[Rovernet] Diagnostic help please

Michael Pellow mp349 at xtra.co.nz
Wed Feb 11 06:54:01 EST 2015


On 11/02/2015 7:36 a.m., LANCE LA CERTE PSY D via Rovernet wrote:
> 1970   3500S  P6B  NADA
> Background----Rebuilt engine (2,000 miles total), rebuilt Borg-Warner 35, replaced differential (lower mileage, not rebuilt), rebuilt rear brake calipers.
> Car has developed a thumping which appears to be coming from the rear of the car.  At speed it disappears, but instantly returns as soon as you take your foot off the gas.  I've had the car up on the lift and with the rear end suspended and the transmission in neutral I can rotate the rear wheels by rotating the propeller shaft, i.e., nothing seems to be 'sticking'.  I also noticed the left rear caliper is not engaging (right disc is hot to touch after drive, left is cold).
> I would appreciate any help in how to diagnose this thumping (and if I'm going to need to drop the differential to address the brake caliper.
>
> Lance La Certe, Psy.D.
> It is absurd to divide people into good and bad. People are either charming or tedious.
>
>
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there are a couple of probable reasons for one of the discs to be hot 
1.: the hand brake cable has been adjusted up too tight. ( both leavers 
should be resting in the backstop screw when the hand brake is off.
make sure that when the hand brake is pulled on  that both leavers are 
at approximately the same amount of travel from the back stop. This 
however can be masked by # 2 locking on
2.: the brake hoses internal rubber has broken down and swollen closed 
so the hydraulic pressure doesn't release when the foot brake is released
this is a very tricky one that took me ages to find.The hoses look 
perfect but if you try to blow through then it is impossible.There is 
enough pressure from the power booster to force the brakes on ,but they 
don't release.

while the brake are dragging it will exaggerate any movement in the
universals
If the left calliper doesn't come on with the handbrake unfortunately it 
will need to be disassembled as either the pin the operates the rocking 
bar has fallen into the grove inside the leaver or the adjusting 
mechanism has frozen and will need freeing up





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