Custom Cafe style 72 Commando

ianashdown · Dec 30, 2014

Hi,

I've just acquired a 72 Commando basket case that I'm thinking of building in to a Cafe style bike. I have a set of nice Morris Mag wheels that I think will look really good but that will dictate a disc on the rear, which I don't mind, but what is the best way to achieve this? I thought I could maybe fit a Mk3 swing arm, caliper etc. obviously there will need to be some engineering to mount a master cylinder etc, but I think that will be not too difficult.

Are there any other suggestions? Has anyone been down this path?

Thanks,

Ian

bwolfie · Dec 30, 2014

Many have ventured down this path. I am using Kimtab magnesium rims with Ducati rotors and Grimeca calipers, all custom mounts.

Watch out, the build can get out of control quite easily, lots of good stuff out there.

trident sam · Dec 31, 2014

ianashdown said:
Hi,

I've just acquired a 72 Commando basket case that I'm thinking of building in to a Cafe style bike. I have a set of nice Morris Mag wheels that I think will look really good but that will dictate a disc on the rear, which I don't mind, but what is the best way to achieve this? I thought I could maybe fit a Mk3 swing arm, caliper etc. obviously there will need to be some engineering to mount a master cylinder etc, but I think that will be not too difficult.

Are there any other suggestions? Has anyone been down this path?

Thanks,

Ian

I'm sure you've thought about it, but sorting some kind of rear wheel shock absorber will be the most difficult part.
The aftermarket wheels I have on one of my Commandos are British made Campbrays, that use a qd wheel as original, but very different in construction. They have metalastic bushes pressed into the main part of the hub, that mount on spindles on the sprocket carrier side of the hub.
good luck with it.
sam

acotrel · Dec 31, 2014

For the rear caliper mount, I use a swivelled aluminium plate which hangs off a spacer on the axle. I have a rod with rose joints on each end which secures the caliper in relation to the rear of the engine plates. It is set up so that when the rear brake is used the force on the caliper tends to depress the rear of the bike. I use the old style dominator or manx clutch with the cush centre. Better for the cush to be in the rear hub.

acotrel · Dec 31, 2014

bwolfie said:
Many have ventured down this path. I am using Kimtab magnesium rims with Ducati rotors and Grimeca calipers, all custom mounts.

Really beautiful bike, Brett. - Gave me a bit of the old feeling I'd forgotten about.

Watch out, the build can get out of control quite easily, lots of good stuff out there.

ianashdown · Dec 31, 2014

I'm new to Nortons so please forgive my simplistic questions, I'm much more familiar with Triumphs.

I assume the question about the shock-absorber is what I would refer to as the 'Cush-drive' which on triumphs is in the primary drive. I guess on Nortons it's in the rear wheel and if I go for a Mag wheel I'd have to come up with some solution. Others have put Mag wheels on Nortons; did they engineer something or just ignore the problem I wonder? How critical is the soft coupling?

Ian

Hobot · Dec 31, 2014

Ian this is a Commando specific forum so this subject has been beaten to death for decades to state > there is hard firm noncontroversial evidence of both perfect tolerance to almost immediate destruction by those running w/o cushions to those always using cushions. This includes all out racers > so flip a coin or follow your best philosophical route. Takes a robust cushion system to take hard Norton hits but all modern wheels you adapt will have more than adequate cush hubs with rear disc brake mount. My logic guided by tapping a hammer on anvil or a hard air tire, with my head off to the side.

74ok · Dec 31, 2014

ianashdown said:
I'm new to Nortons so please forgive my simplistic questions, I'm much more familiar with Triumphs.

I assume the question about the shock-absorber is what I would refer to as the 'Cush-drive' which on triumphs is in the primary drive. I guess on Nortons it's in the rear wheel and if I go for a Mag wheel I'd have to come up with some solution. Others have put Mag wheels on Nortons; did they engineer something or just ignore the problem I wonder? How critical is the soft coupling?

Ian

early commando's and prior had no cush

ianashdown · Dec 31, 2014

"early commando's and prior had no

How early?

The Morris Mag wheels I have in mind are hardly modern; NOS circ 1978-ish I think. There is no carrier for bearings, disc brake or sprocket - all these will have to be designed and made. Now the design brief includes a cush drive! As a mechanical design engineer I can see the preference for some such arrangement, just having only Triumph experience to date assumed it was in the primary drive area. Should have thought this through a bit better!

Ian

Fast Eddie · Jan 1, 2015

Where there's a will there's a way...

Check this out, it may fit your wheels, or be adaptable, or just inspiration to do something similar:

http://www.robnorthtriples.com/parts/re ... drive.aspx

ianashdown · Jan 1, 2015

That's kinda funny! I know Rob North, he lives not too far from me in San Diego. I thought I could just pop down the road an go see him. Then I discover that this is the company he sold and it's back in England! Not so close!!

I wonder if the real Rob North might have some ideas . . .

This is the general idea though . . .

Ian

triumph2 · Jan 1, 2015

Or go this route?

bwolfie · Jan 1, 2015

triumph2 said:
Or go this route?

That looks like a Yamaha XS 650 rotor on the front there.

Also Like the SU carb.

ianashdown · Jan 1, 2015

That's a good looking solution at the front, how did you work out the rear?

Thanks,

Ian

triumph2 · Jan 1, 2015

The front Wheel is from a Yamaha RD400 and is a straight bolt on. You need only make up spacers for the Norton axle to centralise the wheel and if necessary shim the caliper. The rear wheel is from a Yamaha SR500 and required a bit of machining. It has a cush drive in the hub and a disc brake. I had to machine the sprocket carrier to align the chain. the master cylinder and caliper were from a Yammy Seca I think and is handy because it uses a cable and so I was able to use the stock brake pedal and cable. My memory is a bit rusty on this as I did the work in about 1984.

ianashdown · Jan 2, 2015

Having done some research it seems like it shouldn't be too difficult do design in some sort of Cush arrangement in conjunction with the bearing and sprocket carriers. There seem to be a few commercially available bushings or a complete molded ring arrangement that could be incorporated.

If you google 'John Player Norton' and look at images you should find a very nice JPN replica on a Mk3 with Morris Mag (might be Lester) wheels. This is my inspiration . . .

Ian

o1racing03 · Nov 26, 2015

bwolfie said:
Many have ventured down this path. I am using Kimtab magnesium rims with Ducati rotors and Grimeca calipers, all custom mounts.

Watch out, the build can get out of control quite easily, lots of good stuff out there.

I'm curious about the Ducati rotors you used. Are they the same Honda 6 bolt 74mm bolt pattern? I thought the Ducati was an 80mm bolt pattern. I'm doing a Kimtab/disc brake set upon my 70 Triumph Tiger right now.

o1racing03 · Nov 26, 2015

triumph2 said:
The front Wheel is from a Yamaha RD400 and is a straight bolt on. You need only make up spacers for the Norton axle to centralise the wheel and if necessary shim the caliper. The rear wheel is from a Yamaha SR500 and required a bit of machining. It has a cush drive in the hub and a disc brake. I had to machine the sprocket carrier to align the chain. the master cylinder and caliper were from a Yammy Seca I think and is handy because it uses a cable and so I was able to use the stock brake pedal and cable. My memory is a bit rusty on this as I did the work in about 1984.

I like the idea of a cable actuated master cylinder. I'm curious what you used, Seca came out in 83 and all the early Seca rear master cylinders connect directly to the pedal with no cable

tricatcent · Nov 27, 2015

http://s901.photobucket.com/user/tricat ... 4.jpg.html

Here is a picture of my Norton with Yamaha wheels. A friend gave me the wheels. It has a MKIII swing arm and rear brake. I had to narrow the Yamaha speedo drive a bit to get it to fit. I guess the RD 400 front end is wider than the Norton one. I used a Kawasaki speedometer. I made an aluminum holder for it so it looks like a Norton one. It is nice not to have to use the Smiths drive on the back wheel. They are not that long lasting.

It handles and brakes really well. I has an 18" front wheel, the only problem I have noticed with that is that the bike is lower. Nortons don't really have much ground clearance anyway so you don't want to lose any. People say these wheels are very heavy, and the bike won't handle right, but try riding behind me and then tell me what you think! I use a 12mm master cylinder on the front brake and no other improvement is required.

I used the standard Yamaha sprocket, which is a lot smaller than the Norton one so with a 19 tooth gearbox sprocket the ratio was the same as a 22 tooth sprocket with the standard Norton one. The standard 850 engine pulls that gearing with ease. I don't see the point of lower gearing on an 850. If you want more acceleration just leave it in a lower gear longer. With the wheel centered I found the rear sprocket was lined up with the gearbox sprocket within .040". I moved the wheel .020 to one side so that both the wheel and sprocket alignment would be within .020". The Yamaha uses the same size axles as the Norton.

The wheels are powder coated. If I did it again I would just paint the wheels. The rear wheel had to be done about three times sanding smooth each time before the finish came out smooth. It was because gas kept coming out of the castings. The gas came from the oil that had soaked into the metal over the years, when the wheels were baked the gas was forced out. With paint that would not be a problem. I think that black and gold is the best color for a Norton. I painted my tank black even though it is made of aluminum. When it comes to color everyone has their own preference.

The bike started out as a Café, with an XR750 seat, but now it has a dual seal and luggage for touring.

Nigel

lcrken · Nov 27, 2015

Ian, I posted a couple pictures here of a cush drive I made for a Marvic mag wheel for a Norton monoshock racer:

1973-850-mono-shock-showa-forks-t7974-105.html?hilit=cush%20drive

It's a pretty simple system, but worked well. I had a similar cush drive on my Commando PR, but don't seem to have a good picture of it.

I do have this picture of the bike that shows the rear disk brake setup I used. The swinging arm isn't stock, but I'm sure you could come up with a similar system on your bike. You could also make it work using a MK3 swinging arm, but that's a really heavy setup. If you can fabricate that sort of thing, you can make something much lighter. I don't recall what caliper and bracket I used (It was over 20 years ago), probably something off an early TZ250, but you could find all sorts of calipers on modern bikes that would work well.

If you wanted to use a MK3 swinging arm, you could just make your own caliper bracket to take whatever caliper you liked. This is a picture of one I did this year on one of my MK3s using a Spondon caliper.

Ken

Custom Cafe style 72 Commando

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