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Discussion Starter #1
I was at track this past weekend and had my front brakes clamp down with very little pressure to the lever. I was riding one of the last sessions of the day going down back straight away at 130. As soon as I pulled the lever to start braking, the front brakes acted as if I had pulled the lever to the grip. Bike did an Indo then sat back down. I did crash but damage wasn't too bad cause bike stayed on side. Any suggestions on why and how I can prevent this from happening in the future?:idunno:

Thanks,
Brandon
 

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I was at track this past weekend and had my front brakes clamp down with very little pressure to the lever. I was riding one of the last sessions of the day going down back straight away at 130. As soon as I pulled the lever to start braking, the front brakes acted as if I had pulled the lever to the grip. Bike did an Indo then sat back down. I did crash but damage wasn't too bad cause bike stayed on side. Any suggestions on why and how I can prevent this from happening in the future?:idunno:

Thanks,
Brandon

Are the discs blue?
Most likely would be brake drag getting worse as the discs heat up.
 

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Are the discs blue?
Most likely would be brake drag getting worse as the discs heat up.
'
:plus1:
There were other posts recently about people's front brakes locking up on the street due to the pistons not fully releasing because of corrosion or dirt.
Take the brakes apart and clean them to make sure that they aren't binding.
 

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Discussion Starter #6
Thanks for any info you guys can share. I definitely will be re-building everything before I am pushing again.
 

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Discussion Starter #7
Well bike is re-built as well as the calipers. I am struggling to get the front brakes to the point of not being spongy. I have PSR levers on the bike and the #1 setting touches the clip on with no problem. I have some pressure on the #6 setting (lever all the way out) but it is still not right. I cannot seem to get the air out of system. Hours and hours of bleeding, no good results. I have used vacuum, old fashioned method, syringe( which I can't seem to push fluid up because pressure), read every post in this forum, still banging my head in my hands. Sh!t. Anyone have more advice?
 

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The standard mc has a bleed nipple on it, I couldn't get mine right without having to bleed the air out here also, does the psr have this? Also I presume no leaks or seals gone on the calipers? I had that problem also and had to replace piston seals.
 

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I was riding my '93 RS 125 a track day years ago, and had something similar happen. Going down the back straight at Mosport's Rider Development track, the front brake locked up on me. Luckily I was able to pull off, but I couldn't move the bike. I had to wait until the brake cooled before the wheel would turn.

What happened was through use some crud had gotten into the brake lines and fluid, and somewhere along the way a tiny hole in the master cylinder had gotten clogged up. With heat from braking there was some expansion of the fluid, but it couldn't get back up into the reservoir, and could only move the pistons in the caliper. Once that hole got cleared, bleeding the system was super easy, and the brake worked like new.

May not be what your problem is, but if there is dirt in your system, your master may need to be cleaned out as well as the calipers. Just a thought.
 

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I was riding my '93 RS 125 a track day years ago, and had something similar happen. Going down the back straight at Mosport's Rider Development track, the front brake locked up on me. Luckily I was able to pull off, but I couldn't move the bike. I had to wait until the brake cooled before the wheel would turn.

What happened was through use some crud had gotten into the brake lines and fluid, and somewhere along the way a tiny hole in the master cylinder had gotten clogged up. With heat from braking there was some expansion of the fluid, but it couldn't get back up into the reservoir, and could only move the pistons in the caliper. Once that hole got cleared, bleeding the system was super easy, and the brake worked like new.

May not be what your problem is, but if there is dirt in your system, your master may need to be cleaned out as well as the calipers. Just a thought.

Yep, I crashed at 200kph due to the same problem.
 

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JEEEZZZ that's nuts, you guys are freaking me out!!!!! I gonna look at my bikes brakes again just to be safe!!!:eek::idunno::rotfl:

That's why we push so hard to get people to replace their brake fluid regularly, before crud can build up, and CLEAN the pistons every time you replace the pads, before pressing them into the calipers and damaging the seals. If you only replace the pads on rare occasions get in there and clean the pistons more regularly. Fresh fluid and clean pistons every year is good maintenance.

A mate of mine loaned his old racebike to a friend who had come over from England so he could join us in a race. It had been sitting in the shed for a couple of years but there hadn't been time to give it a thorough going over beforehand. He also crashed when the front locked up due to brake drag. This was on a street circuit which was even scarier, but luckily he got away with just a broken kneecap from memory.

You can ignore the rear brake though. I put a new tyre on the back of my ZX6R yesterday. The rear caliper and master cylinder were both locked up solid due to lack of use :)
 

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I am definately looking over my brakes tomorrow! !!

But to the brake bleeding. I did that with clutch today on bobbered goldwing he tried for hours.

Put your lever setting at one lever all the way in. Use a deepwell socket and ratchet or 1/4screwdriver. So you can get a full half turn atleast over 1/4 turn then back to snug for first few bleeds the once building pressure do quicker open closes with smaller cracking of bleeder.

ITS IS KEY TO PUMP SLOWLY

Don't try and speed bleed. Nice and slow in and out 5-10 pumps, fast rapid pumps get you hours behind.
Once you get as much pressure then adjust lever to desired setting.

Patience is virtue Slow easy pumps in and out in and out.
 
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