Does a 5 speed box give any advantage on a road Cdo

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Fast Eddie

Fast Eddie

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Title says it all really...

I'm struggling to see how, with the Cdo motor being so torquey and flexible, that 5 speeds are any better.

Anyone care to offer any first hand experience?
 
An overdrive would be nice when I'm on the highway, but I don't know what I would do with another gear between 1st and 4th.

Greg
 
Fast Eddie said:
Title says it all really...

I'm struggling to see how, with the Cdo motor being so torquey and flexible, that 5 speeds are any better.

Anyone care to offer any first hand experience?
Click to expand...

You already possess the answer, the knowledge is there, Grasshopper.. :lol:

Seriously, it will just split finer.. A few times 2nd was too low, 3rd was too high, but there was always an easy resolve, throttle up... Or gear down.. Not at all a big yank, unless you got $XXXX burning a hole in your pocket.
Just my worth very little, 5,000 miles per 8 month season opinion. YMMV :mrgreen:
 
I doubt the need, having toured across America on my 72 Combat with a 21 tooth front sprocket 70mph at about
4000 rpm all day long, never felt the need to drop the revs lower....

the wind pressure at a constant 80mph is too much for me
 
gjr said:
An overdrive would be nice when I'm on the highway, but I don't know what I would do with another gear between 1st and 4th.

Greg
Click to expand...

+1...I get the idea for racing, being able to keep the RPMs centered in the power band but for cruising, I like the long gears. Its why I love Commandos!
 
I would love another gear on my bike, but not between the gears I have. I have the final gearing very high for highway use which makes 1st gear a little too high for easy launches. Another speed below first would be great. Jim
 
It would be very unusual circumstances where a 5 speed box would give advantage on public roads. It is very pleasant in tight twisty stuff to be able to change down only a small amount to suit the corners without using a heap of revs, however that is usually only a safety factor during racing. The bike will accelerate much faster once it is rolling if the gears are closer - pretty useless on a public road. The comment about the value of the low first gear if you are using high overall gearing is probably most relevant. If you can get the 5 speeder cheap use it, however you probably don't really need it.
 
You Betcha you'd love another ratio to stay on the boil hot dogging it to the max in public, Ya Man, may even allow making a reputation that spreads to seek out for childish games which you'll definitely need it not to drop below 6000 rpm power band or get left behind no chance to catch back up again. Short of that Norton torque sane acceleration is enough you'll most often just short shift or like me on my SV, double shift skip a gear as no need-desire to stay in lower ones for the pull desired. But on the SV 6 spd to barely match a factory Combat must be peddled up or fall above or below its best pulling range. So get all lower close spaced 4 gears and a big jump up to 5th for over drive like long legged curise to the straffing lanes. If its a sweet shifter maybe some gear heads would enjoy the extra repeated action, again and again and again up and down and in and out of turns. I learned to drive on an '40's PU with a low granny 1st, only used for pulling and creeping while calling hogs or cattle so mainly used as a 3 spd, so that's the path my special has taken.
 
I have a different approach - very low first gear and all the rest close and high if you want to go fast. Getting the bike rolling off a clutch start is the most difficult part of racing. Once it has a few MPH the jump to the higher second gear is not difficult. From then on you rarely go below second and the rest of the gears are beautiful. The standard T250 Suzukis were set up like that. If you accidentally engaged first gear while racing you got the big fright. For racing some guys made a higher first gear, so they could use it in anger if necessary when they got baulked in a slow corner. The TZ250 Yamaha has its six gears all close and high, you do the big clutch slip to get rolling off the clutch start.
It depends on how you want to ride your bike.
 
If you want 5th (top) gear to be an overdrive, you need to lower the other four gears. Top gear in most gear boxes is straight through one to one. To make first lower usually only means replacing one pair of gears. If you want to lower the other four gears you'd need to see if the step down to the layshaft is used as one of the ratios or not , and it is probably the sleeve gear pair you would be changing - it could get a bit complicated. Making a pair of first gears is usually cheap, the other way you'd be better to buy the bits if the y are available.
 
I live in Benalla Victoria 200 Km NE of Melbourne. The next major town towards Melbourne is Euroa 40 Km away. It has become a major place where motorcycle engineering occurs for the whole of Australia. A 92 year old friend Keith McKie used to be a fitter and turner, then a machinery salesman. He had a backyard business doing bike work. He has trained up two young men and helped them set up motorcycle businesses in the town. There is also Ford McKernan Engineering there, which is excellent - gear hobbing is a specialty.

http://www.fordmckernanengineering.websyte.com.au/
 
looking at the milage poll and the milage I do, would rather have the 6 grand to spend on useful stuff. :roll:
 
When I blew my '71's gearbox due to a Barnett clutch pack & power shifting in '75 it was an easy choice. I hated the downshift from third to second in the twisties. Norton fixed that with a better 2nd gear ratio, but that wasn't common knowledge at the time. I spent the $450 for the 5 speed cluster and have never regretted it. Because of the higher 1st, the launch from start is more of an effort with the clutch, but no big deal. I love just keeping the rev's in the sweet spot and just shifting to a gear that keeps it there. Dunstall mufflers add to the experience. Now, it's a much more expensive option. I would just go for the later 2nd gear set and spend money on chassis improvements.
 
What make was the 5 speed cluster for $450 - sounds very cheap ? I paid $700 in about 2004 for a 4 speed CR cluster.
If you are building a bike, always begin at the gearbox, if you haven't got that you are beaten before you start. You can have the best motor yet can't do anything with it.
 
For 100 mph cruiseing , yea . If you live in town or it rains on your lawn :P .

When Noah was a boy , you had standard , close , and Enduro / ISDT RATIOS , in the 4 speeds . In Triumphs and other motorcycles . :lol:

I.S.D.T. were typically a close First & Second , for the off road sections . Trails & mud plugging .
a close Third & Fourth , for the Tarmac Sections . On such as a T 110 etc , or 500T , A7 Bezzer ,
etc.
And a Big Gap between Second and Third . as it was in between .

Now , running 23 T to get 130 at 7000 , going up a grassy lawn in the rain , gets fairly intresting . Or a TRAIL or unmade driveway .
for Us Hillbillies .
Also at lights you tend to wait till the vehical in front has moved out before you let the clutch in , so you dont run over it .

So - to keep the revs down while youre tearing up the Autobahn , and get into the shed up the back in winter -

A set of WIDE RATIO Gears in a FIVE SPEED , gives you a Overdrive top , to keep it below the 5900 continuous recomended useage ,
at ' the good old Ton ' .
Therefore ' WE ' need a ' starting gear ' , suitable for walking pace , wooded slopes , and towing trucks .

Sensable fancy transmissions CLOSE the Rev Drops as the Ratios Highten . As you need MORE GO uphigher .
Ideally a 500 rpm drop from fourth to fifth at redline . Though double that in our case - 1000 rpm drop ,
would be perfectly acceptable , increseing as you descend ratios . Remembering its sillyer to run to Max
rpms in lower gears , as theres less time or things there . So typically a Ace drops 1000 for 1st & 500 for
second ,calulateing our speed in gear / rpm figures for ratios in the lower gears . To avoid putting the pistons
through the cylinder head in everyday use . EVERYDAY . However we might press it a bit more on occasion . :D

So we're looking at say between 40 and 60mph in First at redline . Then theres top . And the rest have to fit in between there somewhere ,
as we've mentioned . :mrgreen:

generally it Bad Class to be unable to pull the TON , In THIRD . No atter the number of ratios . So these Germans mightneed SIX speeds . :P
 
acotrel said:
What make was the 5 speed cluster for $450 - sounds very cheap ? I paid $700 in about 2004 for a 4 speed CR cluster.
If you are building a bike, always begin at the gearbox, if you haven't got that you are beaten before you start. You can have the best motor yet can't do anything with it.
Click to expand...
He said nineteenseventyfive... whole different game$$$ :shock:
 
Still cheap - who sells them at that price these days ? Many of the old bikes in our historic racing use Triumph 5 speed clusters in pre-unit shells these days. I would be surprised if you could buy a box for $1900. And it is not a good option. I don't think they would cop what a commando turns out. When I bought the 6 speed TTI box, I thought about that. For $5000 there was a choice of either 5 or 6 speeds - I took the 6 speeder. It was all totally unnecessary, and only caused by the American style clutch starts we have in racing these days. All I needed to do was fit one of the very low ratio pairs of first gears which I have lying in boxes in my shed, and tolerate the step between first and second. The top 3 ratios of the common US 4 speed CR box are more than adequate for racing my Seeley 850. It was simply the problem of getting the bike to lurch off the start line which I was concerned about. What you lose at the start of a race is very difficult to make up. The last time I raced the bike, I cooked the clutch to get it going. It was where it needed to be on the second corner when it stopped - beside the leaders with the track open in front of it. If I get there again next May, it will be a different story. From that point on it is around a part of the circuit where I can be very fast. It won't matter how big their CB750 Hondas are, they will have to work hard. I'm determined to stick it to them before I die.
 
acotrel said:
Still cheap - who sells them at that price these days ? Many of the old bikes in our historic racing use Triumph 5 speed clusters in pre-unit shells these days. I would be surprised if you could buy a box for $1900. And it is not a good option. I don't think they would cop what a commando turns out. When I bought the 6 speed TTI box, I thought about that. For $5000 there was a choice of either 5 or 6 speeds - I took the 6 speeder. It was all totally unnecessary, and only caused by the American style clutch starts we have in racing these days. All I needed to do was fit one of the very low ratio pairs of first gears which I have lying in boxes in my shed, and tolerate the step between first and second. The top 3 ratios of the common US 4 speed CR box are more than adequate for racing my Seeley 850. It was simply the problem of getting the bike to lurch off the start line which I was concerned about. What you lose at the start of a race is very difficult to make up. The last time I raced the bike, I cooked the clutch to get it going. It was where it needed to be on the second corner when it stopped - beside the leaders with the track open in front of it. If I get there again next May, it will be a different story. From that point on it is around a part of the circuit where I can be very fast. It won't matter how big their CB750 Hondas are, they will have to work hard. I'm determined to stick it to them before I die.
Click to expand...

Dave Nourish made a gearbox shell to take Triumph 5 speed internal and fit into Norton engine plates, to satisfy this very market I guess.
I have to defend the Triumph box though, I raced them in all my bikes, inc big Nourish engines and never had a failure. I always ran a belt drive with Triumph Cush in the clutch and good Cush drive rear wheel though. Which probably helped.
 
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