Iv been searching around for an answer to no avail. So Im throwing this one out there.
I have a Ellsworth Joker with what I believe are the early hope minis. Im having problems with the front caliper lockin up. Ive centered the caliper, Clean and collapsed the pistons multiple times. All without success. The brake will begin to lock up as soon as I start to use it so I dont think overfull/overheating is the issue.
The bike is new to me and I noticed the front brake really lacked power. So i cleaned and sanded the front pads. Still seems weak to me. ( Rear seems fine)
My question is sholukd I give up and try something different or should I do a full rebuild on the caliper and replace the pads. If so any sources for rebuild or recommendations for pads?
Dang.... tough one.
Do a search. Somebody did a good write-up on how to do it a few years back. They are pretty easy to rebuild, IIRC. It's probably that the seals are permanently crudded up and sticky. I don't know if you tried cleaning the pistons with DOT brake fluid on a q-tip, but try that. That might lube up the seals well enough to work properly again.
Originally Posted by trodaq
Rebuilding them is pretty cheap. Chain Reaction in the UK has new seals and pistons for a pretty good deal... IIRC like $30 an end for all the seals and new pistons. I had to get the special bore tool as well, but you don't need that for the original Minis. I did one of my Mono Minis myself and it wasn't too tough.... and your older Minis actually come apart.
But yeah, the original minis were pretty finicky. I never had poor power issues with mine, tho. I always used metallic pads for more bite.
Cleaned with a Qtip and CLP. I figured if it worked on machine guns it would be okay on calipers
Well.... I don't know if the chemistry is compatible. Machine guns don't have friction seals surrounded by brake fluid. Using the wrong stuff might cause the seals to swell up.
Originally Posted by trodaq
When I said 'lube the pistons' before, that was a bit misleading. You really don't want the pistons and seals lubed per-se. I meant more like when the seals get old, they dry out and the brakes can get sticky, because it takes too much friction for the pistons to self-adjust....so they SNAP to adjust... usually way too far. When this happend to me, I could feel it in the lever. The brakes would SNAP on. Heh... this happened to me at 2 am during a 24 hour race and I put up with it all night.
The seals and pistons are basically using the friction of the seals to hold the pistons and pads the proper distance from the rotors. If the distance is exceeded, the pistons slips a tiny bit past the seal to self-adjust. If there is too little friction, the pistons don't retract.
Normally, when you apply the brakes, the seal flexes to apply the brakes, then flexes back to retract the pistons. The piston and seal don't move past each other. The piston only moves past the seal to self-adjust the brake pads to compensate for wear.
Also, you can try cleaning the pads with a torch and/or Brake Kleen. Some say use a frying pan and cook them, or a toaster oven. Personally, I would not cook food near anything that had contact with smoking brake fluid.
Do a search on that, too. The procedure has been written up a few times.
<a href="https://picasaweb.google.com/lh/photo/JxGj45LvGjjm91mWZUAxug?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-KfpyQMEZi0s/SXLZg43y8PI/AAAAAAAAFp0/NVZS69wkrTU/s800/2.JPG" height="600" width="800" /></a>
Last edited by pimpbot; 10-06-2011 at 07:27 PM.
You might be on to something. i noticed they freed up for a short while the started to hang again but not nearly as much as before. So I may have gone from piston hanging up to seal sliding over piston.
Ill try to clean out the clp and redo with brake fluid.
So in your opinion these are worth the effort?
Yeah, I really liked mine. They were finicky, but felt great. I gave them up when I switched to a steel hardtail frame, and they howled like crazy. They just resonated badly with that frame.
Originally Posted by trodaq
That said, they are a pretty old product. It might be hard to track down parts for them. There comes a time when chasing after old parts just becomes a drag.
Last edited by pimpbot; 10-06-2011 at 08:14 PM.
I'll give it a go. If it doesn't work I'll look for parts. If I can't find them noone can say I didn't try
Thanks for your help with this . I'll update either way.
Went back last night and cleaned and worked pistons again. I got to the point where I could see the seals doing their thing, retracing the pistons. If pistons wer straight in their bores I could easily collapse them.. Rechaecked caliper alignment and reinstalled. Still hanging up. Took out a little fluid without affect. Going to try to adjust op rod on front lever and see if that works
It's possible that the DOT fluid is in need of replacement, although it also sounds as though it could need new piston seals. Hard to say without having the brake in front of me; but if you remove the MC top cap you'll get an indication of the fluid's condition. They're the same seals as as Mono Minis and easily available. Might as well do the lever seals while you're at it. Service guide is here.
What use is a philosopher who doesn't hurt anybody's feelings? -
I removed some fluid via the bleeder, which came out perfectly clean and clear. Have not removed mc cover as of yet
Upate... Removed the master cylinder cover and noticed some "floaters" in the resevoir. Whitish substance . Looks like if you had taken teflon tape and shredded it into tiny pieces. Cleared that with a syringe. Opened the caliper cleaned out the caliper body and worked the pistons in and out a few times.
Lost the oring between the 2 hallves. Luckily I have several o-ring kits at the shop. New oring and a sysstem leed . Work like a champ. Well except for the fact the pads are junk. Rotor seems glazed and it doesnt stop with the front brake ;-). Atleast it spins free.
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