Hitchcocks Forum

... ok this one has me beat at the moment. Front brake caliper on my efi is seized on again. I have always managed to free it off in the past, brute force usually does it... but not this time. One of the two slider pins is seized in the caliper body, and one of the pistons is mega sticky. I cant free the piston with the slider on and I cant move the slider at all. And I mean not a jot! So, am open to suggestions - cant afford any parts at the moment so destruction is not an ideal option

Hi Michael, Complete guess but this problem usually happens with bikes 25/30 years old that have been parked up for a long time with old fluid in them that blocks the tiny return hole in the master cylinder and the pressure can't release. I can't imagine why yours would be doing this but anything is possible, this is the most common cause of sticking, dragging brakes. Release the banjo bolt on the caliper and see if this allows the caliper to retract, gut feel tells me it might not, indicating a problem with the piston. If it doesn't release you will have to put something like penetrene between the caliper and the fork leg mount after removing the 2 mounting bolts, and with a piece of wood and a hammer work on getting the caliper away from the disc. Then you have to asses what needs doing

Cheers Norm... I got the caliper off the disk eventually, but will try the wood hammering technique to free the slider pin from the caliper body again. It is salt corrosion that does the damage for me. The real trouble is that there are two caliper sliders so you cant twist it free.

Hi Michael once you get the sliders free try a bit of waterproof grease on them it might help keep the salt out or minimize the effect of it

Winter riding buggers up drive chains ...and disc brakes. It is indeed the road salt which does this. I once ended up having to pull the stuck pistons out with a pair of pliers, damaging them in the process. They were not cheap to replace. Try soaking in WD 40 or something, and please avoid what I did!

I like your optimism Norm... 'once you get the sliders out' Is lithium grease ok on these pins? The red stuff just isnt slippy enough on my mangled caliper...

Michael, I have read about this salt stuff, never seen it but I can imagine what it is like.Any chance you could immerse the caliper in diesel still hanging on the hose for a day or so, that might free it up.Then use a "G" clamp on it to get it moving, once it breaks it should free up Any sort of grease must help

I can vouch for the diesel, that and a modicum of heat will shift most things... A pair of wooden wedges tapped in from opposing sides will often start movement whilst keeping things square..
Polish the slide pins with fine emery cloth, also ream polish the receiving holes with the same wrapped around a wood dowel or drill bit...

I've gone off using copper slip as things still seize, so instead use ACF50 corrosion block grease on sliders and bolts..

Used sensibly and sparingly around brake parts i've had no problems with salt corrosion on van or car brakes, and there out in all weathers...

I WON'T recommend this but i've even used the spray product on the pistons as the stuff is not harmful to seals/rubber boots.. But everyone round here knows i'm daft.

Hi,Michael.Try this, put caliper in a pan of boiling water and give it a good boil.This melts any salt and crud,the boiling water heats up the caliper expandig it.You should with a bit of luck be able to extract the piston.

Heat, and lots of it plus wooden hammering worked a treat