anyone else have a front master cylinder sieze from heat??

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bluto

bluto

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I parked my bike for awhile in extreme heat today and when I returned the front brake dragged badly after I used it and the lever had too much free play as though the piston was seized. I cracked the bleeder valve on the caliper (and then closed it) and made it home OK and the front brake is fine now but will check everything out of course. I do know the PO had the master cylinder sleeved and normally the front brake works well....
 
Re: anyone else have a front master cylinder sieze from heat

I have a sleeved front MC on my MK III. Recently, the bike was parked in the sun on a very hot day. When we rolled it onto the trailer and used the front brake to slow it down, the brake refused to release casing a lot of free play in the lever. I checked it again when I got home and found the brake returned to normal. A week or so later, I parked the bike in a hot sun and experienced the same thing. After riding the bike a short distance, the wind seemed to have cooled things down enough to return the MC to normal. Other than heat, I don't know what the problem is, but a little wind on the cylinder seems to correct the problem.
 
Re: anyone else have a front master cylinder sieze from heat

calbigbird said:
I have a sleeved front MC on my MK III. Recently, the bike was parked in the sun on a very hot day. When we rolled it onto the trailer and used the front brake to slow it down, the brake refused to release casing a lot of free play in the lever. I checked it again when I got home and found the brake returned to normal. A week or so later, I parked the bike in a hot sun and experienced the same thing. After riding the bike a short distance, the wind seemed to have cooled things down enough to return the MC to normal. Other than heat, I don't know what the problem is, but a little wind on the cylinder seems to correct the problem.
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Thanks very much for the info, that is exactly what happened to me and it was extremely hot today....I rode home using the back brake only since it wasn't far and by the time I got there all was well
 
Re: anyone else have a front master cylinder sieze from heat

Bluto, Bird, who did the work on each of your respective MC's ??? Were these kits that were then "owner installed"? We've all heard of a few of these doing this & it scares the piss out of me enough that even though mine is basicly good enough I'm still planning on buying a differant set up.
 
Re: anyone else have a front master cylinder sieze from heat

Its a well known problem and solution and can happen in rear m/c too. Its usually the spacer/plunger between the lever and the piston needs rubbing a tad shorter. Best time to do this is when hotter than you'd expect it to get out in sun with hair drier on it till it locks up, then remove lever and spacer and file, grind on cement or delicately mill off a few 1000'ths put back on and pump up and re heat to see if locks or not, if not then take a wee bit more off so really be sure it won't lock up from heat of use going into a turn or crossing metal grate bridge in traffic. If you take too much off it just takes some of the full piston travel out to develop full pressure but a non issue as full tire lock up should still occur before piston runs out of room. But on the other hand it allows piston to draw back a bit more fluid to push on pads. Before I found out how much minimal + some, I put a ball cap or helmet or anything over the bar end to shade it. Wet towel can un lock faster than just fuming at it. its possible an old hose collapsed to keep enough pressure on pads to drag em hard.
 
Re: anyone else have a front master cylinder sieze from heat

hobot said:
Its a well known problem and solution and can happen in rear m/c too. Its usually the spacer/plunger between the lever and the piston needs rubbing a tad shorter. Best time to do this is when hotter than you'd expect it to get out in sun with hair drier on it till it locks up, then remove lever and spacer and file, grind on cement or delicately mill off a few 1000'ths put back on and pump up and re heat to see if locks or not, if not then take a wee bit more off so really be sure it won't lock up from heat of use going into a turn or crossing metal grate bridge in traffic. If you take too much off it just takes some of the full piston travel out to develop full pressure but a non issue as full tire lock up should still occur before piston runs out of room. But on the other hand it allows piston to draw back a bit more fluid to push on pads. Before I found out how much minimal + some, I put a ball cap or helmet or anything over the bar end to shade it. Wet towel can un lock faster than just fuming at it. its possible an old hose collapsed to keep enough pressure on pads to drag em hard.
Click to expand...


thanks very much, I'll try that...the brake line is OK, it is a newer braided one
 
Re: anyone else have a front master cylinder sieze from heat

gtsun said:
Bluto, Bird, who did the work on each of your respective MC's ??? Were these kits that were then "owner installed"? We've all heard of a few of these doing this & it scares the piss out of me enough that even though mine is basicly good enough I'm still planning on buying a differant set up.
Click to expand...

AFAIK mine was an owner installed kit but I'm not sure....had I ridden off it probably would not have been too dangerous to me, the front brake dragged but was not locked, though if I didn't realize what was happening it would have been bad for the bike on such a hot day
 
Re: anyone else have a front master cylinder sieze from heat

I have a sleeved master cylinder and after a minor crash replaced the brake handle with OEM version. I went for a ride and at the end the front end locked up. After rebuilding caliper, replacing warped rotor and still locking up it turned out brake lever was out of spec and brake fluid return wasn't open when blade released!
 
Re: anyone else have a front master cylinder sieze from heat

See I told ya so, every example of this boils down to merely a lever to piston return travel, that usually shortening one of the spacer elements solves it permanently. Some have drilled and tapped a set screw to adjust it that way, but only if there is already slack enough to allow it.
 
Re: anyone else have a front master cylinder sieze from heat

My front master cylinder was store bought from either Rabers or Fair Spares, I can't really remember which. Mine doesn't seem to be from the plunger being too long though. I found lots of space between the lever and the first contact when I was frozen. It seemed like I had 1/4" or more of free play at the plunger end. By the time I got enough air flowing by the plunger released and the brake was fine. It didn't seem to me that filing/grinding down the sleeve would have done anything to free the piston.
 
Re: anyone else have a front master cylinder sieze from heat

By the time I got enough air flowing by the plunger released and the brake was fine. It didn't seem to me that filing/grinding down the sleeve would have done anything to free the piston.
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Hey I'm all ears to learn any new hazard on surprise brake conditions. I hope you discover the cause and report to us if its not plunger length, yet your remark above sure smacks of it via a fix by just cooling down again. I've heard of piston installed backwards but was in rear factory m/c. Best to contact the vendor for their feedback not us guessing long distance.
 
Re: anyone else have a front master cylinder sieze from heat

After my resleeve nipped up I would be wary ! Post soon on new Yamaha fix.
 
Re: anyone else have a front master cylinder sieze from heat

I guess the wierd thing for me is this MC has been on the bike for probably two years and I never had a problem with it until last month.
 
Re: anyone else have a front master cylinder sieze from heat

My first surprise lock up fall down was 30 miles into first out of state trip - after 3 seasons of burning up the Ozarks and practicing stoppie 'attempts' regularly, so I never let bike sit long , on the fly or parked inside. Then hi summer hit and freaked me out on side of the road, while unloading bike to pick it back up, lucky not to have knocked bar controls, signal and mirror to shizt, reviewing reviewing reviewing what I'd read of brake, till I remembered if piston couldn't back up enough to relieve the pressure... also lucked out to have nice side walk cement milling station right there, fixed it permanently in my case.

If not a kinked hose or bug lodged, then where else or how else could a check valve condition develop.
 
Re: anyone else have a front master cylinder sieze from heat

Just had a conversation with Richard at Raber's Parts Mart. He said he is skeptical of spacer/plunger length was the problem, at least as I described it to him especially after the MC was on the bike for well over a year. He, like I, believes it has something to do with heating the MC by the sun. It is possible the piston or the o-rings may be swelling due to the heat. He suggested I try using my heat gun and heating the MC to see if it makes the piston stick or be slow to respond and reset. I will try this after my shoulder is back to abnormal unless someone wants to try it before then. FYI.
 
Re: anyone else have a front master cylinder sieze from heat

Any chance your reservoir vent is clogged? Hot brake fluid causing the brake to lock sure sounds like a closed system / no venting.
 
Re: anyone else have a front master cylinder sieze from heat

I'll check, but I don't think so. Have to wait till the shoulder doc says I can work and/or ride the bikes first.
 
Re: anyone else have a front master cylinder sieze from heat

calbigbird said:
My front master cylinder was store bought from either Rabers or Fair Spares, I can't really remember which. Mine doesn't seem to be from the plunger being too long though. I found lots of space between the lever and the first contact when I was frozen. It seemed like I had 1/4" or more of free play at the plunger end. By the time I got enough air flowing by the plunger released and the brake was fine. It didn't seem to me that filing/grinding down the sleeve would have done anything to free the piston.
Click to expand...

look inside the reservoir to see if fluid return hole is open and pumping fluid back into reservoir. Mine wasn't fully open when blade released and pressure built as heat increased locking caliper!
 
Re: anyone else have a front master cylinder sieze from heat

look inside the reservoir to see if fluid return hole is open and pumping fluid back into reservoir. Mine wasn't fully open when blade released and pressure built as heat increased locking caliper!
Click to expand...

Yep that is what I saw and solved by plunger length shortening, prey tell, how did you solve yours?
 
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