct compatible 4L60E. Now I am trying to remember if we got the correct flex plate with that box or used the 700 one. Checking that this weekend. Thanks for your input.
I have had this problem with my 40 pickup for years, I've checked and re check everything more then twice. Mine doesn't happen when the truck is sitting and running only at 35 to 40 mph. After checking so many times and not being able to fine anything I just gave up and drive the piss out of it.
I had the same problem? After doing the drive shaft, new axles and bearings, and whatever else I could think of? Found I had a bad tire? I know ,yours does it standing still? If its a later engine, like a crate engine, it needs a external balanced flex plate. Something else to check? Good luck!! That crap will drive you nuts!
Make sure your transmission/engine/exhaust aren't touching any part of the body/frame, especially after doing a custom swap. I had a transmission making contact with a cross-member at certain speeds/torque that that caused vibration that rattled the whole body of the car.
I work for GM for many years and one of the things that was recommended when trying to fix a engine vibration that you experienced when raising the RPM with the car not in motion was as I stated above to "Index" the converter to the flex plate by removing the attaching bolts and moving the converter 120 degrees on the flex plate to try to find the "sweet spot". There are three possible positions in this relationship and sometime depending on tolerance stack-up a vibration can be improved or eliminated by changing this relationship. It's easy to do and certainly worth try.
The Jalopy Journal
