Driveline Vibration

[Kit Sullivan]

I have a '79 Lincoln Mk V, and it has an annoying vibration that I can't seem to locate. It happens at around 45-50 MPH, and then lessens as the speed increases. The vibration is not coming through the steering, but it feels like it is coming through the frame of the car itself. I have had a considerable amount of work done to the car, and nothing seems to help. I have installed all new coil-springs, front and rear along with new shocks. The tires are new and properly balanced, and the rims have been checked for 'trueness', and theyr'e fine. There are all new disc-brake rotors and calipers( 4-wheel discs). The U-joints have been replaced, and the driveshaft has been expertly balanced. the driveshaft was in good balance before, but I had it 'fine-tuned' anyway. There are no dents or scrapes on the driveshaft. I have checked the motor and transmission mounts, and they are all OK. The exhaust sytem is new and secure. The rear pinion does not seem to have any excess 'play', but I don't really know what excess is. It seems tight. The front suspension is all in good shape, with new upper control arm bushings, new ball joints, and it all seems tight. It steers wonderfully, and does not 'pull or 'vibrate through the steering wheel at all. I suspect it might be the rear differential, only because I don't know what else to check. Other than that, this is an excellent riding car, and I definately want to keep it. Any help that anyone can give me would be greatly appreciated.

[thecarguy]

im not sure if you have one but it could be a center support bearing that has gone bad, if you have one. Otherwise it could be the u-joints.also any small imperfection like a small scratch on the ring or pinion gear that can be a cause of a vibration. Or a flat spot on your tires.

[bogbronco]

I'd say that the problem is probably in the driveline. Check your torque converter for any wear. Also look at your flywheel, and check for excess play on both ends of tranny. I have seen U-Joints that go bad within hours of replacement, due to poor lubrication. If you greased them good, sometimes the grease doesn't make it's way to all of the needle bearings. I always grease them and after I run the vehicle down the road a little ways, I'll put a squeeze of grease in them again.


If you have them big hubcaps, they could also throw your wheels out of balance.

Goodluck--- I hope this helps! Bogbronco

[rapideo]

Noticed this on Edmunds town hall talk. Probally won't help, but you have done everything else. Unbolt the drive shaft from the diff. and give it a half turn and bolt it up again. Some one posted that could cure a vib. Let us know if it works.