Front Brake Rebuild Problem

OK here is what I have done (all parts from chacal - thanks Len!!)

-new stainless steel lines, rebuilt MC, rebuilt caliper, new EBC rotor, new pads, used mity vac to fill lines. I think I have done all of this correctly so not getting a good "lever" is driving me crazy.

I just can't get a good lever with enough pressure to move the piston in the caliper. I know everyone is going to say you have air in the lines but I don't think so based on clear fluid coming out with no bubbles

QUESTION: once the lines are filled with fluid and I have performed a simple bleed the old fashioned way - if the top is off of the MC, should I be able to pull the brake lever and engage the pads (i.e. move the piston) OR does the top always have to be ON the MC to ever achieve enough pressure to engage the piston???? The answer to this is important, of course I have tried both (with the top on and with the top off - I think I've screwed/unscrewed the MC top about 30 times already :x )

just a note: I am not letting the MC run dry during bleeding and I am getting plenty of fluid throughput (went through a whole big bottle of fluid already)......I just cant get any pressure to the lever!!

any ideas what I'm doing wrong??

 

MC will work fine with the top off. It's just there to keep the fluid in and dirt out. When yo u work the lever some fluid will return through the bypass hole. You don't have to move it far to have fluid spurt out - I generally set the cap on when working the lever **UNLESS** I'm looking for the spurt to verify the hole is open.

The 650 Max is tough to bleed. That rise out of the master cylinder tends to trap air. You can help this by turning the bars to the left to get it closer to level. Another thing you can do is crack the banjo bolt at the MC then squeeze the lever to get some air out of there. Of course you need to re tighten the bolt before releasing the lever or it'll suck air.

There is also the possibility the MC is bad.

 

The cap on or off should make no difference to the operation.
Do you have resistance when the lever is pulled? When the piston was installed into the calliper, did it go in easily? Do you have the MC seals/cup in the correct way?

 

I have almost no resistance when the lever is pulled...I know it makes you think air doesn't it???

when you say "easy" - I did it by hand lubbing it with brake fluid but it didn't just "drop right in" ......I had to push kind of hard with the base of my hand

Yes on the MC seals/cup

 

Don't know how much experience you have with this so forgive me if you already know but I just did mine about a month or so ago. I could not believe how long it took me pumping the lever to get the caliper to move and the pads to engage. I did a mini rebleed check a few times thinking I may have had air. I pumped many times, took a break, came back, took a break etc until finally enough pressure built up and had almost no resistance for most of that time.

 

Thx Rural_Guy......I do not have a lot of experience with this process, I guess my question is with all the pumping were you "bleeding" the old school way at the same time?? did you go through 10 bottles of brake fluid as a result??

 

Give this a try: Open the top on the MC and fill reservoir... with bleeder valve closed, pull brake lever towards handle and tie off for 24 hours. Don't worry if the brake lever is in contact with the handle. The main thing is to have the brake fluid under pressure. Tiny bubbles will slowly release out the MC reservoir. After 24 hours, untie brake lever and check brake function. I have had excellent results getting the last bit of air out with this method.

 

definately will give that a try, thank you (MiCarl, JFstewart, rural guy, and Ski ....very frustrating process......there has to be air in there, the thing is the air must be hiding right??? Otherwise it would come out as I am going through bottles of brake fluid.....

 

No, once I was sure i had the air out and had clear fluid running I tightened the bleed screw, topped up the MC, put saran wrap over it and had it leaned to the left to keep it level. Then I just slowly pumped and pumped and pumped and pumped and pumped. Once there's no air and clear fluid close the bleed screw, make sure your MC is topped up and start squeezing and releasing slowing to build up pressure. Once I had pressure I topped up the MC one last time and put the cap on and finished off. Even when I had pressure it still took quite a while for the brakes to be really good. Now I can't even pull the brake lever all the way in before they grab nice and tight.

 

Gotchya, awesome, that makes sense.

 

got Rural_Guy....Thank you, that technique worked. wow what a difference with new rotor, new pads, and stainless lines!

 

Re-bleed after a couple of "heat cycles" and you'll get a healthy bubble or two.

My theory on the bleeding frustration (and I've gone through it with both of my XJs as well) is it's the machining in the caliper bore. I'm thinking the rather crude machining with all the little circumferential grooves tends to trap micro-bubbles that don't let go easily. Getting the caliper hot a few times seems to help get that last vestige of air out.

 

right on Bigfitz, just finished about 50 miles, little bubble came out. Lever is awesome now. I have new pads and new rotor but I think the biggest difference is probably the stainless steel lines - what a difference - no expansion of the lines at all - everything get transferred right to the Caliper. Sweet improvement to the stock bike!

 

If you went the full monte; EBC floating rotor, pads and stainless lines, you now have a serious front brake. Wait until it gets about 3000 miles on it. Once the pads and rotor have fully "mated" you can chirp the front tire with one finger. It's not just the lines. I've got stainless lines on both my Secas; one has the full EBC upgrade; one has the stock rotor (drilled) and Yamaha pads. The EBC brake is better, although the stock brake is greatly improved.

Bleed again after about 200 miles. Then they'll be like grabbing a rock.

 

EBC floating rotor? Sounds interesting....are they readily available? Any mods required? Approx cost? Thanks

 

Readily available, they make a whole line of replacement rotors for virtually every street bike.

No mods, straight bolt-on replacement for the original.

Cost varies by application (and where you buy it.) Generally about half of what an original rotor would cost IF you could even find one; in the $200 USD range, I got mine a couple years back so don't go by that.

They come with the hub "natural" I carefully painted mine using Duplicolor Caliper paint:

 

Hi adrian1, yes I picked up on the recommended brake upgrades from various threads on this forum. I purchased it from user name chacal @ xj4ever. it is an EBC drilled rotor for better heat dissipation, approx cost $200. Although my stock rotor was not in too bad of shape I just figured if I was going to re-do the braking systems I might as well do everything and the difference is amazing. I wish I could tell you between the new pads, new rotor, SS brake lines, caliper and MC rebuild which of these made the most difference but I can't really. All I can tell you is I can stop on a dime now if I have too and lock the front now if I want, I did not have good stopping power before - especially in the front. Just finished bedding all the new pads and I'm very happy with the upgrades - feel much safer now!

 

Cool! Thanks folks

 

bigfitz You've got mail!