Violent Shudder/Vibration when Downshifting
As the title says, I have a pretty violent shudder/Vibration when downshifting from second to first gear (auto tranny) and haven't found any help in multiple searches.
I recently finished my build on Jeep and towed it up to my cabin on a tow dolly. Rear drive shaft was disconnected and no problems during trip. Upon reconnecting drive shaft and driving, the jeep shudders/vibrates when downshifting and coming to a stop (less than 5mph, maybe 3mph) it shudders so badly it feels like motor is going to stall or fall out. If I shift to neutral-shudder stops, if I reapply gas pedal-shudder stops. No vibrations or problem on acceleration.
Drive shaft was marked when disconnected, however I have attempted to change mounting position with no change in problem. U joints appear fine.
Jeep was taken down to the frame and rebuilt from there up. The only mods from frame down were some rust repair on the frame as well as Chassis Saver. No changes were made to the drive line. I drove it a few thousand miles with lift kit on before pulling tub and no problems then.
INFO- 94 YJ Wrangler, 2.5l, auto trans, 4in RE kit, T/C drop, NO SYE, 32in BFG's, unknown mileage(but alot).
Any ideas on where to start or what to check? I'm thinking changing the tranny fluid as a start. But any other ideas would be greatly appreciated. I've done several searches and not been able to find anyone with a similar problem. I would like to check everything I can before taking it into a shop.