Hello, I have finally had my brake servo repaired (only took them 3 months) and I have fitted new brake pads. This may be totally normal but I took the car for a run to bed in the pads and the front brakes started to seize progressively. On getting back, the car would hardly move from start and the front wheels were pretty hot. However, I left it for an hour to cool down and I was hovering around the front when I heard a few clunks and the brakes suddenly freed themselves up. I didn't have a chance to drive it again, but is this to be expected and will it be OK next time I drive it?

Cheers, bogbasic.

You'll have moved the pistons back in the calipers to a position they haven't been for a while so they may be partially seized. I'd change the fluid, winkle the pistons in the calipers in and out a few times and see if they free off.

Hello, I tried winkling and bleeding and its better but it still seizes up although it took longer to get there and it seems not to be as bad as before. Perhaps I just have to keep taking it for short runs till the pads bed in. Cheers, bogbasic.

are the pads free to slide in the caliper? I have had sets that were tight in the caliper, a quick run over the sliding surfaces with a file might help, dont take too much off tho !

Hello, they seem quite loose in the calliper to start with but after a run the brake peddle is very hard due to pads binding. They are black diamond pads. Do they take longer to bed in?

Funnily enough, just finnished reading your blog on bessy, top stuff, sounds like you have been having fun. Nearly had a coffee soaked keyboard several times
Black diamond pads wont take much longer to bed in than normal, should feel fine after 100 miles or so, But they should NEVER sieze up in the caliper. something is muchos wrong here, I suggest a very carefull examination and reasembly of the pads and guide pins, with haynes manual in hand (no shame in that, I still have to, and I'm doing it for a living).
pay special attention to the parts of the callipers that guide the pads, dirt and rust can cause havoc here. scrape any crap off and finnish with a good wire brushing. Get the new pad you intend to fit, and place it squarely in position in the calliper, slide it back and forth in the way it would if you were applying the brakes, it should be free to slide with no effort, but also should not have more than a few thou slop in the calliper. If they are tight carefully file down the edges of the pad untill a nice fit is achieved.
as Pettaw, are the pistons in the callipers free? difficult to describe how to judge this but on a new calliper, you can usualy just about force the piston back with your bare hands, so if your in there with a crow bar theres probably something wrong !
Guide pins/ sliding parts of the calliper should be free to move with light hand pressure, and should be lightly greased. other than that, the problem is most likely somewhere else , possibles are an internaly collapsed rubber hose which can cause a one way valve effect, but this will normaly only affect one wheel, or possibly damaged master cylinder seals, seals past there best will often let go when the brakes are blead as the master cylinder travels much further than normal, also when you push the pistons back in the callipers it exerts a lot of pressure backwards on the master cylinder seals.

large intake of breath and cup of tea......
I recon it will be the pads not fitting correctly, by the way, if I recall, you used black diamond pads in an attempt to get a better pedal feel/ bite, unfortunately these will do the opposite to what you want, they are designed to opperate at temparatures the stock pads fall apart at, and they will have poor pedal feel and may provoke unnecessary soiling of interior furnishings if you ever had to do an emegency stop from cold, In your case genuine or brand name aftermarket would be best, or if you can find some, some old stock ones made of asbestos, just dont tell anyone I told you to !! and dont breathe !
Good luck

huskyracer wrote:possibles are an internaly collapsed rubber hose which can cause a one way valve effect, but this will normaly only affect one wheel, or possibly damaged master cylinder seals, seals past there best will often let go when the brakes are blead as the master cylinder travels much further than normal, also when you push the pistons back in the callipers it exerts a lot of pressure backwards on the master cylinder seals.

Iain, I think you may just have accidentally solved my problem... I won't go on a major threadjack, but after rebuilding calipers, new rear cylinders, and new master cylinder, I still get pedal drop and one caliper binding every so often (atm, every few weeks) Didn't think about the hose, looked fine from the outside.

Many thanks for all that. Looks like I will have to go back to standard pads (should have spare pair somewhere) and will clean up the slots they sit on.

Hello, I fitted standard pads and cleaned up with a wire brush where they fit into the brake assembly. I then took the car for a couple of test runs and its definitely worse than before, i.e. the front brakes still seize up and get mentally hot and smokey.

So.... there is something mucho wrong. Do you think its the master cylinder?

If it was the master cylinder then I would expect the same to happen to the rears. You could test this by clamping the front hoses and checking if teh rear wheels lock solid after pressing the brakes.

My bet would be on the flexi hoses.

Hello, I forgot to say that all the flexible brake hoses on the car are new.

You may still have air in the system which may be getting in past the threads of the bleed screws while bleeding. This can happen if useing one man bleed systems as the bleed screw is always loose when the brake pedal is released. If useing the 2 person method make sure the bleed screw is tightened before the pedal is released. If useing the one man compressor method then don't unscrew the bleed screw to much.

Try useing a bit of blu-tac around the outside of the bleed screws (not on the main threads) to help stop air getting in past the threads. I've had to use this method of stopping air getting back in to the systems on many cars and motorcycles and so far it has worked for me.

morgan105