Brake Issues

[applecran]

Hi folks

I've got a relatively new to me '90 HDJ81 that is giving me a headache right now.

I had a front brake line blow last week, so I replaced both front lines, and bled the system.

After that brakes were working great, until today. Fluid levels are fine, but every once in a while there is excessive travel - to the floor, and a squeak noise, not the same as brake squeal. Sometimes, while braking, it's as if the brake boost is not working, and then kicks in while braking. Sometimes the boost is there and the pedal feels great, other times the pedal goes to the floor - but the car still stops.

The squeak noise is only there when the pedal has excessive travel.

Does anyone have any ideas where I should start?

Also, can anyone confirm that I need 16" wheels in order to upgrade my brakes to the newer post '93 bigger callipers and pads?

Thanks

 

[robertk61]

Sounds like your master cylinder is stuffed, you probably pushed it down past the normal travel area when you were bleeding it, causing the cups inside to score or tear-just get a new one !
Also yes, you do need 16 inch wheels to do a brake upgrade. I thought about doing it on mine, but have fitted slotted rotors and good pads and they are OK.
If one brake line has blown, the others wont be far behind???

 

[applecran]

Sounds like your master cylinder is stuffed, you probably pushed it down past the normal travel area when you were bleeding it, causing the cups inside to score or tear-just get a new one !
Also yes, you do need 16 inch wheels to do a brake upgrade. I thought about doing it on mine, but have fitted slotted rotors and good pads and they are OK.
If one brake line has blown, the others wont be far behind???

Thanks Robert. That is what I was thinking. It likely wasn't the bleeding so much as it was my wife not wanting to stop when the brakes weren't working, she managed to drive from downtown Vancouver to Coquitlam somehow. Pedal was going to the floor at that point.

I've replaced both front brake lines as the other one was pretty rough, rears seem to be much newer.

In regards to the master cylinder, it's just that part, and not the brake booster that I'd need to swap correct? What is the best way to find part numbers for bits on these rigs? I'm use to old BMWs - part numbers are easy to find through the online ETK.

Cheers

 

[mudbludger]

http://www.toyodiy.com/parts/

 

[scrowley]

Brake booster failure results in hard pedal with no brake power. When bleeding brakes put a spacer on floor to keep pedal from being fully depressed.

 

[scrowley]

Prob just air trapped in the system. These trucks are a bear to get bled. You can test master while in truck.

 

[applecran]

Prob just air trapped in the system. These trucks are a bear to get bled. You can test master while in truck.

What is the procedure for testing the master?
I did the test for the booster and it passes that.

I discovered one of my rear bleeder valves is snapped off, so I can't bleed that calliper. Not sure I should replace the master without replacing that calliper. Since this is a '90 I'm not sure I can easily find a replacement calliper at Napa or lordco...

 

[scrowley]

You can find a replacement at Napa and or other. Maybe have to order and take a day. Do a search for testing the master. Doesn't have to be 80 specific as most are all the same with a front and rear side of the master. If I remember you take off the lines and cap them at master. Your pedal should be like a rock at this point (acting like your brakes are fully depressed). If it sinks then the fluid is leaking past the cup seals and back into res. Someone correct me if I'm wrong.

 

[Gavi2884]

I had a squeaking nose coming from my brake area cause the pads weren't rubbing even on the rotors having a small bit not rubbing at all. The pad was the original size when new whilst the rest of the pad half worn down causing it squeal everywhere. Ended up just getting new rotors & pads from Jonesy, Drilled & slotted . Great stopping power!

 

[Howard705]

If it's intermittent it's the master. x2 on damaging it. The pedal never really completely goes to the floor-just close-the front and rear hydraulics are separate for safety-unless the rears failed also. When it goes way down you're only stopping with the rears and pushing your luck.

 

[applecran]

well, it looks like my rears pads are gone. I dropped it off at the shop today, I wanted to tackle it but I just don't have time right now, wife needs her car!

Thanks for the help everyone.

 

[applecran]

Rear pads were to the metal, that and the caliper pistons were messed up and leaking...

My own fault really.