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Need help with procedure to diagnose XL600 sticky front brake.

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My 83 XL600R front disc brake is definitely sticking. After lifting the front wheel I confirmed that the brake is binding the rotation of the wheel. Does anyone know a procedure to determine what part of the system is the causing this? The brake system has not been disturbed and the brake lever is firm and not spongy and it does stop the wheel when the lever is pulled and the lever seems to return to normal when released. Is there a way to figure out which part of the braking system is at fault without disturbing the part of the system that is still working?

For instance if the master cylinder is working fine and the problem is in the caliper. I loosened and shifted the caliper part way off the disc and then reattached it in place and that little bit of movement allowed the front wheel to rotate freely until I applied the brake lever again and it stopped the front wheel from turning but then after releasing the brake lever the wheel rotation was binding again. I read here many difficulties with bleeding these brake systems. I'd rather not disturb the master cylinder piston and such if the problem is in the caliper or vise/versa. The bike has 8800 original miles so the problem is most likely from sitting instead of wear and tear. Its always been pampered and stored inside. I just finished the dual carb repairs and now since its been sitting since last year this brake issue developed. Thanks for any help you can supply.

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crack the caliper bleeder loose...........if the wheel then turns fine then either the hose is callapsed inside or there is a problem in the master cylinder...

If after loosening the bleeder it still turns hard then pull the caliper and check the slides for seizing.........there could be too much grease in the bottom off the slide pin holes causin a hydra-lock,,could be corrosion on the pins,,pads sticking in the bracket or your caliper piston is sticking...

B

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My 83 XL600R front disc brake is definitely sticking. After lifting the front wheel I confirmed that the brake is binding the rotation of the wheel. Does anyone know a procedure to determine what part of the system is the causing this? The brake system has not been disturbed and the brake lever is firm and not spongy and it does stop the wheel when the lever is pulled and the lever seems to return to normal when released. Is there a way to figure out which part of the braking system is at fault without disturbing the part of the system that is still working?

For instance if the master cylinder is working fine and the problem is in the caliper. I loosened and shifted the caliper part way off the disc and then reattached it in place and that little bit of movement allowed the front wheel to rotate freely until I applied the brake lever again and it stopped the front wheel from turning but then after releasing the brake lever the wheel rotation was binding again. I read here many difficulties with bleeding these brake systems. I'd rather not disturb the master cylinder piston and such if the problem is in the caliper or vise/versa. The bike has 8800 original miles so the problem is most likely from sitting instead of wear and tear. Its always been pampered and stored inside. I just finished the dual carb repairs and now since its been sitting since last year this brake issue developed. Thanks for any help you can supply.

My 85 XR350 had several front brake issues. Looked at rebuilding the caliper and master cyl, $60+ just for the parts, and I needed pads and new line..

So I went on ebay and bought a complete front brake setup, master cyl and lever, brake line, caliper w/new pads, all still together, didn't even have to bleed it. 2002ish XR250 (all later XRs/CRF use the same caliper). Bolted on in 10 minutes. All shiney, clean and "new". $50 😉

Edited by MindBlower

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Update... First many thanks to brianhare. His advice helped me determine that indeed the problem was in the caliper. The Pistons were binding. I see age is a real killer when atrophy sets into the brake system. This machine has done a lot of sitting. The brake fluid looked like old cloudy gas. And so I decided to bleed the old fluid through the bleeder screw so the system had new fluid to work with. I installed a new speed-bleeder screw that I got from NAPA # NOE 6751569 m8-125 and attached a 3/4 inch wood block behind the brake lever as per the Honda service manual and that limits the master cylinder piston throw. Then bled the fluid several times out the speed-bleeder till it ran clear.

Then removed the caliper and the pads and then installed another wood block in the caliper to limit the pistons travel when I operated the brake lever. I could see the pistons trying to push outward slightly and that is why the brakes were stopping the wheel before. But they weren't moving outward as much as I'd expect. So I figured I would try to move them back and forth a little to free them up. I knew that might tear them and the seals up some but I figured I had nothing to lose as I may have to replace these old parts anyway if I couldn't get them to free up. Eventually I managed to get them moving outward when I pulled the brake lever and I could see them move slightly back inward when I released the brake lever. I cleaned up the rest of the parts and slides and reassembled and reinstalled the caliper. I spun the wheel and applied the brake lever and the wheel stopped. So far so good. Then I re-spun the wheel and did turn more freely and didn't seem as bound tight as before when I started this topic.

Now here is my next question for you all. How much tension of the pads against the disc is normal when the brake lever is released. The wheel rotation is still somewhat limited by the pads and I can hear them rubbing against the disc when I spin the wheel now. Is this normal or should the be releasing off the disc completely? If I give the wheel a good tug to spin it the wheel will rotate around about one full turn before the pad to disc tension stops the rotation. With a good tug to spin the wheel is one turn till it stops normal? Or does that mean the pistons are still causing to much tension on the pads. Before I started this work on the caliper the wheel was bound pretty tight after applying the brake lever and the wheel movement was bearly a few inches. Can some spin their front wheel for me and report back on this topic to let me know how much wheel rotation they get. The pads are definitely still rubbing on the disc and limiting the free spin to about one turn. Thanks.

Edited by Tinrudderspar

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well you can flush the fluid many times, but its the seals that are not doing their job properly...there are 2 seals per piston, inner and outer...

also without spending much money you can look at the master cylinder bleed hole in the bottom of the cap...poke a needle in there and see if bubbles come out...

I rebuilt my caliper and cleaned my mc on my xr6

the wheel will spin for a very very longtime on my bike...new wheel bearings and nice grease aids this

pads should only barely rub...however after activating the brake a few times you should hear no rubbing...thats because new seals help retract the piston to their correct position...

buying a used caliper on ebay is no good...all you have to do is replace 4 seals, clean and polish the pistons and 99 percent of the times this will fix a sticky brake

you must also clean and lube the caliper pins...if they are worn and grooved buy TUSK pins for like $5...great deal

cheers

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Yes my wheel will spin a long time also with the caliper removed but my concern now is how much drag on the wheel is normal with the caliper installed. If my memory serves me... as I recall even when the XL was new I could hear a slight drag noise when the front wheel was lifted and the wheel was spun around. I just don't remember how long it would rotate back then. I was hoping that someone here could tell me as a reference, when a known good front wheel and caliper off the ground how many turns their wheel can spin when the tire was given a good tug. Any help on this is much appreciated.

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I thought its clear I was talking about with the caliper ON...as I mentioned once you activate thelever a few times there should be no drag as the pistons cycle a few times and the seals are doing their job

as a reference its more than one rotation like you have....you should get a solid 5-10 spins from the wheel with caliper on, and yes there is almost always 1 pad that barely rubs however good seals and caliper you can activate the lever a few times and you can make this go away pretty much as there is no load on the wheel or caliper in the air...the same method is used to check pedal bike brakes too...

cheers

Edited by elsalvadorXR6

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Many thanks elsalvadorXR6 for your responses to my topic/post. I will heed your advice and order parts for my caliper and proceed with the needed repairs. Can you explain your most successful way to attempt these repairs when I get the parts in hand. Also I'm not to sure what you mean about the pin and bubble thing in the master cylinder. Do you mean when the system is drained? Please explain how you bled your caliper also. One more thing. Where do you prefer to get your OEM parts? Thanks again for your help.

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sorry for being vague

since xr and xl calipers are very similar you can use the same techniques in either manual

what I would do is this

drain fluid

dissassemble caliper

you push out pistons, then with a dental pic you take out all 4 seals

then with a qtip and acetone or similar clean out the grooves where the seals sit...its these crystals that damage and push the seals out and make the pistons fail to re enter...

clean and flush all crud out of the bottom of the piston chambers, and flush out the bleeder hole...

polish pistons with a rubbing compund and a nice clean rag...

the master cyclinder has a clear plastic cap in the bottom that has a very tiny hole...its this hole that gets clogged up again from crystals and grudge from old fluid..then flush out the master cyclinder(if you are rebuilding the mc, make sure the plunger and seals are good) then attach it all....

then use some cheap dot3 liquid and flush out, bleed or reverse bleed or get a speed bleeder and do a normal flush...after that install some nice grade brake fluid...

the pins I am referring too(you can buy new tusk ones) are the caliper pins that attach both halves of the caliper and where the actual pads ride...they wear a groove from no grease and age...so replace them if needed, so that both halves can "float" better

I usually buy from cheapcycleparts...they used to be the cheapest but now it seems there is a better honda warehouse or some similar named site...

good luck

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