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First post here - Got a 1980 gs450L about 4-months ago, first bike, wanted something I can get comfortable on and learn to fix while I go. Been a lot of fixing.
About a month ago my roommate was out riding her and when he went to go from a stoplight, the front brake was locked up. Let it rest about 15-minutes, no problem.
I first tried simply bleeding, got a lot of nasty gunk and fluid out and got it all cleaned. Checked the pads, worn but not blocked, not critical. Rode and rode for hours without any problem, then suddenly it occurred again sitting at a stoplight. Front brake completely locked, almost redlining the throttle just to get to the curb. Let it sit 15-minutes and the caliper piston released, rode her home. Found out later opening the bleed screw would have released it, but it was too hot to turn by hand.
Scary problem, to say the least. Could this occur while in motion? I don't want to find out.
So I set about researching here, there, everywhere I could find, and basically determined it could be 1 or more of the following things:
1.) Caliper piston getting stuck
2.) Faulty brake hose
3.) Blocked up re-intake in master cylinder
So first I attacked the caliper. Drained the system, removed the caliper and completely disassembled it. Had the guys at my local Suzuki dealership use compressed air to blow out the piston (free, 5 seconds), cleaned it all up. Piston was scored all around at the point where it touches the seal when fully compressed. I cleaned it thoroughly with an emery cloth, was polishing out the scoring, but determined it was going to leave divets still. Basically, not something I could ever trust again - and I think this was my issue, with the piston catching just enough in the 'engaged' position to drag the brake pads, super heat the caliper, and from there it's only getting tighter.
So new piston, $35. Also got new piston seal and dust boot, and new boots for the caliper bolts - $25. Cleaned everything out, checked the new piston slides smoothly, re-assembled.
Shortly after ordering that I realized, this hose thing has got to go - still have the stock rubber one, which looks fine on visual inspection, but everyone here says replace with a braided SS one. So I order one of those off amazon, $35. Darn thing came without banjo fittings, which I'm looking at another $20 to get...so I go up to Bent Bike (local after market bike parts brick and mortar store, great spot), eventually find a hose that is the right size with fittings for $20. First one is a waste, but there ya go.
Then I realize, shoot, why go 2/3 of the way with this thing? So, master cylinder rebuild kit ordered - $23.
Couple tips about the M/C - first, removing the front brake switch for the first time, this tiny tiny spring, copper C, and plastic bit drop right out and are practically impossible to find. I'm amazed I did on the garage floor. Use a cup or something to catch when you unscrew the switch.
Re-attaching it is even harder, really I found it impossible even with 4 hands. What I ended up doing is putting a tiny amount of rubber gasket in the plastic bit to hold in the spring and copper C, so that it still springs but won't fall out. It was delicate, but it held the three tiny parts together inverted, which it has to be when it goes back in.
Getting the M/C piston out was impossible, friend had good retaining ring pliers and was able to get it out. Rebuild kit - this threw me - the new piston and spring were different shapes and lengths. I was sure it was the wrong kit until inspecting closer and realizing the entire system - spring, cover, piston, was identical length and diameter to the stock one. So I went ahead with it - except even after trying 2 different C-clamps ($20), I'm unable to get the piston seated to insert the new internal retaining ring.
Took it to Seattle Used Bikes, the guys there are Awesome - popped it right in for me, no charge. At this point I was on my 3rd weekend working on this thing - none of this was remotely quick or easy - and those guys helping me out really lifted my spirits.
Last step - fill with fluid! Turns out these Suzuki's do not want to flow brake fluid at all. Tried a syringe ($2), nothing. Tried a fluid transfer pump ($5), nothing. Disconnect the M/C end of the brake hose and see not even a drop has come down from the reservoir. So I sprung for a Mityvac, $50. Connected first at the M/C, hold the lever down, pump up a vacuum and it starts sucking brake fluid.
Then start sucking at the bleeder screw. This literally took hours of difficult work, even with the tool, but eventually got the fluid coming out without bubbles. No resistance on the brake lever even after getting it flowing. Incredibly frustrating, retire for the evening.
Next morning, yay gravity has solved my last issue, pump the lever a few times and feel the first resistance. Go to do normal bleeding procedure (on lever, open screw, close screw, off lever, repeat - it is amazing how many sources on the internet have this simple procedure wrong), fluid squirts out immediately, so I just left it as-is.
Rode around all afternoon, front brake fulling functioning. May actually have fixed this thing! For now anyway...I'll follow up posting if there are further issues...
Hope this is helpful to the next guy with a brake that locks up!
About a month ago my roommate was out riding her and when he went to go from a stoplight, the front brake was locked up. Let it rest about 15-minutes, no problem.
I first tried simply bleeding, got a lot of nasty gunk and fluid out and got it all cleaned. Checked the pads, worn but not blocked, not critical. Rode and rode for hours without any problem, then suddenly it occurred again sitting at a stoplight. Front brake completely locked, almost redlining the throttle just to get to the curb. Let it sit 15-minutes and the caliper piston released, rode her home. Found out later opening the bleed screw would have released it, but it was too hot to turn by hand.
Scary problem, to say the least. Could this occur while in motion? I don't want to find out.
So I set about researching here, there, everywhere I could find, and basically determined it could be 1 or more of the following things:
1.) Caliper piston getting stuck
2.) Faulty brake hose
3.) Blocked up re-intake in master cylinder
So first I attacked the caliper. Drained the system, removed the caliper and completely disassembled it. Had the guys at my local Suzuki dealership use compressed air to blow out the piston (free, 5 seconds), cleaned it all up. Piston was scored all around at the point where it touches the seal when fully compressed. I cleaned it thoroughly with an emery cloth, was polishing out the scoring, but determined it was going to leave divets still. Basically, not something I could ever trust again - and I think this was my issue, with the piston catching just enough in the 'engaged' position to drag the brake pads, super heat the caliper, and from there it's only getting tighter.
So new piston, $35. Also got new piston seal and dust boot, and new boots for the caliper bolts - $25. Cleaned everything out, checked the new piston slides smoothly, re-assembled.
Shortly after ordering that I realized, this hose thing has got to go - still have the stock rubber one, which looks fine on visual inspection, but everyone here says replace with a braided SS one. So I order one of those off amazon, $35. Darn thing came without banjo fittings, which I'm looking at another $20 to get...so I go up to Bent Bike (local after market bike parts brick and mortar store, great spot), eventually find a hose that is the right size with fittings for $20. First one is a waste, but there ya go.
Then I realize, shoot, why go 2/3 of the way with this thing? So, master cylinder rebuild kit ordered - $23.
Couple tips about the M/C - first, removing the front brake switch for the first time, this tiny tiny spring, copper C, and plastic bit drop right out and are practically impossible to find. I'm amazed I did on the garage floor. Use a cup or something to catch when you unscrew the switch.
Re-attaching it is even harder, really I found it impossible even with 4 hands. What I ended up doing is putting a tiny amount of rubber gasket in the plastic bit to hold in the spring and copper C, so that it still springs but won't fall out. It was delicate, but it held the three tiny parts together inverted, which it has to be when it goes back in.
Getting the M/C piston out was impossible, friend had good retaining ring pliers and was able to get it out. Rebuild kit - this threw me - the new piston and spring were different shapes and lengths. I was sure it was the wrong kit until inspecting closer and realizing the entire system - spring, cover, piston, was identical length and diameter to the stock one. So I went ahead with it - except even after trying 2 different C-clamps ($20), I'm unable to get the piston seated to insert the new internal retaining ring.
Took it to Seattle Used Bikes, the guys there are Awesome - popped it right in for me, no charge. At this point I was on my 3rd weekend working on this thing - none of this was remotely quick or easy - and those guys helping me out really lifted my spirits.
Last step - fill with fluid! Turns out these Suzuki's do not want to flow brake fluid at all. Tried a syringe ($2), nothing. Tried a fluid transfer pump ($5), nothing. Disconnect the M/C end of the brake hose and see not even a drop has come down from the reservoir. So I sprung for a Mityvac, $50. Connected first at the M/C, hold the lever down, pump up a vacuum and it starts sucking brake fluid.
Then start sucking at the bleeder screw. This literally took hours of difficult work, even with the tool, but eventually got the fluid coming out without bubbles. No resistance on the brake lever even after getting it flowing. Incredibly frustrating, retire for the evening.
Next morning, yay gravity has solved my last issue, pump the lever a few times and feel the first resistance. Go to do normal bleeding procedure (on lever, open screw, close screw, off lever, repeat - it is amazing how many sources on the internet have this simple procedure wrong), fluid squirts out immediately, so I just left it as-is.
Rode around all afternoon, front brake fulling functioning. May actually have fixed this thing! For now anyway...I'll follow up posting if there are further issues...
Hope this is helpful to the next guy with a brake that locks up!
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