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indy-tech, Technician
Category: Jeep
Satisfied Customers: 7283
Experience:  Jeep tech ,
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I have a Jeep grand Cherokee ZJ 1998, The rear brakes seem

Customer Question

I have a Jeep grand Cherokee ZJ 1998,
The rear brakes seem to lock up when turning or reversing and turning , when brakes are warmed up..!!! and grinding noise..
Ok in a straight line, and the brakes are cold..!!
I have replaced all the callipers, pads, shoes, hoses and master cylinder !! all genuine crown parts from the USA..
Does the rear proportioning valve under the master cylinder require replacing as well ??
What else can it be ??????.
Submitted: 4 years ago.
Category: Jeep
Expert:  indy-tech replied 4 years ago.

Name is Greg, My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back,.

Sorry you went though all this work and still have the same problem .

But you will find that your brakes are okay and the problem is with your tru loc differential .

To check this lift the rear wheels off the ground and with the transmission in "N" turn the rear wheel in one direction and the other should turn in the other direction if both turn in the same direction you will have to replace the rear differential .

This is a common issue and i see all to often that the brakes will be completly O/H

for a problem with the Diff , so don't feel bad about this mistake .

But if the rear diff is good and you still have a problem you can get back to me for further assistance anytime ,even if you have already accepted .

Need further assistance then please get back to me with the reply box and not the poor or bad service button .

Rgds Greg

Customer: replied 4 years ago.


I have jacked up the rear wheels and with the car in (N) the wheels turned as they should ie One turning Clockwise and the other turning anti-clockwise..

So that is all OK..

This only as stated locks up when the car has done 20-30 mins down the road, and warmed up !!

OK driving in a straight line..

This happens when Turning forward or Turning reversing ??





Expert:  indy-tech replied 4 years ago.
Hi Gleen .

The wheels block only when turning left or right going backwards or forwards .

If this is the case then I'm sure this is still differencail related as if it was the brakes it would do this going forward in a straight line .

Check the diff oil what condition is it in .

What are the tyre sizes on the left and right side are they the same ? check .is one side worn a lot more than the other side .

Check this then let me know Glenn.

Rgds Greg
Customer: replied 4 years ago.


I am using Lucas 75 x140 H/D diff oil and the tyres are the same size.!!



Expert:  indy-tech replied 4 years ago.
Hi Glenn .

I will opt out and see if i can get you another expert that can shade more light on this issue .

Kind regards Greg.