Author Topic: dragging brake  (Read 513 times)

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Offline goatmar

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dragging brake
« on: August 26, 2017, 09:14:38 pm »
Okay everyone put your thinking caps on for this one.  :-\

Basics........... 2001 Connie...........  Rebuilt the front calipers in April, salt really messed them up.  Working fine until now.  In the morning when temps are cooler 40/50's this only happens.  I go to work, I back down the drive using the front brakes no problem, get to the end of the road, use the front brake and they drag, don't want to fully let go.   After about 3 to 4 minutes more of not using them all is okay until you apply them again.  Same thing dragging then 3/4 minutes later okay.

I've changed the fluid two weeks ago using DOT4 no change.......... back brake was okay, but did it Friday just started doing it.  Hadn't done anything to the back. 
But coming home at night, warmer out no issues at all.    Anyone experience this before?

I just changed the fluid again today, see if that does anything????  Like I said only in the cool mornings.

DOT 4 heavy Duty Fluid is what I just put in.   Thanks all.  :great:
Dave Muzzey  St. Charles, IL  COG#7957  '01 Connie  100K miles and counting

Offline mnbikeguy

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Re: dragging brake
« Reply #1 on: August 26, 2017, 10:03:00 pm »
Sounds like the return hole is plugged.

Offline Mcfly

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Re: dragging brake
« Reply #2 on: August 26, 2017, 11:43:56 pm »
Sounds like the return hole is plugged.
:iagree:  Changing the fluid may kick up crud that could clog the return in the master cylinder.

Brake dust also builds up on the caliper pistons which might prevent the pads from fully
retracting.
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Offline WillyP

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Re: dragging brake
« Reply #3 on: August 27, 2017, 01:28:29 pm »
It's either mechanical or hydraulic. Mechanical could be crud buildup on a piston or bent parts. Hydraulic means the fluid isn't returning to the master. Also the seal provides some return, as it wants to go back to it's 'relaxed' position.

I assume you are talking about the brakes dragging enough to prevent the bike from being ridden... not just light contact, which is normal. As the wheel turns, runout and play cause the rotor to contact the pads, pushing the pistons in.
« Last Edit: August 27, 2017, 01:36:55 pm by WillyP »
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Offline goatmar

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Re: dragging brake
« Reply #4 on: August 27, 2017, 10:23:32 pm »
It's either mechanical or hydraulic. Mechanical could be crud buildup on a piston or bent parts. Hydraulic means the fluid isn't returning to the master. Also the seal provides some return, as it wants to go back to it's 'relaxed' position.

I assume you are talking about the brakes dragging enough to prevent the bike from being ridden... not just light contact, which is normal. As the wheel turns, runout and play cause the rotor to contact the pads, pushing the pistons in.

No Willy not light contact, at a stop the bike won't roll freely.  You can feel the brake on, you can move it, just need more effort to do so.

Once again guys why in the morning and not at night?   The only change is temperature.  Return hole is fine watched during blending.
Dave Muzzey  St. Charles, IL  COG#7957  '01 Connie  100K miles and counting

Online Jim Snyder

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Re: dragging brake
« Reply #5 on: August 27, 2017, 10:32:05 pm »
Cold fluid is thicker than warm fluid would be a guess as far as temperature is concerned morning vs afternoon.
When you had them apart did you clean all of the dust residue off of the pistons and polish them before re-install?
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Online MAN OF BLUES

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Re: dragging brake
« Reply #6 on: August 27, 2017, 10:33:22 pm »
When you "rebuilt" the calipers, you likely did the thing that causes the issue.. did you lube the piston, and the new seals using brake fluid?
I've seen this many times... and even tho the FSM, and every joe in the world, says to do so.. its bunk.

Pull them again, and completely clean the piston using a scotchbrite pad, or even 400 grit sand paper and solvent (mineral spirits), and reassemble this all dry.. don't use brake fluid as a lube on the pistons, what ends up exposed to the environment, causes corrosion, and makes a ring on the piston, that prevents it from retracting properly... any brake fluid exposed to air, sucks up moisture, and starts the rust process from the first moment..

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Offline Bud

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Re: dragging brake
« Reply #7 on: August 28, 2017, 09:32:36 am »
I bought rebuild kits with new stainless steel pistons for my 650 Silverwing project.  In the kit is a tiny tub of grease that they want you to use when reassembling the calipers.  Here's a link to their video page on how to rebuild the calipers properly.  Can't remember what the grease is made of but it's not petroleum based.  Watch the vids and they talk about it in the reassembly portion of the vids.

https://brakecraftersusa.myshopify.com/blogs/hints-tips-and-other-brake-motorcycle-brake-information

Offline goatmar

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Re: dragging brake
« Reply #8 on: September 06, 2017, 03:51:56 pm »
Okay here's the plan............ rebuild them AGAIN  >:(  I changed the fluid to no avail.  Yes when I first rebuilt them I lubed seals and pistons with brake fluid.  Won't go in dry as far as I know.  :??:
Will keep you all posted.

Dave Muzzey  St. Charles, IL  COG#7957  '01 Connie  100K miles and counting

Offline connie_rider

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Re: dragging brake
« Reply #9 on: September 06, 2017, 03:57:34 pm »
Goatmar, I hope your rebuild helps.
If not: help us troubleshoot.
   Is it 1 caliper dragging or both?
  If 1, the problem is the caliper.
  If both,,,, the master cylinder is more likely to be the problem.

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Online MAN OF BLUES

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Re: dragging brake
« Reply #10 on: September 06, 2017, 08:56:07 pm »
Okay here's the plan............ rebuild them AGAIN  >:(  I changed the fluid to no avail.  Yes when I first rebuilt them I lubed seals and pistons with brake fluid.  Won't go in dry as far as I know.  :??:
Will keep you all posted.

Sure they will...  I've done a zillion dry...
If you are using OEM seals...
If you bought ebay seals from "XYZ", maybe not...
Get everything clean, and ready to shove piston in... have a clean rag on bench... spray a spritz of WD40 on the rag, run your finger tip across the spot, and around the base of the piston, and jamb it in there... don't spray it on anything else, and you are just wiping the most tiny amount that stuck to your fingertip, on the piston.. once it starts in, shove it home... oh, remove the bleeder fitting first....a nd the hose connections...

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Offline KellyfromVA

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Re: dragging brake
« Reply #11 on: September 07, 2017, 02:16:53 pm »
Okay here's the plan............ rebuild them AGAIN  >:(  I changed the fluid to no avail.  Yes when I first rebuilt them I lubed seals and pistons with brake fluid.  Won't go in dry as far as I know.  :??:
Will keep you all posted.

This may not apply to a motorcycle, but I had something similar happen with my (former) Dodge pickup.  I replaced the front calipers, pads and rotors, then started having random caliper seizing.  Not completely seized, but they would drag at the pressure applied while coming to a stop or slowing down.  After two attempts of returned/replaced calipers, a friend of mine who worked at an independent shop asked whether I'd replaced the brake hoses.  The answer was no, but I was curious how a rubber brake hose could cause the caliper to stick.  Come to find out he was right.  Older hoses when presented with new fresh brake fluid can swell internally, essentially acting like a clogged artery.  Brake fluid pressure flows one way, then the internal circumference of the hose clogs up on the master cylinder side when pressure is released.  It was the goofiest thing I'd ever seen, but replacing the hoses fixed the problem.   

Offline Redbarron

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Re: dragging brake
« Reply #12 on: September 07, 2017, 04:24:50 pm »
Hello goatmar:

KellyfromVA brings up a valid point you might, want to consider replacing your lines and rebuilding your master cylinder.

Consider the age of the vehicle it's just time.   Also when you are done back bleed the system this will push the air up and out.

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Offline m in sc

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Re: dragging brake
« Reply #13 on: September 07, 2017, 06:17:50 pm »
i agree with the post that says clogged return hole. was this checked? pull master apart and clean it. might as well rebuild while you are in there.