'81 Interstate front brake spongy lever issues..


Information and questions on GL1100 Goldwings (1980-1983)
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DeansZG
Posts: 3
Joined: Mon Sep 16, 2013 11:45 am
Location: Southgate, Michigan
Motorcycle: 1981 GL1100A Interstate
2004 Kawasaki ZZR1200
1978 Yamaha ISDT175

'81 Interstate front brake spongy lever issues..

Postby DeansZG » Sun Sep 28, 2014 12:27 pm



The front master cylinder on my '81 Interstate started leaking & instead of rebuilding it, because of the scuzzy reservoir & the overpriced re-build kits, I bought a brand new m/c off of flea-bay. The seller listed it as a direct replacement for "80-'81 goldwings. Got it mounted up, bled it, pressurized w/ a nice & firm lever.....

Now comes the fun stuff... connected all the lines, going thru the prcedure of evacuating the air from the lines & have gone thru damn near a pint of brake fluid trying to get a firm lever again to no avail. :head bang:
Used a mity-vac to help eliminate all air from the lines & tried the rubber-band method of pulling the lever & leaving it set overnite also.
Oh, before you ask, the lines are in good shape also, no swelling, look to be replaced w/in the last 5 yrs. or so.

The bore on the new mastercylinder is 2 mm smaller than the oem ( 14mm vs. 16mm ). Could this be the reason for no lever firmness??? I'm at my wits end trying to solve this....

Thanx in advance...



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WingAdmin
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Re: '81 Interstate front brake spongy lever issues..

Postby WingAdmin » Mon Sep 29, 2014 12:24 pm

You should have more lever travel (because you have to push the smaller diameter piston further to achieve the same volume output), but it should not be soft as a result. I suspect you still have air trapped somewhere.

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RBGERSON
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had every year from 75 to 83

Re: '81 Interstate front brake spongy lever issues..

Postby RBGERSON » Mon Sep 29, 2014 3:33 pm

maybe a crack the bolt at the top banjo to let air out??
HAD LOTS OF GOLDWING 75-83
NOW INTO 1500'S..RIDING A 1998 SE

FAIR WINDS,
RB

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bruce swaybill
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Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: '81 Interstate front brake spongy lever issues..

Postby bruce swaybill » Mon Sep 29, 2014 10:17 pm

You should try reverse bleeding the system. Search on this site. If nothing, google it. There are lots of videos on youtube. Be sure to turn the bars while on the side stand. You want the master cylinder above the banjo bolt before you start the reverse bleed. It worked great for me when I rebuilt everything.

Bruce S.
Have a nice day! :)

moritz1100
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Re: '81 Interstate front brake spongy lever issues..

Postby moritz1100 » Tue Sep 30, 2014 7:46 am

I had the same experience recently, in the end I put the blame on the brake splitter. The part mounted on the forks that takes the single brake line from the master cylinder and splits the fluid into the 2 hoses that serve either brake caliper. It's a great place for air to get trapped no matter how much fluid you bleed through it, ime anyway. I fitted a racing kit, a double banjo bolt for your master cylinder and 2 braided hoses, eliminating that brake splitter from the system. Result is well worth the money(around €75). Razor sharp brakes and easy bleeding.

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bruce swaybill
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Re: '81 Interstate front brake spongy lever issues..

Postby bruce swaybill » Wed Oct 01, 2014 10:19 am

Actually, when I replaced the lines with H-E-L ss lines, I also used a double banjo bolt at the master cylinder and two long lines down to the calipers, eliminating that anoying 1-into-2 setup you mentioned. Much simpler ....

Bruce S.
Have a nice day! :)

DeansZG
Posts: 3
Joined: Mon Sep 16, 2013 11:45 am
Location: Southgate, Michigan
Motorcycle: 1981 GL1100A Interstate
2004 Kawasaki ZZR1200
1978 Yamaha ISDT175

Re: '81 Interstate front brake spongy lever issues..

Postby DeansZG » Wed Oct 01, 2014 9:56 pm

bruce swaybill wrote:Actually, when I replaced the lines with H-E-L ss lines, I also used a double banjo bolt at the master cylinder and two long lines down to the calipers, eliminating that anoying 1-into-2 setup you mentioned. Much simpler ....

Bruce S.



Great Idea! Although I did regain most of the braking action at the lever again, it's still not as firm as my sportbike.
My next step is to do a brake hose update & will go that route. Thanks!




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