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]

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.

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:cool:

[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.

[mattc]

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!!

[thor]

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 (http://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]

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]

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.

[Spanner Man]

Afternoon all.

I came across Never-Seez in the early eighties when us dispatch riders were trying to prevent our brakes seizing up. It differs considerably from normal copperslip, as it's somewhat thicker in consistency, & is a right old cocktail of things including Aluminium & Copper, & it has a melting point around 1100 degrees centigrade.
I certainly wouldn't recommend using ordinary copperslip on caliper pistons, as most cheaper varieties are much more oily, & there is the possibility of the seals swelling if an excess of oil comes into contact with them.

I have found that applying Never-seez to the pistons on top of the rubber lube prevents the rubber lube from being washed away, & also provides another layer of protection when it comes to preventing water entering the caliper & getting behind the seals.

My mates XJ900 dispatch bike retired after 8 years & 215k miles. I had regularly cleaned & lubed the calipers 'my way'. It had never needed a caliper overhaul & the wheels still spun freely. There have also been countless others that I have serviced over many years...I rest my case M'lud!:D

Cheers.

[jambo]

It differs considerably from normal copperslip

I certainly wouldn't recommend using ordinary copperslip on caliper pistons, as most cheaper varieties are much more oily, & there is the possibility of the seals swelling if an excess of oil comes into contact with them.

I rest my case M'lud!:D

Cheers.

Thanks for the clarification, your initial post did not make it clear to me you were using anything other than normal copperslip, which I wouldn't be reccomending. This stuff I've not met, so can't comment on. But you seem to have had no issues which is good to know.

All the best

Jambo.

[Lozzo]

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.


Exactly the same method that I was taught how to service a caliper.

[squirrel_hunter]

Ok so summing up its fine to scrape the recess if other cleaning products don't work.

But can I just check, the red caliper grease should be applied all over both the piston seal and the dust seal? Also I was always told that a little brake fluid should also be applied to the recess IIRC, if this is correct, though not previously mentioned should this be used in conjunction with the grease or is the grease best on its own?

[Spanner Man]

Morning all.

Yes it's fine to scrape the seal recesses, providing you don't get carried away. If you don't have a Dremel, get yourself a small brass brush of the type used for cleaning spark plugs, or indeed the type used for cleaning suede shoes. Being brass, & somewhat softer than the alloy the caliper is made from it'll remove the corrosion without scratching the alloy.

Brake fluid should only be used as a lubricant if you have no rubber lube, there's no need for both, & yes, apply a thin layer of it all over the seal & the piston.

Jambo you're right to question my use of 'copperslip' on caliper pistons. It is somewhat contrary to accepted practise, which is how most people who have been taught bike maintenance are instructed.
All the tricks of the trade I use I have discovered & refined over the last 30+ years. I know this method works.

Finally when cleaning caliper pistons in situ, a looped cable tie makes an excellent cleaning device as it's serrated on the inside. A short length of parcel banding can be used also. This is particularly useful on multi piston calipers where the clearance between the piston & the caliper body is too small for a cable tie. I also urge you guys to get hold of some silicone lubricant. 3 in 1 do an excellent variant which is available from Halfords & some B&Q stores. It has a multitude of uses, & is particularly good at softening the grime that builds up on caliper pistons. It's also very effective on cables, bodywork grommets, & under the rubbers on gearlever linkages.

Cheers.