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[papasmurf]

This may help:-

https://youtu.be/aRF49Jsb2I0

[Mann]

Thanks John, i got them out.

There is no rust in the caliper at all and i expected to see some as i think the caliper is sticking. I had a strange problem last night.

I replaced the pads a few weeks back and since then the caliper has been sticking to the disc intermittently but only briefly i though it must just be the pads bedding in.

Last night whilst riding down a long dual carriage way my bike (C5 2018 ABS) started bogging and losing power after about 300 metres i realised the front brake was sticking on, the disc was glowing red and smoking, i pulled over and let it rest the brake lever was hard.

After a few minutes the wheel moved freely but the brake level was loose and i could pull it all the way in and the brakes did not operate. After about 10 minutes of rest the brakes returned to normal function the lever was normal and all worked well on my way home.

I have striped the caliper now and after one piston being hard to extract and not moving much it all seems fine with no apparent wear or rust. I will reassemble with red rubber grease and refit and bleed the front brake.

Something is not right though, anyone have any ideas?

[Haggis]

Did you take the seals out and clean the grooves behind them?
The only other bit that would cause a problem would be the sliding pins, does the caliper slide freely on the guide pins?

[Mann]

Did you take the seals out and clean the grooves behind them?
The only other bit that would cause a problem would be the sliding pins, does the caliper slide freely on the guide pins?

Thanks Haggis, The caliper slides freely as i greased the pins when changing the pads. I haven't cleaned under the seals, how would i remove the seals? they look quite snug

[stinkwheel]

I'd usually gently lever seals out with a fine bladed screwdriver or a pick tool. I wouldn't generally re-use them, I'd fit new ones because they are invariably deformed by the corrosion pushing up behind them. I suspect you'll be needing that fine bladed screwdriver to scrape out any corrosion or crystalised brake fluid behind them.

For what it's worth (and it's one of those questions like what oil to use) while you'll often see red rubber grease recommended for caliper rebuilds, the manufacturers (Bremob being one of them) almost universally recommend lubricating the new seals and pistons with brake fluid. In fact, new genuine brembo seals come with a small sachet of fluid specifically for this job.

Incidentally, your total loss of braking sounds like you may have boiled the brake fluid so it wouldn't be a bad idea to bleed fresh fluid right through the system.

[Mann]

I'd usually gently lever seals out with a fine bladed screwdriver or a pick tool. I wouldn't generally re-use them, I'd fit new ones because they are invariably deformed by the corrosion pushing up behind them. I suspect you'll be needing that fine bladed screwdriver to scrape out any corrosion or crystalised brake fluid behind them.

For what it's worth (and it's one of those questions like what oil to use) while you'll often see red rubber grease recommended for caliper rebuilds, the manufacturers (Bremob being one of them) almost universally recommend lubricating the new seals and pistons with brake fluid. In fact, new genuine brembo seals come with a small sachet of fluid specifically for this job.

Incidentally, your total loss of braking sounds like you may have boiled the brake fluid so it wouldn't be a bad idea to bleed fresh fluid right through the system.

Thanks Stinkwell for both pointers

[Mann]

Thanks for everyones help,

I removed the old seals and cleaned out the crystallised crud and bled everything through with a air line and fitted new seals from our hosts minor caliper rebuild kit. I put it all back together and bled the brakes fairly easily and the brakes are now really sharp

[Haggis]

Excellent result.