Cleaning Calipers

[squirrel_hunter]

I'm in the process of changing my OE pads to EBC HH's. To do this I need to pop the pistons back in and due to the massive difference in pad thickness I have found it easier to break the hydraulics to get them back in. But before I do that I decided to pump them out and clean them up.

I've done this before and each time I never remove the piston seal but the dust seal usually pops out. This time however I had great problems getting one of the dust seals back in and frankly I need to replace them the next time I take them out (I doubt I will as Suzuki want to charge me my arm, leg, and first born for a couple of elastic bands, but thats another story).

After struggling for some time I realized that the problem was around the dust seal recess on the caliper. It was what was best described as 'grime' and in places this was quite thick. I decided to remove it be scraping it off with a small flat screw driver and then cleaning up the mess. After this the seal went back in and the caliper rebuilt.

So my question is what would be the best way to remove this? Admittedly scraping worked but I remember reading that scraping anything around the piston bore is dangerous. While I don't think scraping the dust seal recess will do any damage, there is a chance of slipping and I assume that this is not best practice, so what is?

[the_lone_wolf]

wurth aerosol brake cleaner, never have i seen a solvent work so quickly, it managed to shift, in less than a second, what swarfega and 5 minutes of vigorous hand rubbing failed to get rid of. god knows i'm probably sterile now but it cleaned the callipers i did today just fine.

are you sure you need to break the hydraulic system though? i pushed the pistons on the DRZ callipers back in today with hardly any effort...

[squirrel_hunter]

Originally Posted by the_lone_wolf

wurth aerosol brake cleaner

Not heard of that stuff I usually use Silkoline Brake Cleaner, will try and track some down. If I really want to shift some stuff I use a carb cleaner (can't remember the name now) but wouldn't use it on the brakes as it will eat the seals.

Originally Posted by the_lone_wolf

Are you sure you need to break the hydraulic system though? i pushed the pistons on the DRZ callipers back in today with hardly any effort...

Yes, I am a weaklin.

[the_lone_wolf]

i read in one of the manuals that some wood and a pair of large mole grips makes it easier to push the pistons back

[Spanner Man]

Morning all.

Corrosion behind the dust seal is the main factor with seizing calipers.
Having overhauled a few (thousand) calipers over the years. I first scrape out the excess corrosion with a 90 degree pick, after softening it with brake cleaner. I then use a Dremel with the little stainless steel chimney sweeps brush attached.
I give the new seals a good all over coat of rubber lube before installing them.
Then I give the pistons a good polish with 1200 wet & dry & silicone lubricant, & wash them thoroughly with brake cleaner.
I then smear a little rubber lube around the closed end of the piston before pushing them (squarely) into the caliper.

When the piston is halfway in, I apply a thin coating of high temperature copperslip, before pushing the piston home.

I have found that if the calipers are cleaned & lubricated as above a couple of times a year, or every time pads new pads are required they never need overhauling.
There's no need to completely remove the pistons when cleaning & lubing, just pump them out a little more than they would go if the pads were worn out.

I think new caliper seals are around £25 per side, this includes new rubbers for the slide bars. Rubber lube is the thing for lubricating them also.

Cheers.

Hi,

One word of caution, I always use my thumbs to push the piston back into the caliper, cars bikes whatever.

If it wont go it is because there is corrosion, as already stated behind the seal. Use plenty of lubrication as said before.

I have seen a few times calipers leaking brake fluid from the piston, this has been after someone has used a G cramp to "ease" the piston back in. It tends to damage the seal by taking a chunk out of it rendering useless.

Hope this helps!!

Originally Posted by the_lone_wolf

wurth aerosol brake cleaner, never have i seen a solvent work so quickly

Have you used it on oil trays? It's phenomenal. Joe used it to clean his hands!

[jambo]

www.wemoto.com do sets of brake seals.

You should always be able to push pistons back in by hand otherwise, push the pistons out, and clean up the recess. Hot water and a small scraper in the caliper recessare usually my weapons of choice, with an old toothbrush and rag to clean up the pistons.

Regarding Spannerman's comment I was always taught to use nothing except red rubber grease on the pistons and seals, and to put copper grease on the back of the brake pads. Copper grease is great stuff but not if it gets in brake seals so better safe than sorry.

Jambo

[Spanner Man]

Originally Posted by jambo

Regarding Spannerman's comment I was always taught to use nothing except red rubber grease on the pistons and seals, and to put copper grease on the back of the brake pads. Copper grease is great stuff but not if it gets in brake seals so better safe than sorry.

Jambo

Yeah well, I've only been using a product made by Bostik called Never-Seez in conjunction with rubber lube for about 25 years & not had a problem yet.

Cheers.

[jambo]

Originally Posted by Spanner Man

Yeah well, I've only been using a product made by Bostik called Never-Seez in conjunction with rubber lube for about 25 years & not had a problem yet.

Cheers.

I've not met Never-Seez, and am not sure if it differs to the standard copper grease I've met before. The method you use for applying it should mean it doesn't get back past the seals, but it's not what I was taught, or what I do. Clearly if it caused massive problems you'd have had complaints in your job.

I'll stick to keeping the pistons and seals lubed in their entirety with red rubber grease though, and not letting the copper slip get too near them.

Jambo.