Help with long running BRAKING problem please :)

[Vombil]

Hi Guys

My HZ ute had shocking brakes when I first picked it up. Since purchase ive done rear wheel cylinders, front recond calipers, brake booster and master cylinder and the POS pg13 still had a sticky (as in fully locked) front left caliper. so... off with the brake line (flexi and ali pipe) and the brake proportion valve. This has improved the problem (not stuck solid) but it still is touching and the wheel is hard to free spin (on a jack stand).

Does anyone have ANY suggestions? I came really close to kicking the door in on it today. Ive spent a long long time on the brakes on this POS and i'm tired of it!

Thanks for any tips n tricks in advance

[Taily]

Couple of things to look at:

Your "reco" calipers (remove) them from the disc and remove the pads to check the following:

• Are the slides moving freely/well lubed/not bent (actually quite common), and is the dust boot on the piston not stuck behind one of the pads?
• Did you buy them from a reputable brake specific workshop/outlet? I have seen bodgy mechanics chuck a round section o-ring in as the piston seal - it doesn't work as the installed seal needs to be a square section to let the pads release properly from the disc.
• Are the threaded fittings on the master cylinder the same size and/or could they have been swapped at any stage?
• Is there any tool damage to the flexible brake line? They have a plastic sleeve in them and are not designed to be crushed off with vice grips, pliers etc to stop the flow of fluid.
• Are the caliper attach bolts tight and are they the right bolts (not too long and hitting the inside of the disc)?
• Are the pads actually sitting properly?
• Check all of the metal lines for any form of crush damage (like the flexible lines) where fluid can get pushed under pressure in one direction easily but not back the other way when not under pressure.

There is other stuff to look at (such as the part number for the master cylinder) as a PBR drum/drum master cyliner does look the same as a disc/drum one (the drum fitting of any master cylinder will hold a small amount of line pressure on that part of the system to hold the linings close to the drum so that you keep a good brake pedal), however am not sure of the fitting sizes of the top of my head (20+ years since having anything to do with them).

That is a pretty good start, let us know how you go....

Dave.

--- Updated ---

Disc brakes do run very "close". especially just after being done-up/repaired. This might be what you're seeing. Check the disc for warpage/run-out too.

[Vombil]

awesome! cheers Dave


I think ill look at the slides on the caliper again. When off the car the left was just as stiff as the right (both moved freely-just not sloppy). They do have correct o rings but ive got a feeling that they were rebuilt by a bush mechanic as they came with some spares off another ute i picked up as a donor.

initially the fluid would not return. If i removed the caliper as though changing pads, they piston would not squash up. I haven't tested this since swapping brake line (hard and flexi) and proportioning value. The cylinder is correct for the model.

I will check the pads too. I did notice that the pads jam quite easily in the tops of carrier/slide (not sure of the correct term). I will file them down so they have plenty of room to swell even when hot.
Thanks

Chris

[thatotherguy]

there were several callipers used, i had some that were alloy body with cast pad bracket (most toranas have them) and i had heaps of problems with them so if they are the same calliper i would change them

[Vombil]

there were several callipers used, i had some that were alloy body with cast pad bracket (most toranas have them) and i had heaps of problems with them so if they are the same calliper i would change them

cheers mate. i think ill chuck em then. mine are the same as the ones you described.. PBR... so bad

[HK1837]

I've always used those calipers and found them OK. They are probably the worst of the lot but still OK if not stuffed. They are popular for Torana owners who want to fit HQ brakes, they use HQ-WB stubs, UC Torana caliper alloy bit (almost the same as yours) and the cast pad carrier off your calipers (bit with HOLDEN on it). The Torana caliper has a top entry hose and a recessed lower attachment bolt to clear the tie rod.

[buck]

i have never had any problems with brakes i think my HZ had girlocks? not sure what the wb has but i flushed the system the other day, put new flex lines on the front as they where perished and a new set of rear cylinder, i think the drums on the rear will need replacing soon as they are getting a bit thin. but never had an issue apart from crushing the rear lines that run down the chassis on the hz hit a large bump at speed.