front brakes locking up?

rwgoldsmith

rwgoldsmith

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hey guys
i have a 01 fz1 and i just put on an 01 r1 master cylinder and braided fuel lines. this was my first time really working on brakes beside pads and rotors. when i went for the test ride i got about 2 miles before the brakes locked up completly.
naturally in a really unsafe spot:) thank you murphy.
any thoughts on why they locked up.
would over filling the mc cause it to lock up like that?
any other ideas?
Thank you
RW
 
Did you bleed them correctly? Can you spin the front tire freely without a rubbing noise? If they drag they heat up and that can lock them up. Do they release after it sits?


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Overfilling can be a problem but is hard to do with the diaphram in the top of the master. It will push excess over the sides and all over the place. Air in the lines can do this from what I understand and a re-bleeding should solve that. One it is bled and all buttoned up put a zip tie on the brake lever in the applied position overnight. Any air bubbles you missed will make there way up into the master cylinder that way.

Also read this link, you may find the info helpful.

Introduction - HEL Brake Doctor click on the tab labled "bleeding"
 
A fitting quote from Lee's link:

Do not overfill the reservoir as this can cause hydraulic locking of the system preventing the pistons in the caliper from fully retracting - this causes binding of the brake.
Click to expand...
 
Like it sais above, the pistons are partially pressing, either from air in the lines or improper lever adjustment. I'd bleed them again, and tie the lever back over night like he said above to bleed out remaining air. The Master cylinder was clean right?


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ok well i took some fluid out so its dead even middle between the marks.
checked that the brakes drag, they do prolly about one turn when i try to rotate it.
pulled the calipers off to check if the axle was to tight. nope spins for ages
going to pull off the pads and clean up the pistons. then scuff the pads and rotors bleed everything again and we will see were i'm at with this
thanks for all the help every one!!!!
 
Are you sure you have the proper brake lever on there? If not and it's slightly pushing on the master cylinder piston then it could very well lead to this condition after a few miles...
 
NJFZ1 said:
Are you sure you have the proper brake lever on there? If not and it's slightly pushing on the master cylinder piston then it could very well lead to this condition after a few miles...
Click to expand...

I was wondering that above as well when I said lever adjustment... So many maybes!!!


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NJFZ1 said:
Are you sure you have the proper brake lever on there? If not and it's slightly pushing on the master cylinder piston then it could very well lead to this condition after a few miles...
Click to expand...

you know that is a very good idea i'm using the lever off of the stock fz1 mc as the r1 unit didnt come with it.
ill add this to the things to check tomorrow.
i pulled apart the calipers and cleaned everything and they wernt too bad so tomorrow is putting everything back together refilling lines
then bleeding calipers and mc and checking that lever.
anyone know if an fz clutch lever and an r1 lever are interchangeable might spring for some adjustables as the dealer wants 50 bucks just for a stock r1 brake lever.
cheers
RW
 
well this is what i have found. it seems like the mc is working correctly as when i bleed i see bubbles go back and forth so it seems to be drawing back in. i filled with a mity vac so i dont belive there is any air left in it. then i double checked with the simple clear tube method. i cleaned what i could of the pistons but i dont have a compressor so i only got to the top portion of them cleaned up. i took the lever off just to see if that was the cause of the dragging but nope its not.
thoughts?
thanks RW
 
ok so i just pulled the caliper off the rt side with everything connected i was unable to push the pistons back in. then i cracked the bleed zerk and was still unable to push them back in. then i pulled it the caliper completly off put it on my bench. unable to push it back in. then i took the pads off and was able to push each piston back in indivudually.
does this mean i need to rebuild the caliper?
 
rwgoldsmith said:
then i pulled it the caliper completly off put it on my bench. unable to push it back in. then i took the pads off and was able to push each piston back in indivudually.
Click to expand...

I would not expect to be able to retract the pistons with the pads in place. If the pads twist any amount they will hangup in the caliper body.

i took the lever off just to see if that was the cause of the dragging but nope its not.
Click to expand...
There will always be some amount of drag. With the lever in place is it depressing the master cylinder piston any amount? If so it might act as if you were riding the brake.

I have an R1 m/c on my 1st gen. I'll take a look see if/how the FZ1 lever fits on the R1 m/c.
 
ok here is a you tube of how much it is dragging is this "normal" or too much. my rear brake doesnt drag this much.

is this right? - YouTube

to nhrider i took the lever completly off and it still drags the same amount so i dont think it was the lever and it looks just like the one on an 01 r1 and fits just fine.

to loosenut i always use new fluid its cheap and my neck depends on it.
 
I watched the YouTube clip. I think you may have similar to or a little more drag than my bike but it is difficult to be certain. It is that totally locking up thing that is the scary part.

During the clip I heard some clinking and clunking off camera. I am assuming that was not from your bike.

I am running out of ideas.

Is it possible when the front wheel was put back on it was put on "backwards"? The lettering that is cast into the spokes should be on the left when referenced from sitting on the bike. I have seen several posts in the past where the wheel did fit but there were clearance issues of some sort because it was backwards. I don't recall any of the particulars though.

Other idea. When you ride do you keep two fingers on the brake lever? That might somehow put some pressure to load the lever. Again like riding the brake.

Yet another left field thought. Wheel bearings going bad? Probably not. But, if you pull the calipers off and it passes the spin test that would at least take them out of the equation.

You said you were using the FZ1 brake lever. What year R1 is your master cylinder from, 04 or newer? 04 was when they started with the radial master cylinder. I have a radial on my bike and compared the lever to the FZ1 and can't see any way for the FZ1 lever to fit on a radial master cylinder. The FZ1 piston moves more left/right along the handlebar. The radial piston moves perpendicular "into" the handlebar.
 
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