GL1000/CB900C Fork Tubes

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broshae
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GL1000/CB900C Fork Tubes

#1

Post by broshae »

In addition to my '79 GL1000, I've got a fork from a '77 GL1000 which I am fitting to another bike. I know the 75-78 forks do not use a lower slider, and have read that the fork lowers (cases) can wear out, after which they are scrap. My question:

Has anyone used tubes from a CB900C in a GL1000 fork? These tubes are also 37mm but use a lower slider. Is it possible? Has it been done? Are there problems with compatibility that I'm not thinking about?

Thanks,
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Re: GL1000/CB900C Fork Tubes

#2

Post by Old Fogey »

I think you have the terminology a little mixed. The slider ( or case as Honda calls it) is the part that holds the axle and slides up and down the fork tube. I think what you are referring to is the slider bearing. The Wing has a top bearing which is not replaceable, no lower bearing. Having said that, the slider lasts for a very long time usually.
The CB900C does have replaceable bearings, but the biggest problem would be the leading axle position, which I guess (since I've never done it) would screw up the handling somewhat. Also I think the fork tubes are longer.
The CB900F might be a better solution.
You could always keep it pure Wing by fitting a set of GL1100 or even 1200 forks.
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Re: GL1000/CB900C Fork Tubes

#3

Post by Shadowjack »

I put a CB900C front end on my 1000/1200 project. Thought about mixing tubes, triples, and brakes, but found that while the tube diameter is the same, the width of the triples is narrower on the 900, and so the threaded axle is too short to use with the 1000 triples.
The 900 triples have different upper and lower offsets, so the tubes rake steeper. The leading axle recovers some of that and makes the trail about the same, I think, but don't quote me. I assume this was all just a styling exercise.
There's no real difference between this one and my stock '77 in regards to handling. Might be just a bit slower steering. The point of the change was to use the newer brake designs.
broshae
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Re: GL1000/CB900C Fork Tubes

#4

Post by broshae »

Thanks for the feedback,

I agree the terminology is not universal. But Honda does not help with the terms they use (eg. CASE, R. FR. FORK (LOWER) 51421-371-003 - or - BUSH, SLIDER 51415-461-003). These are the terms from the Honda parts diagrams for the 1977 GL1000 "right case" and the 1982 CB900C lower "slider" or "bearing", respectively. I've always known these fork parts as tubes, lowers, and bushings.

I'm trying to keep it GL1000 for all the lower-half components (lowers, brakes) because I want to keep the spoked wheel. I thought if the CB900C fork tubes would be a drop-in fit, then it would be simpler than trying to mix/match/space the wheel and brake components between the 1000 wheel and the lowers/sliders/cases from another model.

Since I work at a company with a pretty skookum machine shop, I will probably work with them to build a custom triple. This GL1000 fork will be going on a CB750 sidecar rig. The GL1000 fork has about 10mm less offset than the 750 fork, which will slow the steering. A custom triple clamp will bring the steering geometry back.

Was just checking to see if this had already been attempted by anyone.
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Re: GL1000/CB900C Fork Tubes

#5

Post by Rat »

Gotta love a 'skookum' machine shop ...

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Re: GL1000/CB900C Fork Tubes

#6

Post by desertrefugee »

Rat wrote: Fri Jan 14, 2022 7:16 pm Gird anim-cheers1
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Re: GL1000/CB900C Fork Tubes

#7

Post by Whiskerfish »

lolol lolol lolol lolol lolol
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Re: GL1000/CB900C Fork Tubes

#8

Post by Rat »

Sorry ... fixed ...

G anim-cheers1 rd
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Re: GL1000/CB900C Fork Tubes

#9

Post by Sidecar Bob »

broshae wrote: Fri Jan 14, 2022 11:10 am I agree the terminology is not universal. But Honda does not help with the terms they use (eg. CASE, R. FR. FORK (LOWER) 51421-371-003 - or - BUSH, SLIDER 51415-461-003). These are the terms from the Honda parts diagrams for the 1977 GL1000 "right case" and the 1982 CB900C lower "slider" or "bearing", respectively. I've always known these fork parts as tubes, lowers, and bushings.
"BUSH, SLIDER" = slider bush. A bush or bushing is a type of bearing and the slider is the part of the fork leg that slides up & down so Honda does call it what it is.

BTW: The upper tube is called a stanchion.
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Re: GL1000/CB900C Fork Tubes

#10

Post by taunusrainer »

In case someone might need them:
I got four NOS sliders and four NOS fork tubes for the GL1000.
Contact me at monaco2021@gmx.de as I do not chime in here often.
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