ardiesse
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« Reply #1 on: September 23, 2013, 03:14:18 PM » |
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John,
"Grabby" front brakes in early Holdens are fairly common. Both my earlies, a 48 and an FC, are prone to the problem in cool, damp weather if they haven't been driven for a while. But there are other factors which contribute -
weak brake shoe retractor springs, corrosion products and other gunk between the slave cylinder pistons and the cylinder walls, rust and other gunk between the adjusters and the slave cylinders.
All these have the effect of making the affected shoes not retract properly, so they apply hard with little pedal effort.
If you don't mind a little DIY troubleshooting, before you drive the car next time, jack the RHF wheel up and spin the wheel. It should rotate freely, without dragging. Next, pull the wheel and drum off, and examine the slave cylinder for evidence of fluid leaks - in its early stage a fluid leak will look like a rusty drip at the bottom of the adjsuters, just above the retractor springs. If you see signs of fluid leaks, it's time for a slave cylinder rebuild. If the brakes don't drag, and the slave cylinder looks dry, get someone to push down on the brake pedal slowly and gently by hand while you watch the brake adjusters. They should both start to move almost as soon as your assistant pushes on the brake pedal, and they should move outwards together, at the same rate. They should also retract fully on release of the brake pedal. Push the brake shoes hard "home" by hand to make certain they are retracting fully. If you need to help the brake shoes retract, the pistons are almost certainly sticking, and it's time for a slave cylinder rebuild. Grabbing brakes are frequently made worse by a sticky leading (=front) slave cylinder piston.
If you clamp the hose shut with a G-clamp, you can disassemble the brakes, remove the adjuster, and with care, pop the pistons out for cleaning without disturbing the rubber cup. Only if you're brave.
If everything seems in order, get some medium-grade sandpaper and gently sand the glaze off the linings. Wipe the drum out with a dry rag. Reassemble the brakes and drive the car. More often.
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