02' 1150RT caliper refurbishment

[Alba]

Post the removal of my ABS system and bleeding the brakes I noticed on both front calibers a few of the pistons are not easily extending and are very very difficult to push back in, piston lack of movement reflective in the brake pad wear, so I have decided to put in new seals and pistons.  Having never done such a task before and the possibility of a piston being difficult to remove, has anyone got a tutorial or advice on how to go about it?

 

Thanks in advance. 

[SAS]

If you have the caliper out, then, if you have a compressor you can use some compressed air, very carefully blow into the brake line hose connection, it will cause the pistons to move out.  You can use a piece of wood or of the sort and put it in between the caliper and pistons to block the pistons from flying out and making a big mess, or just use a bunch of rags in a pan to catch the pistons.  One usually comes out first, then you need to ;put that one back in and hold it with a piece of wood and apply more air to get the other out.  There are other ways but this works good for me.

[dirtrider]

18 hours ago, Alba said:

Post the removal of my ABS system and bleeding the brakes I noticed on both front calibers a few of the pistons are not easily extending and are very very difficult to push back in, piston lack of movement reflective in the brake pad wear, so I have decided to put in new seals and pistons.  Having never done such a task before and the possibility of a piston being difficult to remove, has anyone got a tutorial or advice on how to go about it?

 

Thanks in advance. 

 

 

Morning Alba

 

As SAS said, using compressed air will usually pop the pistons out (be very careful to not get your fingers between a piston & the caliper frame or you could easily crush a finger).

 

Try to use pieces of wood to limit individual piston travel so that one doesn't blow out before the others (you want to work them ALL out as far as possible  before the first one comes out).  Even then you will probably have to push the easy ones back into the bore  a ways to get the opposite piston out.

 

CAUTION: do not use compressed air to blow those pistons out anywhere near  a painted vehicle or near pristine plastic things, or near anything that you cherish. Blowing those pistons out with compressed air can cause brake fluid to fly, brake fluid is an excellent paint remover or plastic etcher. If I use my shop's high pressure  compressed air to blow the pistons out I usually put an old towel over the caliper to limit fluid spray if a piston pops out.

 

I have seen some caliper pistons stuck so hard in the calipers that I have had to make an adapter to hook my tractor hydraulics to the caliper then use the tractor's hydraulic pressure  to ease the pistons out. Some even make an adapter to install a grease fitting on the caliper  hose inlet then use a high pressure grease gun (with grease) to force the pistons out. Makes a mess but I guess it works.

[GRIPPY]

As above for the pistons,i just changed the pistons and seals on my front caliper.The seals (two for each bore)can be removed with a small pic.

[Alba]

10 minutes ago, GRIPPY said:

As above for the pistons,i just changed the pistons and seals on my front caliper.The seals (two for each bore)can be removed with a small pic.

Did you think about cleaning up the pistons rather than replacing?

[Lowndes]

Alba,

 

See my comments and pics of my caliper renovation here in :

Dragging frot brake caliper 94 r1100 rs, by GRIPPY, in Oilheads

I reused ALL of my components, except for the rotting brake lines, the cause of my problems.  There were only about 30k miles on the '99 R1100S at the time and that has a bearing on the condition of the components.  

[GRIPPY]

On 8/6/2019 at 3:54 PM, Alba said:

Did you think about cleaning up the pistons rather than replacing?

As far as I can tell BMW only sell kits including pistons and seals,not just seals?Is it possible to get just seals?

[Lowndes]

Grippy: "Is it possible to get just seals?"

 

Both of these sources only show the kits with pistons.

 

https://store.bevelheaven.com/Brake-Related-Parts/Brembo-30/34-Piston-Seal-Kit/

 

https://www2.munichmotorcycles.com.au/product_info.php?products_id=3379

 

I don't know the diameter of the pistons, could be 32 and 34mm,  but you could measure yours, then contact the sources above (Bevelhaven is in CA so a phone call might help) to discuss options on the seals.  

 

A quick search shows eBay has a bunch of stuff, new and used, kits and complete calipers:

 

https://www.ebay.com/b/Brembo-Motorcycle-Calipers-and-Parts/177927/bn_578138

[Alba]

I thought I would give an up-date that may help others.

 

I did have a couple of stuck pistons so well worth refurbing the caliper pistons.

 

I took the caliper off the bike and replaced one piston and seals (2 per piston) at a time.

 

I tie wrapped 3 pistons and used my electric tyre pump to push out the remaining piston.  I used "self amalgamating rubber tape" to increase the pump nozzle size to fit the fluid inlet to the caliper. As stated above be careful of brake fluid spray.

 

Once refitted and bleeding the brakes take your time and ensure you get all the air out. I think it took me over 30 minutes to bleed both calipers, I would do one side then the other, repeating couple of time.