RS Warrior Forum banner

1 - 20 of 24 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter #1
My bikes been sitting for a couple of weeks, I jump on it and take it out for a spin and I have no rear brake. I check my lines they look good no leaks and then I check my brake fluid reservoir and it is bone dry. There's also some dried up white residue on the bottom of the reservoir, I'm assuming its brake fluid. Had no noticeable problems with the brakes the last time I rode it. Is there anything I can check, again, I couldn't find any visible evidence of leaks except on the hose where it runs under the gas overflow hose, at least I think that's the gas overflow hose/ and it's not a lot, just a collection of residue but it is black and oily. any advice would be appreciated. Thanks

AD
 

·
Premium Member
Joined
·
3,359 Posts
Start by cleaning the entire area up as that will be the only way to track something down. The fill up with new fluid and see what happens as the rear system is pretty simple.
 

·
Registered
Joined
·
4,955 Posts
Check your pads. If the brakes stuck on for some reason it can heat up and boil/evaporate the fluid. With the torque we have, this can happen without you noticing. In this case your pads may show extra wear and possibly scorching color or warping.
 

·
Registered
Joined
·
1,323 Posts
This must have been coming for a long time for the reservoir to be bone dry, as the Warriors rear reservoir and line to the master cylinder hold way more fluid than needed for the rear caliper. (I'm not running a rear reservoir at all, just the capped off line. A trick I learned from others on this site.)

My guess is that the small bit of oil you see is a small leak that has been there for a very long time. Check the things mentioned so far.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #6
Here are the pictures. When I first saw the residue I removed a chuck of it with my hand. There is a small amount left in the reservoir and it's on my finger for closer inspection. Brought some Yamalube brake fluid Dot 3 and 4. Will check the brake pads later today and see what they look like. Thanks for all the comments
 

Attachments

·
Administrator
Joined
·
28,369 Posts
Okay so the stock rear reservoir has been nicely relocated under the seat. The other hose is probably a vent line as you suspected. I only say that because I am certain you have already visually verified the brake line hose from the caliper up to the reservoir is in good condition.

That chunk of white material being inside the reservoir is odd even for boiling-away the brake fluid. I have seen dark bits but not white. Maybe a synthetic brake fluid boils to white, dunno.

If it were me I would inspect the entire relocated line between caliper and reservoir including the pedal's cylinder and line. I would remove and clean the reservoir, looking for broken or cooked plastic. I would replace the reservoir if indicated then rebuild the rear caliper (Yamaha kit is affordable) and replace rear friction material and the pins and clips plus the keeper springs.

Along the way you are likely to find a bunch of chunks in the caliper pistons etc.

Have you added fluid before, in the past. and if yes which DOT number? Have you reviewed the owner manual or the free e-copy of the service manual yet?
 

·
Administrator
Joined
·
28,369 Posts
Keeping this separate. You might need to clean both sides of the rear rotor. Looks like if you raise the rear wheel off the ground and put in neutral so the rear tire can be spun by hand, the deed can be done both sides easily. One rotor face at a time. You could use a good quality 400-grit wet-dry sandpaper. Quarter a sheet. Use a thin wood block as paper support to keep the hand-pressure equal across the rotor. Apply light pressure and smoothly rotate the rear wheel. It could take a few sheets. When clean enough, wipe with a water-damp paper towel to remove debris then dry with a clean paper towel.

I am very interested in what you find and what you learn as you go through this inspection and repair. Something seems very odd. I even wonder if the heat source for cooking off the brake fluid is under the rear seat adjacent to its modified home. And I wonder about reservoir integrity.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #9
I switched to Amsoil brake fluid about a year and a half ago. I purchased the current Dot 3 and 4 brake fluid today from the Yahama dealer here in Dubai. They said it was the only brake fluid they had and they used it on all their systems. I can go out and find a singular brake fluid, but assumed since it was a yahama lube product it would be fine to use. When I looked online they only had Dot 4 online and there was no yahama dot 3 or dot 3 & 4 brake fluid. Not sure what’s up with that.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #10
Yes I’m also using the service manual. Are you referring to the 5PX-2580W-00-00 CALIPER ASSY, REAR 2 from the parts list.
 

·
Administrator
Joined
·
28,369 Posts
The Yamaha DOT3 and DOT4 product works great. The Amsoil might have been the trouble, I will need to do some reading. I am not aware Amsoil brake fluid can mix with DOT3/4. Added: the Amsoil website SDS for DOT3/4 does not indicate silicone based, but being marketed as a synthetic that does not attract moisture and does protect metal lines from corrosion. Must be a hybrid product. I see many brands doing the same thing. Need to study more to figure out wassup.

For now I believe the following remain accurate: (you can convert F to C)(brands can vary somewhat)

If you run straight DOT3 you should know it boils at 400F brand new and after awhile that drops to about 280F boiling point. DOT4 starts at 450F new and drops I think to 350F. DOT3/4 is this.

UAE ambient temperatures eat a big chunk of that, and the brake pad selection could make heat issues worse.

You might consider rebuilding the entire rear brake system for silicone-based fluid DOT5.0 to get the highest heat protection.

I should get this said just in case. It seems obvious that all brake fluids are technically synthetic but the word synthetic was saved for silicone based fluid. That seems to have changed so things will be more tricky for us consumers.

For the above, sorry I do not recall the exact numbers. You will find the most accurate numbers by searching differences between DOT3 DOT4 DOT5.1.

Hope this helps. I remain very interested in your solution.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #13
So I've taken the brake pads off and they look decent, but I was missing one of the Caliper Shims, not sure if that would have caused the overheating, doesn't seem like it, but it's suppose to be there for a reason. I've ordered new brake pads for the front and the back once I get them I'll also bleed both lines and add new brake fluid. Once they arrive, I'll follow up with the results. Heres some pictures of the caliper and rear brake pads.
 

Attachments

·
Administrator
Joined
·
28,369 Posts
Have you cleaned and inspected the rear brake reservoir? Also what conditions exist in the rear caliper's piston/valve/bore and the rear hydraulic pressure system and hoses?

Any white chunks anywhere from the rear pedal to the reservoir to the caliper piston can unexpectedly disable the rear brake even if it works awhile first. Just worried about you bro.

BTW this is a great time to do the simple but elegant Jarv/Yamaweezle rear brake tidy (or a subsequent variant).
 

·
Registered
Joined
·
57 Posts
Discussion Starter #17
Finally got my brake pads in, I changed them and then bleed the lines and there were plenty of bubbles, once I got rid of the bubbles test drove the bike no brakes still. there doesn't seem to be a problem with the lines or leakage. When I was putting on the brake I had to use a pair of pliers to push the calipers bake to get them over the brake pads, the manual said I should be able to push it just using my hand. Still not riding now...

Likes like the calipers are not moving at all.

Also is this statement correct:

Brake fluid is clear, moisture causes it to turn amber.

My Yamaha brake fluid came out of the bottle amber, the brake fluid in the bike was also amber.
 

·
Registered
Joined
·
1,323 Posts
All the brake fluids I've ever used have been clear or purple tinted clear. I've also never worried about getting "motorcycle" brake fuid. Any DOT 4 fluid works fine.

Even brown old fluid should give you working brakes, so something is wrong. (even water will work in an emergency) I've had to use a c clamp to push calipers back in on lots of different vehicles, so not being able to push it in by hand wouldn't worry me. It does have to go back in straight though. Hopefully you were able to push it in straight with the pliers.
I would double and triple check bleeding the master cylinder. Master cylinders that are completely dry often need to be bench bled to get all the air out.
If you are sure all the air is out, I would detatch the caliper and watch the pads while operating the brake pedal. The pads should move toward each other smoothly.
 

·
Registered
Joined
·
324 Posts
+1 What Brizzman said. When you squeeze the front brake lever, does the lever stop at some point and have pressure?
 
1 - 20 of 24 Posts
Top