Did my wife break my brakes?

[Danny Crawdad]

The answer of course is always no, it was my fault.

So I did a bunch of maintenance to the bike yesterday while it was sunny. Put new EBC pads on the rear, did a few other minor things, and then decided to look at the front brakes. They had always worked OK, but were rock hard and just weren't confidence inspiring. So I decided I was going to bleed them and mess with the freeplay of the lever while I was playing with everything else.

I asked my wife to help me because she's such great company, of course. I forgot to tell her about not using the full stroke of the lever, and she pulled the brake lever all the way back to the bar several times before I saw it . My fault, I should have told her.

I pulled the MC off, and the piston was stuck at about 3/4 of the way through its travel. I also noticed the bore where the piston assembly goes is basically a rust pit. The end seal came off years ago (there were some petrified dried bits of rubber left) and water had clearly gotten inside the piston assembly. The snap ring is corroded in place as far as I can see. While I was poking at the rust trying to find the snap ring, the piston POPPED back out and slung rusty brake fluid in my eye.

Now that you have the narrative, here's what's happening:

1) The piston moves freely when you plunge it now. I cleaned the MC up, but don't have the right snap rings to take the piston out, but I was able to work it and free it up. However it still needs a rebuild.

2) I have put the MC back on the bike with clean fluid, and tried to bleed again. There is NO pressure building in the lever. I left it overnight with the lever half-squeezed like I read on here, no difference this morning.

3) When I crack open one of the bleeders, I get a TRICKLE of fluid rather than a surge. No pressure. I have bled at every bleeder and every banjo bolt, and after the first round, no bubbles are coming out, just seeping fluid.

4) When I pull the banjo bolt off the MC and put my thumb against the end, I feel a slight amount of pressure when I pump the lever, but it won't build up much with additional pumping, and it's not strong enough to blow my thumb off the hole.

In addition, even at the master cylinder I only get tiny little "puffs" of air/liquid when I bench-bleed it. I can't get it to shoot brake fluid across the room around my finger like I could with the rear MC.

Sorry that was long winded, but that leads to this: does it sound like we flipped the seal by overextending the MC piston? If so, I'm going to go ahead and order a friggin MC from MikesXS and be done with it. I'm tired of playing with brakes .

[tom clisham]

Sorry Man!

You'll never get it clean & working if you don't take it apart.
Clean the are of the snap ring with brake cleaner and/or wd40.
Get the right tool & take it off. I've gotten them off many times without the right tool, but it takes a lot of fooling around with the wrong tools.

If it's REALLY nasty inside (after cleaning the bore) you might want to replace it, but I've never had to. clean the bore with brake cleaner & extra fine steel wool (1500 grit).
If the rubber stuff is shot get a kit from georgefix on ebay.

It should all work out.

[natemoen]

Sometimes when you do the full stroke like that it causes the seal to flip over and then it won't build any pressure. Again, taking ot sort is the only way to know it is going to work right when you need them.

[XS1100_OEM4ME]

Spoog hole

With that much crap in there, you could have clogged the spoog hole that lets the fluid flow one way into the master cyl. You will need to rebuild it after a good cleaning (just did mine a while back) I would get a rebuild kit that includes the new dust boot so it will stay clean in there. I would also remove the white / clearish res. tank and clean out the grove and replace the large O ring (I didnt the 1st time, that is why there was a 2nd time) Super fine steel wool or scotch bright, just till it is shinny in there again and should work like new. Bite the bullit on the snap ring pliers, you use them for other stuff also Mikes has good ones cheap, or you might get local

Sometimes when you do the full stroke like that it causes the seal to flip over and then it won't build any pressure. Again, taking ot sort is the only way to know it is going to work right when you need them.

[Danny Crawdad]

Does not being able to build any pressure sound characteristic of the cup/seal being flipped from overextending the piston?

I just got back from trying to source a set of snap ring pliers locally. We'll see if Harbor Freight's offering works...

I'll be honest, the sound of a brand new master cylinder is appealing to me

Did a thorough cleaning of the spooge hole and bowl last night, but didn't have the pliers to get the piston out.

Edit: Harbor Freights snap ring pliers are TERRIBLE but I got the ring out with a $1.99 set of picks in about 30 seconds . Putting it back in may not be so easy, haha

[DGXSER]

Add my vote to the "need to take it ALL THE WAY apart and clean it" group. If there was that much crap in there, you were wasting your time doing enything elss than taking the MC, and the brake calipers apart and completely cleaning all of it. Also, run some brake cleaner through the brake lines while your at it.

[Danny Crawdad]

Don't get me wrong, it was coming apart to be cleaned anyway. I don't play around with brakes, if they don't work right then I park the bike, which is why I'm so tired of fiddling with them . If it needs a bunch in the way of rebuilding, I am just going to replace the master cylinder, though. That was my dilemma, disassemble and repair, or just outright replace. By the time I buy everything needed to do a proper rebuild I'm about halfway to a new master cylinder.

Calipers are coming off later today to be put in the dishwasher and cleaned. I did that to the rear and it came out sparkling.

I can't get anything to budge now that the snap ring is out.

[Danny Crawdad]

The trick is to yank as hard as you can and send rust and brake fluid flying across the living room.

[XS1100_OEM4ME]

If your brakes were working OK before your wife helped FIX them You can rebuild your M/C to like new most likely Soak the pistion in WD40 till it frees up, don't force it. The new M/C kit will replace all the wearing parts except the res. tank O ring, hardware store part. When you are putting it back togather, have someone hold the piston in to make it easy to put the snap ring in (I tap a deepwell scocket down on it to make sure it seats well Once you have it all back togather, fill it and "gently" work the leaver back and forth 1/2 way till all the bubbles stop comming out, then blead both sides If you want better brakes, spend your $$ on S/S brake lines (Yamaha says to replace all rubber brake lines every 4 years) You will have much better brakes with OEM M/C and S/S lines, then with new M/C and OEM lines As to the dishwasher Not OK IMHO, I try to "never" get water around an opened brake part

Don't get me wrong, it was coming apart to be cleaned anyway. I don't play around with brakes, if they don't work right then I park the bike, which is why I'm so tired of fiddling with them . If it needs a bunch in the way of rebuilding, I am just going to replace the master cylinder, though. That was my dilemma, disassemble and repair, or just outright replace. By the time I buy everything needed to do a proper rebuild I'm about halfway to a new master cylinder.

Calipers are coming off later today to be put in the dishwasher and cleaned. I did that to the rear and it came out sparkling.

I can't get anything to budge now that the snap ring is out.

[XS1100_OEM4ME]

Imho

This is just IMHO, not trying to start a break war If your calipers were not sticking and move in free and the dust covers are in GOOD condition, I would just emty out the old fluid squirt some fresh fluid in to rinse them out and use them Also, I am sure you know brake fluid eats paint, so AFTER the system is sealed, make sure you rinse EVERYTHING WELL

[Danny Crawdad]

OEM4me, you were right, all it took was some cleaning. The cup and the seal were fine, but the bore was filled with crystallized fluid. It was preventing cup from making a good seal in the bore, meaning it was pushing some fluid around, but not enough to do anything.

I cleaned it well, reassembled, and after about 20 combined minutes of bleeding at the MC banjo bolt, then the junction block, then the left then right caliper, I'm getting beautiful clear brake fluid all around, and have a lever that is firmer than... well, I'll leave that to your imagination . The calipers are in good shape, I popped the piston out of the right one real quick and they look brand new, no sediment or anything. The existing brake fluid wasn't in bad shape, so I'm guessing the calipers have been replaced/rebuilt at some point but the master cylinder never has.

These things are so easy to rebuild once you get the snap ring out. I used two straight picks and had no problems. Glad I didn't pull the trigger on a new MC just yet.

How important is the end boot on the piston? The external one. I don't want to buy a $23 rebuild kit just for that part, but I will if I need to. I can see where dust/moisture will eventually get past the washer and o-ring without it.

[Danny Crawdad]

Lack of that boot is probably the reason the inside of the MC got so hosed up and was hard to take apart, not sure why I'm not going to learn the lesson sitting in front of me. Rebuild kit ordered

[XS1100_OEM4ME]

Dust boot

Hey, you got it back togther and it is working with the old parts, I wouldn't worry about the dust cover for now, just take a Q tip with some brake grease on it and give a coat to the piston head and around the C clip, that will slow down the rusting for now. Then, later, when you feel like doing a rebuild, get the kit with the boot and do it all at once. I would check and make sure the old plunger cap doen't have any leak down though. Just pull back like you would if brakeing farly hard on the lever for about a min, if it drops at all, I would order the kit, as the plunger cup is weak

OEM4me, you were right, all it took was some cleaning. The cup and the seal were fine, but the bore was filled with crystallized fluid. It was preventing cup from making a good seal in the bore, meaning it was pushing some fluid around, but not enough to do anything.

I cleaned it well, reassembled, and after about 20 combined minutes of bleeding at the MC banjo bolt, then the junction block, then the left then right caliper, I'm getting beautiful clear brake fluid all around, and have a lever that is firmer than... well, I'll leave that to your imagination . The calipers are in good shape, I popped the piston out of the right one real quick and they look brand new, no sediment or anything. The existing brake fluid wasn't in bad shape, so I'm guessing the calipers have been replaced/rebuilt at some point but the master cylinder never has.

These things are so easy to rebuild once you get the snap ring out. I used two straight picks and had no problems. Glad I didn't pull the trigger on a new MC just yet.

How important is the end boot on the piston? The external one. I don't want to buy a $23 rebuild kit just for that part, but I will if I need to. I can see where dust/moisture will eventually get past the washer and o-ring without it.

[XS1100_OEM4ME]

Caliper

On the caliper you mentioned pulling apart, make sure the dust boot is OK and put back in the piston / caliper groves exactly like it was. If that boot leaks at all, it will pull in moisture and seize the piston in time Most guys worry about the O ring, but if the fluid is clean and the dust boot is right, the O rings rarly fail. Brake fluid is a water magnet, ANY leak there will cause you problems down the road. Also, not forget to wash very well all the parts you don't want to re-paint

[Danny Crawdad]

Yeah, I was surprised at how good the fronts looked. I unfortunately got to be an just about an expert on pulling these calipers apart trying to get the rear fixed a few months ago -- it was in really rough shape, I pulled a pile of solidified brake fluid and rust out of the rear caliper and had to take it apart 4-5 times before I got it working like it should. Same with the master cylinder. I hate brakes . But these have been easy enough to work on so far, at least. Next project is going to be front Galfer SS lines. Pashnit.com has them for $89/set.

I pull the snap ring off the piston boot, then use the master cyl to pop out the piston and dust boot together. Bore looked good so I dumped and replaced fluid, put the piston back in, seated the dust boot, and put the snap ring back on. Got to wait to test ride, which sucks . And it'll have to be a careful ride because I have opened both brake systems, although both are firm and feeling nice.

Hey, how is that MikesXS headlight working out for you? The super bright one.