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Old 09-06-2008, 08:39 PM
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Air Randy Air Randy is offline
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Join Date: Aug 2008
Location: Franktown, CO
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Default FJ40 Brake Issues

I bought SOA front & rear axles complete with lockers, disc brakes on the front and new shoes in the rear drums.

I also purchased the Toyota single reservoir high flow master cylinder that was recommended when adding disc brakes.

I installed the new master cylinder and rear axle last weekend but am having a weird problem with the rear brakes. I bled all of the lines really good and the pedal is rock hard. However, after driving around for some time and using the brakes the rear brakes seem to eventually lock up and get so tight I can't even move the vehicle.

I pulled the drums off, couldn't find any problems and adjusted the shoes down so they weren't dragging too much. That seemed to take care of the problem until I installed the front axle today with the discs on it. I bled the front lines and took off on a test drive. All seemed well until about 30 minutes into the drive and the back brakes locked up again, so tight they were smoking by the time I could get pulled over.

Fortunately I had a small wrench with me and was able to pull the plug out of the bottom of the master cylinder. About a tsp of fluid came out but that was enough to release the rear brakes. I was able to get home without problems.

I know I've read somewhere that the drum brake system have a 6 lb residual valve but I have no idea where it is. Unless its defective and hanging up it shouldn't be an issue, though I understand I'm supposed to go to a 2 lb residual valve now that I have the dics on the front.

Anyone have any ideas as to what my issue is?
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