Brake caliper

[oletam]

Just replaced my discs and pads on my UK300. 

Found one of the front pistons was a bit sticky and might still be cos of the amount of dust on the wheel.

Obviously the easy way is to replace the caliper, but has anybody tried replacing the piston and seals? How much hassle and is it worth the bother?

[WRC No 1]

what i have done in the past and work is ( 4 pots ) what ever side it is sticky keep the pad in the other side of the caliper

spray a bit of wd40 under the piston rubber get some body to pump the brakes till the pistion comes out then push it all the way back in do this 5 or 6 times and thats it put pad back in if so do the other side of the caliper.

i do this every time i renew the pads on my wagon and have never had any probs with the brakes and it has 4 pots.

it is up to u if u want to do that or go the full hog and get new seals and rubbers.

wullie

[AlanG]

Haven't done it on a Subaru but fitted new seal kits to other  calipers in the past.

Isn't a big job to do. I wouldn't replace the piston unless it's fairly well corroded but you'll see that when you press the pistons out of their bore.

It could have been "sticky" cause the piston was further out of the bore than normal and so less support for the piston in the caliper.

I'd drive the car with the new pads and discs and re-check if it's still sticky after a while but i think it should be fine. If not, remove the pistons and have a look at them. If they're fine just buy a seal kit.

[wilky]

The seals are fairly easy to replace once its all apart, the rubber gaiter that protects the piston is probabley what is shot, causing water to get into the piston hence causing corrision on the polished piston causing it to stick.

heres how I did it to both 4 pots and brembos.

take the caliper off and drain all fluid.

Using compressed air blow all your pistons fully out you will see which ones are corroded and need a polish with whatever you choose to do it with.

Its easier to clamp 3 pistons and blow them one at a time if they are sticking.

Your seals will no doubt be okay so you wont have to strip the caliper and replace them, just the rubber gaiter that covers them as they push in and out. the gaiter goes back on the same way as they come off. I found a bluntened small screwdriver good to tuck the gaiter retaining lip back under again to hold it all in place.

there is a varied train of though on lubricating the pistons. I used copper slip, some others use all sorts of strange stuff.

Piston seal kit is about 20 earth pounds.

Hope this helps.

Callum

[oletam]

Thanks guys. I've already had a squirt of WD40 under the seal and it seems to be free now.[]