• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Brake pad drag.

  • Thread starter Thread starter spyug
  • Start date Start date
S

spyug

Guest
I need my memory refreshed as its been awhile since I've installed new pads. Should there be any appreciable drag as in the wheel will turn ok but will not spin freely? There are no weird noises or scoring of the disks, it all appears normal.

I didn't install the pads myself but they were freshly installed last Sept and there are only a few hundred Km on them.There is still a lot of material on them. I did, last week, install new ss brake lines and fresh fluid but I did not dissassemble or clean the calipers or the masters.

Now reading through the archives, I started to think that the return port in the master might be clogged and the test for that is to release pressure by opening a bleed nipple which I did. There was no change to this drag, indicating that it's not a hydraulic issue more a mechanical problem.

Before I rip into the calipers am I getting paranoid or is there something I should be concerned about?

Cheers.
 
how "draggy" are they? can you turn the wheel by hand, or push the bike with no extra effort? if yes on those 2 i wouldn't worry.
if no on any of those 2 i would pull the calipers off and clean all the slidey bits and lube them up......
 
Which bike are these on? Single piston or opposed piston calipers? Are both pads dragging, or just one side?

So the question comes down to either the pistons aren't retracting enough or the caliper(s) won't center on the disc(s).

You can hit the caliper with a deadblow (or rubber) hammer on the piston, sliding it towards the disk, then tap it back lightly with from the inside to retract your piston. If that frees it up, pump the brake back up and see if the drag returns.

If the piston retracts fine and it's still dragging, it's not uncommon for people to fail to properly grease the slider pins, per Max's suggestion above. Synthetic brake grease recommended.
 
I am watching this thread with great interest as I am having this issue as well. I've ridden 250km since installing new pads and they are still dragging. When I back up the bike the brakes squeal too. Before installing new pads these issues didn't exist. This is on a 1979 GS1000S.
 
This is on the new to me FZ with dual piston dual calipers. Knowing the state of the master cylinders and fluids when I was changing the brake lines I don't doubt now that parts were not properly greased, so I'll start there.

The wheel does turn but it requires a bit of force to overcome the inertia. It will not spin, unlike the back wheel that will, even with a chain and sprocket.

After seeing the crap job done, it is my intention to clean and rebuild the complete brake system but I don't, at present have the time and I'm trying to avoid more work.

I'll let you know what I find.

Thanks for the input.
 
Also note that these brakes do not have any mechanism to retract the piston(s) into the calipers. They rely on the slight imperfections of the disc surface to 'kick' the pads and push the pistons back. A tiny bit of drag is normal, although a lot of drag should NOT persist after you've ridden the bike. (AJ, who once worked on a brake drag detection system for a major automotive brake manufacturer that was developing low-drag brakes for improved fuel mileage.)
 
AJ said:
Also note that these brakes do not have any mechanism to retract the piston(s) into the calipers. They rely on the slight imperfections of the disc surface to 'kick' the pads and push the pistons back.
Click to expand...
Besides the slight imperfections of the disc surface, they do also rely just a bit on the deformation of the square-section o-ring between the caliper and the piston. When pressure is applied, the o-ring deforms a bit as the piston is pushed out. When pressure is released, it straightens up, but that distance tends to be measured in thousandths of an inch, and precious FEW of them (maybe 1 or 2).

.
 
spyug said:
This is on the new to me FZ with dual piston dual calipers. Knowing the state of the master cylinders and fluids when I was changing the brake lines I don't doubt now that parts were not properly greased, so I'll start there.

The wheel does turn but it requires a bit of force to overcome the inertia. It will not spin, unlike the back wheel that will, even with a chain and sprocket.

After seeing the crap job done, it is my intention to clean and rebuild the complete brake system but I don't, at present have the time and I'm trying to avoid more work.

I'll let you know what I find.

Thanks for the input.
Click to expand...

(EDIT: I just caught that the FZ is a 1985 FZ, not a modern one. My response below probably does not apply, but still something that might apply to somebody someday.)

Ohhhh, the FZ. You don't have a speedo drive on the front wheel, do you? (it's a takeoff on the countershaft sprocket, right?)

I once installed a new front tire on my Busa and the brakes dragged terribly. They wouldn't free up even when banged with a deadblow mallet. A little research and I discovered that I had mounted the tire backwards and flipped the wheel. It looks the same from either side and the rotation mark is very subtle. But it is not symmetric side-to-side, just off by x thousandths. I remounted the tire (%&$#!), reinstalled the wheel correctly, and all was good. Just a thought.
 
Last edited:
Steve said:
Besides the slight imperfections of the disc surface, they do also rely just a bit on the deformation of the square-section o-ring between the caliper and the piston. When pressure is applied, the o-ring deforms a bit as the piston is pushed out. When pressure is released, it straightens up, but that distance tends to be measured in thousandths of an inch, and precious FEW of them (maybe 1 or 2).

.
Click to expand...
You are correct, sir! The brakes I was working on actually had special springs to move the pads back quite further, but you are right about the o-rings. Bravo!
 
i had problems a while back where the pads were too thick compared to the originals, so the pistons weren't retracting far enough to allow the pads to lose the grip on the discs.
the pads are a b1tch to sand or file back, so i had to remove some of the material that was on the pistons. worked fine after that
 
Thanks guys. My next move, tomorrow, will be to pull the calipers and have a look at the bits and pieces. I'm thinking that a) the pads are too thick or b) the parts have not been properly greased maybe even c) a combination of both.

I'll let you know what I find.
 
Dunno about the FZ ones, but most calipers are fairly easy to disassemble, inspect, and reassemble. On a bike that's new to me, I'd do it even if they seemed to work fine!
 
On a bike that's new to me, I'd do it even if they seemed to work fine!
Click to expand...

You know I generally do as well but I was led to believe (with documentation from the "professional" shop that did the work) these brakes had been cleaned and rebuilt last Sept, less than 600Km ago. Only when I got to changing the brake hoses did I realise nothing had been done other than swapping of pads. The one time I break my rule and I get caught out.

That won't happen again.
 
Well, true to form, the right caliper is fudged. One piston is stuck and doesn't move at all and is holding the pad tight to the disk. I was able to get the other piston out with compressed air but this one doesn't budge. I've split the caliper and once I figure out how to block the transfer ports, I try more air or possibly a grease gun. I've used both methods with about equal success.

The piston that came out was not too bad and cleaned up nicely but there was quite a bit of gunge around the seals. The seals themselves look ok once cleaned but i'll replace them.

So note to self, "Always check the calipers on new to you bikes".

I'll let you know how this goes.

Spyug
 
spyug said:
Well, true to form, the right caliper is fudged. One piston is stuck and doesn't move at all and is holding the pad tight to the disk. I was able to get the other piston out with compressed air but this one doesn't budge. I've split the caliper and once I figure out how to block the transfer ports, I try more air or possibly a grease gun. I've used both methods with about equal success.

The piston that came out was not too bad and cleaned up nicely but there was quite a bit of gunge around the seals. The seals themselves look ok once cleaned but i'll replace them.

So note to self, "Always check the calipers on new to you bikes".

I'll let you know how this goes.

Spyug
Click to expand...
Sometimes the simplest answer is the correct answer, even if the "evidence" (your shop receipt) indicates otherwise. At least you now have a clear path to salvation.

That old FZ should be a fun bike when you're done with it. A riding buddy of mine had one in the early 1990's as we ripped through northwest Jersey together.
 
This may work...

This may work...

I have had success unsticking a piston that was badly stuck...
The air wouldn't pop it out...so I used a clamp (woodworking style) and put presure on the piston to go back in...
Once you get it moving a little bit -- it will eventually pop out with compressed air...
But mind where your fingers are! The last one I did flew across the room as the popsicle sticks (2) of them fell out of the caliper and didn't stop the piston from popping out with force...
 
Well I did get them all cleaned up and working as they should so that's one less worry. And I made a big mental note to never believe anything I maybe told or hear and always check things over myself......especially brakes.

thanks for all the input folks.

spyug
 
The pin mentioned in the earlier post always needs a good cleaning before applying grease.
I lightly engaged mine as you would a bit in a drill and used a green dish scrubby while turning it with the drill.
Worth checking that the pins are not warped by rolling on a mirror and checking.
 
You must log in or register to reply here.
Back
Top