[Rovernet] Diagnostic help please

[Roger Matheson]

Yes, I agree with Michael that checking the front mountings of the diff is 
step 1. My experience with worn diffs is also whine not thump. If the left 
calliper is not engaging then checking the universals may be difficult that 
side because the handbrake wont hold the disk still and rocking the tyre 
backwards and forwards to test for free play may be misleading . So you 
might have to jam the tyre and put a screwdriver through the inboard 
universal to detect any free play. In my experience there is very little 
that can be done with the calliper in place. However get someone to operate 
the handbrake and watch its operation to make sure that the operating levers 
go through their full motion. With the handbrake on you should not be able 
to turn the tyre by hand. If you can then the self adjusting mechanism is 
faulty. Try taking the operating lever off the left calliper and use a 
spanner to turn the lever through its full movement. Watch the pad inboard 
pad as it closes on the disk, it should push out but not quite return by the 
same amount. The clicking noise will at least tell you that the mechanism is 
in place even if not working properly. There is a small window of 
opportunity for you that is caused by dirt and hardened grease stopping the 
piston from progressing properly. If you dare: Take the half shaft, pads and 
disk off. This will allow you to rock the calliper on its hinge pin and 
remove the cover. Also to inspect the piston cup assembly. (email me if you 
want the exploded diagram) It may be partially seized in the body of the 
calliper by sticking to its "O" ring seal or stuck on the threads of the 
push rod. You MAY be able to unscrew it right out, clean, re grease, replace 
the "O" ring and screw back in provided you can stop the push rod from 
turning (by jamming it inside the mechanism accessed with the cover off. 
When you screw it back in you will need to align its lip so that the inboard 
pad will engage and seat correctly. If you are very lucky this will enable 
the self adjuster to work correctly. If unlucky you are well on your way to 
removing the calliper. On another matter, do you think the right calliper is 
faulty because the brake is dragging and hence getting hot. Its no wonder P6 
owners find that non expert servicing often neglects (ignores, pretends they 
don't exist) the rear callipers.

Good luck Cheers Roger (roger.matheson at bigpond.com)
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