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Re: 84 Nissan 720 rear brake lock-up
Was the proportion valve and mater cylinder replaced? The problem most likely is a bad proportion valve it doesn't allow the fluid to return to the master and therefore stays in the system and locks-up the brakes.
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'84 ...*lotsa* miles on it ....like 450K plus if you drive the "normal" 15K/year. First, and most likely, thing that comes to mind is the wheel bearing has seized. Since this is a front wheel drive car, there are sealed roller bearings for the rear wheel hubs. At 450K on the odometer there are *lots* of components that have reached or exceeded their normal service life. I would suspect the left rear sealed wheel bearing is one of them ...followed closely by the right rear wheel bearing. If it's the bearing? Get them both done.
change the hardware , and also flush the system and put in all new brake fluid, , if you've replaced all of what you describe, thats your best bet, also,, at times emergency brake cables, look like they release but they actually don't,, be sure that this isn't causing you headaches !! Fords and jeeps are known for having a single brake that will stick or not release right away , normally a rear brake, a fluid change often helps
You could have gotten the wrong drums or brake shoes. When you do the drums there should be some adjustment that you have to do to get the shoes closer to the drum. If you have removed all the slack then I would guess your shoes are wrong. You should compare them with the old ones if you still have them. It has happened to me before.
When the ABS light is on, the brakes should revert to standard braking.
The only time ABS should invoke is when the tires are slipping as sensed by the wheel speed sensors when the wheel locks up on any of the axles.
--- ANTI-LOCK BRAKE SYSTEMS General Information Fig. 1: RWAL brake system diagram Fig. 2:4WAL Component locations — except 1996 models
p>Fig. 3: 4WAL Component locations — 1996 models Fig. 4: Three sensor 4WAL brake system diagram — Except 1996 models Fig. 5: Four sensor 4WAL brake system diagram — Except 1996 models
There are two basic types of anti-lock systems available for this vehicle; a Rear Wheel Anti-Lock (RWAL) brake system and 4 Wheel Anti-Lock (4WAL) brake system. The 4WAL system has two variations; a 3 sensor system and a 4 sensor system. The 2WD vehicles will be equipped with the 3 sensor system, but the AWD vehicles can be equipped with either. The systems are easily identified by looking at the rear wheels for a sensor harness. If there is a sensor harness and thus, rear wheel sensors, it is the 4 sensor system. If the vehicle is not equipped with a harness, it is the 3 sensor system. The 4 sensor system takes it speed references from each of the wheels. The 3 sensor system takes its speed references from each of the front wheels and the vehicle speed sensor located in the transmission (2WD) or the transfer case (AWD).
The RWAL system components consist of the Vehicle Speed Sensor (VSS), the Electronic Control Unit (ECU), the isolation/dump valve and the Vehicle Speed Sensor Buffer (also known as the Digital Ratio Adapter). The ECU also receives signals from various brake switches.
The 4WAL system components consist of the Electro-Hydraulic Control Unit (ECHU) valve (also known as the Brake Pressure Modulator Valve or BPMV), the wheel speed sensors, Vehicle Speed Sensor (VSS) on 3 sensor systems and the VSS Buffer.
Inspect the brake rotors for grooving and score marks and also look to see if there are any heat cracks, if there is grooving or very little brake pad material remaining replace the brake pads and also two new rotors, it is also possible that it is just a frozen or stuck brake caliper, this would be indicated by an uneven rotor one that has more metal or meat on one side that the other also uneven brake pads indicates an uneven brake caliper application