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Discussion Starter · #1 ·
About me huh? This is my 1st venture into a forum. l came here hoping someone here might save my life. I quit riding in 82 when I became a dad. Fast forward to 2018 when i bought the 2017 Kawasaki x 300 versus intending to stay off the roads of texting drivers. A month later after a safety course I am back to my old vintage 1982 self, riding aggressively enough to stay ahead of traffic putting myself in the sweet spot. I now have 3 additional bikes. A 98 Honda Valkyrie Tourer, which led to 99 Honda Valkyrie Interstate (wanted the CB/FM radio full dresser look) and an 03 Honda VTX 1300 I got really great deal on. The Interstate is my baby and has taken me to Tennessee and back twice. I am having issues with the rear brakes on the Interstate just disappearing from time to time. Pedal goes down and bam, no rear brakes. Topped off fluid, tried putting weight on it overnight and thought it was fixed. Coming home today, lost rear brakes again. Got home, shut off bike. Went back in 10 minutes and had brake pedal pressure. Any one with ideas of what could cause this. I'm here to learn more about how motorcycles work and to become a better rider.
 

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There is a purge hole in the master cylinder. They get plugged. Take it apart and clean all the bits. The caliper may be sticking. Propper brake grease works. And the purge hole has a different name that I forgot. The brake grease on the seal, makes bleeding easier. If you are removing the piston, pump it out. Do not disconnect the hose first.

UK
 

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Discussion Starter · #4 ·
Sounds like perfect timing.
Some pretty exciting stuff going on here now.

Sounds like an odd brake problem. Have you tried bleeding them?
There is a purge hole in the master cylinder. They get plugged. Take it apart and clean all the bits. The caliper may be sticking. Propper brake grease works. And the purge hole has a different name that I forgot. The brake grease on the seal, makes bleeding easier. If you are removing the piston, pump it out. Do not disconnect the hose first.

UK
Thank you Sir! What is Propper brake grease? Available in the U.S.?
 

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The auto store will know what it is. Comes in a very small package, usually green. It helps the piston slide in the caliper. After cleaning the caliper, the O ring goes in place, then some grease on the O ring and the caliper. It should slide nicely in to place. Anti seize ( grey stuff ) is used on the metal to metal parts that more a small amount. Some bolts or pins, or rubber bushings may also need a little grease. the calipers can be similar, but all have a slight difference. Also check the brake pedal. They get stuck from all the road ****.

UK
 

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The only thing I would put on the piston seals would be brake fluid. Then I would use caliper grease on the guide pins.
 

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Using brake fluid is a common practice with many folks. I have tried both. The grease slides better IMO. Brake fluid is designed to be brake fluid. The grease is designed for the pistons. I may have some here to read what it says.

UK
 

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You are not supposed to contaminate the brake fluid with anything. Greasing pistons and piston seals would do just that.
 

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SIL-GLYDE brake lubricant. They have a site. Greasing the O ring should not contaminate the brake fluid. I am aware that many folks use only brake fluid. I have used the brake lubricant and found that it works better than just brake fluid. In particular it made bleeding the brakes easier. I have also used brakes in a most extreme manner, and not have problems. Save for one instance. The new O rings I fitted to twin floating discs from Paul Dunstall, using only brake fluid, failed as we removed the bike from the back of the truck. I can only assume the O rings and the brake fluid did not like each other. I turfed the twin discs and installed a single 12 inch Lougheed unit. The OP can do his own research, and possibly talk to someone who has worked in a brake shop. I have talked with many folks about this, including the fluid only folks.

UK
 

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If you get grease or any thing else in the hydraulic area of the brake system, then the brake fluid has been contaminated. I don't even see how this is up for debate. You can't even mix 2 types of brake fluid together.


I do agree the OP should do his own research. The best source being the service manual specific to the bike. Something everyone should have doing any type of work on their bike.
 

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If you get grease or any thing else in the hydraulic area of the brake system, then the brake fluid has been contaminated. I don't even see how this is up for debate. You can't even mix 2 types of brake fluid together.


I do agree the OP should do his own research. The best source being the service manual specific to the bike. Something everyone should have doing any type of work on their bike.
In this case it sure looks like they suggest brake fluid. I'm with the brake fluid folks though. I see anything else being used as a possible contaminate. UK must be using as little as possible and not slathering the stuff on like I do on some items when I use that stuff. Mine came with a big brush so I use it that way. UK must be almost removing it all. He'll have to confirm that it he wants though.
 

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Discussion Starter · #12 ·
Thank you, I'ved anti sieze lubricate before and can see it being a contaminent in a closed systeM. The pin hole getting clogged is valuable information to me.
 

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Discussion Starter · #13 ·
If you get grease or any thing else in the hydraulic area of the brake system, then the brake fluid has been contaminated. I don't even see how this is up for debate. You can't even mix 2 types of brake fluid together.


I do agree the OP should do his own research. The best source being the service manual specific to the bike. Something everyone should have doing any type of work on their bike.
Makes sense. My Valkyrie calls for dot 4 only. Thanks for pointing this out.
 

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Discussion Starter · #14 ·
Sounds like perfect timing.
Some pretty exciting stuff going on here now.

Sounds like an odd brake problem. Have you tried bleeding them?
My neighbor suggested that I should crack the bleed valve just a hair and allow it to slowly drip over night while adding fluid to get any air out of the system.
 

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When you push the piston in, the correct grease stays on the O ring seal. If the O ring did not retain the grease, then the brake fluid could escape for the other side, as in leak.
There is much debate about this on the interweb. Most say use brake fluid. These folks have not done any different. Those that have used grease, stay with the grease. I am quoting here from someone in the know. " Use the grease. it will be outside of the seal, so will not contaminate anything " You fluid folks please continue to do what you are familiar with. Every so often tho, someone has a better plan.
BTW, some O rings roll a little in their groove when pressure is applied. No pressure and the rolling motion moves the piston back. The principle of most calipers is the same, but the design varies.

Back to Fryde #14. I often do that, let it drain. Did that with all four calipers on my Dodge van. The new calipers come assembled so no playing with them. After a few years they do not release properly. I did say above, a bit of grease on the O ring helps with bleeding. But to help the skeptics, check with the brake shops for another opinion.

There are quite a few things I have done over the years, that many have not, can not, or will not do.

UK
 

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From the Triumph manual. On the type C caliper there are two seals. The inner pressure seal must be soaked in brake fluid for 10 minutes, or be smeared with grease. The outer seal must be smeared with grease. The Clymer book for Yamaha says take the caliper to the Yamaha dealer. The Yamaha manual just says put it back together. No info on fluid or grease. The most common of course, is to use brake fluid. The purge hole is a common problem on the XS1100 Yamaha. So is the pedal binding on the shaft. My Suzuki did that too.

UK
 
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