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Rear brakes problems on XR 600

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The rear brakes on my XR 600 are not functioning as they should. I've only had the bike a relatively short time and recently replaced the rear rotor and pads to try and improve performance (both were pretty well shot).

The pedal is quite soft and only really engages towards the bottom when pushing on it. Even then there is not a strong feel to the brake and it won’t lock up the wheel.

I took off the pads and tried and the piston moved slowly out after each pump. I also bled the brakes to see if this would help. I placed some tube on the bleeder and put it into a clear container of brake fluid and pushed down on the pedal with the bleeder open. Then closed it before returning to the top and repeated. Every push of the pedal expelled some fluid (no air seen) but not a great deal. The hose looks fine (no leaks or bulges).

I’m thinking that pulling apart the MC is the next step. Any suggestions?

Cheers

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I recently had the same kind of issue. I fixed mine by taking the caliper apart and cleaning it. The piston needed a little clean up wits some 600 grit sandpaper. I flushed all the other parts with a bunch of clean brake fluid. I didn't take the master apart, just flushed. I then re assembled and the rear brakes are working right again after bleeding. Get a big can of fluid and be liberal with it's use. If it needs it take the master apart too. Look for corrosion and replace any part that looks bad.

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+1 on Cleonards advise.

Also be aware the brake will not feel good until the new pads and rotor are "broken in". This will take several stopping events. Try not to make complete stops or lock up the wheel until the pad material starts to transfer to the rotor.

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Also be aware the brake will not feel good until the new pads and rotor are "broken in". This will take several stopping events. Try not to make complete stops or lock up the wheel until the pad material starts to transfer to the rotor.

+1

especally with new pads & rotor u must "bed in" the brakes...basically it's progressively harder braking(not quite to a complete stop & no dragging the brakes) from higher & higher speeds...almost to the point of having them fade...then allowing them to cool down.

wut ur doing is slowly building up heating up both pads and rotor to a point where it allows the transfer of pad material to the rotor...this also burns off the glues/resins used in the pad manufacturing that will release gasses until it's reached high enough temperatures.

i had a gud link but somehow lost it :D

also if ur testing ur brakes on the street, in gear and clutch engaged ur rear brake will always loose against the engine...try it in a safe place with the clutch pulled in...it shud lock up.

if that fails ur looking at a caliper and/or master rebuild which is a pretty easy job.

:)

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Thanks for the advice guys!

I'll give them a bit more time to bed in and if no real improvement is seen I'll then start looking at cleaning up the caliper and see how that goes.

Cheers!

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I' ve just stripped, cleaned, replaced seals, reassembled and bled the front and rear calipers on my 600R, to cure dragging. In both cases, the dust seals were shot, and fragments of the seals looked to be jamming the pistons, preventing them from retracting when the lever/pedal is released. After rebuild with new seals, the dragging problem remained. I must admit to pressing in the piston to get past the new dust seals.

Recently, I discussed caliper problems with an experienced bike tech. He told me that brake dragging is almost always caused by problems with the dust seals. He also mentioned that often times, he would fit caliper pistons without the dust seals, and pack the gap with copper slip instead. I think although I would like to try doing this, I would be wary of grit getting into the caliper.

Anyone got any experiences or thoughts about this?

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I' ve just stripped, cleaned, replaced seals, reassembled and bled the front and rear calipers on my 600R, to cure dragging. In both cases, the dust seals were shot, and fragments of the seals looked to be jamming the pistons, preventing them from retracting when the lever/pedal is released. After rebuild with new seals, the dragging problem remained. I must admit to pressing in the piston to get past the new dust seals.

Recently, I discussed caliper problems with an experienced bike tech. He told me that brake dragging is almost always caused by problems with the dust seals. He also mentioned that often times, he would fit caliper pistons without the dust seals, and pack the gap with copper slip instead. I think although I would like to try doing this, I would be wary of grit getting into the caliper.

Anyone got any experiences or thoughts about this?

Did you clean and lube the slider pins? The ones that allow the caliper to move side to side?

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with most disc brake systems there is going to be a slight drag on the rotor since there is not a release/return spring on purpose...part of the design is so they self adjust with rotor wear...

just think if u went to grab the brake and it wus setting 1/4" off the rotor🤣

unless the drag is VERY heavy and/or ur rotor is warped it's probably normal...unless u spin it real hard don't expect more than maybe two rotations out of ur front wheel and plenty of brake to rotor noise🤣

...and like Rich advised, keep the pins lubed and relatively clean :banana:

i have never heard about not running dust seals...:p

🤣

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The rear master cylinder is also adjustable at the lever pivot, you may just need to increase the travel. The part that connects to the brake pedal can be moved down the threaded rod to give the MC more range.

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It's important to clean up the pistons when you take the caliper apart. A little 1000 grit sandpaper will get rid of dirt, rust or corrosion and still leave the piston surface smooth enough so it doesn't leak. If you leave any crud on there it can cause the piston to hang up and cause drag. If the pistons have any significant pitting they have to be replaced.

I usually just do this without replacing any seals unless there are leaks.

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