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Discussion Starter · #1 ·
So i noticed a slight drag lately. Felt the back brake rotor and it was scalding hot. Had only been used once during the ride. The drag is not excessive but enough to get the rotor extremely hot. I have taken apart the caliper and cleaned the pistons. When I bleed the line is relieves the pressure that is built up in the line and releases the calipers fully. In other words you can press the caliper together and see the rubber boots compress and decompress. Before that occurs the rubber boots are comperessed and only slight movement is able to be achieved.

Is it a faulty master? Are the rubber boots faulty and not pushing the caliper apart after the brake is disengaged? Is it possible the caliper is not aligning properly with the rotor? If that is the case how do you go about checking that. All I have been doing is making certain the rear wheel is set evenly on the hash marks when tightening chain.

I cant figure out why so much poressure is being held in the line and not releasing.

The seals dont appear to be swollen or faulty - I do have to press really hard to get the pistons back in.

I have order a used caliper off of ebay along with new seals and rubber boots. I also ordered a new rebuild kit for the master.

I doubt I have a rear wheel bearing going out but the hub of the rear wheel is getting hot as well but I figured it was heat being transferred from the rotor.
 

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Official Noob Greeter
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55,856 Posts
http://www.gravesport.com/Graves-Motorsports-Sport-Bike-Rear-Brake-Return-Spring.html



Graves Motorsports Sport Bike Rear Brake Return Spring

Simple solution to the problem of the rear brake dragging. This billet aluminum spring plate and spring install easily onto the motorcycle rear brake master cylinder rod and keeps the brake pedal pushed out when not in use. A simple and effecitive option for fixing motorcycle brake drag.

Fits the following:
Suzuki GSX-R 600 + 750 + 1000 : 1996 to present with stock or aftermarket rearsets
Yamaha R1 + R6 : All years with stock or aftermarket rearsets
Note: These return springs also fit other motorcycle models (see image to determine if your bike uses the same style rear master cylinder as shown).
 

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Parts Pimp
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http://www.gravesport.com/Graves-Motorsports-Sport-Bike-Rear-Brake-Return-Spring.html



Graves Motorsports Sport Bike Rear Brake Return Spring

Simple solution to the problem of the rear brake dragging. This billet aluminum spring plate and spring install easily onto the motorcycle rear brake master cylinder rod and keeps the brake pedal pushed out when not in use. A simple and effecitive option for fixing motorcycle brake drag.

Fits the following:
Suzuki GSX-R 600 + 750 + 1000 : 1996 to present with stock or aftermarket rearsets
Yamaha R1 + R6 : All years with stock or aftermarket rearsets
Note: These return springs also fit other motorcycle models (see image to determine if your bike uses the same style rear master cylinder as shown).

Woodcraft also sells one and it's more affordable. Cheap ABS for run offs. :laugh


:YEA
 

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Reads the rulez
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An over filled reservoir will also do that. Double check and make sure your brake fluid isn't above the max fill line. The little brake springs are nice, but I don't have one with my woodcraft's, and I have zero brake drag problems.
 

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An over filled reservoir will also do that. Double check and make sure your brake fluid isn't above the max fill line. The little brake springs are nice, but I don't have one with my woodcraft's, and I have zero brake drag problems.
Yes, this as well, as the fluid will expand when hot, and if it has nowhere to go from being overfilled, it will push on the caliper pistons and create brake drag.
 

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Discussion Starter · #6 ·
Well I think I have possibly found the issue. My rear caliper has none of the 4 shims surrounding the pads. I must have had this problem all along - bought the bike (it was wrecked) over a year ago. Replaced pads all around within a few weeks of having it and didnt know any better.

Feel like a real dumbass......

The shims serve some purpose I reckon and should help explain why the pads are sticking to the rotor......

If that doesnt solve the problem then I will really be at a loss.

The spring on my rear brake foot lever is plenty strong and pulls it all the way up withoutout any slack left over. i will probably go ahead and install the spring any way since it is on the way - along with used caliper, used rear master, new seal kit, new boots and on and on......

Flame a way :)
 

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"The Dude abides .. "
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the shims serve very little purpose, other than to provide even more "sponginess" to the pedal/lever feel. ANY aftermarket rear or front pad, will tell you to not use the backing pads that came on the stock pads.
The rear rotor is gonna get a little hot even if you aren't using it just from the mild friction of the pad rubbing the rotor at highway speed. It won't be as hot as the front rotors obviously, that can literally blister your skin if you touch the back of your finger to em after hard riding, but the rear rotor will get a bit warm..

do you have a thermal temp gun ? go ride, take a reading on the front and rear rotor. Now if the rear wheel is really hanging up, and hard to turn by hand on a rear stand.. well, yea, ya have some real binding.
ONE thing i can tell you, i had a similar issue with my rear rotor on one of my race bikes. Come to find out that the caliper BRACKET was slightly bent from a crash. Replaced the bracket.. nothing else.. was perfect. I could see it wasn't lined up as when i pressed the rear pedal, the entire caliper would try to straiten up in line with the rotor again .
 

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Discussion Starter · #8 ·
the shims serve very little purpose, other than to provide even more "sponginess" to the pedal/lever feel. ANY aftermarket rear or front pad, will tell you to not use the backing pads that came on the stock pads.
The rear rotor is gonna get a little hot even if you aren't using it just from the mild friction of the pad rubbing the rotor at highway speed. It won't be as hot as the front rotors obviously, that can literally blister your skin if you touch the back of your finger to em after hard riding, but the rear rotor will get a bit warm..

do you have a thermal temp gun ? go ride, take a reading on the front and rear rotor. Now if the rear wheel is really hanging up, and hard to turn by hand on a rear stand.. well, yea, ya have some real binding.
ONE thing i can tell you, i had a similar issue with my rear rotor on one of my race bikes. Come to find out that the caliper BRACKET was slightly bent from a crash. Replaced the bracket.. nothing else.. was perfect. I could see it wasn't lined up as when i pressed the rear pedal, the entire caliper would try to straiten up in line with the rotor again .
I sure was hoping the shims served more of a purpose than that which may have solved the problem - doesnt sound like that is going to be the solution.

The rear rotor gets scalding hot without being used at all but spins freely by hand whicle on a lift - very confusing. There must be enough friction going on to cause it. The bike was wrecked and does have some scuff marks on the caliper. I will be replacing it along with the caliper mount, with the set-up I got off of ebay in case either is bent, will replace the seals in the caliper, make sure pistons are clean, will use the shims and make sure fluid level is not above full. If that still doesnt solve problem I will look at the rear master and rebuild it. Very frustrating.
 

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A rear pad could be cocked enough to touch the rotor. Happened on my gsxr.
Should be noticeable with the bike on a rear stand.
 
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