Fading rear brake pedal on 02 model


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Flyn Tiger
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Fading rear brake pedal on 02 model

Postby Flyn Tiger » Sun Feb 23, 2014 10:39 pm



I have a 02 with ABS and here is the problem. If the front and rear brakes are applied at the same time, the rear pedal works just fine and applies at a higher height. If I am sitting still and I allow the bike to roll backwards even 6 inches and apply the rear brake only, the brake pedal will lower 2 inches or so but the brakes will still work. If riding, and I apply the rear brake only, the pedal goes way down, (or so it seems) if I let up and hit it again the pedal is firm as if it is pumping up. Even when the pedal goes down I still have good brakes...just have to push further down than usual. Brakes have been bled and I have good pads all around, fluids are good and fresh. Is this just something I will have to live with or is some something wrong? I don't know if there is a valve that separates the front from the back in something like that so any info on this would be great. Shop says it is normal on the 02 but right now it seems alittle worse than normal.



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cihilb
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Re: Fading rear brake pedal on 02 model

Postby cihilb » Mon Feb 24, 2014 6:57 pm

Try hanging a 5 lb weight on the rear brake pedal overnight. I had the same problem on my '04 and that cured it.

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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Mon Feb 24, 2014 11:16 pm

Seriously??? I'm not sure how that will help other than if there is some air in the line somewhere it will mash it out???? Where did you hear that remedy from? In any case I went out and pressed the rear brake and down it went...second time, firm pedal. So I have it set up so it will be depressed until I remove it. Only thing I did not mention on my opening post was I did change out my front left brake pads just before this problem got worse but that should not have anything to do with this problem. I took off the old pads, pushed the pistons back and installed the new ones. Hey I'm willing to try anything, just want to know what is causing this. Also thanks for you input on the cd player also.

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Re: Fading rear brake pedal on 02 model

Postby WingAdmin » Tue Feb 25, 2014 10:37 am

Flyn Tiger wrote:Seriously??? I'm not sure how that will help other than if there is some air in the line somewhere it will mash it out???? Where did you hear that remedy from? In any case I went out and pressed the rear brake and down it went...second time, firm pedal. So I have it set up so it will be depressed until I remove it. Only thing I did not mention on my opening post was I did change out my front left brake pads just before this problem got worse but that should not have anything to do with this problem. I took off the old pads, pushed the pistons back and installed the new ones. Hey I'm willing to try anything, just want to know what is causing this. Also thanks for you input on the cd player also.


Exactly, if there is air in the line, it compresses the bubble, making it small enough that it can migrate upward to the master cylinder where it might otherwise possibly not be able to.

Pushing the pistons in like you describe forces a large amount of brake fluid up the narrow brake lines and into the master cylinder. This is dirty, contaminated brake fluid that normally lives in the caliper, where it is subjected to many heating cycles and any foreign particles that get past the piston seals. All dirt and sludge particles in the brake system are also drawn down by gravity and collect down there. By forcing the pistons into their bore, you're forcing all of this dirty, contaminated brake fluid back up into the master cylinder, where it clogs the return port and causes you to have to eventually tear down the master cylinder and clean it out. That's why when you put new brake pads on, you should open the bleeder valve before retracting the pistons, so that the dirty fluid inside the caliper squirts out (well, squirts into a collection jar - not onto the plastic bits!) and is then replaced with fresh fluid that you add to the reservoir.

That said, I have encountered exactly the behavior you are describing - soft brakes on the initial push, hard brakes on the second push. In the case I'm thinking of, it was failed brake caliper piston seals, and it started immediately after new brake pads had been installed.

The pistons were filthy - having collected tons of grime and road grit. Because the old pads were worn, the pistons were extended, exposing a fair amount of the piston to the outside world. This exposed area of the pistons were covered in crud. The owner put new pads on, and simply shoved the pistons back into the calipers. The crud on the pistons got shoved up against the piston seals as the pistons were retracted, so the seals were now pressing against a layer of crud instead of the bare metal of the pistons.

When the brakes were applied, the pistons would push outward, like they should. However, instead of sliding along the surface of the piston, the seals would stretch outward, holding onto the crud. If you pumped the brakes again, the piston would push out even farther, engaging the brakes fully. However, when you let go of the brakes, the stretched seals would pull the pistons back into the bore, retracting them farther than they would normally be retracted by the tiny runout of the rotor. This meant the next time the brakes were applied, the piston would have farther to travel before engaging the brakes - which gave you the soft brakes.

Rebuilding the calipers solved the problem.

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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Tue Feb 25, 2014 4:05 pm

Ok I have read this a couple of times and understand the thinking here but here are my questions......if I replaced the front left pad, why is the rear brake fading when only the rear brake is applied. Now if I apply the front AND rear brakes at the same time, the rear brake is fine. It is only when I apply the rear only and on the first push that the brake pedal fades. Next question is which piston seals do you replace? All on front and rear, just rear, just front? I can understand them wearing out.....the bike is 12 yrs old and I have almost 65,000 miles on it.

Oh I took out the wood I had depressing the rear brake all night and the brake still faded......oh well I tried.....

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Fatwing Chris
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Re: Fading rear brake pedal on 02 model

Postby Fatwing Chris » Tue Feb 25, 2014 6:00 pm

The front and back are linked together.The hand brake operates one front caliper and the foot brake operates one front and the rear.Sure sounds like it has air in the system.Probably from what Scott has described.The only working properly going ahead may have something to do with the anti-dive valve having air in it.Bike has to be going ahead for the ADV to actuate.
If I'da known it would last this long,I'da taken better care of it.
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Flyn Tiger
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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Tue Feb 25, 2014 7:41 pm

Took my pad to my local wing shop and let them ride the bike and read the post and we looked some things over. I keep my bike pretty clean. There is hardly any grit in around the pistons but hey who is to say that some had not gotten in. It seems that if air was getting in around the pistons there would be a fluid leak which in turn my levels would drop. That is not happening front or rear. A new anti dive valve was installed a good while back when I was looking at updating the front suspension because we thought there was too much dive in the front end under braking. Ended up replacing that and adding new Progressive springs was the ticket to making that bike handle like a dream. So with that being said my next move is to do a brake line flush and add all new fluids to ensure all air is out if that is the problem. If that dont work, guess well move on to the next level to try and figure this out. As I said I still have brakes but when that pedal goes down like that you cant help but wonder when will you press that pedal and maybe nothing happen?? You are definately giving me areas to look at so any thoughts are appreciated. Keep them coming and I'll let you know what works. Now I just got to get someone to press that pedal so I can bleed those lines.......

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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Tue Feb 25, 2014 7:47 pm

@Fatwing.....on the adv, would deactivation or the bike rolling back a few inches cause the rear pedal to fade. I haven't felt that on any other wing. Oh also found out there was a recall on the pvc valve back in 03 or 04. I got to check to see if that was taken care of back then by having Honda check the Vin number.

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Fatwing Chris
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Re: Fading rear brake pedal on 02 model

Postby Fatwing Chris » Tue Feb 25, 2014 9:12 pm

Flyn Tiger wrote:@Fatwing.....on the adv, would deactivation or the bike rolling back a few inches cause the rear pedal to fade. I haven't felt that on any other wing. Oh also found out there was a recall on the pvc valve back in 03 or 04. I got to check to see if that was taken care of back then by having Honda check the Vin number.


More of a guess than anything at this point.My thinking is that the ADV is attached to the LH caliper & back caliper and when it activates there could be some backpressure from resistance in the front forks trying to collapse.You maybe getting a harder pedal because of this backpressure that you wouldn't get with the bike rolling backwards or rolling it back is releiving that backpressure due to the fork pressure releiving.Like I said it's more of a guess at this point.I'd have to go back and read how the whole brake/ADV sys works together.You would probably only notice this if there was air in the system,that's why you haven't felt it on any other Wing.That and the fact that only the 1800 has this setup with this particular ADV.There are a couple of Techs On GL1800Riders.com that could probably help you out more than I can as I'm fairly new to the 1800 myself.

BTW That brake recall was for the rear brakes dragging and overheating.
If I'da known it would last this long,I'da taken better care of it.
Chris
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jlkeene
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Re: Fading rear brake pedal on 02 model

Postby jlkeene » Wed Feb 26, 2014 5:51 pm

If you have bleed the brakes according to the manual you should also do these two additional steps to be sure you have no residual air in the rear system!!
1 - Pressure bleeding the lower Junction block. (Upper left side of frame sitting on bike). Follow rubber hose from Secondary master cylinder to the Junction block.
2 - Pressure Bleed the top Banjo bolt on the Secondary Master Cylinder. (To be sure any air is completely out)

John
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Flyn Tiger
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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Wed Feb 26, 2014 7:16 pm

Going to have to look those two areas up in my manual. Do these areas have pressure release points and when bleeding these areas I'm guessing you use pressure with the rear brake? All of my problem is in the rear brake and I wondered about any other areas in the system that air could be trapped.

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Re: Fading rear brake pedal on 02 model

Postby Dusty Boots » Thu Feb 27, 2014 6:39 pm

Installing a set of Speed Bleeders makes bleeding the calipers and clutch an easy 1 man job! ;)

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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Thu Feb 27, 2014 8:30 pm

:D Well just got in from bleeding the brakes again. Went through the first 4 of the 5 steps, clear fluid coming through. Got to step #5 (top rear outlet) and bloop! What looked like a wad of air bubbles came through...then clear fluid. Kept bleeding then again 2 more times, BLOOP.....more air bubbles. I don't know where they were hung up but after those 3 times of the bubbles coming through I didn't get anymore. Now I had to fill the rear fluid holder 3 times and we went through the press, release sequence many times and as I said I don't know where they were hung up but my brakes are now working perfectly. ;) Moral of this story is I guess when bleeding out the brakes, go through the process many times, especially on the top rear, to make sure all of the air is out of the system.

Thanks to all of you who came up with alot of good ideas of places to look to help me solve this problem of the rear pedal fading. I appreciate it! :D

Going to have to check in to these brake bleeders because the top rear is the hardest one to get to and deal with. Thanks for that idea also.

Flyn Tiger
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Re: Fading rear brake pedal on 02 model

Postby Flyn Tiger » Thu Feb 27, 2014 8:36 pm

Dusty Boots, those speed bleeders look like the thing to have, especially on the top rear of the Goldwing.




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