BMW R1200RT/R1250RT Forum

Hi, anyone done a front brake caliper service entailing replacing the pistons. Just had my 30,000 service and one side is dragging slightly. The techy recommends servicing the calipers.
The Haynes manual pictures are pretty poor quality.
Any advice gratefully accepted.

Google
JVB productions,
Jim pretty much is a Bmw guru, has DVDs covering just about everything for hex,cam and LC bikes

Ganesh wrote:Hi, anyone done a front brake caliper service entailing replacing the pistons. Just had my 30,000 service and one side is dragging slightly. The techy recommends servicing the calipers.

Do the pistons need replacing or just cleaning, http://www.motorcyclenews.com/new-rider ... -calipers/

Thanks David very quck response, will look at the video. They come in a service pack, referred to as a gasket set and the techy says normally they replace the lot once the old ones are out. It seems quite common when ridden all year round especially if there's a lot of dirt and grit when going through puddles particularly. The dirt gets behind the dust seal.
They are £75 a set and need 2 one each side.

It appears JVB doesn't have anything on the caliper servicing, although interesting site.

Can the pistons & seals be replaced with or without splitting the caliper.

This Video shows "How to" fit new brake caliper seals on your motorbike/motorcycle", it's a Tokico caliper.

https://www.youtube.com/watch?v=HYy-vPLmL0E

I had a look at the Moto site and they recommend not splitting the caliper. Going to have a chat with the tech at Bahnstormer to check how they do it. He did recommend how to ease them out but didn't mention splitting them. Recommended the banjo washers need to be replaced at the same time. The brakes are BMW and not Brembo, mountings are slightly different, although the pistons seem to have the same part number.
Will go back after Christmas and have a proper chat, his view is if it doesn't need to be taken off then less work.

Brembo & Tokico have both made calipers for BMW.

Ganesh wrote:Identified a sticking piston on one of the front calipers.

If only one of four pistons is sticking, it may be possible to free it off. With a piece of wood between the free pair of pistons & a G clamp holding the free piston opposite the sticking one, gently squeeze the brake lever to see if the sticking piston will move. Take great care, don't want any of the pistons popping out. If in any doubt, seek further advice.

Some of the photos in this MCN article may be helpful, http://www.motorcyclenews.com/new-rider ... -calipers/

I did ask if that was an option. Unfortunately it looks like it could be a little more than that. When it was serviced there was a lot of grit behind the pads which they had to remove and clean, while the pads were out they eased the pistons out to check. They did want to do the replacements then as there were indications the seals were a bit worn and stuff had got behind it. Offered to clean the calipers and pads which should suffice for the time being. Not serious enough to drag the disc just not allowing it to freewheel as easily.


Think if one is playing up won't be long before the others start.


I've ordered the parts and think while I have them out might as well do the job properly.

Update, d[size=2px]id one at a time as recommended.[/size] The calipers required a T45 star driver to get them off and a T30 for the pads.
Wrapped the reservoir with an old cloth to stop it dripping before taking the cover off, also covered the tank with an old tablecloth.
Took the pads out then the calipers, suspended it on a bungee of the handlebar to take the weight of the hose. Not recommended to split the caliper as there is an "o" ring required which is not available, so if anything happens to it new caliper!

Eased the pistons out using the brake pressure and wedged a high density foam pad to stop them coming out completely. Used a tie to hold the brake lever down to prevent too much coming back up, although don't think I did it in time.
Had to push opposing and adajacent piston in slightly to give room. Used a pair of grips to ease them out and put a bowl under the caliper to catch the fluid. They did need a reasonable amount of effort and as they were being replaced wasn't worried about any scratching. Doubt if they could have come out without causing some damage, as they were fairly firm.
The dark ring at the top of the piston in the photo is the amount of debris, not sure if sanding them down to remove it would have altered the tolerance between the seals and the piston.
Used the point on the leatherman knife to take the oil and dust seal out, carefully so as not to scratch the chamber.
Cleaned out all the chambers out with brake cleaner and dried them out. Inserted the seals the smaller of the two is the dust seal and is closest to the top, they came out as the grey rings in the photo. The grease in the pack was used on them as well as inside the chamber and the pistons when they went in.
Bled the side that was worked on using a bleed kit with a non return, worked a treat. Then did the other side.
Major problem was no pressure after doing both sides. Quick trip to see the Danny the Tech and chat about the bleed nipple on the Master cylinder.
Back home, bled the Master and RESULT. Also at Danny's suggestion put the bike on the side stand, pulled the steering to get the reservoir to the highest point then pumped the lever pulled it in as far it would go then tied it off and left it over night.
Good experience but not sure about value for money as it took about 5 hours, not including trying to find a T45, 1/2inch driver and a bleed kit.
Now need to take it for the dreaded road test, once it stops raining and the small lakes disappear.


If you managed to get this far, well done.

nice job there, Well done!

Interesting story - thanks for posting.

Thanks gogs01 and simbo. Forgot to mention this is on a 2010 twin cam and noticed other models in the dealership don't appear to have a bleed on the Master, unless I missed it.

Been having a problem with the front brakes binding on a 2012 TC with 22,000 miles on the clock. The bike isn't ridden in the winter & the calipers/pistons are cleaned & exercised every year or when the tyres are changed around 5,500 miles. If necessary, AJ's have offered to replace the pistons & seals for an hours labour (circa £100),  plus two repair kits at £77.27 each. Have managed to free off the pistons, will see how the brakes perform over the weekend & take it from there.

Are these isolated issues or more common than reported on here?