Yamaha R1 Forum: YZF-R1 Forums banner
1 - 20 of 23 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
Been on the Facebook groups and did everything advised, still no fix. Here’s my issue.

bought a 2012 R1 with 5600 miles back in June. Decided to do brake flush and coolant. Did the brake flush with motul 600 and now the front brakes lock when they get warm. Once the bike cools, they release.
Changed eBay levers to ASV, rebuilt the master with yamaha kit, reflushed with new fluid, cleaned the calipers and polished the pistons. There was plenty of gunk.
Got back on the road, locked up. I’m stuck. Don’t know what to try next. Bike is now at my local shop and they are talking with Brembo now but no help thus far.
Any suggestions? Maybe try new calipers (used set)?
 

·
Registered
'08 r1
Joined
·
3,350 Posts
You've got contamination. Probably water. Flush the piss out of the system with some budget dot 4. If you are getting lock like that just poking around on the street, I'm 99.9999% sure you've got water in there bud.
 

·
Astronomer not Astrologer
Joined
·
11,149 Posts
Take the calipers off the bike, dissassemble the pistons, clean and replace the seals. Reassemble and bleed the brakes. Ride the bike.


I had a few less movable pistons when I did mine.


YOu can see some of the less movaebale and crusty pistons here. Not all of them would press back in because they had all sorts of crud stuck to them. All the pistons cleaned up nicely and they worked MUCH better after the rebuild.



Oh also, did you recently install a new brake lever? Some cheap levers, dont have the right clearance/free-play and can keep a bit of residual pressure, causing the brakes to drag.
 
  • Like
Reactions: Numbers

·
Registered
Joined
·
2,182 Posts
A lot of the time when you are talking about it actually locking while not applying the brakes it's a freeplay/ clearance with the lever but since I read the original post I'm not going to suggest you change them as asv is a good brand. I would suggest you pull the master off so you can see inside clearly and make sure it has clearance. Since your saying this happened after your fluid change I wanna say that I'm suspect of that fluid, maybe grab a bottle of Motul 5.1 and try a bleed with that. I also would suggest getting a laser temp gun and when it starts to lock up next measure the temp of each caliper and each disk and see if there's a difference left to right that is significant. If they are equal Then it's a fluid or master issue. If it's one side then look at that caliper.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #6 ·
Take the calipers off the bike, dissassemble the pistons, clean and replace the seals. Reassemble and bleed the brakes. Ride the bike.


I had a few less movable pistons when I did mine.


YOu can see some of the less movaebale and crusty pistons here. Not all of them would press back in because they had all sorts of crud stuck to them. All the pistons cleaned up nicely and they worked MUCH better after the rebuild.



Oh also, did you recently install a new brake lever? Some cheap levers, dont have the right clearance/free-play and can keep a bit of residual pressure, causing the brakes to drag.
I did disassemble and polish the pistons. They did have gunk in them.
Original levers were eBay levers. But the brakes were working fine. Did the brake flush and BAM. Locking. Changed levers to new ASVs. Problem still persists.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #7 ·
A lot of the time when you are talking about it actually locking while not applying the brakes it's a freeplay/ clearance with the lever but since I read the original post I'm not going to suggest you change them as asv is a good brand. I would suggest you pull the master off so you can see inside clearly and make sure it has clearance. Since your saying this happened after your fluid change I wanna say that I'm suspect of that fluid, maybe grab a bottle of Motul 5.1 and try a bleed with that. I also would suggest getting a laser temp gun and when it starts to lock up next measure the temp of each caliper and each disk and see if there's a difference left to right that is significant. If they are equal Then it's a fluid or master issue. If it's one side then look at that caliper.
That’s a good idea about the temp. It just doesn’t lock on its own. I can ride using rear brake all day. Once I start using the front, issues happen and locks. I pull over. Cool off for 10 min and it releases.
 

·
Registered
Joined
·
2,182 Posts
Yea so when it does that it's typically a clearance issue it keeps the piston in the master slightly depressed and when heat starts and pressure builds in the calipers/lines it doesn't let pressure relieve back into the reservoir so it does the only other think it can do with that pressure and pushes the pistons out. 9/10 times it's ebay levers but you've been doing that road so that's why I say physically inspect. Could be contaminated fluid but usually gets contaminated with water which makes it appear dark and if the master was working correctly it would relieve the pressure. Is your reservoir all the way full by the way? If so maybe take some out and see if that helps. Maybe no space and a venting issue. Grasping at straws. Also if they are even temp then the next time it locks pull the lever off right away and see if that fixes the issue
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #9 ·
Fluid is below the top line so it isn’t too full. I was about to buy a set of used low mile calipers to change and reflush with 5.1.
I did the master rebuild kit. Maybe just do the entire kit new? Again, it was fine with eBay levers. All good until my initial flush lol
 

·
Registered
Joined
·
2,182 Posts
I wouldn't buy calipers yet don't just guess and throw parts at it. Do a bit of diagnosis. Could be some wear in the master and a kit won't fix it. Do te bleed and the temp check to start. If it ends up not being the calipers or fluid then it's master just buy an RCS from brembo and never look back lol
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #11 ·
I wouldn't buy calipers yet don't just guess and throw parts at it. Do a bit of diagnosis. Could be some wear in the master and a kit won't fix it. Do te bleed and the temp check to start. If it ends up not being the calipers or fluid then it's master just buy an RCS from brembo and never look back lol
I get that. I just figured it’s only $100 and they have 1500 miles on them. I’ve flushed it twice with 600 so I guess I’ll do a flush with 5.1 and go from there.
 

·
Registered
Joined
·
2,182 Posts
A bad caliper should be dragging all the time. With the wheel in the air does it spin free? If you spin then hit the brakes then spin again does it still spin free?
 

·
Astronomer not Astrologer
Joined
·
11,149 Posts
You still in the stock rubber brake lines?
 
  • Like
Reactions: Numbers

·
Astronomer not Astrologer
Joined
·
11,149 Posts
They can break down and form a check valve. I have seen it a few times (mostly in cars). I would put better braided lines on there.
 
  • Like
Reactions: Numbers

·
Racing4Fun
Joined
·
36 Posts
Hi, I did not read through all the answer. I hope I don't repeat what somebody already told before. I had the same problem on a race bike 2015 R1. I used Motul 600 as well. The Problem was the break cylinder. There was corrosion material in it that blocked the back flow into the reservoir. I replaced the whole break cylinder and since then I do not have any issues. I doubt that the break fluid was the problem. Unless the Motul had some chemical reaction with the old fluid that caused the corrosion. I did not cleaned and refill the break lines. I simply pumped the new fluid through.
 

·
Registered
Joined
·
13 Posts
did it lock up after you put the brakes on? then get increasingly worse? If so take the master cylinder off drain the fluid and look in the bottom of it. There's 2 holes there above the piston. if the front 1- from memory- is blocked it won't let fluid flow back into the master cylinder from the piston after you've put the brakes on and it will not release, clean the hole and it should be ok.
 

·
Registered
Joined
·
32 Posts
Remember DOT 5 and DOT 4 do not mix. There's a chemical reaction that makes the fluid crystallize. Even if it's just a small amount left in the calipers and master. You don't need dot 5 unless you race. Save yourself lots of grief and get SS braided hoses. Piston rebuild kit and since you've done the master. I went with the Galfer GP kit which mimics stock. I hate the dual banjo fittings. Good luck.
 
1 - 20 of 23 Posts
Top