Rear upper control arm

wfd1350 · **Posted:** Thu Jul 19, 2012 10:05 pm

Is anyone aware of how to check the rear upper control arm for play. I suspect mine meet need replacing, but I am unaware of how to check. Any info would be greatly appreciated.

Thanks, Tony

Glend · **Posted:** Fri Jul 20, 2012 4:38 am

It might be easiest to just pop the balljoint out of the diff bracket and then see if you can move the upper control arm back and forth or side to side. There is a known problem (for a few people down this way) where the caged nuts in the body mount locations break loose and allow the arm to move. The ball joint can also get very sloppy but that's pretty easy to check when you pop it out of the bracket - see if you can feel any play in the ball to socket, it should be smooth but not too loose and definitely no gaps between the ball and socket that allow it to rattle around in there. The bushings at the top of the arm ends (where it bolts onto the body caged mount) should be checked for cracking and pulling out of the centre section.

wfd1350 · **Posted:** Fri Jul 20, 2012 9:26 am

Thaks for the info.

ChooChooman74 · **Posted:** Fri Jul 20, 2012 11:44 am

Why do you feel that it is going?? If you think it may be going because you feel something thump when you stop, try greasing your drive shaft yoke on the transmission. That what my problem was. I thought it was the rear UCA at first. Thankfully, easy fix.

wfd1350 · **Posted:** Sat Jul 21, 2012 6:35 pm

The symptom that I'm trying to relieve is a low RPM vibration. I have recently checked the U joints and checked them for play, and also greased the driveshaft slip yoke. To no avail, the vibration is still there. It is a little more noticeable when towing. Thought that if the upper cotrol arm bushings were worn could possibly lead to differential rotation and vibration.

Thanks, Tony

papaindigo · **Posted:** Sat Jul 21, 2012 8:37 pm

Did you check the "u" joints on the CRD or did you pull the drive shaft? I ask because several folks have said "u" joints checked on the vehicle turned out to be bad when checked off the vehicle.

slasher · **Posted:** Sun Jul 22, 2012 10:29 am

papaindigo wrote:

Did you check the "u" joints on the CRD or did you pull the drive shaft? I ask because several folks have said "u" joints checked on the vehicle turned out to be bad when checked off the vehicle.

X 2

I've been down the same route as yourself, vibration/rumble at different speeds/rpm. Took it to garage thinking it might be TC (exactly the same feel as when the TC went on my old C220, without the stall) Upper arm bushes were shot but the U joint was fine as was the TC. Another garage replaced the upper arm and checked the U joint, the vibrations/rumble pretty much went but there was still something there. Took the old (rear) U joint off and 1 cap was cracked and dry with no pins, looked fine until I actually removed it. New one in and no vibrations since

wfd1350 · **Posted:** Sun Jul 22, 2012 11:28 am

Thanks for the info. I'll pull the driveshaft next week. I'll let you know how it goes.

wfd1350 · **Posted:** Thu Aug 02, 2012 2:44 pm

Well it was the U joint after all. Thanks for all the input.

wfd1350 · **Posted:** Wed Oct 31, 2012 2:18 pm

I finally got a chance to check the rear upper control arm ball joints. They are shot and need replacing also.

Rear upper control arm

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