Caliper Overhaul

[skoda_dragon]

I'm planning on overhauling my calipers over the weekend as I believe they have seized up. I've got the new piston and seals ready to do the job and require some advice on doing the job from anybody who has done this before.

Is it possible to remove any rust from the caliper bore with sandpaper without causing damage to the caliper itself?

[fruitbat]

I rebuilt a pair of calipers earlier this year - I soaked them overnight in a bucket of hammerite rust removing solution from Halfords, rinsed them and dried them off with a hot air gun. This really brought the caliper bore up nicely without the risk of damaging the surface.

[skoda_dragon]

Originally Posted by fruitbat

I rebuilt a pair of calipers earlier this year - I soaked them overnight in a bucket of hammerite rust removing solution from Halfords, rinsed them and dried them off with a hot air gun. This really brought the caliper bore up nicely without the risk of damaging the surface.

Did you rinse them simply with water or do you have to use some sort of solvent to make sure all the solution is removed?

[fruitbat]

You can just rinse the hammerite stuff off with a hose - the trick is to make sure the caliper is completely dry before you reassemble or paint - hence the use of the hot air gun.

[TeflonTom]

Originally Posted by skoda_dragon

Is it possible to remove any rust from the caliper bore with sandpaper without causing damage to the caliper itself?

you will more than likely ruin the caliper if you do it with sandpaper... there is a special tool for honing those bores and they aren't even expensive

[skoda_dragon]

managed to find a cheap honing tool, is there any particular grade grit thats good for the caliper bores?

[TeflonTom]

around a 400 grit is good... make sure you use plenty of honing oil (or brake fluid is a good substitute ) then thouroughly degrease and clean it all out afterwards

[skoda_dragon]

does anybody know how to get the piston back in the bore with the seal when putting the caliper back together. Haynes says that you should place the dust seal in first and then push the caliper back in. if i do it this way then i damage the seals. I have already damaged two seals and don't want to do it again. any ideas?? thanks in advance

[skoda_dragon]

finally managed to get it done but there was much swearing going on in the process. I put the seal on the piston first and tried to clip it into the bore from there. It looks like it went on ok but I guess i won't know fully until it decides to seize up again. I think next time I will simply stop being cheap and buy a new caliper. Good for experience though.

[TeflonTom]

i was going to suggest using plenty of wd40 but it looks like you've done it.. the most important thing is ensureing the piston goes in square, if you but them in slightly off, it will just jam and it's almost impossible to get them back out again

[daverapid]

Bit late now, sorry, but I usually soak the seals in clean brake fluid before fitting them.