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Discussion Starter #1
Did a quick search, but most threads I found were about the rear brake not grabbing after pad change...

BLUF: My issue is the front brakes grabbing after riding a 1/2 mile or so.

I did a full front / rear brake bleed, as there was some very old brake fluid in it. Probably factory. It had sat the last 6 years or so in storage, and the front brakes were locked up just getting it into the U-Haul (hydraulically locked, brake lever was tight. Not rusted up)

That helped get it to be movable, but the front was still getting hot and locking up / lever getting stiff after riding.

Did another bleed, along with pulling calipers and making sure the pistons aren't seized and no water trapped in them, cleaned out banjo bolts, and purged the brake lines with calipers disconnected. Cleared out any muck and brake debris from calipers and pads.

Front brakes are still dragging a bit, and after a 1/2 mile ride, begin grabbing harder and harder until I'm just spinning the back tires in 2WD.

Is there some sort of valve adjustment on the master cylinder I can do? I ordered a MC rebuild kit from the local Yamaha franchise, but after 8 weeks of waiting, they failed to even bother telling me there is a big back order on it. Called around to the (few) other places around (Fairbanks, Alaska) here, and none had in stock / were waiting on this back order.

Any other ideas?

Thanks!
 

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I would check the front wheel bearings.
 

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Discussion Starter #3
Are the brake disks mounted separately from hub? I'll have to pull the wheel off again and see. I would think that, even if the bearings are going bad, that the hub/disks/calipers would remain in-line with each other.
 

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A caliper has to be mounted to something that doesn't move/turn. The rotor turns with the wheel and the bearing keeps this alignment right/straight through the caliper. If the bearing is letting the wheel lay over, so is the rotor, rubbing as it goes through the caliper.
I know, I had a bad bearing causing the front brake to over heat, so when I pulled the lever, the brakes faded.
 

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Discussion Starter #5 (Edited)
Oh, of course, yeah. I get it now. I was visualizing it wrong haha. The bearing is IN the knuckle, caliper mounted TO the knuckle, rotor and wheel to the hub, and bearing between the hub and knuckle... In my head, I guess I was just imagining the caliper magically floating while the rotor spins through it, thinking "if the wheel and rotor are leaning, so is the caliper".

Funny how you got brake fade, but I get locking brakes.

Also intriguing, that the bearings (may have) failed while sitting in dry storage, and only 750 miles on the clocks.

I'll have to get the front back in the air, and see if I get any play in the hub. With all the messing around with the brakes I've done, I'd hope I would have noticed slop, but then again I wasn't exactly looking for it...
 

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I was mentioning something that caused my brakes to stop working, something easy to check for without spending money.
Mine was so slight I had to feel the hub, not pull on the wheel, and it was so slight I was in question until I pulled the knuckle. The axle nut had everything squished together so tight I wasn't sure if there was movement.
If the bearing is good, look for something else....maybe in the brake line.
My first bearing failure was with low miles, and if you washed then put it up, there could have been water in that area and over time rust set up, then the bearing failed the first time back on the trail.
 

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Discussion Starter #7
Pulled the front wheels again. Checked knuckles for play and didn't find any. Made a small gap between pads and rotors, and visually checked while spinning hub/disk, couldn't see any warping.

Disconnected the hard line / T-fitting, pushed fluid down and out from reservoir, and used calipers to backwash fluid out of T-fitting. Didn't get any junk out from either... This leads me back the MC somehow not returning fluid after the brake is released, and / or not able to compensate for temp fluctuations... As of the last ride (where I didn't use the front brakes) I got home fine. But then the next day, the front brakes were locked again. The only factor being the warmth of the garage.

I failed to post that I also had the MC apart. There was a tiny bit of corrosion on the plunger, but easily removed with a scribe. No marring inside the housing / cylinder walls. Spring not broken or collapsed. O-ring and seal weren't hard, cracked, overly swollen, or mushy. The only thing other than slight buildup on the plunger was a bit of a mess under the fluid return port in the reservoir. I pulled the clear plastic port cover thing (I can only imagine this as a fluid pressure buffer / anti-splash / restrictor valve. Can't find it on the Yamaha IPB) to clean out the hole, chamber, and the valve itself. This was all slimy and / or crusty orange junk, not black rubber seal or hose material.

I guess after all this, maybe an inner-lining of rubber could be collapsing when fluid goes to return from calipers... Preventing it from getting back to the reservoir when expanding due to heat.
 

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Discussion Starter #8
Update:

Just got a new upper brake hose (MC to hard line under steering head).

The brakes were, once again, locked up on the front when I started working. Once I pulled the banjo bolt out, the pressure in the brake lines dropped, freeing the front wheels. If this line was holding pressure from being internally collapsed, then this shouldn't have released pressure, correct?

I'm kind of at a loss now. When MCs fail, they usually won't hold pressure because a seal went bad. In another post, I had the MC apart and all seals looked good, no rubber rot in the assy at all. The cruddy brake fluid was washed/wiped/picked away before reassembly.

I can crack a bleeder valve or the banjo bolt, burp the air out and go for a ride, but the next day, the brakes will be locked up again.
 

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Just thinking out loud to ask......
You can have the bike in neutral after a ride and the bike will roll freely, and you can leave it alone without changing anything, and the next morning it will not roll like the night before?
 

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Discussion Starter #10
Exactly. ^^^

It doesn't tend to get hot (enough to feel at least) while riding anymore, as long as I burp it before heading out.

Not doing any downhill or anything, and it's generally at/below 20°F now. Garage is at 55-60°F.
 

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Sounds like the return hole in your master may be clogged.

Open the reservoir. Look inside at the bottom of it. There is a TINY hole in there. Should be fairly close to the port that supplies fluid to brake line.. Use a needle to probe it and make sure its not plugged up.
 

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So now a question is;
Does it suck in air (for burping) during the ride? I wonder if it needs burping when getting home.
This doesn't explain the problem occurring during the night, just thinking here.
Have you raised the front off the ground after getting home, to turn each tire that night, then in the morning? Are both sides with pressure, or just one side?
 

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Discussion Starter #13
Sounds like the return hole in your master may be clogged.

Open the reservoir. Look inside at the bottom of it. There is a TINY hole in there. Should be fairly close to the port that supplies fluid to brake line.. Use a needle to probe it and make sure its not plugged up.
Yeah, that is one of the places I focused on when I had it all apart and cleaning it. The little hole is under a clear round disk, that has restrictor hole in it. The hole in the MC/reservoir and the holes in the restrictor are all clean. I can watch the spring/plunger moving when the lever is squeezed.
 

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Discussion Starter #14
So now a question is;
Does it suck in air (for burping) during the ride? I wonder if it needs burping when getting home.
This doesn't explain the problem occurring during the night, just thinking here.
Have you raised the front off the ground after getting home, to turn each tire that night, then in the morning? Are both sides with pressure, or just one side?
Yeah it's weird. Even if it was getting air into it, that would rise up through the system and give a spongy feel, not expand pressing the calipers tight...

Yes, both wheels are free after a burp/bleed (don't ever get any air, just to relieve pressure). And both wheels are locked up the next day.

Bleeding just one or the other of the calipers will release both sides. Pulling the upper hose/banjo bolt releases both sides.
 

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I was wondering about moisture, and if one wheel locks up or both the next day after sitting in the garage, before a burp.
 

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Both wheels locked up.
OK.....
When you burp it, does a little brake fluid drip off? If so have you added more to top off the MC?
I haven't heard of this problem before, you're so lucky :) so if this was my bike I would start eliminating parts of the system as the problem.
I would get two caps, remove one line from one caliper and cap it off tight. Then make sure it rolls easily before bed time, then see what is going on the next morning. Is one or both free, or stuck?
In a few night you might determine the calipers are good, and the problem is in the line(s) or the MC. The caps are to hold pressure, to see if the lines removed from the calipers need a burp in the morning.
If you can't find a problem, get rid of the cat roaming around in the garage at night. :)
 

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Discussion Starter #18
I'll have to check if fluid comes out. I usually squeeze the brake lever like I'm doing a bleed, so that air doesn't get into the caliper. Any time I'm getting fluid out, I make sure to add more, and not suck any air into the system. I have tried full, half, and fairly low (but still enough to keep from sucking air) fluid levels.

I'll have to try the hardware store and see if I can find caps that will seal correctly. Sealing a banjo that's not on the caliper might be tricky... maybe use the banjo bolt, a nut and some extra copper washers.

I think I've ruled out the calipers and the lower/split brake line(s), though. Even with the reservoir cap off, I couldn't push fluid out of the caliper. If I pull the line off at the T-fitting, they will both push fluid back out, even by hand (no C-clamps, etc.) This led me to the upper line and/or MC/reservoir.

The teardown/cleaning of the MC had me believing it was good, but can obviously still be suspect. Being the most expensive part, I held off on buying one yet. Plus, everywhere I have called can't get a reputable brand/source. Suppliers seem to be back ordered with no expected availability dates. Not sure if I want to risk an Ebay/Amazon model. Plenty of reviews about them failing almost immediately.

I do still have the new upper brake line, not fitted yet. I just started second guessing everything when I pulled the banjo bolt out of the old line, and it released the pressure that I thought it was holding... Could be some form of "fluid dynamics" I'm not grasping. Where even though the line is collapsing internally, pulling the banjo somehow un-collapses it from air getting in or something.

I have the new line, so might as well install it, and see what happens. If it magically fixes it, yay me. If not, I'll chase down the hardware to plug the lines like you mentioned.

After that, all that's left is the MC...
 

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I'll have to check if fluid comes out. I usually squeeze the brake lever like I'm doing a bleed, so that air doesn't get into the caliper. Any time I'm getting fluid out, I make sure to add more, and not suck any air into the system. I have tried full, half, and fairly low (but still enough to keep from sucking air) fluid levels.

I'll have to try the hardware store and see if I can find caps that will seal correctly. Sealing a banjo that's not on the caliper might be tricky... maybe use the banjo bolt, a nut and some extra copper washers.

I think I've ruled out the calipers and the lower/split brake line(s), though. Even with the reservoir cap off, I couldn't push fluid out of the caliper. If I pull the line off at the T-fitting, they will both push fluid back out, even by hand (no C-clamps, etc.) This led me to the upper line and/or MC/reservoir.

The teardown/cleaning of the MC had me believing it was good, but can obviously still be suspect. Being the most expensive part, I held off on buying one yet. Plus, everywhere I have called can't get a reputable brand/source. Suppliers seem to be back ordered with no expected availability dates. Not sure if I want to risk an Ebay/Amazon model. Plenty of reviews about them failing almost immediately.

I do still have the new upper brake line, not fitted yet. I just started second guessing everything when I pulled the banjo bolt out of the old line, and it released the pressure that I thought it was holding... Could be some form of "fluid dynamics" I'm not grasping. Where even though the line is collapsing internally, pulling the banjo somehow un-collapses it from air getting in or something.

I have the new line, so might as well install it, and see what happens. If it magically fixes it, yay me. If not, I'll chase down the hardware to plug the lines like you mentioned.

After that, all that's left is the MC...
I just purchased a 06 Kodiak 400 with almost the same issues prior to me purchasing. Wheel bearing bad from sitting for whom know how long. All three brake calipers were locked up. The PO sent the bike to the dealer and had whole brake system drained of brake fluid, changed all three brake calipers, brake pads and bleed system. I'd focus on brake calipers and brake master cylinders.
 

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Discussion Starter #20
The fluids have all been changed/bled multiple times. Calipers can be squeezed by hand, full travel, so they aren't seized. All lines flow fluid in both directions. Despite opening up the MC and not finding anything wrong, it's the only thing that can lock both calipers up simultaneously, yet opening only one caliper bleed screw releases pressure on both. Getting a rebuild kit has proved near-impossible, with everyone's suppliers being back ordered with no expected fulfilment date. So now I'm stuck debating if I want a copy-cat re-pro MC from Taiwan off Amazon... Where many of the reviews claim DOA, or go bad after/during first ride.
 
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