Rebuilding calipers?

Anybody got any tips?,
Mine are jammed on and need a good rebuild,the seals are probably ****ed on them,whats the best method,toothbrush and ?
THanks
Darren
Btw merry xmas!

Originally Posted by irl_dar

Anybody got any tips?,
Mine are jammed on and need a good rebuild,the seals are probably ****ed on them,whats the best method,toothbrush and ?
THanks
Darren
Btw merry xmas!

I wouldn't waste my time, you might find that after you fiddle around cleaning and rebuilding for several hours that the calipers are worn beyond rebuilding

my dealer ate several hours of labor doing that for me trying to save me money, new calipers only cost 2 hours of labor

if you can leave them coupled to the bike and pump them out ( you may need to top up your resevoir )

A trick here to get stubbon pistons moving is to leave the caliper in position but take out the pads on the half of the caliper that is stuck then the free side will not pump out first

once out you could use a rotary wire brush in your drill i use a zip wheel in a grinder if there terrible though with big pits you need new pistons but hey its worth a try

either that or 600 wet and dry and clean them up once clean grease well with rubber grease
( this type of grease doesn`t degrade the seals any )

the first method is more a last resort really but id sooner take a caliper to bits and repair it for an hour than replace it for myself

for a customer id replace it that way down the road any problems and you dont get called if your so called repair suddenly goes wrong its down to the new part and not you

if they are silly money like ive done in the past i will overhaul them though

[Viney]

Just buy a rebuild kit from Fowler ins Bristol(mail order) Comes with pistons and seals, Take out pistons (Use a set of 5 holes..or waterpump pliers...the ones that you can open up to a huge span) dig out the seals, thouroughly clean all the seal recesses with a pick/scrapper(not a srewdriver) or a softish wire brush on a dremmel. clean the caliper all over...personaly id replace the beed nipples with S/S items from HEL.

Then thoroughly rinseout the claiper with clean brake fluid, empty, and dry (Get a can of air duster from an electrical shop) then place the calipers indoors near a radiator to make sure that they are dry.

Rebuilding.

Put the seals in, then dip you clean finger into some clean brake fluid and rub over the seals. Dip the clean pistons into the clean brake fluid and insert them very carfuly into the holes and push both fully in. Undo bleed nipple slightly, and fill the cliper through the banjo hole, nip up the bleed nipple. Fit back to bike using new copper washers and tighten the banjo to 23ftlbs.

Repeat for other side.

Bleed brakes in one of the many ways that there are.

When re assembling, the thing is to be clean, spotlessely.

excellent post,
thanks alot
Dar

My tips (from personal experiance of damaging calipers!!!!) are with stuck ones is to take the caliper off - then the pads out, then lighlty pump the brake until one of the free pistons are at the top, and then put a g clamp on that one to create pressure to pop out the other then they should just wiggle out.

Chances are they may just need a good clean and you can save yourself a lot of money, just buying new seals. So before using pliers etc. and risk scoring the pistons do the above procedure to pop both pistons out without damaging them. Then they may just need a clean, new seals and some brake grease. If the pistons are found to be extensively pitted replace them as this will leak brake fluid and can cause it to sieze as well. Ive dealt with calipers and some times it is just a case of clean, new seals, and grease.

Good tip from the guy aboves post - buy new s/s bleed nipples as they can easily be sheared off when they are rusted, and then you would need a whole new caliper!!! (or very tiny helicoil, lol)

A trick here to get stubbon pistons moving is to leave the caliper in position but take out the pads on the half of the caliper that is stuck then the free side will not pump out first

surely if you do that, you risk warping your disks?

[Viney]

Originally Posted by Ash999

Chances are they may just need a good clean and you can save yourself a lot of money, just buying new seals. So before using pliers etc. and risk scoring the pistons do the above procedure to pop both pistons out without damaging them. Then they may just need a clean, new seals and some brake grease. If the pistons are found to be extensively pitted replace them as this will leak brake fluid and can cause it to sieze as well. Ive dealt with calipers and some times it is just a case of clean, new seals, and grease.

True but Brakes could save your life. Is it worth saving £30?

Originally Posted by Dan_SV

surely if you do that, you risk warping your disks?

not really you only warp hot ones cold ones you bend but you wont bend them they arent that soft


they float aswell to a degree


EDIT ( use your discretion here really seized ones will need like the g cramp method ) this is a quick fix for no tool numptys

It is possible to rebuild even some very badly corroded callipers.

First of all I would agree with the suggestion of replacing the bleed nipples. A corroded bleed nipple will only cause air to get in to the system in addition to being difficult to use.

When cleaning out the grooves where the seals sit I would use something wooden or plastic that isn't likely to damage the surface to scrape off some of the worst corrosion and plenty of brake cleaner or WD40 helps also.

When rebuilding I have found that rubber grease rather than a bit of brake fluid works best. Apply it liberally to the seal, the grooves and the sides of the pistons to help keep the air out.

Once everything is back together bleed it the best you can and then hang it upside down overnight which should help shift the air bubbles caught in all the little cornes where they can't get out easily.

Good luck.