1986 R80 g/s Twin disc conversion

Damien

Damien

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I have recently acquired most of the parts to convert my mono to a twin disc.
However, when I put the disc on the wheel, it wont fit through the forks. Both discs are identical.

So should one of them have a different throw or am I doing something wrong?
I loosened off the fork brace but that made no difference. All I can think of now is to try it with both calipers off.

Any suggestions kindly received.
 
Special hub required for twin disc g/s (2 ribbed). That or or a standard 3 ribbed hub and a machine shop

Nick
 
It would appear that I have a 3 ribbed hub, i.e. 3 ribs running circumferentially around the hub.

What machining is required to convert to a twin disc set up?
 
Hi, just checked mine again.i have a2 rib hub.apparently off a police bike.

Howmuch has a twindisc set up, he got this from thunder,who got it from another gser.
I seem to think it was a 3rib when we met and compared them.

a close friend has a 3 rib hub with twindisc set up.he did it years ago and cant fully remeber,but thinks he took a mill of each disc and made wheel spacers.
It can be done .

i know his and my front wheels are a tight fit to get between the forks.
you need one caliper off to get the wheel off properly.

in the fork legs you will see a small recess notch.the rivets on the discs just clear this.
you may need to take a bit more of the fork leg notch ,to clear the rivets.
 
I had another go and yes I can get the wheel through the forks but its very tight and wont rotate. I noticed the flat spots for the rivets so the clearance must be minimal.

If anyone has a 3 rib hub converted and would like to measure it, I would be grateful.

I imagine it would be better to mill down the hub rather than touch the discs.

I have also noticed that there are spacers between the original caliper and the fork leg- I don't know if this is standard but it does not show up on the parts fiche.
 
I see the spacers now. I will organise some tomorrow for the left side.

With the two discs assembled on the wheel, the distance between outside faces of the discs is 138mm. I see on ADV rider someone has measured their twin disc distance as 135.5. So If I was to mill 2.5mm off the left side of the hub, the twin discs would fit and keep the right side standard.

Does this seem reasonable? Or are there other pitfalls I have not considered?

Also, could some one with a twin disc set up please verify the distance between the outside faces of their discs before I go machining?

Many thanks,

Damien
 
colt said:
paging that shiny G/Ser How Much:comfort
he will be able to measure up hopefully.
Click to expand...

well remembered Jason

mine is a 3 rib hub, and it is frightening how tight a fit it all is..

there is only 1.25mm clearance between the disc and the inside of the forkleg on each side and there is a "flat" on the inside of each fork leg to clear the rivets... and it does only just clear the rivets:eek:

calipers have specers tween caliper and fork leg, spacers are 5.25mm thick

i swear if the wheel bearings wear.. the disks will slice into the fork legs


623426177_bF8UG-M.jpg



hm
 
mine measures 135 accross the outside faces of the disks

same size spacers on both calipers


hm
 
Thanks for all the replies, its great to have so much good advice on hand.

I will get some spacers made up to the same size as How Much has, and then have a measure up. I will probably then get the disc milled down to the required size, at least that way I can revert to original in the event of a cock-up.

I will keep you posted.

Damien
 
nick.ct said:
Special hub required for twin disc g/s (2 ribbed). That or or a standard 3 ribbed hub and a machine shop

Nick
Click to expand...

Hello.
Do you mean that the "retrofit kit" included a new hub (2 ribs) to replace the standard one?
And what about wheel axle spacers? The hub on a standard G/S is about 6mm offset to the left, so you need to move the wheel 3mm to the right to make it centered.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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