5 Speed Commando Gearbox

Classic Norton Commando Motorcycles.

5 Speed Commando Gearbox

Postby utahnorton » Tue Sep 21, 2010 12:51 pm

I've been lurking on this website since June and finally have some time to post a couple of things-this being my first. I hope to finally finish an 850 short stroke in a Rickman frame for next race season. This will become my main BEARS/Formula 750 racebike and will allow my Commando to become my back-up racer (AHRMA 44x). Talked with KC at the Bonneville Vntage GP http://www.bonnevillevintagegp.com and he recommended the new gearboxes being made in OZ but they are a bit pricey for me right now as some medical related stuff as taken a toll on the finances. I have heard of doing a conversion putting the Triumph 5 speed gear cluster into a stock Commando gear shell (I have one of Dreers new reinforced cases). I was told to make it work you might need to make a 3/4 inch spacer of the cases between the main and inner case. I can do that with not much difficulty on my CNC mill (I can scan an outline of the case and have a program that will take the drawing and convert to G code -there is always some tweaking involved) Has anyone done this conversion and know what is invoved? Is it worth it? I'm not sure what the crank horsepower will end up being but pretty sure it will be more than my current racebike which is heavily modified. Don't want to blow up gearboxes on the track-I've already grenaded a motor once before and don't want to go through that kind of experience again even with a gearbox. :shock: I might have located a 5 speed gear cluster already but haven't purchased yet.

Cheers,

Tom
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Re: 5 Speed Commando Gearbox

Postby Vulin » Tue Sep 21, 2010 5:38 pm

I am also very interested. Also if you dont mind passing over the program for the spacer:)

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Re: 5 Speed Commando Gearbox

Postby utahnorton » Tue Sep 21, 2010 6:46 pm

I haven't spent anytime making a spacer yet-still trying to find out what else is involved in doing the conversion. Also wondering if you can still use the commando clutch basket as I already have a Maney belt drive and outrigger bearing.
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Re: 5 Speed Commando Gearbox

Postby Holmeslice » Tue Sep 21, 2010 7:40 pm

Tom,

Sounds like you're on the mend. Thanks again for letting me wind up your beautiful Commando at Miller.

The gearbox you are referring to is a Nourish Triumph 5-speed with a custom mainshaft for Commando clutch, etc. When I was looking to replace my 4-speed I phoned Dave Nourish, and he told me he didn't have any more mainshafts, and they weren't in his future to make more. And that was 3 years ago. From everything I've heard he's on his way out of biz - used to have 2 engineers with him, now just him filling orders on inventory he has on the shelves. This is the way it goes with our beloved suppliers as they retire.

Now, if I may - I have NEVER felt anything like the TT box. It's a dream. It one of those things you never knew you needed until you have it, and then can never go back. When I was offered to ride Bruce Yoxsimer's G50 in the back of my mind I mulled how I was going to handle running a Quaife again. Fortunately it was a well sorted box and caused no problems. But I do think the TT is worth every penny, and Bruce Verndon is a stand up guy. Just keep your eye on the US dollar vs. NZ Dollar, and strike when the time is right!

You can ride my bike next time!
Kenny Cummings
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Re: 5 Speed Commando Gearbox

Postby Doug MacRae » Tue Sep 21, 2010 9:36 pm

I have been using the NRE (Nourish) gearbox shell with a Triumph 5 speed cluster in it and it lasted a good 4-5 years of racing before I finally broke a gear in it - which was undoubtedly due to me doing a lousy clutchless shift. I picked a new shell just this spring but I don't know about the availability of mainshafts- that may be harder to find, but give Dave Nourish a ring and you will find out. This gearbox has worked very well for me with few problems, mainly having a bushing back out twice causing it to miss shifts. Here is a pic of it in the bike, the cover is a butchered Triumph. I would love one of Kenny's TT gearboxes but it is out of my price range. Quaifes are junk once you start making close to 70 hp at the rear wheel on the dyno- they just blow up.

Kenny I have your wrench sitting on my desk- I have to send it out to you (along with your coil)

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Re: 5 Speed Commando Gearbox

Postby Holmeslice » Wed Sep 22, 2010 7:03 am

Doug MacRae wrote:

Kenny I have your wrench sitting on my desk- I have to send it out to you (along with your coil)


Dougie! Bring it with you to Barber. C'mon... don't even begin to tell me you're not coming. We need you out there.

Gonna be a lot of good Nortons there this year, including Jamie Waters' replica of his '73 Monocoque he had Norman White recreate - the replica being incredible in its own way, mainly because it can be flogged (unlike the delicate original) and externally is almost identical to the original but with some updated motor bits inside. It'll create quite a stir. Plus, Maria Costello is coming over to ride the Dunstall Lowboy Norton 500cc Twin I've built up. She's the real deal.
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Re: 5 Speed Commando Gearbox

Postby utahnorton » Wed Sep 22, 2010 12:21 pm

Kenny,

Is there an email for Nourish? I may have to get the short stroke 850 built and in the frame with a spare stock treansmission and depending on the power it puts out on the dyno decide if I need the TT transmission. I have some Dunstall and other Norton stuff to sell-maybe I can turn them into a new transmission for the racebike. I may be heading to Barber for the first time. There would be four of us Barber newbies coming from Utah. Not sure if I have the endurance yet for a full race schedule yet but have transportation for the Commando racebike if I can make it. I was planning on keeping the same gearing I had for Miller. I came back from from Boston without a new zipper-contact off list for details. I 'm trying to post a couple photos-can't seem figure out how to upload them yet. Typical newby :oops:

Tom
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Re: 5 Speed Commando Gearbox

Postby Holmeslice » Wed Sep 22, 2010 1:37 pm

utahnorton wrote:Kenny,

Is there an email for Nourish? I may have to get the short stroke 850 built and in the frame with a spare stock treansmission and depending on the power it puts out on the dyno decide if I need the TT transmission. I have some Dunstall and other Norton stuff to sell-maybe I can turn them into a new transmission for the racebike. I may be heading to Barber for the first time. There would be four of us Barber newbies coming from Utah. Not sure if I have the endurance yet for a full race schedule yet but have transportation for the Commando racebike if I can make it. I was planning on keeping the same gearing I had for Miller. I came back from from Boston without a new zipper-contact off list for details. I 'm trying to post a couple photos-can't seem figure out how to upload them yet. Typical newby :oops:

Tom


Tom, I wouldn't even consider running a short stroke without at least a 5-speed. Your power band is much smaller than the wide rainbow a standard stroke Commando provides. In fact, if (I should say WHEN) you get a TT box for your new bike, I would go for the 6-speed. No one says you need to use all the gears!

And yes, gearing for Barber is very similar to Miller. It'll be great to see you out East.
Kenny Cummings
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-Colorado Norton Works
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Re: 5 Speed Commando Gearbox

Postby hobot » Wed Sep 22, 2010 1:55 pm

racing gearbox

01. A local innovative team of engineers in Nelson are producing racing gearbox's and casings for older British motorcycles. TT Industries who operate just around the corner from Thunderbike are headed by Bruce Verdon, who has raced in South Africa, Australia and New Zealand, displayed his gearbox's at Australian and NZ race meetings and now has geared up his manufacturing with CNC machining centres to cope with the high demand for his products. Trans Tasman Industries manufacture to order 4, 5 & 6 speed heavy duty gearboxes for use in Manx Norton, Matchless G50 or similar racing motorcycles.
They also manufacture 4 & 5 speed extra heavy duty gearboxes for use in big bore Norton Commando, Vincent HRD twins or similar high powered racing motorcycles. Using a fresh design approach, they have built a completely new and modern, quick changing & reliable gearbox. These gearboxes are available in Burman or AMC casings, and in either heat treated aluminium or magnesium. Due to the strength & reliability of these gearboxes the affordability of these gearboxes is unparalleled.
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Re: 5 Speed Commando Gearbox

Postby hobot » Wed Sep 22, 2010 1:58 pm

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Re: 5 Speed Commando Gearbox

Postby lcrken » Wed Sep 22, 2010 6:19 pm

Here's another Commando Racer with a Trilumph gearbox conversion. This one is Rob Tuluie's AHRMA racer and occasional street bike. Rob did the conversion back in the late '80s. As I recall, he somehow adapted the Norton clutch to the Triumph mainshaft, maybe with a modified clutch center. He made his own adapter. He didn't do it because he thought the Triumph was any better. He did it because it was a lot cheaper at that time than buying a Quaife 5-speed.

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Re: 5 Speed Commando Gearbox

Postby comnoz » Wed Sep 22, 2010 7:00 pm

Tom, I go with Kenny on needing at least a five speed for a shortstroke. But I do have a close ration gearset in a stock box on the shelf if you need something before you get a better one. It has a fairly big gap from first to second and the top three gears are close. It worked pretty well for Daytona. I believe they are Swanson {?} gears. Good for maybe 65- 70 horse if you use it like a gentleman. Jim
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