Brake booster adjustment advice needed

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R.K.

R.K.

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Joined
Feb 26, 2002
Threads
341
Messages
1,948
Location
Roxboro, NC
I’ve got a ‘75 FJ40 with JTO front and rear disc brakes, along with the JTO 4 wheel disc master cylinder. Just installed a City Racer brake booster. The brakes work outstanding!

The only issue is that after driving a few miles, the rear calipers won’t release from the rotors unless the rig sits for an hour or so. Unbolting the master cylinder from the brake booster immediately releases the rear brakes.

I’ve adjusted the booster rod in a couple of times, each time the duration of time it takes for the rear brakes to lock is increased.

But I have now adjusted the rod all the way in. I can cut the rod down shorter if needed, it’s plenty long for that. Anyone else experience this and have ideas before I cut the rod down?
 
Do you have the adjustment tool? You can usually pick one up at an a/p store.
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On the few occasions where I have encountered this problem, it has been at the dry assembly stage. IOW, those measurements are checked before the parts are installed in the truck. No possibility of the pedal throwing the measurements off.

I have a box of extra booster rods in the service bay, so if I have a need , I search for a longer/shorter rod there first. They are not all the same.

If there is nothing short enough there, AND the distance needed to get the proper clearance is less than 1/8”, I will grind. If it’s more, it is time to look for a different master cylinder.

For those who find this tech useful, you are welcome to hit the like button.😊
 
Last edited:
Have you adjusted the pedal as well? The pedal rod could be too tight (long) and always pushing on the booster.
 
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