Practically Classics Forum

...and this week's Totally Stoopid Award goes to... ME.

The brakes on the GT6 have seized, a rock hard brake pedal.
I bled the system and the master cylinder moved perfectly so it's not that.
Stripped down both rear brakes, no problems as they were replaced last Summer.
Took both front wheels off and both calipers were really tight - I put EBC Greenstuff pads on and to be honest I'm not impressed at all.
So - had to use my piston separator to get them out. Boy they were stiff, the pistons wouldn't retract at all. Piston looks to be straight in the caliper, no wear but it won't budge. So just a little more force on the wrench...
Then... Bang. My piston separator flies into two bits, sheared by the force being used. I gave up, intending to commence a complete caliper rebuild on Monday.
I went to put the top back on the brake master cylinder...
...and it hadn't been removed. No wonder the pistons wouldn't retract...!!
D'OH!

Hmm.., not sure about that, every disc braked car I've ever owned, I've been able to retract the pads with the cap on. It should have an air hole in it. Are you sure the flexible hoses haven't collapsed? Let us know how you get on.

^^^WHS^^^

Try releasing pressure in caliper via bleed nipple. If piston then retracts you know hose has collapsed internally.
We had a Chrysler Neon on which main agent diagnosed ABS unit faulty (£1500 + fitting + vat) as similar problem with calipers. Turned out to be both front hoses faulty (£26 pair)

Paul H

Stripped down the entire brake system and rebuilt today. I found one rear cylinder quite tight on the drum so adjustment needed in any case; but the front caliper that broke the piston spreader had both pistons seized solid.
What had happened was: I used EBC Greenstuff pads for the first time ever last season, but covered less than 200 miles all year. The pads had been quite tight in the caliper to begin with and due to the low mileage hadn't really begun to bed in. The caliper was therefore sticking due to little use all year.
When I used the pad spreader after removing the pads I first screwed it tight to the disc then extended both pistons right out to free them up. On screwing them back in, due to the design of the pad spreader it pushed them back at a slight angle. Both pistons then stuck in their bores. When I removed the caliper and applied pressure to the other side - the side you can't get at because of the disc - they both went straight back in.
I won't be using EBC pads again - due to my low mileage these days they're not as forgiving as cheaper pads - but neither will I be using that sort of piston spreader again. I'll make one up myself that tightens across both sides at once and applies pressure equally across the piston. (G clamps and bits of wood? Been there, done that, and this tool was supposed to replace the need for four hands.....)
So.. it wasn't the cap!

im sorry you only get the award if you do it again.....