ATV Riders Forum > ATV Riders Mechanical Section > ATV Steering & Suspension > HELP!! Brake caliper rebuild!
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fenix0069
12-05-2002, 08:26 PM
Does anyone know how to rebuild the front brake calipers on a 250r. My pistons are locked up inside and I haven't the slightest idea how to take the d*** things apart!
Mxbubs
12-05-2002, 08:38 PM
Carencro? Ill be at Breaux Bridge Sunday if it doesnt rain.
Calipers? Cant be too hard.
fenix0069
12-05-2002, 08:41 PM
at the drag track?
Yah the calipers are pretty tough. I can rebuild pretty much anything else on the bike but I havent figured those out yet.
12-05-2002, 08:49 PM
are the lines still hooked up..if so pull the lever and see if the pistons move. .if not heat up the caliper alittle
fenix0069
12-05-2002, 08:54 PM
No the pistons dont move, the pistons are stuck inside for some reason.......right now i've got the calipers off the bike and the pads are out......thats where i got stuck.
Mxbubs
12-05-2002, 09:05 PM
Since they are broke, want to sell them cheap?:D
The Mx track
12-05-2002, 09:07 PM
are the pistons presed all the way in like they would be when replacing pads. if not try c-clamping them and see if you can get them to colapse in
12-05-2002, 09:12 PM
are you trying to remove pistons?
12-05-2002, 09:16 PM
i hope he was..that is what i thoughthe was taliking about
fenix0069
12-05-2002, 09:19 PM
yah im trying to get the pistons out so i can see what is damaged and replace the piston and dust seals. The pistons are pressed all the way in.
12-05-2002, 09:30 PM
hmmmm?your goning to have to build some preasure or something some how to get them out.
plus dual pistons one will probably pop out and the other won't..i can't think of anything to help so good luck.
12-05-2002, 09:32 PM
he is correct
but you can do it
i pm'd ya ...you got msn?
fenix0069
12-05-2002, 09:35 PM
Thats awrite fellows i'll think of sumthing
12-05-2002, 09:36 PM
heat them up with a torch if you can . if that don't work.. i dunno
12-05-2002, 09:40 PM
do not heat em up
I can expalin ..read your pm ..
hit me on msn
CHAR250R
12-06-2002, 07:48 AM
Hook the calipers back up to the lines. Don't put the pads back. Don't put the caliper back on the knuckle. Put a large C clamp on both calipers so the piston can't come out. If the pistons are out a little, gently compress the C clamp until the pistons bottom out. Bleed the front brakes. Remove the C clamp. Pump up the front brakes by using the brake lever. This should push out the piston on one or both of the calipers.
If only one side comes out, you need to remove that caliper and plug that line up with a cap. Put the C clamp back on the caliper that still has the piston stuck in it, and bleed it. If you don't have the other line plugged up on the side without the caliper, you won't be able to bleed the stuck side. After you bleed the remaining stuck side, remove the C clamp and pump up the front brakes until the piston pops out. Put a rag over the calipers so you don't get a brake fluid bath. Put a pan under the calipers so you don't get brake fluid all over the floor. When yo get them completely apart, make sure you do a VERY good job of cleaning them. Check for corrosion and scratches. Scotchbrite and water works good. Dry them off comepletly. Reassemble with all new seals and you should be good to go. The manual says you can remove the piston by blowing compressed air into the inlet hole for the brake line. Your pistons are frozen, this may not work. Take your time and do a good job, it will be worth it.
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Let me know how you make out. Charlie.
12-06-2002, 08:09 AM
this is good instructions
..a way to avoid having to work with 2 at same time is to put front caliper on rear line(provided you want or have the rear off too ,good idea to rebuild all at same time ) ...this is easier to work with ..while getting pistons to move in order to rebuild &
& much quicker to bleed 1 then 2 ..
CHAR250R
12-06-2002, 09:27 AM
Good idea. Didn't think of putting it on the back. You'll need 6 crush washers instead of 4 if you go that route.
fenix0069
12-06-2002, 02:30 PM
sounds like a good idea....thanks i'll do it as soon as i get home!
12-06-2002, 02:32 PM
;)
fenix0069
12-09-2002, 09:48 AM
Thanks fellas it worked great!
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Service of the brake system of the car includes the following operations:
Preparations used in the maintenance of brake mechanisms:
Checking the thickness of the brake pads and the condition of the caliper pistons is necessary at every vehicle maintenance. Replacement of the pads is necessary when it is obvious that the brake pads of the pads have worn out more than critical, until the next service.
Replacing discs: when the thickness of the working surface of the disc is less than the permissible one (measured with a caliper), with critical runout (see the instructions for the car), the runout is measured with an indicator stand. And also in the presence of severe corrosion, cracks and other damage.
The replacement of brake discs is carried out only in pairs, both on the same axle of the car with the simultaneous replacement of brake pads (regardless of their condition).
Checking the condition of the brake fluid: performed at every maintenance, but at least once a year. Replacement criteria: fluid life (see vehicle manual), sudden change in fluid color (ex: darkening and turbidity), fluid boiling point less than 165 °C. Synthetic brake fluids tend to absorb water during use, resulting in a lower boiling point. The boiling point of a liquid can be measured directly or by a relative indicator - electrical conductivity. The simplest and easiest way is to measure by electrical conductivity. The tester has three indicators. If, when the electrodes are immersed in the brake fluid in the tank, the green indicator lights up, then everything is in order, the brake fluid is fresh. If yellow, then the moisture content is within 1-1.5% and further operation is possible. If red is on, then the moisture content is limiting - about 3% and the fluid should be replaced as soon as possible.
Pad Replacement Procedure: All caliper designs require spraying MoS2-Rostloser Part No. 1986 Moly Rust Remover onto fasteners and brake pad seats for ease of work. On the "floating" caliper, unscrew the lower bolt that secures the brake cylinder to the bracket. Fold the caliper up and secure in this position for the suspension parts. For fixing it is convenient to use a wire hook. Remove the old pads from the guide grooves. Remove the caliper guide pins from their sockets. Clean the pad seats with a wire brush and spray on any remaining dirt Schnell Reiniger Quick Cleaner, Ref. 1900. Clean the caliper guide pins and their seats from old grease and completely degrease with a quick cleaner. Dry the parts.
Press the pistons of the brake cylinders (it is convenient to use a clamp if there is no special tool). In case of sticking or excessive force in the movement of the pistons, remove the rubber anthers of the cylinders, remove dirt and spray Silicon-Spray, article 3955 (7567), under the anther.
“Swing” the caliper piston, successively squeezing it out of the cylinder with the brake pedal and pushing it back with a clamp. Check the ease of movement of the piston and re-spray silicone spray under the boot. Put the duster back on. If it is impossible to restore the operation of the brake cylinder, replace it or repair it with obligatory polishing (or replacement) of the piston and replacing the brake cuff with boot.
Assembly: before installing the brake pads, lubricate their guide (pad contact) surfaces on the caliper with synthetic brake lubricant, Bremsen-Anti-Quietsch-Spray, article 3079. The back sides of the pads and the surfaces of the anti-squeal plates ( if they are included). Lubricate the caliper guide pins and their boots with Anti-Quietsch-Paste. Avoid over application.
Reinstall the parts, assemble the caliper. Before tightening the mounting bolts, it is recommended to lubricate the threads with a choice of aluminum spray, copper paste or synthetic brake lubricant.
After assembly, be sure to clean the disc from traces of used compounds and from conservation grease, use the Schnell Reiniger Quick Cleaner, article 1900.
The sequence of actions when working with opposed calipers is the same. Difficulties can only arise when removing the pads, therefore it is necessary to use MoS2-Rostloser Rust Remover with Molybdenum, article 1986. Lubricate the springs and fixing pins of the pads before installation with a choice of aluminum spray, copper paste or synthetic brake lubricant.
Attention: when working on vehicles equipped with the ABC system, handle the ABC sensors and their connectors with care. Be sure to clean the comb from which the sensor reads the wheel speed signal.
Replacing brake discs: To replace the brake disc, spray MoS2-Rostloser Rust Remover with Molybdenum, article 1986 on the mating surfaces of the disc and hub, into the holes for the studs or bolts. Completely remove the caliper, unscrew the disc mounting screws (if any).
