Steve Maney components

depends on application(s), rear wheel belt drives are usualy tension adjustable,

threads about maney stuff tho & easy to start another

Onder said:

In a non unit Norton is not the belt fitted rather loose, and that it tightens up as the engine gets hot?
Mine sure did. Is this the result of the power unit being non unit?

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No. It's the result of running a belt reinforced by an aramid yarn (e.g., Kevlar 49 by Du Pont). Aramid is the only fiber material which contracts with rising temperature. CTE of Kevlar-49 for instance is quoted at -2.7E-6/degr. F . Compare this to steel wire which is +3.7E-6/degr. F. Sure, the CTE of the composite comprising the belt will be somewhat lower but still negative.

Running a belt in a Norton without a tensioner will only work if using an aramid reinforced belt.

-Knut

84ok said:

outrigger bearings are new to me, i assumed that it was mostly a hi-po option here, the stock box being suitable for usual street use

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The AMC g/b was designed in the mid-50's based on the old Burman design and produced at Plumstead in high numbers for AJS/M and Norton. Remember, it was designed at a time when power output was hardly more than 35 hp. If used gently in the Commando it will probably never be overstressed. However, by utilising the power of a Commando the mainshaft and layshaft start to bend due to the cantilever at which the clutch is located, causing fatigue cracking of the g/b shell as well as layshaft bearing failure. You may also withness pitting at the gear wheels. I believe most people agree the AMC box is overstressed in the Commando and that the outrigger bearing serves a purpose even in a street bike.

-Knut

ah, didn't know the reasons for case cracking, layshaft bearing failure or related pitting at the gear wheels, some things i've noticed mention of

I believe most people agree the AMC box is overstressed in the Commando and that the outrigger bearing serves a purpose even in a street bike.

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i'm mostly all ears, on the last part in particular, not having come across it much so far,

i didn't even know about the maney option until recently, so the point of the link was that it added general, background info, for me or other new folks who might be interested, related to discussion in this thread that is more advanced,

i think the recent speed record & runs (~150mph), were done setup with the basic box, tho that doesn't necessarily get into a need for extended use

given where i'm at & the mk3 being a 1 year model run, my thoughts were there was little demand, or a viable market, for someone going there

here's a 200k miles report
https://www.motorcycleclassics.com/mc-dispatch/200000-mile-1973-norton-850-commando

lcrken said:

For those interested in the idea of an outboard bearing tied to the engine cases, this is a picture of the way Jim Schmidt (jseng1) did it on his monoshock Norton back in the '80s. It was two pieces, with the front plate was welded to the crankcase, and the rear plate bolted to it. Worked quite well.
Ken

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The plate was welded to the engine case to prevent case failure and cracking. The outrigger bearing was necessary because my full race 850 was flexing the tranny mainshaft so badly that the gears were actually WEARING ON AN ANGLE. Something had to be done before disaster struck.

mdt-son said:

Very nice and informative. They look rugged enough. Thank you for posting, Ken. I see no sign of the inner chaincase being welded to the crankcase though?
-Knut

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Me either Knut! Remember what I said though, I got the info second hand from the Redferns. Not much chance to get a good look at works stuff back in those days unless you knew the right people who had it stashed away, this was '76/'77 ish. The Redfern solutions as I understood it was a standard commando inner case modified. As you can see from lcrken's posts, the works solution was an all bespoke casting! His post clarifies things for me, a bit, however, as Ken suggests, it could be they welded some on earlier bikes before they developed the bespoke casting and smaller lighter AJS stormer based clutch.

One issue with a welded on chaincase would be installation and removal......I don't know how they did that....But I think their frames were more Seeley like, they may have installed engine and gearbox as a unit. It would have been pretty much impossible on my Rickman without some for of bolt together solution, maybe more like Jim Scmitt's.

There must have been some of this stuff hanging about in Tony Smith's Brize Norton workshop when I visited in around '77, but I didn't have my mobile phone to grab a few hi res pictures!

On running with fixed shaft centres with a belt. My belt drive was made by Norman White (based on Stormer derived design). It is fitted to a Rickman for race use. Norman set the shaft centres for correct belt tension knowing that my intent was to drill the engine/gearbox plates for a fixed locator on each plate, tomaintain that set shaft centre distance, he was happy that was a good solution. The only way to adjust it would be with a different set of plates, which was the original Rickman solution, I don't have any, or need any. Replace belt with same size, which I have done two or three times....no adjustment needed. No apparent stretch in (brutal) use.

mdt-son said:

Hi guys,
I am wondering why no one has come up with a beefed-up Mk3 inner primary chaincase featuring an integrated mainshaft bearing similar to the one provided by Maney? Sure, this would be limited to chain drive primary only. Having watched close up pictures of the g/b mounting and the final drive sprocket, see e.g., the Commando workshop manual companion, it seems there is ample space for a cotton reel steel spacer between upper g/b bolt and inner primary case. For the lower bolt, a direct attachment isn't possible because the frame rail obstructs. However, a stiff exchange member either in steel or aluminum is easily fabricated as there is ample space between bolt and final drive sprocket. For a trial test of the design, the chaincase facing the final drive sprocket could be skimmed around the mainshaft boss and a strenthening plate be fitted by bolts or nails. Function of the OEM seal could be maintained by a sealed bearing.

Is there an obvious reason why such a design wouldn't work? OK, additional shimming may be required to overcome casting tolerances and to avoid bending stresses in the inner chaincase, but that's a one-time operation. Any thoughts?

-Knut

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Knut, you won't believe it, I have done just that. Please write me an E-Mail I will send you the complete documentation with photos, assembly drawings partslist etc. By the way, everyone who wants this documentation please write me an E-Mail to: klaus.monning@freenet.de

Klaus Monning said:

Knut, you won't believe it, I have done just that. Please write me an E-Mail ...

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Very intriguing, Klaus! You have eMail.

-Knut

mdt-son said:

Very intriguing, Klaus! You have eMail.

-Knut

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Hello Knut,
You also have an E-Mail including the promised documetation in German and English. The English version may not be perfect but you may understand what I mean.
Best Regards
Klaus

Klaus was kind enough to send an English language version through, he suggested i might want to proof read the English before uploading but it reads pretty well to me so no changes made.
I have, i hope, attached a pdf version.

yes, good pdf file

It is worth noting that the race solution to gearbox shaft flex includes changing the primary drive ratio to spin the box faster. So yes they had outriggers, but the also removed some of the torque loading from the shafts. Steve Maney does the same, check out his belt drive ratios. Of course you cannot go so far with a road bike and alternator, so I fully see the sense of Klaus' approach.

My own approach in the '70s was to use the Commando clutch with a 33 tooth crank sprocket and to use a 4 speed rather than 5 speed, and to fit a manx type ball race, having thrown out the kickstart mechanism. This was good enough for 4 seasons racing without removing the gearbox cover! Since the 4 ratios were the same as the top 4 in a 5 speed, and we had to push start, the lack of a really low ratio wasn't much of an issue.

Today it is a lighter and smaller clutch, same raised primary ratio and.....a TTi box....

The last time I raced, it was with the Commando close ratio 4 speed box. I had three rides and in the first two I could not get a decent start because first gear was too high and it was clutch start, not push start, as in the old days. In the final race, I was 3 rows back on the start-line with only a couple of guys behind me. So I revved tits off the motor and dropped the clutch, expecting a blow-up. On turn two I was up beside the leader who was on a 1000cc methanol-fuelled CB750. That is when the fuel line popped off. Which was probably a good thing, because I had other problems.
I have never raced 'historic' because of the mixed grids - two strokes and four-strokes. If I race that mix, I am on the two-stroke NOT a Seeley Commando. At the time I last raced, I had a good TZ350 G - why would anyone used that in a mixed race ? So I made a conscious decision to sell the TZ and buy the TTI box for the Seeley. I've now had it for yonks, but cannot afford to race. If you have got the good gearbox and a good handling bike, the motor does not have to be that flash and you can still do OK. My motor has not had much done to it, however it amazes me how fast it is when given a dose of methanol and a re-balance. From experience, I know it is quick enough to win. I just wish I'd raced the bike when I first built it back in 1978. With me, it is not really about winning - a good competitive ride is enough to have a bit of fun. If I'd really wanted to win an historic race, I'd have been using the expensive TZ350 G and proved what ?

The primary drive on my Seeley is floating Jawa speedway engine sprocket on a special carrier, single row chain and Manx racing clutch, with no oil feed to the chain. I simply spray it with chain lube now and then. That setup will stand up to racing abuse for a fairly long time, as long as you remember to wire the clip on the chain. If you think about it - what do the primary chains do on a Manx on the IOM ?