Close ratio gear set

Thanks for the replies chaps, couple of things.
The bike is not really used as a town bike, I have a T140 for that, the Commandos are used for distance work, even nowadays I can't think of a better bike to go long distances on.

Andy ----- is your Quafe a 5 speed with kickstart facility ? do you mind me asking what the cost was .

Martin ----- yes I do really love my Commandos but a TTI is out the question for a while, as I'm still helping to pay off Neil Beadling's mortgage :wink:

sam

Sam,
At least the mortgage with Neil is money well spent. My OIF T160 is full of Neils goodies. I really don't think you would be disappointed with the RGM CR cluster, as it's not a town bike. I guess there is only one way to find out!!
Martyn.

Hi Sam

Sorry to take so long to chip in. A 5 speed is the only way to go. Micky Hemmings lists the 5 speed with kickstart option. I haven't looked at the price for a few years. Hopefully the kickstart area has been looked at. If not keep an eye on the bearing & bushes on the layshaft & the bush in the kickstart shaft bush. As you may know the Rickman did both the 1st gears in the Quaife 4 speed box. Unfortunately they hav'nt been made for years. This little disaster has taught me a lot. For example the 5 speed Quaife in my 750 race bike is a road box ie Kickstart. It had been built by Micky with a conversion to race spec. The inner case has a steel plate machined & fitted to take a bearing & do away with all the steel bushes & the kickstart shaft. The lay shaft has to be ground to suit the bearing. My 4 speed came apart as the shafts have too much movement especially disliking down changes under engine braking.

The interesting story is that when I was talking to Mick about asking Quaife for a price to make me 2 gears he told me that he broke his gearboxes in the period (they all did) & as he needed to be out there racing he fitted a standard box!!! His proddie bike race win results are staggering to think that he must have won a fair few races with a standard box fitted is staggering.

Please note though that this is racing. I am sure a 4 speed would be fine on a road bike. I was offered another 4 speed for £850 if it was a 5 speed I would have gone for it. I have not found a 5 speed for under £1100 & that is too much.

Chris

Yes, mine is a road-spec box (for my Proddy Racer replica).
You'd have to talk to Mick (Angie!) regarding the current price, but it was a shade over £2.5K if I remember correctly, a couple of years back.
He only seems to build them to order, so plan ahead. It took me a while to 'bite the bullet', but the 4-speed ratios leave loads to be desired for open road work.
funnily enough, I also regard my Bonnie as a great town bike, but it feels like I'm thrashing it at anything over 70 - not so with the Commandos

Once you got gear charts , for what teeth mixed , and coustom fitted ratios to purpose .
Trgic seeing a wall with over fifty rusty Norton Cogs on Nails .

ANYWAY , generally , If you want 23 Teeth for 130 mph or 3500 @ 65 mph , then maybe you need a LOWER first gear .
particularly if your suberban or the sheds up a grassy hill . Which is where a 5 speed'd be handy , Gear 24 t , std 4 speed ratios ,
plus a lower 1st for starting / getting away on hills . PARTICULARLY if you do the two up touring & luggage thing .

Thus therefore and so on , YOU calculate what rpms per mph in TOP , then speed in gears 9 each ) to chose required cog tooth numbers .
Norton ratios are within cooee of triumph 4 speed .

Triumh supplied std. , close , and Trials . ( like I.S.D.T. ) the TRIALS had 1 & 2 LOW ,( and Close ) and 3 & 4 High ( and Close ).
if you think about this , youd have a gear in the middle - thus Five Speeds . or Close with a gear under , ditto . Even on Std
if your a autobahn freak . Or a couple more .

The nature of dual purpose riding off road requires a wide range of gear ratios, from a stump pulling first gear that will let you climb a cliff, to a relaxed over-drive top gear to get you home on the road. Modern Adventure bikes cover this ground with 6 speed gearboxes, so how did the Triumph riders of old cope with only four relatively close spaced gears

Click to expand...

http://www.adventuresnz.com/isdt-triumph---3.html

maybe someone can find a Norton Gear tooth / ratio chart .





Hailwood . com . ! :shock: gotta be quick . :wink: click on whatever to get the whole chart .

anyway , you get the picture . Generally the rpm drop on change should be less as the gears change .
Observing a RPM Vs Speed in Gears , Showing H.P. at rpm's , you can see ifitll drop out of the power band
as you shift up from third at the ton . 23 T on std ratios give you about 112 in 3rd ,
but if it had a lw first fitted thatd be 4th of 5 , if you get the picture .



which gets to the part where CLOSE ( Manx ) first aint gottenough ROOM inside for the Kick Start Pawl set up .
SO , a ' tall ' kickstart first will be alfway between Std. & Mank , olde bean .



Or ,

:?

The nature of dual purpose riding off road requires a wide range of gear ratios, from a stump pulling first gear that will let you climb a cliff, to a relaxed over-drive top gear to get you home on the road.

Boy oh boy matt have i stressed over getting that scope of ratios. The need to shift much is mostly d/t the speeds turns can be taken and power to weight so I had TTI make a custom low granny 1st for easier kick offs and wide gaps to tall over all ratio 4th, ugh because I can't count up'dn very far or fast Ok.

[/quote] I had TTI make a custom low granny 1st .[/quote]

Best spelling mistake of the day prize

Most CR 4 speed boxes have first gear which is the equivalent of second in the standard ratio box. Try riding your standard commando without using first gear anywhere. If you can live with the bike almost stalling on take-off and giving the clutch and mainshaft a hard time, you won't have a problem with the CR box. The difference is that once the bike is mobile acceleration is much faster up through the gears.
In a racing situation it is very useful to be able to change down two thirds of a gear relatively speaking and blitz another rider. It is all about using peak torque at all times. It also helps the smoothness situation when you can back off without using a heap of revs on the down-changes. As stated previously it depends on what you intend to use the bike for. Three close gears up top might be very useful for passing trucks on a freeway in high speed traffic. I've never liked the idea of top gear being an over-drive.

" Most CR 4 speed boxes have first gear which is the equivalent of second in the standard ratio box. Try riding your standard commando without using first gear anywhere. If you can live with the bike almost stalling on take-off and giving the clutch and mainshaft a hard time, you won't have a problem with the CR box. "

Thats actually a good suggestion and will give you a fair idea of what a normal CR box first gear would be like on the street.

Personally I can tell you I would hate it!!

If you are seriously keen and want to throw a lot of money at this yes TT Industries in Nelson NZ will supply you a five or six speed box with a close to standard first gear and 2nd thro top gear CR.

Then you have the best of both worlds. Just be ready to spend about UK 2500 to 3000 pounds.

I spent about 3 years collecting and testing gear ratio sets for my 4 speed AMC (Norton) box used on my 500 race bike. And in the end we used a RGM CR third gear pair, a Mk 111 Mk 11 A second gear pair and a standard Commando first gear pair. In a 4 speed box this gave us the best gear off the line with a closed up 2 nd thro top gear set.

But this was still wrong somewhere on almost all race tracks. Hence my move eventually to a 6 speed box for racing. This was excellent for a 500 but the same rider also was competing on a Commando and there the 5 speed was better. 6 speeds were unnecessary on the 750 and slowed him down.

I suggest 6 speeds might be better when the overall gearing is raised. I found gearing to the commando motor is very deceptive. You might believe you are getting the most out of the bike, however one tooth off the back sprocket gives better acceleration. It seems to me that the motor is often not pulling as hard as it can. With more speeds in the gearbox, it is possible to climb to a higher speed at the ends of the straights. And that is where more modern bikes often win out.
If you have the situation where you are using a 6 speed box and the overall gearing is too low, you can have the condition where you are doing many shifts and going nowhere. Just because the bike is under-geared, doesn't mean it will accelerate faster. With my own bike, everything I've done to it has been about improving mid-range power - especially the exhaust pipe and the cam timing. So keeping the revs up and well within the torque band and making it pull hard at the same time is very important. There are two things I recognise or believe about the commando motor - it is not smart to try to increase power by raising the operating rev limit, and the standard crankshaft is very heavy compared with other bikes. If you wind the crank up and then use the gearbox to get acceleration, it is a much better way to go than purely relying on horsepower and the acceleration of the internals when you open the throttle. With my bike the drop of revs on every up-change is really minimal, and you have to be careful not to over-rev. - I keep the crank spinning at near the optimum output level.
In a race with the 4 speed CR box, the bike lurches off the start line (unless you cook the clutch), then it is excellent everywhere. I still haven't been able to afford a practice session with the 6 speed TTI box, however I've raised the overall gearing again and it should be much better at the ends of the straights as well as off the starts.