Front fork leg question..

pommie john said:

Mick Hemmings uesed to do a 11 or 11.5 inch floating disc that fits the standard wheel.

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There's no shortage of disc choices available in the UK at the moment at least, and there is also a large selection of complete kits, Norvil are currently offering 16 different options from a larger cast iron disc, caliper and adaptor to a 14" lightweight double disc kit (including a new hub and fork sliders) costing £1621.50 (inc. UK tax).
Mick Hemmings and RGM both offer their own similar range of discs and kits.

fork leg question

Driggs, greetings from your humble southern servant. I realize that our inability to communicate must stress you to the limit, however, in the interest of fostering better regional relations, I will do my best not to offend or refer to "anyone up there" and to make myself as clear as possible. Yes I do agree there are regional dielects, and I quiet enjoy the opportunity to have a dialouge with anyone from any section of this great nation.

The Aussie you are refering to is Brian. He has helped a lot of Brit. guys in this area with their projects. His shop is full of contracted projects, but he is always willing to take a minute or 30, to help you out. Ring him up and give him a chance, he will give you good solid advise based on years of practical expierence.

By the way, Brian was just elected president of the 2nd oldest British club in the Atlanta area, I believe it is The British International Owners Club, not to confused with the USNOA branch in Atlanta.

Best regards,
GT
(Presently in Long Island, NY where the Italian food is wonderfull, the beer is tasty and the women are lovely).

I doesnt stress me out, and i wasnt intentionally making fun of. It struct me odd to talk to an aussie with a slight southern accent.. I wonder the troubles he must have with people down there..

Brian was very excited to talk to me too it seemed. I might give him another ring very soon and ask a couple of more questions. the work they do down there seems great and very unique.

fork leg question

Driggs, To your question at hand, I have gone several routes over the last 15 years or so to obtain better braking. In my expierence the 11mm master cyl. route worked well at first but as soon as I tried to use the new found power in real world combat, later braking, etc, the lever would come back to the bar and the fluid would start to boil. this was with the stock caliper and -3 line. I have found the cheap way to go is a later 750 Triumph master cyl(not the new stuff), seems the fulcrum point is different and I was able to purchase a dogleg lever, although the piston cyl size is the same as the Norton.
The most succesfull from all points for me was grafting an entire Darmah fromt end to a Commando with early BMW 4 pot Brembos, which bolt up with no brackets needed. Good luck

now spare my lack of certain knowledge as im only 2 years into this norton..

would i be able to use my existing triple tees, and use the legs and wheels, brakes, etc. from another more slightly modern bike? would the triple tee holes be large enough? would i be able to grind them out.. im going to look thru my manuals about the whole setup on the front end, but would it be possible??

I'm very envious of you folks that get decent front brakes on the Commando. When I was involved in test driving, we had that pathetic Italian twin-leading-shoe drum brake that was basic on the early models.

With a moderate pull on the lever, you could get it all the way to the handlebar and get no extra braking effort. I did some tests with a stress/distortion technique called "Brittle Lacquer", where you paint something like shellac over the component to be tested, then operate it. Wherever there's significant distortion, the lacquer cracks, showing the stress lines.

I tested the brake backplate this way and found that, once you'd reached a certain force on the cable, anything additional went into deformation of the backplate, not into applying more braking force.

We tried to develop a disk brake package, but the insistence of top management on a sliding disk, rather than a sliding, single-piston caliper, wasted a lot of time and money to no benefit. I left N-V before they finally figured it out.

Front fork/brake upgrade

Driggs, There are two basic aproaches to upgrading front brakes. One: Custom fit a brake system to work with the original forks. The development of the system is done by you or someone you pay, with a possible mix of effort vs money by both parties. Generally requires skills in precise measurements and design. Fabrication and modification of parts will be necessary.
TWO: Swap a complete front end that has a proper brake system. You start by measuring your bike, then look for a doner bike that has a front end with the appropriate dimensions. What is simplest is to use everything, including the triple trees. You are unlikely? to find trees with the exact bearing spacing/size to match the frame. But, if everything else is ok, then bearing adaptors may be all you will have to make and install. You want bearing spacing to be at least equal or greater than the Norton. (Don't want to cut the head). The adaptors are bored inside for the bearing and outside to fit the Norton. It may be possible to extend the adaptors far enough into the steering head, with a tight fit, to avoid welding them.
I have a photo of a Norton that we put a complete Honda GL1000 front end on. From tire to mirror! This was in 1976. Quite a change from drum to double disc. Last I heard, circa '86, the bike was sitting with a broken engine mount? in the Ft Lauderdale, FL area. It was a '71 black Fastback, originally a yellow Hi-Rider.
The newer the doner bike, the better the fork internals and brake designs. In theory.

My concern with an entire front end swap is that changing triple trees can change the geometry of the front end leading to an ill handling machine. The most elegant solution would be custom made trees that retain the same steering angle (rake and trail), but this would require the services of a competent machinist.

Some late model Italian or Ohlins or certain Japanese forks could make for better handling as well as better braking.

I think I am right in saying that in the commando triple clamps ( or yokes as we call them where I come from) the forks are not parallel to the steering stem.
I think you will have difficulty finding a replacement set that keeps the standard steering geometry.

I must add that I am not 100% certain of that, but maybe someone here can confirm or deny it.

Pommie John,
You are correct. Not only that, but there is a 1 degree difference between 750 trees and 850 trees, with a corresponding 1 degree difference in the neck angle between 750 and 850 frames to keep the wheelbase and track the same. You should not mix 750 trees with 850 frames or vice versa.

Re: Front fork/brake upgrade

Jota said:

I have a photo of a Norton that we put a complete Honda GL1000 front end on. From tire to mirror! This was in 1976. Quite a change from drum to double disc. Last I heard, circa '86, the bike was sitting with a broken engine mount? in the Ft Lauderdale, FL area. It was a '71 black Fastback, originally a yellow Hi-Rider.
The newer the doner bike, the better the fork internals and brake designs. In theory.

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would you be able to post this photo? or email it to me.. i was thinking about an gl1000 because of these really nice looking wheels i saw on ebay..
also, get me in touch with that bike owner! ill buy it! haha seriously


i think my approach may go like this..

im going to keep my triple tees.. find some legs that with the appropraite wheels, they are the same length as the stock ones (also keeps the bike at the same height).. if they are slightly thicker in diameter then ill see about getting the triple tees bored out, or if they are slightly thinner, then ill work on an adapter or a custom triple tee..

brakes are the least of my concern on my bike now, but its been on my mind a lot lately.. and seeing the bikes on southernclassiccustoms, has got me itching to do it

The fork tubes are a bit on the small side already. Don't go smaller. The Norton tubes have a taper at the top, so I doubt you will find any to match. The top tree (yoke) will have to be bored to a straight through profile. I don't recall if there is enough material to open them up for bigger diameter tubes.
It seems I should have been more descriptive when I said to look for a front end "with the appropriate dimensions", and to "measure your bike". First, look for an article or book that discusses the parameters of front end geometry, so you will know what dimensions are important. Then collect the info from the Norton shop manual. Then take a tape measure and note pad to any collection of bikes and find ones that look good to you and have reasonably close sizes. Then, look up their specs to see if they are useable. Figure out what is needed to mount them, and then calculate cost, appearance, and mount/bearing needs.
Cautions: Be aware that using upside forks may reduce steering lock due to the larger parts hitting the frame or tank. Also, avoid the front ends using 16" wheels because tire selection is limited.
The photo is a Polaroid. I'll see if a digital photo of it will work. Might take a day or so.
I lost touch with the owner. I'll try a Google. Who knows? Might turn up, but don't hold your breath!

thanx! im going to start looking into this all a little bit more seriously now.