When I stop at a red light and then start up again there is a noticable clunk, lots of vibration while cruising to a stop and slight delay if slowly accelarting. Is it my u-joint?

It "could" be a U-joint. There have been more than a few reports of them having to be replaced on the R51's.

slight delay when accelerating? Sounds like tranny slipping

well.. there are several ways to check..

one is to jack up one of the rear wheels and then rotate the tire back and forth as far as you can (emergency brake off) while you eyeball the u joints.

its usually pretty obvious that the yoke on the punkin will move before the driveshaft does and sometimes you can even hear it.

there are two u joints on the drive shaft you have to check though.


The best way is to put the thing on a lift and get under there and check it up close and personal


its hard to check them with the car on the ground because whenever you put the car in park, it puts a load on the driveshaft and it can be impossible for you to make the u-joint wiggle by hand.. (and i DO NOT recommend crawling under a car in neutral wheels blocked or not as some old timers used to do)


while tranny slip is one cause of hesitation on acceleration..

the vibration combined with the "clunk" is a common sign of a bad u joint on any car.

My u joints squeaked like metal on metal when the started to go. You can hear it best when moving in reverse at about 5mph. It has a gradual increase in intensity and frequency as you accelerate, sounds like a pebble in your brake pad. If there is any play in your driveshaft, its time to replace the u joints. 20 bucks at oreileys and how someone else put it on the forums.. "the force of 10,000 suns" i actually ended up cutting them off with a torch (ofcourse off the car). Just dont make the same mistake i made and get the smaller 4 wheel drive u-joints, they dont work; I hope thats your issue... tranny issues are not fun.