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Discussion Starter · #1 ·
Hey everyone!
I just got a wrecked 04 gsxr 600 for cheap.
and im having a little trouble with the front brakes locking up.
Ive bleed the brakes twice and its the same. I noticed a small leak at the rubber hose that goes to the MC from the reservoir.

the bike would work good for a couple of mins then id take it for a ride and after about 5min of doing about 50-60 the from brake would start the get really hard and them would stop the bike completely. its kind of scary.

O and I think my rotors are also warped?

I did us a hand pump vac to help bleed and i noticed that i was slowly lossing vac as i was pummping.

help

Ty
 

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First reaction is the reservoir hose leak is introducing air into the system. As the brakes heat, the air is expanding and effectively engaging the brakes. That hose basically feeds straight into the master cylinder, and a problem with a leak in that hose would show up quick.

Excessive heat into the rotors from this sort of condition can indeed warp them.

Recommend find the leak and replace the elbow, seal and hose between the master cylinder and reservoir if you can't find the issue. Those are pretty cheap.

You should also try hand bleeding as the vac pump type can introduce air past the bleeder nipple threads. That is the likely reason the pump was losing vacuum - not necessarily indicative of your problem.
 

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Discussion Starter · #4 ·
ok so i did as per your advice and there is no more leaking of the elbow. But the brakes still locked up. this time at about 2 miles. Ive bleed the brakes and made sure that there was no air in the system. So I cant understand why the brakes still locked up? Is it because of the warped rotors making to much friction on the pads causing some kind of expansion?

Ill replace the rotors and pads and see what happens.
this is really weird.

TY
 

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Discussion Starter · #7 ·
with the rotors warped how will the excess heat cause the brakes to lock?
the pads are being dragged against the rotor causing the brake fluid to head up and therefor expanding causing the lock up? I don't think that brake fluid heat up or expand. I think there is still air getting on there and causing the lock up.
Can the bleeder valves leak? and introduce air into the system? Can I use Teflon on the bleeder valves to seal it?

Im getting new pads in a couple of days, So ill replace them and mybe put some Teflon on the bleeder valves to see if that solves the problem..
 

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I have exactly the same problem on my 06 1000. I've done f****** everything except replace the master cylinder. It's driving me nuts! I posted a thread under "seized brakes". Bleeding my brakes is a nightmare, so maybe air IS in there and expanding... Problem with that theory is that when the brakes eventually lock up(2-3 miles), the lever is solid. If there was air in there, it would still be spongey.. somehow the fluid isn't returning to the master cylinder. ntai3g, do you have aftermarket hoses or brake lever on the bike? I'm thinking maybe I over tightened the banjo bolts on mine and it'll let fluid one way, but not the other....????
 

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Banjo bolts don't work like that. Air or M/C return problem. Note that air under sufficient pressure to cause lock-up isn't particularly spongey.
 

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I have exactly the same problem on my 06 1000. I've done f****** everything except replace the master cylinder. It's driving me nuts! I posted a thread under "seized brakes". Bleeding my brakes is a nightmare, so maybe air IS in there and expanding... Problem with that theory is that when the brakes eventually lock up(2-3 miles), the lever is solid. If there was air in there, it would still be spongey.. somehow the fluid isn't returning to the master cylinder. ntai3g, do you have aftermarket hoses or brake lever on the bike? I'm thinking maybe I over tightened the banjo bolts on mine and it'll let fluid one way, but not the other....????


you just described the same problem I am having. I bleed them (from either the master cylinder or the calipers) which releases the pressure... then ride on it for awhile (for me its about 7-10 miles) then the front brakes lock up and I have to release the pressure again... its scary cuz it happened to me once while I was on the freeway... I did also notice that it happens rather quickly and locks harder on a curve (not a literal curve, rather in regards to math or a graphical curve) ... slowly at first then progressively faster until the front tire won't move at all... so i'm thinking it is heat.. and possibly air in the system... but again.. i've bled the damn things so many times.
 

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OK let me as you this, if you dont ride the bike and just squeeze the brakes in the garage will it do the same thing eventually lock up?


Its not the MC im guessing its one of the calipers that is bad! If it was wrecked it probably sat, if when it wrecked any of the brake lines, which you said one was, got damaged it could of gotten water in it. This could cause rust inside the caliper!

Dont keep riding the bike man! If it gets worse locking up at 65 mph is very bad! MKKAY!
 

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Has it been dropped on the RHS? My bike had the same problem and it turned out that the previous owner dropped it and the brake lever pushed into the MC and broke a spring inside. Fixed it by running a MC kit.
 

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Alrighty folks. I think I've figured this one out. On mine at least. I had an aftermarket brake lever on, which is when the problem started. I thought it might be a bad master cylinder but since it was fine before, I guessed it had to be something I did. Well, I had the old lever (OEM) on and it did the same thing. The curious thing was, when I set the adjuster so the lever was closest to the handlebar it would pull back all the way, but "bottom out" halfway to the handlebar. Normally the lever would practically touch the handlebar. I found out the hole on the lever where the m/c piston rod goes in has a small "roller" in the bottom. If you rotate that roller, you'll see another drilled out hole in it. The m/c piston rod end has to fit all the way into this hole to allow the m/c piston to FULLY extend and allow the brake fluid to return from the calipers. I haven't test ridden it yet, because of a thunderstorm, but I'll post the results by the end of today. Fingers crossed!!
 

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No, the fluid was not returning. But, yes, the problem is fixed! I test rode it and now the brakes work fine. so, kids, to recap... The indentation in the brake lever has to accommodate the m/c piston rod sticking out. If it's not seated ALL the way into the lever's indentation, it won't allow the piston to completely cycle and let the fluid back into the reservoir. Hence the build-up of pressure. I don't know if you guys with the same problem have the same lever issue, but it's worth looking at. It's taken me a month of an hour here and a hour there of dicking around, but I'm finally fuckin' done! Thanks to the guys out there that threw out suggestions! You got me thinking and had looking in the right area. I'll check back to see if anyone had any luck with their problems and try to help, if I can.
 

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No, the fluid was not returning. But, yes, the problem is fixed! I test rode it and now the brakes work fine. so, kids, to recap... The indentation in the brake lever has to accommodate the m/c piston rod sticking out. If it's not seated ALL the way into the lever's indentation, it won't allow the piston to completely cycle and let the fluid back into the reservoir. Hence the build-up of pressure. I don't know if you guys with the same problem have the same lever issue, but it's worth looking at. It's taken me a month of an hour here and a hour there of dicking around, but I'm finally fuckin' done! Thanks to the guys out there that threw out suggestions! You got me thinking and had looking in the right area. I'll check back to see if anyone had any luck with their problems and try to help, if I can.
I had to replace that lever recently... maybe thats my same problem.




*edit*

So I just went out to look at my lever, and to my surprise I didn't put the rod into the little toggle either. I took it off and readjusted it and will find out tomorrow if it also works.
 

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Alrighty folks. I think I've figured this one out. On mine at least. I had an aftermarket brake lever on, which is when the problem started. I thought it might be a bad master cylinder but since it was fine before, I guessed it had to be something I did. Well, I had the old lever (OEM) on and it did the same thing. The curious thing was, when I set the adjuster so the lever was closest to the handlebar it would pull back all the way, but "bottom out" halfway to the handlebar. Normally the lever would practically touch the handlebar. I found out the hole on the lever where the m/c piston rod goes in has a small "roller" in the bottom. If you rotate that roller, you'll see another drilled out hole in it. The m/c piston rod end has to fit all the way into this hole to allow the m/c piston to FULLY extend and allow the brake fluid to return from the calipers. I haven't test ridden it yet, because of a thunderstorm, but I'll post the results by the end of today. Fingers crossed!!
Thank you very much for the great post! My son has been having problems with his brakes locking up on his GSXR 750K7. Saw your post had the problem fixed in 30 minutes.
 
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