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Datsun Patrol MQ 1982 RB25DE NEO
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Discussion Starter · #1 ·
After my recent brake upgrade, Skyline R34 brake booster and master cylinder, I suddenly started experiencing brake binding. At 1st I suspected the rears as I rebuilt the drum brakes, but the 2nd time it happened, I reralised that it was the front disk brakes.
If you leave it to cool down for and hour, it's fine again. Alternatively, loosen one of the front brake bleed nipples and relieve the pressure and it's good again.
So as a "fix" I put back my spare MQ master brake cylinder but kept the R34 booster and it seemed fine...
Went on a 150km trip over the weekend and I did experience some "lower power" moments, which I know think it was my brakes binding at speed on the freeway, but overall nothing else was wrong with the brakes.
It was only when I got to about 3km from home that I felt the binding again at low speed. I pulled over and stopped but I could hear metal on metal. My front pads are now worn down to the metal and the rotors damaged.

So with the R34 master is was worse than with the MQ master. Since the R34 brake booster matches the R34 master push rod, the problem may be push rod between the pedal and the booster too long sort of dragging the brakes... More noticeable on the newer and stronger R34 master brake cylinder.
So I will disconnect the brake pedal to brake booster rod and see if it is too long... Otherwise I have no idea!

Anyone else ever experienced front disk brakes binding?
 

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2003 GUIII - TD27T
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199 Posts
I had this happen about 4 months ago on the Mrs series 1,
the rubber hose from the chassis to the front diff had perished on the inside.
This was causing the rubber hose to act like a one way valve.
fluid could get to the brakes from the master cylinder, but was having trouble returning.
 

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Datsun Patrol MQ 1982 RB25DE NEO
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921 Posts
Discussion Starter · #3 ·
I had this happen about 4 months ago on the Mrs series 1,
the rubber hose from the chassis to the front diff had perished on the inside.
This was causing the rubber hose to act like a one way valve.
fluid could get to the brakes from the master cylinder, but was having trouble returning.
Excellent thanks. Yes it seems to act like a one way valve since bleeding it fix it temporarily. I did replace the rear when I changed the rear diff. Will order the front as well as the brake caliper hoses while I am at it. It is time to change it after 40 years....

Sent from my BISON GT using Tapatalk
 

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nissan gq
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3,387 Posts
I had this happen about 4 months ago on the Mrs series 1,
the rubber hose from the chassis to the front diff had perished on the inside.
This was causing the rubber hose to act like a one way valve.
fluid could get to the brakes from the master cylinder, but was having trouble returning.
I found a similar thing with a HQ holden,the steel crossover pipe on the front crossmember was pinched and led to one caliper hanging on causing the car to swerve 😲,very difficult to find. 💩
 

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Datsun Patrol MQ 1982 RB25DE NEO
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921 Posts
Discussion Starter · #5 ·
Ordered all new hoses, rotors, pads, caliper rebuilt kits etc. Just wating for it to arrive in the post. Nowhere to go since I send in my drive shafts for balancing and adding an additional 65mm to the front. Apparently there are long queues for this everywhere so it's going to take 2 weeks. In the meantime I have lots of things to do to the interior like fitting the dynamat and new carpets. Also new door seals and cup holders.. imagine that! ;)
 
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Datsun Patrol MQ 1982 RB25DE NEO
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Discussion Starter · #6 ·
Dynamat in, all new rotors, pads, hoses and front brake seals in. Ready to put the interior back in including the new carpets.


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Datsun Patrol MQ 1982 RB25DE NEO
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921 Posts
Discussion Starter · #7 ·
Done around 200km since. Brake don't bind anymore and feels like a new cars brakes. Better be because I cleaned and replaced just about everything. I couldn't find any debris in the pipes blocking the return. There was a lot of sludge in the calipers which probably was the main problem.

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