Brake flushing aggravation

[racurley]

Sometimes I think I am a bad motorcycle mechanic and other times I know I am.

My front brakes felt a little mushy lately. Hard braking would pull almost to the grip. It was time anyway for the annual brake fluid replacement. I decided to replace the pads as well. The front brakes seemed to be sticking closed a little and I wanted to give the pistons a good cleaning.

I did the right front ok I think. Disconnected the brake line after extending the pistons and was able to really clean them well. New brake fluid in. On the left side, I left the brake lines attached and cleaned the pistons. They were dirtier than the other side. Bottomed them out, replaced the caliper, and installed the new pads. Bled the lines and pumped up the brakes. Nice solid feel. When I spun the front wheel I noticed they were grabbing a bit so the wheel wouldn't spin completely freely. Took the bike out for a short spin (barely missing a downpour) to test and seat the pads. Brakes felt great. But, they weren't really spinning freely.

I found Cyclerob's awesome write up on brakes in this thread
http://r1150r.org/board/viewtopic.php?f ... 59#p239089

I decided to go back and try his Caliper Piston Push-Back-Push-Out Purge-N-Replace Procedure on the left side. I removed the pads and pulled the caliper off, inserted a large screwdriver to stop the pistons. As I pumped the brakes, I noticed that only one piston would move at a time. I kind of expected all of them to extend together. Not sure if that's normal or not. Cleaned the pistons again (determined my first cleaning could have been better). I pressed the pistons back in with the bleeder open and the brake level pulled back slightly. Went to pump the pistons back out and realized I couldn't do it with the master cover off so I had to replace it and pump. Pistons came out in sequence again. Pressed in again to purge old fluid (which really didn't look bad). Refilled master, cover back on, pumped again. Realized I didn't have my screwdriver in straight and one piston came out way to far. When I was pressing the pistons back in I managed to basically pull the over extended piston completely out spilling fluid on the floor. I carefully pressed it back into place and and bottomed them all out. Reinstalled the caliper, pads, and refilled and bled the line. First attempt was mushy but I bled it again to remove more air I had apparently missed and had a nice solid brake. BUT, it still doesn't spin freely. Gggrrrr.

So, is it normal for the brakes to not release fully with new pads? I'm thinking not.

Is it a big problem that I popped the piston out and reseated it?

I don't have a complete maintenance history on the bike but the guy who had it 2009 to 2013 seemed to get regular maintenance. I bought it 2014 with about 42k on it. Flushed the brakes and clutch shortly after getting it. I don't recall the fluid being overly dirty. Not sure when to consider a complete overhaul of the calipers.

[riceburner]

Sometimes I think I am a bad motorcycle mechanic and other times I know I am.

My front brakes felt a little mushy lately. Hard braking would pull almost to the grip. It was time anyway for the annual brake fluid replacement. I decided to replace the pads as well. The front brakes seemed to be sticking closed a little and I wanted to give the pistons a good cleaning.

I did the right front ok I think. Disconnected the brake line after extending the pistons and was able to really clean them well. New brake fluid in. On the left side, I left the brake lines attached and cleaned the pistons. They were dirtier than the other side. Bottomed them out, replaced the caliper, and installed the new pads. Bled the lines and pumped up the brakes. Nice solid feel. When I spun the front wheel I noticed they were grabbing a bit so the wheel wouldn't spin completely freely. Took the bike out for a short spin (barely missing a downpour) to test and seat the pads. Brakes felt great. But, they weren't really spinning freely.

I found Cyclerob's awesome write up on brakes in this thread
http://r1150r.org/board/viewtopic.php?f ... 59#p239089

I decided to go back and try his Caliper Piston Push-Back-Push-Out Purge-N-Replace Procedure on the left side. I removed the pads and pulled the caliper off, inserted a large screwdriver to stop the pistons. As I pumped the brakes, I noticed that only one piston would move at a time. I kind of expected all of them to extend together. Not sure if that's normal or not. Cleaned the pistons again (determined my first cleaning could have been better). I pressed the pistons back in with the bleeder open and the brake level pulled back slightly. Went to pump the pistons back out and realized I couldn't do it with the master cover off so I had to replace it and pump. Pistons came out in sequence again. Pressed in again to purge old fluid (which really didn't look bad). Refilled master, cover back on, pumped again. Realized I didn't have my screwdriver in straight and one piston came out way to far. When I was pressing the pistons back in I managed to basically pull the over extended piston completely out spilling fluid on the floor. I carefully pressed it back into place and and bottomed them all out. Reinstalled the caliper, pads, and refilled and bled the line. First attempt was mushy but I bled it again to remove more air I had apparently missed and had a nice solid brake. BUT, it still doesn't spin freely. Gggrrrr.

So, is it normal for the brakes to not release fully with new pads? I'm thinking not.

I've always found that the calliper and disc aren't exactly aligned. But because the front disc is 'floating' it still allows the brakes to work fine, there will often be some 'scraping' as the wheel rotates. As long as the wheel CAN rotate freely (ie it doesn't jam after a 1/4 turn) then you'll be ok - check it after a few hundred miles.

Is it a big problem that I popped the piston out and reseated it?

As long as no dirt got in, and you managed to bleed out any possible air-incursion afterwards, you should be ok. Remember that brake fluid is rather corrosive to paint so make sure you cleaned up WELL!.

I don't have a complete maintenance history on the bike but the guy who had it 2009 to 2013 seemed to get regular maintenance. I bought it 2014 with about 42k on it. Flushed the brakes and clutch shortly after getting it. I don't recall the fluid being overly dirty. Not sure when to consider a complete overhaul of the calipers.

Which callipers do you have - Tokico or Brembo?

If Tokico - you can source the 2 rubber seals that live between the calliper bodies from any decent Kawasaki parts source. (If required I'll try to dig up the part numbers). BMW don't supply these seals, and recommend that you don't split the calliper bodies, but it's the best way to fully rejuvenate the callipers.

[Keppelj]

I went through this last weekend following cyclerob's directions too. Very helpful guidance. I was switching to stainless lines. I found pumping the pistons out and compressing them a bit fiddly at first. I used little C clamps to control their pumping out and used a small board 3/8" thick to pump them toward each other but not out. The board was wide enough so all 4 pressed to it. I made a clamp of two pieces steel flat bar, drilled with a bolt holding them together at one end and a larger c clamp at the other so I could compress each piston evenly so it didn't wrack going into its hole. Didn't have much success with various spreaders.

[racurley]

Here's a short video of the wheel spinning. Took it out for a run to visit a friend at the hospital. Beautiful 75 degree day. Got to break out the mesh jacket!

https://www.youtube.com/edit?o=U&video_id=GBm4Rb3vAqk

[riceburner]

I went through this last weekend following cyclerob's directions too. Very helpful guidance. I was switching to stainless lines. I found pumping the pistons out and compressing them a bit fiddly at first. I used little C clamps to control their pumping out and used a small board 3/8" thick to pump them toward each other but not out. The board was wide enough so all 4 pressed to it. I made a clamp of two pieces steel flat bar, drilled with a bolt holding them together at one end and a larger c clamp at the other so I could compress each piston evenly so it didn't wrack going into its hole. Didn't have much success with various spreaders.

Interestingly - a part worn brake pad is pretty much exactly the right thickness to push all the pistons out against.... AND it's exactly the right size to fit in the caliper....

I also find that you can compress 2 pistons at once by spreading the load - using the old pad. I use an adjustable plier ( https://www.google.co.uk/search?q=adjus ... 9&bih=1095 ) but you have to make sure that it's central to the calliper - ie the force is acting on the middle of the pad - not directly over one piston or t'other.

[CycleRob]

racurley,
Your bike is 13 years old. The caliper pistons not retracting when you let go of the brake lever/pedal is caused by:
--Old/hardened caliper piston seals. Yours certainly are not new but they can still be reusable after paper towel cleaning in new DOT4 fluid.
--Caliper piston seals that are wedged in place by gunk, on their sides and O.D. where they contact/occupy the channels machined in the caliper casting.

The caliper halves have to be split to remove the pistons for seal removal and cleaning. Use and old toothbrush and Brake cleaner spray to clean the seal grooves after all the rubber seals are removed. Do NOT allow brake cleaner fluid to contact ANY of the rubber parts! Each of the seals can be ratchet-rotate pulled thru a DOT4 soaked paper towel, sequentially finger squeezing the opposing Left/Right sides and then the ID/OD sides. Squeeze the paper towel with the fingers pinched snuggly on the seal surfaces, but not so tightly that the seal snaps-cracks-n-breaks.

After everything is fully cleaned, dip the seals in a small/clean puddle of DOT4 to ease both the seal and piston installations. Wipe up the excess fluid soon after everything is in place. Then follow the outline in the main post where it covers total disassembly.

I've found that even when everything is cleaned perfectly, there still can be initial brake pad drag on a centerstand wheel spin -until- 3+ successive, very hard stoppie force pedal/lever squeezes at highway speed force the pistons to center themselves around a floating brake rotor that seconds ago was brutally forced to occupy its neutral "center-of-float" position. Works every time.

[racurley]

Thanks.

I went out to the garage this evening to clean the seals. Got the front right caliper off and split it open. I'm guessing there's some trick to removing the pistons? I've been using some needle nose pliers spread open with some rubber disks on the inside of the piston to get some grip. Moved the some with much effort. Gave up and came in. Ideas?

[AZBMWRIDER]

Compressed air will usually remove a piston, but brake fluid will go every where .

[racurley]

Ok. I've overcome this little difficulty. Removed the calipers from the bike. Pressed the pistons in to drain the brake fluid. Used a bicycle hand pump with a little adapter to inflate a ball and used it to move the pistons out. One side will pop. Unbolted the caliper to split it and cleaned up the one side as CycleRob described. Reinserted the pistons, seated them all the way in, and then zip tied an old brake pad to this side. Put the caliper back together. Used the hand pump to press out the other side and repeated the process. The hand pump let me control the amount of pressure pretty well. Zip tied brake pad held the newly cleaned side in so the other side would come out.

I seem to be missing one of the little copper washers for the banjo bolts so I will need to pick some of these up before I can try the brakes out again. Are these something I can pick up from another dealer or elsewhere? BMW dealer here is closed Sunday and Monday.

[riceburner]

Ok. I've overcome this little difficulty. Removed the calipers from the bike. Pressed the pistons in to drain the brake fluid. Used a bicycle hand pump with a little adapter to inflate a ball and used it to move the pistons out. One side will pop. Unbolted the caliper to split it and cleaned up the one side as CycleRob described. Reinserted the pistons, seated them all the way in, and then zip tied an old brake pad to this side. Put the caliper back together. Used the hand pump to press out the other side and repeated the process. The hand pump let me control the amount of pressure pretty well. Zip tied brake pad held the newly cleaned side in so the other side would come out.

I seem to be missing one of the little copper washers for the banjo bolts so I will need to pick some of these up before I can try the brakes out again. Are these something I can pick up from another dealer or elsewhere? BMW dealer here is closed Sunday and Monday.

copper banjo washers are all the same - just get the correct inner and outer diameters.

[Keppelj]

Cyclerob, I've put 100 or so miles on the bike since full bleed/lines replacement and still have some drag on the spinning front wheel - more than I remember having. It isn't likely but I've wondered if I got pads swapped side to side on one of the calipers. If so go to new pads? I braked, of course, but not 3+ stoppies from hi-way speed (!!!) as you recommed above. The brake lever is fine, but I also may not have the same front wheel bite I had either.

[racurley]

Bought the banjo bolt washers from local BMW dealer. I asked if they could provide the seals for the caliper halves. They said their catalogue didn't include them. Told me the calipers weren't supposed to be split anyways. Which is also what the Clymer manual said. Powerhouse in the UK has the seals for the caliper halves on their eBay store for around $15 shipped. They do not carry the seal replacement kit without the pistons. You can order the kit for like $111 per caliper for OEM from several places. I think I will try putting the back together and seeing if they stay tight with no leaks. If not, will order the new seals.

[riceburner]

Bought the banjo bolt washers from local BMW dealer. I asked if they could provide the seals for the caliper halves. They said their catalogue didn't include them. Told me the calipers weren't supposed to be split anyways. Which is also what the Clymer manual said. Powerhouse in the UK has the seals for the caliper halves on their eBay store for around $15 shipped. They do not carry the seal replacement kit without the pistons. You can order the kit for like $111 per caliper for OEM from several places. I think I will try putting the back together and seeing if they stay tight with no leaks. If not, will order the new seals.

The Tokico caliper inner seals can be had from various places: Kawasaki and Honda dealers will stock them (do a search in R1150R.net for 'Tokico', you'll find the details).

I'd recommend that you always replace them if you do split the calipers.

[racurley]

Ordered the seals from Partzilla. Be here Friday or Saturday. About $12 shipped. I got the Honda ones.

Have you determined which Kawasaki used the Tokico calipers with the same sized pistons which are gather to be 32mm and 36mm? Seems awfully hard to weed through all of the offerings since you can't really search by size.

[racurley]

Put everything back together with new caliper half seals, clean piston seals and cleaned up pistons, new banjo bolt washers. Did the careening down the road and slamming on the brakes exercise recommended by CycleRob. No more dragging. Slight noise when spinning the wheel but seems more normal. Yay.