1978 GL1000 brakes

[pogo3033]

Hi, I have a 1978 GL1000 that has sat for a long period of time. I have removed and rebuilt the front and rear master cylinders. My current problem is with the rear master cylinder, I cannot get it to bleed. I have had the piston out several times, polished the inside of the cylinder and reassembled. When I push the piston down it will stay stuck at the bottom and not return so I can see that it will not pump fluid if it stays stuck at the bottom of the stroke. My question is how free should the piston be? Should the pressure from the spring return the piston to the stop washer? I can use air pressure to pop it back up but the first time I push on the pedal the piston stays at the bottom of it's stroke.

I have assembled it according to the Honda service manual. Actually I have two GL1000's and the same problem exists on both,,,what can I do to free up the piston and primary cup?

[WingAdmin]

Hi, I have a 1978 GL1000 that has sat for a long period of time. I have removed and rebuilt the front and rear master cylinders. My current problem is with the rear master cylinder, I cannot get it to bleed. I have had the piston out several times, polished the inside of the cylinder and reassembled. When I push the piston down it will stay stuck at the bottom and not return so I can see that it will not pump fluid if it stays stuck at the bottom of the stroke. My question is how free should the piston be? Should the pressure from the spring return the piston to the stop washer? I can use air pressure to pop it back up but the first time I push on the pedal the piston stays at the bottom of it's stroke.

I have assembled it according to the Honda service manual. Actually I have two GL1000's and the same problem exists on both,,,what can I do to free up the piston and primary cup?

The spring should easily push the piston back out - in fact, you should have a considerable amount of force from that spring - enough that it is very difficult to depress it with just your finger. Something is definitely wrong.

[Placerville]

I'm not sure I'm on the right track for this one but, is it possible that the 'spooge' hole may be the problem? If it's clogged, it would prevent (in this case) air from entering the cylinder thus restricting the release of the piston. Both the front and rear masters have them. (Very small hole at lower right.)

[WingAdmin]

I'm not sure I'm on the right track for this one but, is it possible that the 'spooge' hole may be the problem? If it's clogged, it would prevent (in this case) air from entering the cylinder thus restricting the release of the piston. Both the front and rear masters have them. (Very small hole at lower right.)

Air is not supposed to enter the cylinder. The master cylinder piston should retract easily from the spring. If there is a vacuum, it should suck fluid from the reservoir to fill the cylinder, not air.

[Placerville]

I'm not sure I'm on the right track for this one but, is it possible that the 'spooge' hole may be the problem? If it's clogged, it would prevent (in this case) air from entering the cylinder thus restricting the release of the piston. Both the front and rear masters have them. (Very small hole at lower right.)

Air is not supposed to enter the cylinder. The master cylinder piston should retract easily from the spring. If there is a vacuum, it should suck fluid from the reservoir to fill the cylinder, not air.

I Agree. He has his M/C off the bike and they're not filled with fluid at this time. In my description, I said, "in this case" meaning, that the hole would now be sucking air instead of fluid. Therefore, is the piston not able to spring back because the hole is clogged?

[WingAdmin]

No, the very small hole on the right is the one that allows fluid to return from the caliper when it heats up (or when the caliper piston is retracted). The larger hole on the left is the one that leads to the reservoir.

[Placerville]

Well, then I'm stumped on this one. Odd that he has the same problem with two bikes.

[pogo3033]

Thanks for the advice and I'm still workin' on it. I will take some pictures and post them later.

****

[pogo3033]

Well I worked and worked on the old master cylinder for the GL1000 but never could get it to work. I finally ordered a used one from an Ebay store that the guy said was frozen and was just for parts, so when I got it I tore it apart and cleaned it and reassembled it and hooked it up and it worked fine. So I got the problem fixed on one of the bikes, the other one I ordered an aftermarket master cylinder that was meant for a Honda 500cc something or other and made a bracket to mount it and it solved my problem with the original equipment master cylinders. I think I spent more time on the brakes than anything else.

[SnoBrdr]

Well I worked and worked on the old master cylinder for the GL1000 but never could get it to work. I finally ordered a used one from an Ebay store that the guy said was frozen and was just for parts, so when I got it I tore it apart and cleaned it and reassembled it and hooked it up and it worked fine. So I got the problem fixed on one of the bikes, the other one I ordered an aftermarket master cylinder that was meant for a Honda 500cc something or other and made a bracket to mount it and it solved my problem with the original equipment master cylinders. I think I spent more time on the brakes than anything else.

That's the rear?

How well does it work and where did you get it from.

Pics of the bracket too please !

A link of some kind would be very helpful.

[pogo3033]

[pogo3033]

http://www.amazon.com/shops/A1EPE8GMWC6 ... ingdocs-20


Link address for 50 Caliber Racing Products through Amazon.

$40 was what I paid
I have not ridden the bike as of yet but with it on the center stand the brake worked just fine. I used a spare one piece brake line that was for a front brake and did away with the 2 piece Honda brake line.
Mount was one of the original mount holes for the Honda master cylinder and a piece of 1/8" X 1 1/2" flat aluminum stock that I had on hand but came either from Lowes or Home Depot..

Picture on the web, the reason I ordered this one was that it had the dimensions shown.

[SnoBrdr]

http://www.amazon.com/shops/A1EPE8GMWC6QK5/ref=aag_d_sh


Link address for 50 Caliber Racing Products through Amazon.

$40 was what I paid
I have not ridden the bike as of yet but with it on the center stand the brake worked just fine. I used a spare one piece brake line that was for a front brake and did away with the 2 piece Honda brake line.
Mount was one of the original mount holes for the Honda master cylinder and a piece of 1/8" X 1 1/2" flat aluminum stock that I had on hand but came either from Lowes or Home Depot..

Rear master cylinder..jpg

Looks pretty sweet, hope it works fine.

I asked cause I am always looking forward as far as needing parts.