I have an ongoing vibration issue with my 1986 Syncro. I know it is not wheel bearings, brakes, tires or alignment. A couple of years ago I had a mechanic replace my drive shaft with a Non-VW one. I think it was a Chevy. Is it possible that this could create such a problem? The vibration is very loud! I'm running out of possible solutions.
Obviously, for a vehicle such as yours, modified away from factory specifications, any input I can give would be limited. First, a couple of background questions. Can I ask HOW you know your problem isn't due to the wheel bearings, brakes, tires or alignment?
When you say that your mechanic replaced the driveshaft, are you referring to the center driveshaft running from the transmission to the front differential, or the CV axles? Did your noise issue originate at that time?
I'm curious as to why a non-VW part was installed. It seems that a non-VW part would likely have to be pretty heavliy modified in order to fit your Syncro.
Remove the center driveshaft and check if the u-jounts are binding... if the joints are ok, drive the van with the shaft out. If the vibration is gone, check / compare all tires for equal size (wrap measuring tape around circumference.... tire size differences will wind-up the drivetrain.
All wheel bearings have either been checked or replace. I just had the brakes, alignment, balance & rotation done.
If I shift the weight of the vehicle while driving, swerving, it does not change the vibration. My experience with wheel bearings has indicated that if I do this and the vibration does change, then it indicates wheel bearing issues.
Last night I noticed that the vibration decreases if I let off the accelerator or coast. The vibration is loudest while the engine is powering the vehicle.
I need to did up the paperwork to see what specific part(s) of the drive shaft were replaced. My knowledge of auto mechanics is very limited.