Dragging front brake

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Zombie Master
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Re: Dragging front brake

Post by Zombie Master »

GBClassic wrote: Mon Apr 19, 2021 4:01 pm gloopy and make them cock over on the return.
George


Could you please translate?
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SteveD
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Re: Dragging front brake

Post by SteveD »

Zombie Master wrote: Mon Apr 19, 2021 4:59 pm
GBClassic wrote: Mon Apr 19, 2021 4:01 pm gloopy and make them cock over on the return.
George


Could you please translate?
that the paint on the pads had gone gloopy and make them cock over on the return
My guess...the paint softened, lifted, clumped and caused the pad to lose it's correct parallel to disc orientation and caused it to catch on the disc a tad. Doesn't take much does it? I wonder if the application of brake grease to the back of the pad would prevent or worsen that? I'm guessing it'd help and also reduce/prevent brake squeal.
Cheers, Steve
Victoria, S.E.Oz.


1982 R100RSR100RS supergallery. https://boxerboy81.smugmug.com/R100RS
2006 K1200R.
1994 R1100GS.
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gspd
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Re: Dragging front brake

Post by gspd »

"the pads had gone gloopy and make them cock over on the return"

Reminds me of a quote by supreme court justice Potter Stewart : " I can't explain hard core pornography, but I know it when I see it". :lol:
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Gibson
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Re: Dragging front brake

Post by Gibson »

Hey Guys, after a thorough clean , flush, master rebuild and line replacement, the right side caliper is still dragging. I am going to need to rebuild at least the right side caliper.
Euromotoelectric has the kit for the R1100RS for 89.99. Includes seals and new pistons.
I think what happens for whatever reason, its difficult to get all of the old fluid out or the right side caliper on these bikes. Bleed is on left caliper only. Maybe there is some stagnant fluid in the right when bleeding...
I have changed the fluid approx every couple of years.
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Gibson
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Re: Dragging front brake

Post by Gibson »

The kits for the r1100rs are the same. Euromoto kit doesn’t list the mystic or r100r for some reason. The pistons were stuck on both sides! Kit came with new pistons, seals and silicone lube to assemble. Problem solved.
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gspd
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Re: Dragging front brake

Post by gspd »

Gibson wrote: Sat May 08, 2021 3:54 pm I think what happens for whatever reason, its difficult to get all of the old fluid out or the right side caliper on these bikes. Bleed is on left caliper only. Maybe there is some stagnant fluid in the right when bleeding...
You can bleed the right side caliper separately by loosening the pipe that comes out of it that connects to the left side. Just treat it as a bleeder, just a bit messier. I've had to do this on occasion but it's not usually necessary.

FYI -The following is applicable to any and every hydraulic brake setup if you are not 100% satisfied with the firmness of the lever (or pedal).
1 - Remove the wheel and pads and push all the pistons back into the calipers as far as they can go.
This minimizes (fluid and air) volume in the caliper.
2 - Find some wood wedges (cedar shingle pieces work well) and jam them between the pistons to solidly block the pistons all the way in.
3- Bleed the brakes again. You'll instantly notice a much firmer lever. No mushiness at all.
4 - Once you have a rock hard lever (and you will), remove the wedges and re-install the wheel and pads.
5 - Slowly pump the the pistons back out while carefully adding fluid to the reservoir.
You do not have to put the top back on the reservoir each time you add fluid while bleeding, it makes no difference

Note: On some bikes the caliper(s) MUST be removed and tilted so the bleeder is at the highest point for bleeding. If the bleeder is not the highest point of the bore you can't evacuate all the air.

PS - Once in a while you'll come across a piston that moves back into the caliper a bit too much each time you release the brake because of seal stiction, and this causes sponginess. When this happens you have to remove the disc, pump the piston out a bit further than it can go if the disc was there, and then pry it back in just enough to squeeze the disc back in.
Ideally there should be almost no visible movement of the pads when pressing the brake. The pad(s) should stay snugly right up against the disc at all times.
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gspd
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Re: Dragging front brake

Post by gspd »

Gibson wrote: Sat May 08, 2021 3:54 pm the right side caliper is still dragging.
I'm not sure how you determined this. Slight drag is normal if you're just spinning the wheel while stationary and the degree of this can vary. You should do a firm panic stop with the front brake and then ride a few miles without touching the front brake and then come to a stop with just the rear brake. If one front disc is noticeably (by touch or thermometer) hotter than the other you have a problem, otherwise it's OK.
Mechanic from Hell
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My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
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Zombie Master
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Re: Dragging front brake

Post by Zombie Master »

So there is a situation where you install new pads, and the sweep of the new pad is slightly different than the old pads. This could make the brake drag. If this is the case you may have to "fit the pad" to the rotor by removing some pad material. Some replacement pads may not be manufactured exactly the same. I know of one issue with EBC pads where this happened. :|
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