had the day off due to the Boston marathon and decided to work on the GT500's front brake for the first time. the drained fluid was a disgusting brown so I decided to pull the caliper and master cylinder to look for buildup as when I bought the bike last year it had been sitting for a while. there was quite a layer of gunk in the reservoir so I disassembled the whole thing and found a lot of buildup.
more interesting, the assembly doesn't match that on the GT500 parts list - started to look at my computer and realized the assemblies were different (no large circular piece held down by the assembly screws) and that the image of the castings didn't match up. I was going to replace the o-ring but need to figure out what the part number would be. any ideas on this?
also thought about pulling apart the piston assembly to see what was in there but could get the rubber boot on the lever side off. I was being careful as I didn't want to tear anything. any tips?
Most of the boots are held in place by a lip on the cylinder shaft and a built-in ring on its lower end thats pressed down into the body.
Use some WD40 to lube it up and first place a tooth pick under the cylinder shaft end of the boot to guide it up and out its groove. Then you can hold it carefully and spray more into the lower part pulling on it slightly to help ease it out of the lower body.
By the looks of things, you need to dismantle the entire thing and get rid of the contaminants everywhere. A dull pick, or some such thing, should get the spring clip and plastic washer out of there, and then the rubber boot should come out OK. The C clip under there is a bit more difficult, but do-able. Clean everything scrupulously with solvent or whatever, and finish with hot soapy water, and let dry completely before assembly. The bore of the master cylinder I have had great success cleaning with a 45 caliber bore brush wrapped with scotch brite. does a grand job without removing metal.You have to remove the piston and seal ring of the caliper as well and clean the grove the seal fits in, because I guarantee there is corroded crud in there that pushes on the seal, and impedes the free movement of the piston. As far as the seals and O rings are concerned, I have found that most survive quite well and can be reused to great effect, if you have trouble finding replacements. They also, of course, need to be clean,clean.
I have gotten into the habit of bleeding my systems every two to three years to avoid having to do any of this again. I'm sure you will get other points of view, but this procedure has served me well over the years, when dealing with my old girls. Even my newer girls get regular fluid changes. That brown crud does that to guy. Good luck with it. The efforts are well worth it in the long run, and the short run too. Cheers.
Fred
You have to remove the piston and seal ring of the caliper as well and clean the grove the seal fits in, because I guarantee there is corroded crud in there that pushes on the seal, and impedes the free movement of the piston.
Thanks Fred,
I think you have just diagnosed an intermitent problem I have had with my 550 ever since I put it back on the road a couple years ago.
Kevin
Everything Commeth
To He Who Waiteth
So Long As He Who Waiteth
Worketh Like Hell While He Waiteth
At least you have something to work with. Here's a pic of the one on my buffalo. The bike had sat in a barn for 25 years. The reservoir was stone white chalk. As you can see, the screws that retain the reservoir are all but gone. This unit went in the trash.
I was born with nothing and still have most of it left.
so cleaning things up in the caliper and my solvent is leaving a black residue behind that I can't eliminate - most of it wipes/scrubs off but there is some that doesn't seem to want to budge. should I try burning it off with a propane torch or cleaning up with a fine grit paper?
sorry if I'm making rookie mistakes or asking dumb questions - its all new to me.
A-Dubs wrote:should I try burning it off with a propane torch or cleaning up with a fine grit paper?
I would not suggest trying to burn it off, and definitely would not suggest using any sort of grit based paper in there. I think Fred suggested using a scotch pad. I've done this also, and it worked for me. Try using a bit of Simple Green and after a good rinse, and blow dry, see how that looks.
Ian
If at first you don't succeed, just get a bigger hammer !
I dont know what is in it but I found a product called "Purple Power" that works better than the simple green stuff. The purple power seems to be a bit more caustic and ate the paint off of my front rotors thus a new coat of paint was done. I dont know if the paint would have also come off with simple green but I really like the purple stuff.
maybe someone else can chime in on these products.
Dont believe in God ? Eternity is a long time to be wrong !!!!
Thanks for the tips, got most of the residue with some serious scotch pad time this morning. Here's the cleaned out caliper - as you can see in the 2nd photo there's some black 'stuff' along the groove for the o-ring which doesn't want to go anywhere and what seems to be some pitting. Nice seeing everything without the gunk buildup, but should that pitting in the groove be a concern?
And again, thanks so much for the help on everything, its very much appreciated.
