Sticking brake

[Underdog]

I know this subject has been beat to death but I thought I had this fixed. The brakes were all stuck when I got this bike so I rebuilt everything. Meticulously cleaned all the calipers and cyls and rebuilt with genuine Yamaha kits. Repaced all the lines with braided stainless. The paint was burnt on the rear rotor so I redid it with matching gold. I'm useing Dot 5 fluid like comes in the Harley from the factory. Sorry but I can't deal with putting paint remover in the system. Anyway, I have about 500mi on it since and all seemed OK. Today I'm out and the rear hangs up again, once again burning the new paint! I stop, put it on the center stand and the brake pedal is locked up solid. I get the tool kit out & crack the bleeder and then it's working normal. By the time I get home there is no rear brake at all. I've also noticed that altough I've bled them repeatedly. the front ones seem to still pump up. That is, the lever has more free travel on the first hit and they seem to grab harder on the second application. Any ideas?? I'm the type that believes in doing a thorough job the first time cause I HATE comebacks. This is starting to remind me of my MGB. I had to do most everything on it twice too.

[chevy45412001]

ouch

AAAhhh the tripple m/c reclean.pull em apart and clean again,then pull'm apart one more time ,clean them throughly don't forget the spooge hole both front and back. It seems that the carbs were built at the same place as the brake system...lol

[Underdog]

Well I guess it's possible but I really cleaned this stuff. Parts cleaner wash several times, ran a cleaning brush through, blow out with gum cutter, compressed air...I dunno. So I either have a foriegn object in my bike or a foriegn bike with an object in it??

[ratbyk]

Brake Bleeding/Lockup

Underdog, on the rear, it is possible that you have the push rod for the rear master adjusted in too far. It is not allowing the master cylinder piston/cups to return far enough to uncover the compensating port (spooge hole) to allow the excess pressure and heat expansion to escape back into the reservoir.
Back off the push rod a couple of turns and re-bleed.
On the front, unbolt the master from the handle bars. Leave everything else hooked up. Tilt the master to a more vertical position and re-bleed. Have found that air can be trapped inside the master cylinder bore in a position that won't allow it to bleed out. By repositioning you will be able to purge all the air out and firm up the lever,
I have also had to use this trick on the rear master to purge all the air out and get a hard firm pedal. Remove from frame leaving line etc. hooked up. turn to a more horizontal position and re-bleed by hand.
Ken/Sooke

[ratbyk]

Brake Bleeding

Oops! Correction. On the rear master cylinder push rod. Turn it "IN" a couple of turns. It is too long and must be shortened. You likely adjusted it "OUT" to try and shorten the distance pedal must travel to apply brakes.
Sorry.
Ken/Sooke

[skids]

Re: Sticking brake

DOT 5? I heard that it curdles with DOT 3, so I hope you had no traces of DOT 3 in there, or it could be "spooge hole hell."

Originally posted by Underdog
I'm useing Dot 5 fluid like comes in the Harley from the factory. Sorry but I can't deal with putting paint remover in the system.

[pathfinder]

Underdog, hopefully you did not use any teflon tape on the bleeder screws, it turns to mush in about 2 seconds in dot 5 same thing on dot 3. It will then migrate thruout the whole system and clog it up. You will love dot 5 in the system when you get it right. I've had in my 78E for years and love it. I used to rebuild MG's to and know just what you mean. "Lucas" Master of Darkness. You know why the MG car Co. went out of business? They couldn't figure out how to make a computer leak oil. MG folks will know what I mean.

[ratbyk]

MG

Pathfinder, it was the greed of the unions that put BMC/MG down.
They swolled up so much money that there was nothing left for development and new product.
Sure Lucas etc. had short comings but with every penny going for labor there just was not anything available to up grade and to compete with the rising sun. It almost happened in North America. Might still.
Ken/Sooke

[Shadow]

Sorry for intruding on your thread underdog, but I'm curious on something. My rear brakes have started to drag & I just want to make sure I understand one of the suggestions.

Ratbyk If the pedal is adjusted wrong it can cause the rear brake to drag when warm? So it maybe something as simple as adjusting the pedal?

BTW this forum has been a great help so far.

[John]

If the pushrod that activates the rear m/c is too long it will not allow the fluid pressure to completely bleed off, and therefor hold some pressure on the rotor. This happens more when the fluid heats up and expands. Try shortening the rod 1-2 turns at a time.

[ratbyk]

Rear Brake Drag

Shadow, next time you encounter rear brake drag/overheating open the bleeder screw. If brake fluid comes out with some pressure behind it then you are building pressure between the master and the caliper.
Several possible causes. Push rod adjusted in to far as suggested. Also, if any oil inadvertently got put in the reservoir it will make the natural rubber cups in the system to swell up. This will in turn block off the compensating port.(spooge hole) Plus this port can be blocked off by containments in the system. (rust, grunge, jelly like brake fluid)
If you do not have a pressure build up in the system but still have dragging/overheating brakes it is time to do a caliper rebuild.
Ken/Sooke

[Jerry]

Couple of us have had to remove the brake lever asembly, clean and relube the shaft, and put it back together. Crud on the pedal shaft will prevent the brake lever from returning to the full up position, introducing drag on the rear brake.

[randy]

One more thing to check. If you have removed the brake lever, pay attention to the locating marks when you re-install it. It can be tricky to get them lined up right AND get the spring to sit properly. If the marks are off, your actuating rod may be too high in the air, applying pressure to the M/C even when at rest.

HTH

Randy

[Underdog]

I have no reason to think the pedal has ever been off. I will check the pushrod and stop adjustment per the Clymer manual. Like I said, everything was meticulously cleaned and rebuilt so no traces of DOT 3. Since it cooled down, it's seems to function fine. I'm sort of confused by the fact that it worked OK for 500mi. It was a rather hot day and I was in some traffic (sitting at a couple of lights) when it happened. So heat could account for the pressure buildup. I'll check that adjustment and try to get it under similar conditions. I'd like to be sure I have it this time before I go to the trouble of repainting the rotor again. Thanks for the suggestions.

BTW, an interesting bit of info from the HD world. As I've mentioned before, HD uses DOT 5 also. I was looking through the service manual for my Softail and came across the procedure for rebuilding the calipers. In bold print it says " Use the special GE silicone grease provided in the kits to lubricate the pistons, caliper bores and square ring seals. Use of DOT 5 fluid to lubricate these parts will case exessive lever travel." Perhaps this would account for my frt brakes haveing that pump up feel??

[scalded dog]

I have the same trouble, I released the pressure on my bike one day when it started dragging, the brakes worked fine for awhile without adding fluid back after I released the pressure, also when my wife is riding with me it will start to drag a lot quicker, does anybody have any suggestions as to why it will do it quiker with two up? Thanks 'Dog