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Discussion Starter · #1 ·
I have a 81' GL500 and the front brakes keep sticking. I have noticed others have the same problem and will try their resolutions but was wondering if it is common to have the rotor resurfaced? A new one is $300. I have called several places and nobody will touch it. Any suggestions?
 

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I have a 81' GL500 and the front brakes keep sticking. I have noticed others have the same problem and will try their resolutions but was wondering if it is common to have the rotor resurfaced? A new one is $300. I have called several places and nobody will touch it. Any suggestions?
daren,others will chip in on this,but.

i dont think your brakes are sticking because of the disc.a disc only gets smaller,not bigger.in extreme conditions,i suppose it could be warped,but i doudt it.

have you serviced your front brake set up.there is a tiny hole in the MC. if this is blocked,or partially blocked,fluid is unable to return...hence keeping your pads touching the disc.

 

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If your brakes are sticking, it's likely one or more of your calipers needs rebuilding. Disc surface should have no affect on sticking brakes.
 

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What is the maintenance history of the bike? It is likely that both the master cylinder and caliper are in need of attention.



The MC probably has fluid jelly jam goo in it and the caliper likely has debris and corrosion in it. Check the hose as well, if it is old it wouldn't hurt to replace it at the same time. The parts to do the whole job with set you back about $100 including a stainless hose. Add in the expendables and fluid, and it will be about $125 and four to six hours of work (maybe less) when the dust settles.



Considering the alternative of not being able to stop safely in an emergency, it is cheap insurance.
 

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Also, if your bike still has it's original soft brake lines the inner liners can swell with old age.



The master cylinder provides sufficient pressure to apply the brakes but the return pressure is lower so this can hold pressure in the calliper and cause binding or drag.



With your bike on the centre stand and jacked up with the front wheel off the ground spin your front wheel, apply the brake and release. Now, if the wheel still feels stiff to turn slightly open and then close the bleed nipple{s}.



If the wheel now turns more easily you have released built up pressure either caused by swollen lines or a blocked M.C. return hole.



If the brake still binds after releasing the pressure it is more likely to be old, stiff calliper seals or piston corrosion.



With the callipers removed, spin the wheel. If it still doesn't spin freely your issue is with the wheel bearings, bent axle or even possibly bent forks.





If the wheel now spins freely, while you still have the calliper{s} off spin the wheel and check the discs for runout using a screwdriver held against the fork.
 

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Also, if your bike still has it's original soft brake lines the inner liners can swell with old age.



The master cylinder provides sufficient pressure to apply the brakes but the return pressure is lower so this can hold pressure in the calliper and cause binding or drag.



With your bike on the centre stand and jacked up with the front wheel off the ground spin your front wheel, apply the brake and release. Now, if the wheel still feels stiff to turn slightly open and then close the bleed nipple{s}.



If the wheel now turns more easily you have released built up pressure either caused by swollen lines or a blocked M.C. return hole.



If the brake still binds after releasing the pressure it is more likely to be old, stiff calliper seals, piston corrosion

or a build up of crap behind the piston.



With the callipers removed, spin the wheel. If it still doesn't spin freely your issue is with the wheel bearings, bent axle or even possibly bent forks.





If the wheel now spins freely, while you still have the calliper{s} off spin the wheel and check the discs for runout using a screwdriver held against the fork.
 

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Discussion Starter · #7 ·
Wow, thanks for all the prompt replies and great suggestions. Let me provide more details. I have completely cleaned the caliper and flushed the line due to a previous episode of the front brakes sticking, so the fluid during the current episode was clear. The pistons are fine and the line is clear. The one thing I have not done is check for that small hole in the MC. But my rotor is not longer smooth and needs to be resurfaced and new pads installed. The pads are worn down the and the rotor is slightly grooved, hence my resurfacing question. Thanks again.
 

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If you really end up needing one buy a used rotor rather than a $300.00 dealer rip off. Come to think of it I bought my entire bike for $300.00? I'd go with Bandit's answer.

Cheers, 50gary
 

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If you are carefull and have a flat surface and a flat sanding block you can do a basic resurface yourself. Just use a semi-fine wet sandpaper and make sure your surface is flat and don't go too crazy.
 

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Yellow pages and a decent local motor engineering company.Mine will do a set for around 40 beer tokens.There must be enough meat left on the discs for the job so check service limits for your model via the manual.
 

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Grooved disks are not much of a problem unless they are really cut up. New pads will wear into them quickly. Resurfacing these "single layer" SS disks is not child's play, the machinist needs to know what they are doing. Be careful about riding with sticking calipers as the disk can easily overheat a lot and be ruined. Installing new pads without doing any maintenance on the calipers and master cylinder will probably make the sticking worse, as the caliper pistons will be retracted further and the seals will ride on the even rougher formerly exposed surface of the piston walls. Mild whacks on the calipers with a rubber mallet usually will temporarily free the front brakes, until you apply them again. I always take a mallet along when I go to pickup a used bike, just so I can roll it onto the trailer. I use the mallet after the price is negotiated.
 

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I always take a mallet along when I go to pickup a used bike, just so I can roll it onto the trailer. I use the mallet after the price is negotiated.


The mallet could potentially save you money if used during the negotiation.
 

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I've taken the glaze off of disks using an orbital sander and a really aggressive sanding pad -- 40 or 60 grit where the abrasive is embedded in adhesive rather than simply sand glued to the backing.



It works well. You'll have to remove the disk from the wheel to get both sides.
 

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i didn't read the other posts but to answer your questions yes you can resurface the front brake rotor provided it stays within the service tolerances. a standard brake lathe can do it. instead of the standard carbon steel rotor that leaves dust shavings, the rotor will leave curly q's that are unbelievably hot when they come off.



also this is not the reason your brakes are sticking. if the caliper is not retracting when the lever is released you probably have a caliper piston that's hung up



i'm answering this from experience
 

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Resurfacing these "single layer" SS disks is not child's play, the machinist needs to know what they are doing.


I am an experienced machinist and will agree with Rich. Make sure that any "shop" you take them to has specific experience resurfacing SS motorcycle rotors/discs. Don't let your buddy who happens to have a lathe and has turned the rotors and drums on his pickup touch your disc. Also look for all other possible causes first.
 

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Wow, thanks for all the prompt replies and great suggestions. Let me provide more details. I have completely cleaned the caliper and flushed the line due to a previous episode of the front brakes sticking, so the fluid during the current episode was clear. The pistons are fine and the line is clear. The one thing I have not done is check for that small hole in the MC. But my rotor is not longer smooth and needs to be resurfaced and new pads installed. The pads are worn down the and the rotor is slightly grooved, hence my resurfacing question. Thanks again.


When you say you cleaned the caliper, did you put in a new seal? If not, then you might want to consider getting a kit and installing it. You brake sticking problem is likely in the master cylinder. Do a proper rebuild and you should be good to go. The hardest part was getting the resevoir off. Otherwise a straight forward job.



As for the disk, I'd slap a new set of pads on it and ride. You really wouldn't be gaining anything by resurfacing the rotor unless it is glazed over. If it is cracked on the surface or warped, then I'd replace it rather than resurface it. Even a $300 rotor would be worth it to have good brakes (and you could get it for much less). Having it resurfaced may cause more problems than you cure if the shop doesn't do it properly.
 

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Discussion Starter · #17 ·
Well, I have finally been able to spend a little time on this issue again. I agree the main issue is with the MC and have taken it off the bike (81' GL 500) and cleaned it. It appears to be in good shape. I forced some compressed air through both holes at the bottom of the reservoir to make sure the return hole was clear as well. So now that the MC, brake line and caliper are clean and clear, what is the trick to get fluid back through the entire system? I poured new brake fluid into the MC, squeezed the handle and made sure the zerk fitting on the caliper was open and nothing happens.



thanks!
 

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Being stainless they will need to be ground on a surface grinder, they cannot be turned on a brake lathe.





Greg
 

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Well, I have finally been able to spend a little time on this issue again. I agree the main issue is with the MC and have taken it off the bike (81' GL 500) and cleaned it. It appears to be in good shape. I forced some compressed air through both holes at the bottom of the reservoir to make sure the return hole was clear as well. So now that the MC, brake line and caliper are clean and clear, what is the trick to get fluid back through the entire system? I poured new brake fluid into the MC, squeezed the handle and made sure the zerk fitting on the caliper was open and nothing happens.



thanks!


I don't think just blowing air through will dislodge any gunk in the tiny return hole in the master cylinder. That needs to be cleared out with a thin wire, very thin. That would explain why you don't get any movement of fluid. It takes a long while to get all the fluid into all the lines and caliper after being emptied, unless you use a vacuum bleeder to fill it.
 
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