Servicing brakes - solve sticky issues, prevent corrosion, general and Juicy
Permatex makes a product called Ultra Slick Synthetic Brake Lubricant. Not to be confused with typical automotive type slide pin lube although this new lube can be used there. This lube is intended to get mixed and exposed to brake fluid internally. Coating the caliper piston internal portion and its seals plus the master cylinder piston and its seals.
I have found that Avids Juicy type without a doubt get buggered after 1.5 years of typical one day a week 4 hour use. Usually the caliper seal will need attention much sooner and usually the "solution" is some combination of open it up, replace the fluid and bleed it well.
I seriously doubt new fluid is solving anything directly although if free air is in there a bleed is necessary but simply freeing things up and effectively re-lubricating the 2 piston workings and seals with brake fluid is what is "fixing" things albeit temporarily.
To this end using the Permatex product UPC 22063 Ultra Slick Synthetic Brake Lubrication, a super sticky green lube in a sufficient but not crazy amount in appropriate places will extend the "happy" functioning of the brakes.
With respect to Avid's Juicy system I have found that after 4 years the lever or master cylinder piston itself does swell and doesn't move freely as well in the bore and leads to slow or no snappy lever return.
The seal may get buggered as well but the piston I can measure and it does get larger. I haven't got good numbers for the caliper piston but I do know new seals fix things up for a year although I do clean up this piston and lightly sand it if rough as well as lightly sand the bore. Usually after 2 years the caliper piston has enough nicks on the brake pad side to trap dirt that replacement should be considered.
Avid Juicy Parts sourced from Cambria Bikes and ChainReactionUK
(do check your year as there are changes but high level of part reuse)
Lever Master cylinder complete kit 11.5311.567.000
Caliper piston/seal pressurefoot kit 11.5311.551.000
each kit does one end, about $10-15 each, you generally do not need the $40 odd kit.
Work/service with these parts has restored the brakes to perfect working condition every time as long as I have done a sufficiently good bleed.
Also the split clamp can be replaced with the Elixir split one
11.5015.029.010 which is black
I have been using the proper bleed kit but end up having to replace the syringes every few years. Best source aside from drug store is a kitchen supply stores "food injector" .
SS or braided cables do not meaningfully improve the brakes even on 5 year old hydro cables.
Don't leave the Juicy design in a hot car for too long as the MC will puke out the vent hole when hot and suck in air when cool which likely will necessitate a bleed.
Resist the urge to over tighten bolts.
I have also found that with the Juicy and Elixer brakes the Ashima AI rotors, the ones with the very large braking surface cutouts don't work that well although are sufficient for XC largely flat courses with cheater type racing tires but insufficient for much more regardless of pad material choice, most likely a comment directed to the rotors not the brakes as too little is just too far.
This is good information. Can you explain how you use the brake lubricant. Do you take the brake apart and apply the lubricant when you put it back together? Or do you actually put it in the fluid when you bleed it.
What is your procedure for bleeding. Do you follow the Avid procedure (line, caliper, lever) or other approach?
In dry, dusty SoCal, I have found that the piston's in my Hope's definitely do need regular cleaning. I extend the pistons, wipe them down with a dry Q-tip, then wipe again with a Q=tip soaked in brake fluid. Cycle the pistons a bit and things are good again . . . for a bit. Given your description, it sounds like this might be pretty thick stuff . . . I wonder if it would make things better, or worse, here in our dust bowl?
Alcohol may lead nowhere, but it sure is the scenic route!
I was unaware that the pistons on hydro calipers needed cleaning and I think dry Texas did the same to me. Especially after the past year where better than 90% of my miles were on my commuter and very little on the mtb, thereby drying out the seals and giving me some terrible sticky piston issues. I worked the pistons the other day and it helped, but it looks like I am going to have to physically go in and lubricate the pistons as you did. These are Magura brakes, too...but these are 11yr old brakes. They've lasted much longer than the aforementioned Julies without needing this kind of work.
Originally Posted by 007
Once in a while I take out my pads and pump the lever a few times. I dump Shimano oil on the exposed piston surface and push the pistons back in. I'll cycle them back and forth as much as needed if one is acting sticky. My 555s are 12 years old now; still work perfectly. Same technique for my xtr 975s.
The brake lubricant again this is not slide pin stuff but something that is happy with the insides of the system, fluid, rubber seals and the various metals involved.
While a common automotive hail mary don't mix anything with the brake fluid. Just use fresh Dot4 or whatever your system calls for. Personally Dot 5.1 is too expensive and hard to find. Generally changing out an average fluid frequently performs better than a less frequent expensive fluid. Again I would bet our problems are due to lack of lubrication and things getting sticky. So more frequent maintenance with average fluid is a good thing.
After taking the caliper and master cylinder apart I put a thin film of the brake lube on areas attached by corrosion and importantly on the caliper piston where it is inside the system ( I don't do the last 3 mm of the outside of the piston where it meets up with the back of the brake pad as that will only help get crap inside the system and mess with the sliding of the piston) inside the piston seal's recess in the caliper and all over this seal including where it meets with the piston. I also put a little where the fluid travels throughout the caliper and on the rubber oring seals inside the caliper.
For the master cylinder and lever. Take it all apart. You will need a set of snap ring pliers for some Juicys and a small pair of needle nose pliers for others to yank out and reinset a 3/4 metal ring that does the same job as the snap ring. Those with the pad adjuster star wheel will need to pick out a "snap on washer". I have found that a good set of manicure scissors are handy for picking and as a snap ring tool. (You'd steal the turkey baster if you needed it and would try to put it back.!)
I've often found after a few years the master cylinders piston swells and is the cause of the wimpy lever return. I replace this piston and its two rubber seals and put a thin coat on these parts as well as ensure nothing is stuck to the cylinder bore in the lever. You should only see the few holes that brake fluid goes through. Often a bit for the seals will stick to the bore and ruin things. Get it clean and smooth. Now from the various Juicy's I have worked on they share a similar next piece which holds the lever rod into a part which actually pushes on the piston. I don't see any use lubricating this part with anything and could see how lube here could do bad things for free movement. Of course you cleaned out the remainder of the lever, bushings and parts.
Bleed procedure for Juicy brakes I would on.
Lay down a drip mat or something as you will spill and brake fluid can do bad things.
Have brake cleaner or even better low water content rubbing alcohol handy.
Well maintained system.
Get bike in stand or right side up leaning against something solid.
Fresh or less and 6 months old well sealed fluid kept in a cool dark place.
Fill the two syringes. One half+ and the other 1/4 full.
Attach the 1/4 syringe to the brake caliper
Attached the 1/2 syringe to the lever then move the lever downwards so the filler hole is at the top of the fluid cavity. Like the Avid videos.
Then I push fluid from the top master cylinder to the brake caliper. As I am slowly doing this pump the lever half a dozen times. Helps free trapped air and get out old fluid. Stop pushing with 5mm left in top syringe. Clamp off the top lever syringe if you can. Pull the brake lever in as far as you can and secure in that position, like the Avid video. Then tap on the brake caliper with a non marking non metal tool then while holding this syringe upwards to prevent air bubbles from returning into the brake caliper pull up the syringe piston to create a little pressure and tap the caliper as well to help free trapped air. Repeat a few times. Do not make such a vacuum pulling on the syringe as you can easily pull air in past the brake piston seal. Then just wait 15 seconds with the syringe upwards to allow any equalization to occour. Then replace the screw into the brake caliper. Back at the lever, release the brake lever slowly while holding the syringe upwards to prevent air from getting sucked in. Then pull up on this syringe making a vacuum to suck out air. Repeat a few times. Not too forcefully. Pump the brake lever half a dozen times with vacuum and also gently pushing fluid back into the lever. Then rotate the brake lever upwards, wait 15 seconds for equalization and remove the syringe and dribble in fluid to fill the screw hole then put the screw in and tighten. Atleast here you will spill some fluid so quickly clean it up. Also clean up the any other spills as they happen, first spash/spray and get the fluid off then rub if necessary. Check the brakes. You may have to repeat the entire procedure a few times. Any more something else is wrong in most cases.
For neglected brakes take an empty syringe and attach to the brake caliper. Open the lever fill screw and let gravity and help the old fluid out. Start with a 3/4 full top syringe and follow the above instruction with the understanding that you will have let alot of air in but with tapping and repeating pushing fluids from the lever to caliper you will get it out, just a little more work.
Yes it is thick but also terribly sticky.
I would think it would still help provided you keep it inside the system.
I sympathize fine dust gets everywhere plus it drys things out.
Originally Posted by 007
Servicing Brakes - Forgot one thing - Check if piston cocked in bore
I forgot to add and this could cause the sticky/slow return lever and that is to ensure that the piston is not cocked in the bore. Make sure the piston is evenly positioned and travels perpendicular to the caliper housing. If one side is coming out faster or easier or further the piston will bind in the bore and not willingly retract. This may be fixable by just fiddling with the piston by going in and out and pushing it back in or perhaps the piston is scored or chewed up which occurs especially on the outside edges which contact the brake pad.
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