Binding rear brake!!

First topic message reminder :

Not having much luck! I now seem to have a binding main rear brake. I cleaned it all out & polished the outer surfaces of the pistons. That's when I thought the parking brake was the culprit! Thanks again to all who helped there.

It's worse after I start the bike because, as you all know, you gotta squeeze that brake quite a lot to activate the starter circuit. That's when she is binding tight. Now, a few thumps on the calliper with a gloved fist or a light rubber mallet does the job and after a short distance it's freed up but after I use the brake a few times it tends to lightly bind again.

I need to change brake fluid in both brakes so was thinking of I taking off the rear calliper completely for attention. Any advice anyone? Perhaps replace all seals, pull the pistons out and really polish them?

Cheers

Martyn

I wonder if swapping the pistons would still show the same delayed result from the same piston bore?

It may but I'd bet it's the seals that are dragging more on one than the other. The main point is that it really doesn't matter once the pressure is evened up on both pistons by the first one landing on the pad the other one will quickly follow.
In my old shop I used to get completely frozen pistons out of calipers by drilling the length of a bolt that would fit the banjo bolt fitting on the caliper and brazing a Zerk fitting on the bolt. Then I'd pump grease from a grease gun into the caliper. The grease gun will develop a very high pressure in the caliper pushing out the stuck pistons. Inevitably I'd have to hold one piston into the caliper to generate enough pressure to break the other one loose. The same thing seem to be happening in the subject caliper, one piston moves sooner than the other, completely normal.

Gentlemen, EVERY day is a school day! My problem seems to be solved.

I dismounted the brake calliper and took it to my local motorcycle mechanic, who also used to run a small racing team. Explained the whole sorry saga and I picked up the repaired unit today.

What I had initially done had all been correct, seemingly. Turns out that, upon putting in the new seals I had inadvertently stretched the dust seals and consequently, when the pistons went in, they caught on them, pinched them and this caused the enormous drag I continued to experience.

Calliper re-hung this morning and the binding is gone! My wheel turns freely at idle with the motor running and the brake doesn't drag any more. It's still a bit spongy, indicating some more perseverance needed to get all the air out but it's working, it's effective and it's not sticking! Yeehaaa! back on the road.

Thank you all for your help, support, advice and for being frustrated with me. In all my experience as a DIY mechanic I'd never have thought of that as a cause, nor did my brother in law who used to be a professional mechanic. Thank **** that's over!

Cheers

Martyn

Now start riding!!!!!!

Nice result.

Now go for a ride and release all that stress.

I will ride her, hopefully tomorrow. Right now it is RATHER cold and I'm tired gettin cold in my cold garage in the cold outside at this cold time of year!!

cheers

guys,

Martyn

One simple trick that often works on brakes that are spongy is to tie back the lever to keep pressure on the caliper over night. It's worked for several of that great Irish website, Steve Saunders Goldwing's members.

Thats great news

Yes, it is rather cold here too. I've just returned home from work but I still enjoy passing all cars stuck in traffic

Exavid, I'll try that, thanks RArch, it's Baltic all across the British Isles today. here at the mouth of Belfast Lough we had a high of 1c, average of 0. No wind though but that just made it feel like 'heavy' cold coming down on me. I guess lying on the garage floor didn't help!

BTW guys, see that bloody wee brake pad retainer thing that sits atop the rear calliper to stop the pads from moving excessively? It gets my vote for the Bloody Frustrating Automotive Component From Hell. Awkward bloody thing!

Exavid that wee trick worked. Just back from a test flight, all seems well. Still a bit spongy but effective. I'll keep working on it over the next few days. Quite a bit more air came out the morning.

Now I can get back to simply enjoying her and planning outings.

Quote :

My wheel turns freely at idle with the motor running and the brake doesn't drag any more.

Dramhunter: my rear wheel doesn't do that! Does it still do it now that you have had a run out and used the break?

Can anyone else confirm that their wheel spins while on ticking over on the stand?

Yes it does. It did this when I bought it, just as my son's does on his 125cc scooter. Went for a 5 mile test run, brake worked effectively (though as I said it still needs a bit more bleeding), disc was warm to touch but not roasting hot as before. I decelerated from 50mph to 10 just by closing throttle and pulling left lever only several times. No problems. Bike moves freely now when being wheeled around.

THis is the first of this kind of bike I've owned and I just logically expected that the wheel would rotate when the engine was at idle, given the type of drive it has. Something my mechanic told me he did when servicing the calliper, he left out the upper dust seals. Told me it's an old trick from his racing days and it's because his experience showed that these seals tended to trap dirt and also swell and cause drag. I'll see how it goes but mine is certainly not bragging now.

Oh I feel a job coming on...

Thanks for the feedback.

My wheel spins free on canter stand ,I can stop the spin with my hand and spins when release.

One thing that can cause either seal to swell is oil or any petroleum grease (including copper grease). They must be replaced if ever exposed even to tiny amounts. They can't be cleaned to reuse them after exposure, either.

One thought a friend had when I told of your experience was that you might have a small oil leak that is causing oil to get blown back towards the caliper - perhaps from recent engine work. It doesn't take much oil on those seals to cause a problem. That might have been your first problem. It also can swell/soften brake pads (again you must replace if exposed).

Depending on your warm-up idle speed and slight variations in the clutch shoe springs your wheel could possible rotate when on the center stand.

The wheel on my SW does that occasionally, but I can always stop it by hand. However, after everything warms up and the idle speed drops to ~1000 RPMs the wheel stops rotating.

So I guess what I'm saying here is maybe you should check your idle speed

Tim

The Honda manual at least the Goldwing one, recommends lubing the seals, pistons and bores of the brakes with new brake fluid prior to reassembling them. Makes sense since those parts will live their lives in contact with the stuff. Oil and grease aren't very compatible with DOT4. To me that "old mechanic's trick" seems like a bad idea. The two seals tend to hold the piston away from contact with the cylinder bore, with only one seal in the bore it's easier for the piston to become cocked a bit. Also the outer seal is supposed to wipe the piston clean and prevent dirt entry while the inner seal is more to prevent leakage when there's pressure on the brake fluid. Leaking brake fluid onto the rotor and pads is a real good way to have ineffective brakes.

Guys, excellent feedback as usual.

When I replaced the seals I noticed that there had not been any dust seals installed in the first instance. I also lubricated them with DOT4. It seems, according to Davey the mechanic, that I hadn't quite installed the dust seals properly (though I thought I had) and the pistons caught on them when reinserted, nipped them and began dragging against them.

I take the point about the reasons for dust seals but right at this moment, I feel that if the solution works, I'll leave it alone. Perhaps later I may buy another set of seals and install the dust ones and see what happens, knowing what I did wrong last time.

As for wheel turning when motor running, it certainly happens when the bike is on centre stand and motor is at warming up speed. Don't know if it happens at normal idle speed but I'll check, sorry for the confusion there. I remember remarking upon it to myself when I bought her because by old Beemer's back wheel used to do the same though that was simply from vibration, nothing to do with the drive.

Well she's been operational again for two weeks and things are fine. The linked brake works ok though, despite extensive and patient bleeding, it still has a different feel to before. Not spongy but very much lighter, lever easier to pull but with less feel to it though the brake is activating and doing it's job.

Anyway, I've sold her! Got tempted by a 2010 model in black being sold by a friend. I had always intended the 2001 machine to be an experiment to see if I liked this kind of motorcycle and then change to a younger one in a year or so. This one came up early but I couldn't resist.

On the test ride I immediately noticed refinements. The drive seems to take up earlier and smoother and doesn't cut out so suddenly as the 2001. Brakes are even better and I feel suspension and frame have been tweaked as the 2010 steers very positively, feels a bit more rigid and it doesn't seem to feel all those road defects as much as the 2001.

It has just a standard screen, I'll likely fit the GIVI Airflow. But riding it wasn't too bad with regards to wind draft. The high Honda screen on my 2001 actually creates too much of a still air zone behind it because I can't get enough airflow through my helmet vents to keep the visor clear.

Anyway, I'll post a few pictures of it soon, haven't picked it up yet and I got a good price for my 2001. SWings are something of a rarity here and hard to find.

Thanks again,
Cheers