Strange JuJu.......Need Thoughts - Ducati.ms

Motard-Menace · Oct 5th, 2011, 8:29 pm

Okay here is the conundrum....

I changed out my brake lever two days ago, put the stock lever back on with a slight adjustment. The adjustment was spinning the mc pin pusher out a little. Not sure what you call it. This was to hopefully add a little more feel to the brakes.

Anyway I took it out and initially no problems, then about three miles down the road I start to notice the front brake seems to be binding, ie; being applied and the lever is tighter then shit with no play. I pull off as soon as possible, I was in town yet. Not sure how far I went with some braking application going on but could not have been much more then a mile or so.

So I pull out a screw driver and adjust the lever back to give it some room. Now I have mush for brakes after only a turn and a half the other direction. I crank it back the other way a little at a time and eventually past where I had it adjusted when the issue happened, still mush.

So my first thought is the damn brake fluid went to boiling so my brakes have faded big time but now after a couple days I went back out to take a look and same issue.

My question is WTF happened. Could the brake fluid rising to a boiling or near boiling level cause air issues or is my master shot to shit now? Now sure what is the problem.

Anyhow ideas from everyone would be great so I can figure out what to do next. Thanks

stryder · Oct 5th, 2011, 9:24 pm

I've never adjutsed a brake lever on a 2001 ST2 so I'm just guessing: Since you didn't mention bleeding the brakes, I guess fluid level in the reservoir is low enough, and moisture or air in the system are not issues. It sounds like you blocked the return weep hole when you dialed the screw in, and the expanding heated fluid had nowhere to go other then to push the pistons out. Then, when you turned the scew back out, it was too far out and the plunger could not push enough fluid to push the pistons out enough for solid feel. Maybe you just have to find a sweet spot where the plunger will have maximum effect without blocking the return weep hole. Pull the caliper and pump the lever once or twice to push the pistons out a bit. Dial the screw in. See if you can push the pistons back in. If so, the return weep hole is not blocked by the plunger, refit the cali, and see if you get a solid feel at the lever after pumpng it back up. Repeat until you find a good spot. Test ride very carefully. Good luck.

Motard-Menace · Oct 5th, 2011, 10:27 pm

Stryder,

Thanks for the info, I will give that a try this weekend.

Bill_Anderson · Oct 6th, 2011, 12:13 am

I recall a post some time back from Fariborz explaining in great detail that what people think is a brake lever "adjustment screw" is not really an adjustment screw and messing with it will result in what happened to the OP's brakes. Someone with more technical knowlege than I (which is nearly everyone) can elaborate further.

va duc · Oct 6th, 2011, 6:10 am

Clutch Master Cylinder Adjustment

Stick · Oct 6th, 2011, 10:19 am

I'd guess that you did boil the brake fluid. Not sure what side effects happen as a result. *MAYBE* boiling produces bubbles that remain inside? I'd start with changing out the fluid. Just remove what you got in the master (dedicated turkey baster, and a lot of drip cloths!). refill reservoir with new fluid. Bleed as normal. Be sure to keep level in res. adequate while bleeding. Just try to get fresh fluid into and down thru the calipers.

If "mush" still presides, top up reservoir, put cover on, lean the bike WAY to the left and flick the lever rapidly while leaned. this usually removes the pesky bubble that likes to hide in the banjo botl at the end of the master.

Make sure that screw is out far enough to allow the bleed hole to be uncovered. Usually, this is noticed when you pump the lever, you can see the fluid jump a bit at the 1st part of the stroke. harder to see on remote reservoirs...

stryder · Oct 6th, 2011, 2:13 pm

Quote:

Originally Posted by Stick

..Just remove what you got in the master (dedicated turkey baster, and a lot of drip cloths!)....

Or just a honkin' wad of paper towels gently/slowly pressed into the reservoir to soak all the fluid up.

Motard-Menace · Oct 7th, 2011, 1:07 am

Quote:

Originally Posted by Bill_Anderson

I recall a post some time back from Fariborz explaining in great detail that what people think is a brake lever "adjustment screw" is not really an adjustment screw and messing with it will result in what happened to the OP's brakes. Someone with more technical knowlege than I (which is nearly everyone) can elaborate further.

Nice Bill, would have been better to see this before I screwed up......

thanks though because it sounds like what happened. Now I just need to figure out the solution. I am going to try and bleed the brakes and get some new fluid into the system this weekend and see if that cures it. Will keep evereyone posted....thanks for the advice fellas

Motard-Menace · Oct 7th, 2011, 3:22 pm

I believe I have found the problem. I didn't notice it at first but the seal around the MC piston was cracked. Unfortunately I discovered this today after noticing a blemish in my paint where the brake fluid seeped out. The rag I had sitting on the fairing fell off. I suspect a 5 or 2 year old had something to do with that. It is not too bad so I am not going to cry over spilled milk but looks like I need a new master. Might be a good time to upgrade I guess....

What are some of the MC upgrade options that are available. I don't want to have to do a bunch of modification however to make it work. Thanks

tonered · Oct 8th, 2011, 11:17 am

That boot is just a dust seal. Steve at bevelheaven can help you out with rebuild parts. As long as you can see the disturbance in the resevior, you should be good.

Have a good one.