Quaife boxes...

15 years trouble free racing use is high praise indeed John! Although my engine is quite highly tuned compared to many, and I do like to use the revs and power available, the stresses I would put on the box on the road are no where near that of actual race use.

You made me laugh with your rear set story... I had the same once... Or perhaps even twice... !

The comment about standard AMC boxes being durable without a support bearing behind the clutch amused but if my very olde memory is correct I can remember when factory race Commandos would very rarely complete a lap of the Isle of Man due to gearbox failures....If my very old memory is correct Mr Peter Williams to overcome the problem incorporated a support bearing behind the clutch(a CORRECTLY designed and mounted one) to stop the gearbox main shaft deflecting causing gears to run incorrectly meshed. I believe he also altered the primary ratio to increase gearbox speed thus reducing the torque into the box giving the box an easier time along with employing a smaller clutch to considerably reduce clutch rotating weight to give the box an even easier time.
As for the comment that the Quaife boxes were good for 200 h.p. i remember Mr Quaife doing his development testing on the 500cc single ridden by Pat Mahoney and I believe prepared by ex AMC race mechanic Tommy Mortimer and the last dyno results I saw for a rather competitive 2 valve G50 showing that at the crank it produced a max of about 50 h.p. and just over 40 ft lb of grunt. As I suspect Mr Quaife designed the boxes for the 350 and 500cc singles being raced by everyone at the time why would he of designed them for 200 h.p.?? mind you are gearboxes not designed for torque rather than h.p ?.......200h.p. at 12,000 r.p.m equating to 87 ft lb of torque while at 5,000 r.p.m. 210 ft lb ........ I can even remember the development 5 speed box failing several times over one Easter weekends racing and thenext time I met Mr Quaife 9carrying his son on his shoulders that how long ago it was) told me the problem was traced to the gears being incorrectly heat treated. (case hardened?). i knew very little / nothing about metallurgy in those days of youth.....
I used to spend a few of my weekends trying to learn a few skills by staying with Mr Mortimer and his wife and son in an attempt to have some skill rub off on me as building erecting and testing fairly big AC and DC motors and generators during the week was a somewhat different form of Engineering....in the days when the UK still had some Engineering left....
Interestingly I notice in a Wakefield-Dick Lubrication book 'Gear Lubrication' it states of the Burman 4 speed box and I quote 'The box is guaranteed for 50 b.h.p. at 2,500 clutch shaft r.p.m'. Did not the Burman 4 speed box with a few detail changes become the AMC/Norton box or are my nickers in a twist yet again?? Wonder what the design criteria was for those TT Industry 5 and 6 speed boxes. Wonder if anyone using them knows??

J. M. Leadbeater said:

The comment about standard AMC boxes being durable without a support bearing behind the clutch amused but if my very olde memory is correct I can remember when factory race Commandos would very rarely complete a lap of the Isle of Man due to gearbox failures....

Click to expand...

I only spoke from first hand experience in that I campaigned and heavily abused an AMC box in an overweight Commando for several years with no problems whatsoever. My team mate had the same experience with a Commando engine in a Featherbed with an AMC box and no rear cushion drive whatsoever. The outrigger is not necessary if you do the internal modification which is minor in nature. It sounds like they did not figure this one out back in the day.

J. M. Leadbeater said:

Wonder what the design criteria was for those TT Industry 5 and 6 speed boxes. Wonder if anyone using them knows??

Click to expand...

I currently run four TTI's (without cushion drives) and the design criteria is ...... do not break. They have exceeded my expectations as you install them and more or less forget them. I know of at least 4 others which have performed flawlessly. I also run a Nourish conversion which is rather robust (without out rigger bearing nor any cushion in the drive) and never gave trouble.

Dances, are you running Commando or Atlas type clutches?

Commando clutches, all of them.....with Barnett plates. Specifically, Steve Maney baskets.

J. M. Leadbeater said:

As for the comment that the Quaife boxes were good for 200 h.p. i remember Mr Quaife doing his development testing on the 500cc single ridden by Pat Mahoney and I believe prepared by ex AMC race mechanic Tommy Mortimer and the last dyno results I saw for a rather competitive 2 valve G50 showing that at the crank it produced a max of about 50 h.p. and just over 40 ft lb of grunt. As I suspect Mr Quaife designed the boxes for the 350 and 500cc singles being raced by everyone at the time why would he of designed them for 200 h.p.?? mind you are gearboxes not designed for torque rather than h.p ?.......200h.p. at 12,000 r.p.m equating to 87 ft lb of torque while at 5,000 r.p.m. 210 ft lb ........ I can even remember the development 5 speed box failing several times over one Easter weekends racing and thenext time I met Mr Quaife 9carrying his son on his shoulders that how long ago it was) told me the problem was traced to the gears being incorrectly heat treated. (case hardened?). i knew very little / nothing about metallurgy in those days of youth.....
I used to spend a few of my weekends trying to learn a few skills by staying with Mr Mortimer and his wife and son in an attempt to have some skill rub off on me as building erecting and testing fairly big AC and DC motors and generators during the week was a somewhat different form of Engineering....in the days when the UK still had some Engineering left....

Click to expand...

You managed to spend 200 words casting doubt without having fully read the one or two sentences that you are attempting to correct. Either that or your reading comprehension needs work.

The Quaife gearset I mentioned was for a Vincent 1000, or bigger if one chooses. Quaife's gearsets for those machines have stood the test of time better than any other.
My point was that when placed behind big torque V twins and raced, Quaife's five speeds have stood up extremely well, for example, much better than the Nourish/Triumph sometimes used on cut down engines.

My memory was off by ten percent though. The figure given to John Lumley by Rod Quaife was 180 HP for the Vincent gearset, not the 200 I remembered. Still enough to do the job, although one Quaife gearset in Oz is subjected to 165 hp @6500 engine rpm.

Summary (for Commando gearbox at least):

TTI = fit and forget
Quaife = fit and remember (why you didn't spend the extra £ or $ or whatever on a TTI)

I have to mention that I know a sidecar racer who completely wore out his TTI gearbox in a few seasons (Nourish engine). The rebuild cost almost as much as a complete box. It didn't fail however. He used standard AMC, Quaife and Nourish gearboxes before and they all failed.

The mainshaft in the TTI box is much fatter than the one in the usual Norton box.

Dances with Shrapnel said:

J. M. Leadbeater said:

The comment about standard AMC boxes being durable without a support bearing behind the clutch amused but if my very olde memory is correct I can remember when factory race Commandos would very rarely complete a lap of the Isle of Man due to gearbox failures....

Click to expand...

I only spoke from first hand experience in that I campaigned and heavily abused an AMC box in an overweight Commando for several years with no problems whatsoever. My team mate had the same experience with a Commando engine in a Featherbed with an AMC box and no rear cushion drive whatsoever. The outrigger is not necessary if you do the internal modification which is minor in nature. It sounds like they did not figure this one out back in the day.

J. M. Leadbeater said:

Wonder what the design criteria was for those TT Industry 5 and 6 speed boxes. Wonder if anyone using them knows??

Click to expand...

I currently run four TTI's (without cushion drives) and the design criteria is ...... do not break. They have exceeded my expectations as you install them and more or less forget them. I know of at least 4 others which have performed flawlessly. I also run a Nourish conversion which is rather robust (without out rigger bearing nor any cushion in the drive) and never gave trouble.

Click to expand...

Dances, what are the internal mods you refer to? I have a light Barnet clutch and will be raising the primary gearing and I have an outrigger in the shelf too. But haven't thought about any internal mods hitherto...

johntickle said:

The Quaife 5 speed gearkit still uses the camplate. The gears are quite narrow, not suitable for high torque engines.
The Quaife 6 speed gearbox uses the drum but is not available with kickstart shaft. The price is similar to the TTI gearboxes.
All TTI gearboxes (4 speed extra heavy duty, 5 speed, 5 speed extra heavy duty, 6 speed) can be supplied with kickstart shaft.
The "cheap" option is the Nourish gearbox shell and mainshaft combined with Triumph 5 speed internals, inner and outer cover (as used by Doug Mc Rae).

Click to expand...

dunno if up to date info
speed-commando-gearbox-t7565.html#p78804

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.

Click to expand...

Dances, what are the internal mods you refer to?

1++

Alas I was unaware that long after Mr Quaife did his development testing of the original 5 speed box that he maqnufactured stronger boxes with clearly beefed up internals. Personally I could never afford them and stuck to 4 speed boxes using for racing the old18-28 t 4ths converting them to 1sts along with the 20-22 2nd and 3rd gear pairs and the 18-28 for 4th giving a very nice set of ratios for a big grunty twin and a LOT cheaper than a 5 speed box.
A friend has a 4 valve Vincent twin side car race outfit and I believe it has an AMC box fitted which to date has given no problems . However it does have a Vincent type shock absorber fitted into the engine pulley. If memory is corrrect it gives a bit over 94 ft lb of grunt at the crank(on his dyno) and with the 30mm wide Gates HTD GT3 belt running on 40-68t pulleys that equates to just over a max torque at the clutch / gearbox input of of 150 ft lb about 30 ft lb more than a std 920 Commando can IN THEORY put into it. He changes the belt once every season needed or not as it costs a LOT less than entry fees for one meeting so why risk not finishing a race for the cost of a belt...The clutch incidentally is easily operated with two fingers all day long, weighs 61/2 lb and employs 4 friction plates and actually has an in theory clutch torque capacity of 240 ft lb..ASSUMING he has not played with it and set the diaphragm spring up differently that is and he does love to play with things...

Kvinnhering said:

Dances, what are the internal mods you refer to?

1++

Click to expand...

The short description is doing away with the kick start shaft and installing a steel bushing which carries a small bearing for support of the right hand side of the lay shaft.

The kick start shaft is removed and the outer cover is blanked off and sealed.

Best to be looking at an AMC inner cover when going over this, so...........

The rivets and striker plates are removed from the inner cover and a steel bushing is placed inside the inner cover. The bushing is stepped and fits snug into the inner cover where the kick start shaft once was. The bushing is held in place with a recessed washer and bolt which goes through the now vacant rivet hole where a nut is used to hold it in place.

The steel bushing receives a bearing which then receives the right hand side of the lay shaft. In order to properly fit the lay shaft to the inner race of the bearing, one must use a thin wall sleeve which can be slightly peened into the inner bore of the bearing (with green locktite).

This modification eliminates the inherent slop that a bronze bushing eventually allows (both radially and axially). The modification also reduces the effective span of the lay shaft. All important things for the durability of the box under race conditions.

The "kit" was given to me at a race shop I was a team member of.

I still have a 4 speed CR box in an AMC housing. The internals were bought from the US and first gear is higher than a standard Manx ratio. It is excellent once the bike is moving. I bought the 6 speed TTI box before I'd really thought about that first gear ratio. I have a few gearbox internals sitting around, and probably three choices of which first gear I could use to get the bike off the line during a clutch start. Depending on where the first two corners are, there would not be much difficulty in getting competitive.

Dances with Shrapnel said:

Kvinnhering said:

Dances, what are the internal mods you refer to?

1++

Click to expand...

The short description is doing away with the kick start shaft and installing a steel bushing which carries a small bearing for support of the right hand side of the lay shaft.

The kick start shaft is removed and the outer cover is blanked off and sealed.

Best to be looking at an AMC inner cover when going over this, so...........

The rivets and striker plates are removed from the inner cover and a steel bushing is placed inside the inner cover. The bushing is stepped and fits snug into the inner cover where the kick start shaft once was. The bushing is held in place with a recessed washer and bolt which goes through the now vacant rivet hole where a nut is used to hold it in place.

The steel bushing receives a bearing which then receives the right hand side of the lay shaft. In order to properly fit the lay shaft to the inner race of the bearing, one must use a thin wall sleeve which can be slightly peened into the inner bore of the bearing (with green locktite).

This modification eliminates the inherent slop that a bronze bushing eventually allows (both radially and axially). The modification also reduces the effective span of the lay shaft. All important things for the durability of the box under race conditions.

The "kit" was given to me at a race shop I was a team member of.

Click to expand...

Thanks Dances, that's good info.

Doesn't help me out on this particular job though as its a road bike and I need the kickstart.

Hi
Just got my racer ready and raced two weekends ago. Had the same trouble that has been described on quaife 5.. That is false neutrals between 4 and 5. That causes some overrevving rsiking the Engine and very annoying loosing time on the straight. I can´t understand why the rearsets could be a problem as that would happen in every gear?
In my box I found that the gearchange quadrant could move as I find it to much excessively and if the middle cover was of you could actually get the camplate to go past 5 th gear like spinning a Wheel. Either the camplate stays in a false neutral in between 4 and 5 th or it overshiftes after 5 th and gets into it when you go back and forth again.
If it overshiftes one woud need to weld a stop for it to do so on the ratchet or in middle cover alloy. Or if in the middle maybe a harder spring in the plunger and to check that the plunger rests perfectly. The harder spring would need harder shifting from 4 to 5.
My gearbox fully checked as well.

Anyone there with suggestions?

Fast Eddie said:

Doesn't help me out on this particular job though as its a road bike and I need the kickstart.

Click to expand...

For those relying on E/S, RGM sells inner and outer g/b covers for racing or street use (p/n 050124, 050125). The inner cover provides a bearing wich supports the layshaft, as discussed above. The outer and inner covers have no k/s facility.

Regards

Knut Sonsteby