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FZJ80 front brake issue


New Member
Jan 6, 2023
Country Flag
Hey guys this is my first time posting on here so g'day, I've recently bought an FZj80, I'm a first-year mechanics apprentice but this problem has stumped me, whenever the car is driven in hot weather and the brakes hit a certain temperature the calipers start engaging slowly to the point where its undrivable, I'm planning on putting new pads and discs on it once I can afford them and also do a full caliper rebuild but also heard it could be something to do with my brake lines, I don't think its the master because as soon as the brakes have some time to cool down they're perfectly fine again. if anyone here has any ideas about what it could be. first time it happened was Christmas day, pads and discs aren't in the best of shapes as well but other than that the car is basically bone stock. I'm also thinking about replacing the brake lines but planning on doing a 2-inch lift on it later on, I don't know if ill need extended brake lines or not for that yet and if so is it alright to put extended brake lines before the car gets a lift
Just a thought, but if it's affecting both front brakes, it could be worth checking the flexible hose that runs to the front axle (90947-02815). Sometimes when they get old, they can start to break down internally and restrict the reverse flow of the brake fluid.
Another thought would be change the brake fluid..... if it's old and contaminated with water then is that expanding and applying the brakes ? It's a viscous circle because once they start to bind they will generate their own heat .
Another thing I've seen is a faulty brake servo cause the same symptoms
The problem is more often than not in the servo. Was the master cylinder replaced recently? If so the plunger in the servo was not set properly, if at all. To confirm this is very easy.

Get together four washers that will fit the studs holding the master cylinder to the servo. Cut slots in the washers and take the car for a drive, if you feel the brakes start to bind pull up and switch off the engine, loosen the master cylinder nuts enough to slip one washer on each stud between the master and servo, then tighten up the nuts trapping the washers. See if this cures the problem, if not add the second set of washers.

Note this is a fault finding exercise, you must NOT keep the washers in place even if it works, the master cylinder will not be seated properly. You can remove the nuts and pull the master gently off the studs and adjust the servo pushrod. If the master cylinder was not replaced and the problem just happened out of the blue, I would replace the servo.