Still can't bleed front brakes after adding NEW Master

OK, WE HAVE PRESSURE. What a Nightmare.

I took the caliper off, leaving the pads still attached. I then found something to take the place of the disc, but the catch was to find something about 4 or 5 mm smaller. In this case, it was a screw driver.

I then stuck that in the middle of the pads and put air to the caliper. It clamped immidiately on the screwdrive. Once I stopped the air, it realeased ever so slightly.

I then filled the caliper with using a syringe making sure there were no air pockets.

Next, I attached the line to the caliper, and then put the caliper on the bike. The pads were now rubbing the disc. They weren't before.

Again, using the syringe and a modifaction to some tubing, I pumped oil through the bleeder up the line and into the master cylinder. I put three syringe fulls through until there were no bubbles.

Topped up the master cylinder, made sure the travel screw on the brake leaver was all the way in, and BAM! We've got pressure.

I ended up having to take the leaver adjuster screw out, remove the locking nut, and put it back in so it could travel the full distance. I'll have to replace the screw with a longer one so that I can put the lock nut back on for safety.

Now the question is how much pressure? It still seems soft, but I understand the brakes on Maxim's were soft right out of the factory.

 

Just to be confident that you're A-OK.

Look on the Rubber Expansion Reservoir.
Is there a Notch that should be lined-up with a Vacuum break on that cover?

I guess from looking-over these Brake Threads ... you have that Pincher-style Caliper. That's not considered to be the finest Caliper ever designed to do braking. But, with those new brake lines you installed; you should be able to get more gripping out of them ... than the old lines could provide.

How well is it working? Are you going to do some additional bleeding; just to be sure the lines are totally evacuated of air ... or, do you think you nailed it?

 

Rick,

Having trouble picturing what you're describing regarding the rubber expansion Reservoir???

Yes, it's the old pincher style. It seems to be working well, but I've only had it in second gear. I had an openning to get my new tires put on so I had to take the tires off ASAP.

I'll report back soon.

 

The Expansion "Diaphragm" is the Rubber Gasket under the Master Cylinder Cover. It expands to keep the fluid from sloshing-around as the pads wear and the level decreases.

Some Covers are "Vented" with a very small notch ... that often fills-up with grime and disables the Diaphragm from unfolding as it should.

Its a very small notch on the cover. Sometimes overlooked because its soo small.

 

Thanks Rick, I'll double check that.

 

Something still isn't right. I think the brakes are too soft. I had my brother check them out, and he agrees they are way to soft. I can pull the handle right down to the bar pretty easily. Although there's stopping power, I feel that it's not enough under higher speeds.

 

Usually because there is air in the system. Air will compress, hydraulic fluid will not.


Dan

 

Hey Dan,

I bled the lines over and over. I went through probably 1/2 quart of no bubble line bleeding. I figured that would have been enough.

Well, I'll bleed them again.... and again just to make sure.

 

Tap on everything to dislodge trapped air bubbles. They stick to the walls of the hoses & chambers.

Dan

 

Take a small line from the ones you must have after the switch to stainless.

Seal-off one end with a bolt and a couple good-sized plumbing rubber washers.

Hook-up the other end to the Master.
Loosen the bolt on the washers and bleed that small section of hose as a test for the Master putting-out as it should.

After all this fussing-around ... that Master Cylinder is giving me a headache and I don't have one like it to help figure what' not right.

If you keep bleeding ...
And,
Nothing's LEAKING
The Master Cylinder is where you focus the spotlight!

 

lots of info here an I just need to add I have had to take the master off an rotate it at the same time of pumping the lever to get all the bubbles out seams they like to find pockets that can't be pushed out.
,,,,I also do the same for the calipers,,,
I think it's been said before I also do what I guess could be described as a reverse bleed I get the caliper pistons out then push it back in forcing fluid back up at the same time rotating the caliper an lines to get the bubbles to rise instead of going down witch is just what they don't want to do,,,,,
I have seen systems that will not bleed bolted up get your brain thinking like bubbles trapped in there,,
just my 2 cents but if it don't bleed right away I go through it this way,,,Dan

 

Look ...

Don't even bother with hooking-up a section of Brake Hose.

Get a bolt with the same Thread Pitch as the Outlet of the Master Cylinder and Plug-off the Outlet.

Have the Master Cylinder at least half-full and work the Brake Lever with the Bolt preventing fluid from leaving the Master.

If if feels like the Lever wants to develop some resistance ... Pull the Lever and let fluid bleed-out the bolt threads by loosening it a bit.

The ACID TEST will be the Brake Lever becoming Firm or Not.
If you get some HEAVY Resistance and even a point where you cannot Pull the Lever ... the Master is Good.

No favorable results ... Lever still Spongy or a Sloppy Pull right back to the Grip ...

That Master Cylinder is NO GOOD!

Simple as that!
Bottom line.
Bedrock.
Ka-put
Done
Bad
NG

 

Rick,

easy test. Thanks. I'll try it.

Dan

 

FYI:

My stock XJ650J is quite firm. There's a good gap between the grip and the lever when it's pulled as tight as I can squeeze.

I'm with Rick, I wonder if you have a problem with that MC. Find a way to plug the outlet (a piece of the old brake line will be great as Rick suggested). The lever should move very little.

Another thought, is your lever bent?

 

I had my front wheel and caliper off yesterday to free up the rotation of the caliper and do a few other things. I ended up using a c clamp to compress the piston before putting it back together.

This morning I noticed I had that spongy feel again, and could squeeze the lever quite close to the handle grip. I knew there should be no air in the system, but in case that was the problem I tried something new to free up any bubbles and let them rise.

With the bike on the centerstand I sat on it and rocked my weight back and forth to bounce the front end up and down a bit, being carefull not to roll off the stand of course. I could hear the gas sloshing around in the tank, and I would stop and work the brake lever a few times, then repeat.

Very quickly my brake lever returned to it's normal feel of bottoming out fairly solid (still has rubber lines) well before it reached the grip. Braking is dramatically improved now that I'm using both pads too.

I don't know if I disloged air or freed something up in the MC, but it might be worth a try for you as well.

 

Problem solved. Bled the lines for like the 100th time. This time, I moved the master cylinder to a position on the handle bar that made it perfectly level. Then, with the help of my brother... pumped the handle some more.. sure enough, a few bubbles popped out of the bleed screw. Front brakes are rock hard now.

Thanks for all your help everyone.

 

Amazing how much a couple of really tiny bubbles can mess it up, isn't it?

 

YAY!! You are now a qualified graduate of the school of Hard Knocks!
You should publish a "paper" on replacing brake components for the next XJCD version!

Well Done, your perseverance paid off.

Dna

 

Welcome to Motorcycle Wrenching.

I'm glad you finally got a big handful of brakes.

Just a few tiny bubbles ... that was it ... huh?
Imagine that?

Son..of..a..gun!?

 

Yeah, a few bubbles short of tossing the caliper and master cylinder clear across the shop floor. Took it out on saturday for a nice half hour ride with my wife. It was great. First time in my life that I didn't mind going the speed limit with a motorized vehicle! ;-) It was great just cruisin' around.