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JordansCycles
Front Brakes Question
The front brakes are double disc on my bike. When I go out to ride they lock up.. I let a little fluid out and let it suck in a little air and it was better for about 5 minutes then they locked up again. Not sure what to do, is a new master cylinder in order? If I need to rebuild the master cylinder or replace it I plan on buying a brand new whole master cylinder set up for a honda cbr because they are selling for $50.Last edited by Guest; 07-24-2010, 05:43 PM.Tags: None
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Sounds like the system needs stripping down and cleaning very thorougly ie complete strip and complete clean. Could be crud in your lines blocking the tiny hole in the MC or too much gunge down on the pistons. If you haven't already done so I'd advise replacing the lines with braided.79 GS1000S
79 GS1000S (another one)
80 GSX750
80 GS550
80 CB650 cafe racer
75 PC50 - the one with OHV and pedals...
75 TS100 - being ridden (suicidally) by my father
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It sounds like you only need to clean the master cylinder. There is a very small hole that is a return port that clogs easily if the fluid is not changed regularly. When that port closes, pressure builds up due to the heat generated by the pads dragging on the disk. The fluid is normally allowed to vent back into the reservoir, but the clogged port forces it to squeeze on the pads, applying the brakes.
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mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
#2 son: 1980 GS1000G
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Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
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JordansCycles
If I was to clear that port do you think just flushing all the fluid would suffice? as supposed to a complete tear down
Originally posted by Steve View PostIt sounds like you only need to clean the master cylinder. There is a very small hole that is a return port that clogs easily if the fluid is not changed regularly. When that port closes, pressure builds up due to the heat generated by the pads dragging on the disk. The fluid is normally allowed to vent back into the reservoir, but the clogged port forces it to squeeze on the pads, applying the brakes.
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SqDancerLynn1
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Originally posted by JordansCycles View PostIf I was to clear that port do you think just flushing all the fluid would suffice? as supposed to a complete tear down
In the process, you will end up changing all the fluid, anyway.
Simply changing the fluid will NOT clear the port.
You will need to remove the piston so you can examine the bore and you will need to remove the inlet fitting (the one on the side that receives the fluid from the reservoir) to see the tiny little hole. When you remove that inlet fitting you will see two holes. The smaller one that is closer to the top is the one that is clogged. Use a single strand of copper wire from a 16 buage or 18 gauge wire to poke through the hole, then spray some brake cleaner through there to make sure. When you have the wire strand through the hole, you should be able to see it through the end of the cylinder.
.sigpic
mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
#2 son: 1980 GS1000G
Family Portrait
Siblings and Spouses
Mom's first ride
Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
(Click on my username in the upper-left corner for e-mail info.)
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JordansCycles
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Forum LongTimerGSResource Superstar
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Super Site Supporter- Mar 2006
- 35520
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There was a member here a while back that crashed out because the front brake locked up on his bike. Brakes are nothing to mess around with. I suggest a full system tear down, clean out, and replacing the old sacked out rubber brake line if your bike still has them. Pumping clean fluid though doesn't get all the crud out of the system; it's like rinsing your dirty/oily hands with water but not using any soap.Ed
To measure is to know.
Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182
Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846
Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf
KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection
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TooManyToys
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JordansCycles
i cant seem to find the return port.. I opened the master cylinder and in the bore I just see three holes on the side coming down from the resoviour. am I supposed to take the resoviour off? I blew 90 lbs of compressed air through each hole then cleared the bore with it and I blew the same threw the calipers after opening each end of them...
Update: I reassembled the whole system and tried it out, it bled for 3 pumps then completely stopped bleeding or doing anything. The lever is dead. The master cylinder is leaking from the main seal and the resoviour. The pistons on the calipers were stuck in too far which caused the pads to be shoved against the rotors so I pushed them back.. hopefully that'll be enough. The plan now is to buy a working cheap master cylinder I don't want the new one it's some junk aftermarket brand.Last edited by Guest; 07-26-2010, 05:45 PM.
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