GL1800Riders Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
When I retired almost 2 years ago I left my 02 GL1800 in the garage for at least 10 months before I rode her. The ride over to my destination was uneventfull. I left the bike parked out on the driveway of my sons house. When I went to return home I noticed the front brake lever was getting harder, i.e. no play before applying pressure. Eventually I noticed it was getting harder to accelerate and when letting off the throttle the bike acted like the brakes were being applied without actually using the brake lever. I had to get off the freeway quickly because this situation was deteriorating quickly. Had the bike towed home. I ended up completely flushing the front the rear brake systems but did not check and see if the problem was corrected for sometime. Many months later finally got around to checking the brakes again, Just by riding around neighborhood still experianced the front brake problem. Checked maintenance manual to ensure I was properly flushing, which I was. Reflushed front and rear brake system. This still has not corrected the problem. I checked front brake pads and found that they were in bad shape probably from overheating when engaged against rotor under bike power. Anyway, during the replacement of the pads I noticed the left caliper pistons could be pushed in with no problem and new pads were put in. When getting to the right side the middle piston, which is accuated by the rear brakes could be pushed in but the other 2 pistons could not be pushed simultaneously. I had to loosen the top bleeder in order to get the 2 other pistons pushed in. I have flushed the front brakes again, using fresh DOT 4 brake fluid every time, with no change in the problem. When I take it out for a test run and I notice the brake lever getting hard after several hard braking events I parked the bike and loosened and retighten the top bleeder on the right caliper and all was back to normal. Once back home I removed the pads to see if I could push the top and bottom pistons in. I was unable to do so without loosening the top bleeder. I'm thinking the problem is with the caliper and I am thinking about replacing it. Any thoughts from you quys would be much appreciated.

John
 

·
Registered
Joined
·
878 Posts
It appears that fluid flow in the reverse direction is restricted at some point... Can you verify the middle piston on the front left does push back in okay??? If so then the master cylinder is not likely at fault..
What may be the case here is corrosion behind the piston seals causing them to bind on the caliper piston... This corrosion must be completely removed and a new seal installed (I put caliper grease in the groove to help prevent corrosion reoccurrence)...

If the above is not the case then it has to be a restriction somewhere else in the return path... Verify the little port in the master cylinder is not obstructed
 

·
GL1800 Doctor
Joined
·
20,471 Posts
You probably have rust on the pistons that are sticking. When you release the lever there is a little negative pressure that slightly pulls the pads away from the rotor. If there's any corrosion on the pistons where they are trying to slide on the seals, they will stick and not retract. New pistons, seals, and dust seals should fix it.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #4
The middle piston pushes in just fine. The top and bottom piston will push in just fine so long as the bleed screw is open. So, based on that I do not believe there is corrosion problem with the pistons. So what is the reverse path for the fluid to the master cylinder?

John
 

·
Registered
Joined
·
320 Posts
In light of you being able to push the piston back in when you crack the bleed screw, I wouldn't think it rust or corrosion on the caliper pistons.... I would check for an occlusion in the brake line feeding those caliper pistons.
 

·
Registered
Joined
·
24,624 Posts
In light of you being able to push the piston back in when you crack the bleed screw, I wouldn't think it rust or corrosion on the caliper pistons.... I would check for an occlusion in the brake line feeding those caliper pistons.
I agree. Just the same I would clean it all, and install new seals .

But I think it is occlusioned too, stopped up. When the bike sat it stopped up at the caliper.
 

·
GL1800 Doctor
Joined
·
20,471 Posts
Well, keep in mind that the 2 outer pistons are in a different hydraulic circuit than the center one. I think if the front master cylinder has a problem you would see the middle piston on the left caliper sticking, since it is in the same circuit as the 2 outer right ones. With the bike sitting for the unused time, I would still tear down both calipers and go thru them, if you're going to keep the bike for awhile, you might as well do it right once. :thumbup:
 

·
Registered
Joined
·
878 Posts
I asked the middle piston on the "LEFT" caliper be checked... It appears you checked the middle piston on the right caliper... I think you'll find the left side middle piston is also sticking... It appears a good look (or rebuild) of the front master cylinder may be in your future...
 

·
Registered
Joined
·
7 Posts
Discussion Starter #9
Ed Z

I believe that when I raplaced the left side pads the middle piston on that caliper was not a problem but I will double check.

Thanks everyone for your inputs. I'm currently leaning to some kind of occlusion in the right caliper but that could change if the left caliper middle piston behaves like the upper and lower pistons in the right caliper.

John
 

·
Registered
Joined
·
80 Posts
I have seen this same problem in automotive brakes. the brake line at the caliper was plugged near the caliper and not allowing the fliud pressure to release. or possible that the delay valve has plugged.
 

·
I U Turn
Joined
·
888 Posts
Check the pins to see if they are froze up.The tow halfs of the calipers might not be sliding.
****
 

·
Banned
Joined
·
11,396 Posts
Ed Z

I believe that when I raplaced the left side pads the middle piston on that caliper was not a problem but I will double check.

Thanks everyone for your inputs. I'm currently leaning to some kind of occlusion in the right caliper but that could change if the left caliper middle piston behaves like the upper and lower pistons in the right caliper.

John
John.with the front wheel dragging,open the banjo bolt at the master cyl and see if the caliper relaxes it's grip on the rotor?. If so your restriction is in the master.
If that's not it then go from one brake line to the next opening each banjo bolt on the oposite end of the caliper to rule out a collasped internal line.
 

·
Vendor
Joined
·
18,104 Posts
Can we assume that when you are retracting the pistons that the caps are off the master cylinders?
 

·
Registered
Joined
·
7 Posts
Discussion Starter #15
I have not got back to looking at this problem until today. when the problem occurs all I have to do is crack open thene close upper bleed screw on the right caliper at which time the front tire rotates freely. I removed the upper banjo bolt on the right caliper this morning and found nothing wrong with the bolt itself. However when looking into the caliper hole it threads into with a flash light I saw what looks like corrosion down inside the hole. Based on this observation I am going to replace the right side caliper.
 

·
Registered
Joined
·
878 Posts
If it's in there then likely corrosion is in the master cylinder as well... And quite possibly in the left side caliper as well... Likely you could just do a rebuild on the calipers and the master (cleaning out all the corrosion of course) and be just fine... If you go that route be sure to clean the seal grooves very well... Even a tad of corrosion there will cause the pistons to bind...
 

·
Registered
Joined
·
7,616 Posts
Here is likely your problem. You will need to get 16gauge stranded wire and take one strand from it. Insert the strand in the little hole under the baffle (not the big hole). If that little hole gets plugged with something, the lines will not release pressure. The baffle is there because that hole squirts fluid when you release the lever and you don't want that squirt to breach the surface and cause bubbles/foam to form in the reservoir. Same reason those little plastic "boats" float in there... .keeps foam from forming when the bars vibrate the surface of the fluid.

 

·
Registered
Joined
·
1,714 Posts
Waldo, thanks for the picture and explanation, your post answers two questions about that reservoir I've had for a while.
 

·
Registered
Joined
·
17,034 Posts
Dang Waldo! And all this time I thought the little white "surf board" was intended to make a nice visible white line in the sight window to tell the fluid level.

prs
 

·
Registered
Joined
·
7,616 Posts
Dang Waldo! And all this time I thought the little white "surf board" was intended to make a nice visible white line in the sight window to tell the fluid level.

prs
If you've removed and replaced as many sight windows as I have (we used to plate reservoirs) you would know that the white board is not visible from the outside. I believe that because of the absence of this "board" in the rear MC and its location inside the hot engine side cover you will get problems with your brake pedal being spongy from foam in the fluid back there.

I know about that little hole too, because if your clutch one gets plugged, your clutch will start to slip. Been that way with Honda for a long time.
 
1 - 20 of 21 Posts
Top