brakes binding

[Vern Groves]

I went for a ride yesterday on my '86 GoldWing Interstate. Riding along a lake shore, I came upon a suddenly stopped vehicle in the road. I had to put a quick bind on the brakes (front and rear). I didn't lock them up, but a quick stop. Just down the road, afterwards, I noticed that the bike was dragging a great deal and so I stopped. The brakes - front right disc and rear disc - were both hot on the caliper body and on the discs themselves. I waited and then I tried riding slowly down the rode. Eventually they loosened up and I was back okay. I hesitated to use my front brake from there onto home.

Does anyone have any ideas on how to prevent this or what exactly happened?

thanks! Vern

[WingAdmin]

I can tell you exactly what happened, and how to fix it.

In your rear brake master cylinder, where it connects to the reservoir are two ports - the main port and a tiny return port (on the right):



When you let off the brake, the slight movement of the rotors back and forth push the pads (and the pistons) back into the caliper. This pushes the brake fluid back up the brake lines, into the master cylinder piston area, and finally, through that tiny port into the brake reservoir.

This tiny return port gets clogged with sediment and deposits over time. When you do a hard stop, a tremendous amount of heat is generated. This heats the brake fluid, making it expand drastically. Because your return port is mostly (or completely) plugged, there is nowhere for this brake fluid to go - so it does the only thing it can do, it pushes the pistons out, which pushes the brake pads against the rotors, causing them to drag. This in turn generates more heat, which makes the problem even worse. In Goldwings 1983 and older, the rear brake pedal operates the rear brake and one front caliper, so both of those brake swill drag.

You have to drain your rear brake system of brake fluid, then remove and disassemble the rear master cylinder. You will need a very thin wire - like a guitar string, or a piece clipped from a wire brush - to poke into the hole and clean it out:





Have a look at: How to rebuild your rear master cylinder for more details.

[maestro319]

Wow!! I am always amazed at what you guys on this forum know. Pictures are a great plus too!! Maybe I'll get enough courage to work on my bike myself rather than pay a garage to do it. IF and when that happens, I'll turn to this forum and the guys on it to help.

[Vern Groves]

What you told me makes perfect sense. I haven't done the work on the master cylinder yet, but now I've got a plan and will do it soon. Thanks so much for your insight and helpful pictures. You guys are super. I am amazed at the knowledge available on this site. Thanks! Vern

[tricky]

If that doesnt do the trick another simple cause of binding brakes are the slide/mounting bolts on the caliper.

If routine maintenance is not performed these bolts can get very cruddy and when the brakes are applied the bolts do not allow the caliper to move off the rotor sufficiently to allow full wheel movement.

to check, grip the caliper and attempt to move sideways, you should feel a very tiny movement in the caliper.

I use never seize to lube the caliper bolts.

Also make sure the dust covers on the anti dive and calipers are in good shape... replace if they are cracked or split.

Its a 25/26 year old bike, maybe you got it because the previous owners got tired of it.

[WingAdmin]

Chances are, however, because it is his rear brake AND the front right brake, that it is something common to both (i.e. the master cylinder). It could of course be caliper pins on just those calipers binding, but far more likely that it's the return port in the master cylinder.

[tricky]

I have seen bikes with brakes in such bad condition you would wonder how they ever get to stop.

If one brake is bad usually the others are in the same condition, probably the brake hoses are the originals so deterioration on the inner lining will cause the problems in the master cylinder.

If the fluid is in such bad condition as to plug up the return duct then maintenance on the all parts of the brakes is required.
Is that going to happen..... likely as not.

[GWLDL]

With great instructions here-I rebuilt the calipers-both Fronts and the Rear. New brake lines all around-HEL. New Brake pads. Bled brakes-all seems good-except-rear. Bled Front 1st then rear.
Went for 2 hours ride yesterday-and check the disks to see if brakes were binding/dragging. Front disk-normal temp-only slight warm. Rear disk was hot. Rear brake pads o' dragging. It seems that the PO had this same problem-cause when I took the rear caliper off for re-build-there was a lot less pad remaining-than the fronts-and-they seemed like they were binding.
My Questions-
1. Does anyone else agree that it seems like the famous 'return port' is clogged in the Rear M/C?
2. How do you get the hard brake line loose from the Rear M/C. There seems no way to reach those 2 -10mm line fittings with a open end or a line wrench. I have the passenger Foot rest off. Bolts loose on the M/C....
Any help great..

[tricky]

I did it two times on two bikes......

If you remove the battery and battery box you can access a bolt that holds the clamp in place.... been a while..... I think... I guess it's memory loss kicking in

Item 29 and item 14

Oops your talking about the master cylinder

[tricky]

I have never had a reason to remove my master cylinder all I can do is give you the instructions from a manual

[seabee_]

Flushing the hydraulics every 2 yrs(minimum) will help cut down the possibilities of the clogging. Brake fluid is cheap, compared to parts replacement. Don't forget to flush out the clutch, too. Happy riding.

When I flush out the brakes on cars, fluids that have been in there more than 100,000 miles come out as a green color. Comes from absorbing moisture and copper from the brake lines.

[GWLDL]

Tricky, and Seebea
Thanks for the input. I'm taking out the rear M/C to clean the port inside the reservoir. Have to take the reservoir off the rear M/C to get to that port. I have been following the 'reuild your rear M/C' on this site. Just can't seem to get a good angle on those flare fittings.
Most likely will have to go over the caliper work again to see whether or not one of the seals rolled over. The pistons push the pads fine, and do release some-so tire can turn-but seems that they should let go more-and allow more free tire spin.

[seabee_]

Some guys buy one flare nut wrench that has a flex head on it. Makes it easier to get at the rear m/c brake lines. Also make sure the caliper slide pins are clean and lubed so the calipers move freely.

[GWLDL]

Bent-end Flare nut wrench worked!! Re-bled the system-again.Thanks seebea

Went out to bike-after work last night- to see if I could get more free wheel spin from the Font Tire and Rear Tire.
I take it that they should spin more freely than they do. So...thinking..I decided just to squeeze the calipers by hand-both fronts and rear. After that squeeze-both wheels will free spin-as much as the tires/bearing allow. When I apply the brakes-front and rear-they all go back to binding. Is there something wrong with a piston(s)? I have cleared out both Front and Rear M/C return ports-they were not plugged-but I ran a B guitar string wire through them-they are clear. Hopefully you gurus here can help me figure this one out. This site is great-thanks for any response.

[virgilmobile]

It could be aluminum oxidation under the caliper piston seals.It WILL cause the piston to stick in the bore as it swells up and binds the "O" ring.
Personally,I'd be pulling all the calipers apart,removing the piston and "O" ring seals,scraping the crud from under it.You'll be amazed how much there is in there.
Be certain the piston will slide smooth into the bottom of the bore before you reassemble the caliper.
On my 1100,1200,and the 1500,I had this problem.
Each one had copious amounts lodged in the seal groove.
I simply removed it with a bent hook tool(careful not to scrape up the aluminum casting),blew it clean,polished the pistons and re-used the seal.That was many miles ago.

[WingAdmin]

Yup, exactly what virgil said. I had the same problem on my 1100, just copious amounts of buildup causing the pistons to seize in place. You need to clean all of the crud out of there, polish and clean everything so that the pistons will slide easily to the bottom of the cylinders without binding, then replace the seals and put it all back together.

[zamboni920]

Now, what if the pistons are so stuck you can't get them out of the bores? That is how mine were when I bought the bike. Air pressure(with a wood block between the pistons) would not budge them. I remounted the calipers on the bike, less brake pads, and with a thin wood shim between the pistons and the disc. I pumped the rear brake pedal, and they immediately started to push out. Problem is, you have to make sure both can be removed at the same time. If only one gets loose, and you remove it, the other one is stuck and brake fluid will have free flow, no pressure. So, pump the pedal, then squeeze it together again with c-clamp, pump again, squeeze, etc,etc. Hopefully you will loosen them up enough to be able to remove them both on the bench....It worked for me.
Now it is happening again on mine(probably did not do good enough last time) , so I see a good spring cleaning of calipers and masters coming up.

[WingAdmin]

I've used the same technique many times, only using a piece of flat welding stock:



Just put it in place of the brake pads:



Then start pumping the brakes. The piston that moves more easily will come out first until it contacts the steel, then the other one will get pumped out:



The steel is thin enough that when both pistons contact it, the pistons can then be easily removed by hand.

[GWLDL]

Thanks for all the input.
Just a note...I have rebuilt both Fronts, and Rear Caliper with kits from Parts N More-like WingAdmin advised in his rebuild caliper instructions (awesome). All new seals and dust seals, banjo bolts, crush washers, bleed valves. Cleaned all the pistons-600 and 1500 wet/dry to get them clean clean clean-there was no "gold shine" look to any of the pistons. I know that all the channels for the o-rings are clear of build-up-I cleaned them. I cleaned all the cylinders as well. All new brake lines front and back. Bleeds out really well.
My thoughts now are...that of the 6 pistons that I put back into the 3 calipers upon reassembly..I think 2 or maybe 3 went in....too tight. How much force should be needed to get the piston back into the cylinder?
Some went in really easy...others not. Should you be able to insert it with just hand pressure?
I used a short piece of pipe that fit into the pistons perfectly-so that I did not get them in sideways. Like I said....I think a couple went in harder than the others. I will be taking it all apart again this week to find out...any insights would be great.
Thanks.

[virgilmobile]

When ready and lubed with brake fluid,all mine could be pushed in by my thumbs.Firm yes ,but not really difficult.

[WingAdmin]

The pistons should definitely be able to be inserted by hand. My test is to insert the pistons BEFORE the replacement seals have been installed into the cylinders. The pistons should drop all the way in without any help from you. If they don't, and the pistons are clean, it usually means there is still residue on the inside of the cylinder that needs to be cleaned off.

[GWLDL]

I know that Front M/C is clean and rebuilt so...This weekend I decided that I would just go after the front left caliper. I took it apart and cleaned it-again. It is very very clean. The seals and dust rings are new. I've lubed the piston and seals with brake fluid. Put it all back to together and still it is binding the disc when installed. With the other front caliper removed-I can not get 2 full spins of the tire-after putting this caliper back on-bled correctly. It seems that the whole caliper itself is hanging up or the pistons??? When I take this caliper off-remove the brake pads, and squeeze the lever I can see the pistons moving out and back (a little)-seems like enough to be right...but still bindage...

1. Is the piston seal directional (dust seal is in right). Is one of the inner edges supposed to be up or down? do I have them in wrong?

2. The lower caliper bracket-part #18 45113-MB7-610 in the Front Caliper diag. Is that supposed to be flat? Or do those have some special twist/bend? Both of the front calipers have these, and both seem to have a different bend/twist.

Getting frustrated, riding time is good right now. Anyone with any help is greatly appreciated. Thanks.

[virgilmobile]

Ok..I've been following your steps and nothing seem out of the ordinary.

However,here are some things to check and consider.

1st..Get the brake to bind the wheel and gently open the bleeder valve.
If opening it relieves pressure and the wheel turns again it's not bleeding the pressure back off.
If the lever doesn't allow the master to full stroke,it could cause this.
2nd..... Assuming that it's not hydraulic related,then it must be mechanical in some way.
The caliper,holder and pads must hang free and exactly parallel with the rotor.
If a pad is worn on one side making it wedge shape or the pins,guide pins,pivot point,or caliper frame are bent,there will be a angular binding.

To identify,loosen the caliper and apply a little brake and release till it just starts to drag and release the brake.Get right down and look at it.Look for any gaps that are not equal... like the pad touching on the top but not the bottom.
Remove the lower pin so the whole assembly can pivot from the top.
Does it move free?
Put the caliper back in place without the lower pin and operate the brake and watch the caliper.
Does it twist.?

[GWLDL]

Virgil-thanks! The wheel does move after cracking the bleed valve. So the pressure is not backing off. I did clean the return port in the MC when I did the rebuild. Do you think this is a MC problem? Or do you think that the lever is a replacement-that is not moving the MC piston enough/too much?

[seabee_]

When you cleaned the return port, did you use a wire and blow out the hole? Shined a light to make sure everything was cleaned? It's acting like the port is still clogged. I would try cleaning it again before replacing anything.