85 250R caliper seals

[jeffs250Russell]

ok..as I was trying to replace my rear pads fluid came out the back side,just bought a e-brake block-off got some pressure now ,but it bleeds off.I got the new seals and just tryin to make sure I don't run into any issues I don't know about. I'm gonna start with taking off the pads a c-clamping the e-brake piston then the other piston should push out by bleeding then the other one I can push out with the e-brake shaft..is that right so far?

[atv innovations]

First off the block off plate dose nothing but make the caliper look pretty. It is not a seal your oring in the back of the caliper is shot and bleeding off and chances are the ebrake shaft on the caliper is pitted also. To remove to pistons take the caliper and put it upside down on the floor take the pads out and lay a rag between the pistons and the caliper lip. Now put your foot on top off the caliper covering the opening were you put the pads in and use a blow gun with a rubber tip and blow '100PSI' into the the brake banjo bolt hole and the piston will come out. DO NOT PUT YOUR FINGERS ANY WHERE NEAR THE PISTONS WHILE DOING THIS IF YOU WANT TO KEEP THEM! Now you can inspect the pistons and bores for wear. If you have a problem with it I can plug off the ebrake hole and I make S/S pistons for it.

[Dirtcrasher]

I find it safer to put a grease gun on the bleeder loosened up and plug the bango bolt hole with a 10mmx1.0 pitch bolt.

Sometimes your thumb can block the hole enough to hydraulicly remove them. Sometimes air is not enough to remove 25 y.o. dirty pistons.

But yes, you do need a new o-ring and may have a pitted shaft that contacted the o-ring when you pushed it way in.

The o-ring is easily squished in from the rear, for some reason many people cannot get it in but don't use any tools to do so. And make sure the inner surfaces for the dust and fluid seal are spotless. I use a dremel wire wheel and a dentist pick to get the grooves clean.

It's also important to free up and grease both slide pins with silicone based grease......

Have fun :beer

[jeffs250Russell]

so far so good,I couldn't get the air to work so I came up using a small dowl pin slightly smaller the the e-brake used some washered out longer bolts and push it through using the block-off plate,and sure enough the outer seal and O-ring are broke,and ideas on how to seat the O-ring if I need too?

[jeffs250Russell]

138411138411after I read dirtcrashers post again I now know how to get the o-ring in and now just waiting to get grease tommorow for the install,no pits think I'm good to go,one more question,does the rubber gromets do anything on the caliper bolt just under the bleeder?

[Dirtcrasher]

If your referring to the slide pin with the ripped seal? Yes, it should seal well and the bolt should slide freely. Otherwise your caliper does not "float" and hangs up.

Many of them are seized and not fun to get out unless you know how ;)

The other slide pin and grommet are all the way in the front in that view.

I'd be smoothing up that piston with 1500 grit in my lathe but it can be done by hand also........

Next week will be your "brake bleeding" question :lol:

[pantera1975]

What is the trick to getting the master cylinders blead? I'v had some that did right away and others that have took hours!

[Dirtcrasher]

^ The easiest way is to crack all the bolts and get them leaking to remove most of the air.

Then we can have 15 different opinions; But I have had fantastic luck with a large syringe filled with fluid and a well fitting hose. I can force it through the bleeder or pump it up, crack it and pull it out. Has worked for me forever.......

I do not own a mity vac but they do the same thing, you just have to know when to lock the bleeder down and always keep the resi full.

[Mosh]

That rubber under the bleeder bolt is there to stop dirt from going down into the threads of the bleeder and corroding. It does not seal any fluid or anything.

Just a few tips for you. When you put your brake block off plate on, seal it with some good RTV Silicone. Most guys dont, and water and dirt gets in there and chews up that little oring seal again.

Also don't overtighten the bleeder screw. Too many of them get over tightened, and that is what causes problems with them getting stuck, and breaking a few years later.
You would be surprised at how easy that bleeder screw seals, and does not need more torque that what a hand screwdriver torque range can apply.

[pantera1975]

^ The easiest way is to crack all the bolts and get them leaking to remove most of the air.

Then we can have 15 different opinions; But I have had fantastic luck with a large syringe filled with fluid and a well fitting hose. I can force it through the bleeder or pump it up, crack it and pull it out. Has worked for me forever.......

I do not own a mity vac but they do the same thing, you just have to know when to lock the bleeder down and always keep the resi full.


So to get this strait, you force fluid thru the bleeder up into the fluid reservoir? I have a vacuum bleeder and that dont even seem to help bleedin the master cylinder.

[atv innovations]

I see you said grease to put it back together. DO NOT use grease on the pistons to reinstall them use brake fluid or brake assembly fluid. Also never use DOT 3 fluid on any motorcycle type brake systems it will blow past the seal. As Dirtcrasher said I also drive the fluid up from the caliper .

[pantera1975]

1 of you 2 must be that guy on tv with the question mark suit trying to give away the free book! Ill have to try that idea. What brake fluid should a guy use???

[atv innovations]

Dot 4 is good all around If you go silicone you must start with a clean system its not good to mix it with regular fluid.

[Dirtcrasher]

^ Your a smart dude, whom I know little about; I may be a future customer for some porting depending on what you do :beer

However, I must say, I have run DOT3 in all my trikes for over a decade and once properly rebuilt, I never lost a caliper or had leakage.

Again, you may know more than I but I do ride my stuff (hard) and it's all held up :D

[pantera1975]

I guess I've never looked that close I thought #4 was all silicone

[jeffs250Russell]

138878update on putting it back together...that little freaking o-ring can be a pain in the ass..It doesn't look like it's gonna fit the whole time your seating it,the boom your done,I'm going tommorow to get a wire brush for my dremal to do the outer one, got stuff off e-bay too. wondering if thats factory stickers on my new shrouds

[jeffs250Russell]

I just wanna say thanks to everyone who helped, it all worked out just perfect. dirtcrasher, everything you said came true. and the install went good.

[Dirtcrasher]

Glad to hear bud :beer

At least you WANT brakes! :lol:

[midsouthtrikes]

Dot 3 and Dot 4 fluid are both poly glycol fluids that are hygroscopic. The only difference is Dot 4 has a boiling point about 40-50 degrees higher than Dot 3 fluid. Dot 4 is slightly thicker due to the added chemicals to raise the boiling point, I can't tell the difference by touch. Dot 5 is the only silicone based brake fluid, not very popular today due to ABS systems. Dot 5 will foam up when used in an ABS system, foam = air. Sorry to chime in on this but I couldn't help it, I just lectured on brake fluid at the college I teach at and one of my students informed me on this post. Don't want to come off like a know it all, just love to pass on knowledge.