Front Master Cylinder - '80 GL1100


Information and questions on GL1100 Goldwings (1980-1983)
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OldguyGlen
Posts: 51
Joined: Sat Nov 24, 2018 10:55 am
Location: Mound,MN
Motorcycle: 1980 GL1100 STD/Vetters
1966 Honda 90

Front Master Cylinder - '80 GL1100

Post by OldguyGlen » Fri Mar 29, 2019 10:22 am



Rebuilding all brake components. Trouble with newly rebuilt front MC. It won't "spring back" after being depressed. It sometimes felt OK in my hand. Seemed better before I seated washer and circlip. Tried extra lube with brake fluid on seals. And silicone lube outside the secondary seal (just under the washer) Sometimes slightly better, but mostly unacceptable. It is definitely the secondary seal on the piston. Primary seal on the spring is fine.
New rebuild kit is K & L #32-1102. Reinstalled original piston... works perfect. Compared old and new. See pic below.
Pistons are slightly different. Pic shows secondary seals "out of place" for visual clarity. They are slid up away from the shoulder they seat against so you can see the difference in the piston itself. The new seal is narrower, and seats completely between the shoulder and the small rib on its piston. The old one is wider and covers up the small rib when seated.
But the big difference is diameter. It is hard to measure the OD on a rubber ring, but my best effort says the old one is 0.630" and the new one is 0.668" That's nearly 0.040" bigger.
So, do I have the wrong kit ?? Will the new one "wear in" with usage?? Should I just re-use the old one. There was no sign of leakage when I got the bike, just some corrosion around the washer. (main brake problem was totally seized calipers)
Also I tore the new outside dust boot removing this newly installed piston. How critical is the dust boot, if it's not perfect but somewhat intact?
As always, Thanks for your advice and comments.

Old, New MC pistons w/ seals displaced for clarity
Old, New MC pistons w/ seals displaced for clarity




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redbug
Posts: 496
Joined: Fri Sep 30, 2011 8:22 am
Location: Broken Arrow,Ok
Motorcycle: 1983 Gl1100I
1986 Harley FLHT

Re: Front Master Cylinder - '80 GL1100

Post by redbug » Fri Mar 29, 2019 2:02 pm

no its not the same even tho it kinda is. already wear or scoring on the new piston but really you answered your own question. I would go directly to honda and get the proper kit from them. Do we know if this is the original master cyl? Should be..OEM on the master kits thats all I will say. There are other kits out there lower price etc. Oem part for the kit is 45530-463-305 that is a updated number also. check to be sure. for reference from the goldwing service manual pg 2.9 master cyl. i.d. 0.6248-0.6265 service limit 0.6270...master cyl. piston 0.6231-0.6242 service 0.6226. Keep us posted..
" Riding on Tulsa Time "

User avatar
redbug
Posts: 496
Joined: Fri Sep 30, 2011 8:22 am
Location: Broken Arrow,Ok
Motorcycle: 1983 Gl1100I
1986 Harley FLHT

Re: Front Master Cylinder - '80 GL1100

Post by redbug » Fri Mar 29, 2019 2:03 pm

redbug wrote:
Fri Mar 29, 2019 2:02 pm
no its not the same even tho it kinda is. already wear or scoring on the new piston but really you answered your own question. I would go directly to honda and get the proper kit from them. Do we know if this is the original master cyl? Should be..OEM on the master kits thats all I will say. There are other kits out there lower price etc. Oem part for the kit is 45530-463-305 that is a updated number also. check to be sure. for reference from the goldwing service manual pg 2.9 master cyl. i.d. 0.6248-0.6265 service limit 0.6270...master cyl. piston 0.6231-0.6242 service 0.6226. Keep us posted..
The kit does come with the boot
" Riding on Tulsa Time "

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Johnyy Smoke
Posts: 701
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Location: Se Minnesota
Motorcycle: 1980 GL1100
Vetter. "Its like Deja Vu all over again".

Re: Front Master Cylinder - '80 GL1100

Post by Johnyy Smoke » Wed Apr 03, 2019 8:09 am

Put a zip tie on front brake lever after you have pumped several times. let it sit overnight. Excessive air in the brake lines is the cuprite. Regards, Johnny

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OldguyGlen
Posts: 51
Joined: Sat Nov 24, 2018 10:55 am
Location: Mound,MN
Motorcycle: 1980 GL1100 STD/Vetters
1966 Honda 90

Re: Front Master Cylinder - '80 GL1100

Post by OldguyGlen » Wed Apr 03, 2019 4:03 pm

Thanks for the responses. I reassembled with the new primary seal and spring. But used the original piston and secondary seal. MC felt much better and doesn't leak. I have bled the brakes with vacuum assistance, and have tried the old "tie it down overnite" technique, which actually does help get some of the softness out of it. Front brakes are usable now. But I can still pull the lever all the way to the handgrip if I try hard enough. Does it still have some air??

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Johnyy Smoke
Posts: 701
Joined: Sat Nov 26, 2011 6:44 am
Location: Se Minnesota
Motorcycle: 1980 GL1100
Vetter. "Its like Deja Vu all over again".

Re: Front Master Cylinder - '80 GL1100

Post by Johnyy Smoke » Sat Apr 06, 2019 10:05 pm

Probably, These brake lines can be a B****h to bleed sometimes. Did you wrap white plumbers tape around the threads of the bleeder screws? If you didn't, you will be chasing your tail. Regards, Johnny



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