Maney gearbox outrigger bearing: help please...

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john robert bould said:
JohnTickle showed me his TTi box..it looked very robust! If you have £3000 spare it looks the way to go.
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For a race bike it is actually good value, unless you are extremely unlucky, or have a fleet of race bikes, you will only ever buy one......mine was used so a bit less than £3K......

For a road bike it seems to me overkill, but then, so is any 5 Speed on a road Commando....

As Hobot has shown, it takes a bit of effort to locate a TTi in a Commando.....
 
Fast Eddie said:
john robert bould said:
Peter Williams and others at the time [early seventies] where having problems with the gear box's, was that due to the shaft bending, or poor manufacturing? .
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The shafts bending, I believe.
The race shop would have had choice of all the best parts and / or would have machined their own if required. So I doubt poor machining or even assembly would have been behind such chronic failures.
Design limitation would seem the culprit.
Consensus appears to support the shaft bending theory.
What I've never understood though, is why Norton boxes suffer this and Triumph boxes don't!? Apart from the silly design of having bearings so big there's no metal between them in the housing, the rest of a Norton box looks at least as strong as aTriumph. Yet I've raced 90bhp Nourish engines with standard road based Triumph 5 speed boxes and never had a failure!
Maybe I just ride like a girl!!
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Re; “with standard road based Triumph 5 speed boxes and never had a failure!”
There was a lot of BSA, Triumph 3 gearbox failures when they first came out in the 1970s due to the manufacturer using 650 Bonneville gearboxes, I myself towed a Triumph 3 all the way home off the motorway once (Never again- I stuffed my clutch plats towing that big heavy beast :!: )
 
SteveA said:
Fast Eddie said:
But many 4 speed boxes crack their case, even in road use.

Isn't flexing of the shafts the primary cause of these cracks?
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The cracking of the area around the bearings seems worse after 40 years! It is not that it didn't happen back then, after all Norton strengthened it for a reason, but my expereince was the bearing turning in the case, as was that of others....but more had broken layshafts....

My main point is that the works racing experience with Quaife 5 Speeds is largely irrelevant to road 4 Speeds.

There are ways to keep your transmission together without outriggers, and you have gone a long way towards that Eddie.

In my opinion the fitting of an outrigger now is a nice to have and good for peace of mind. If you were going racing I might say different, but Chris Tyler's Rickman has a close ratio 4 Speed with a kickstart shaft in it and it was raced without one last year, and recently at Pembrey with Chris on it and yesterday with young Dan Rootes on it! (Best news here is that Dan enjoyed the Norton)

If I was concerned about gearbox reliability on that bike my next choice of action would be to remove the Kkckstart shaft and fit a Manx style bearing in the inner cover....assuming I couldn't afford a TTi for it, which I would want mainly in the search for more gears...
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Good point about there being more cracked housings now than 40 years ago Steve, it is only cast alloy at the end of the day so a guess fatigue is starring to show.

You're making me feel better the more you write about this Steve!
 
Eddie,
Read about alloy getting tiny stress fractures due to vibration...just a mater of time and most things fail...well acording to my doctor that is...Oh dear!!..."wife! get here now! i'm 64 shortly!!! :oops:
 
Herb Becker builds for Doug MaRea seem to get away with the Triumph tranny upgrade. Twisting-bowing shafts can put a cracking load on AMC shells. I've called vendors world wide a decade ago d/t cracking DS main shaft bearing right through the case so found out any vendor worth his salt has a pile of cracked and worn out bores AMC shells just waiting for Al prices to go up and sell for scrap, a long time before this list came online, so not a new issue at'tall.
 
hobot said:
Herb Becker builds for Doug MaRea seem to get away with the Triumph tranny upgrade. Twisting-bowing shafts can put a cracking load on AMC shells. I've called vendors world wide a decade ago d/t cracking DS main shaft bearing right through the case so found out any vendor worth his salt has a pile of cracked and worn out bores AMC shells just waiting for Al prices to go up and sell for scrap, a long time before this list came online, so not a new issue at'tall.
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I didn't say it was a new problem, just that it wasn't the prominent problem in the '70s, of course ten years ago all original production Commando shells were only 30 years old, even ones that had been on the pile for 10 years were at least 20 years old! My, doesn't time fly.....

The Triumph 'upgrade' is mainly to get access to later 5 Speed Triumph ratios, which can be fitted into a pre-unit box.

It wasn't all good!

http://www.triumphrat.net/classic-vinta ... arbox.html
 
Well the piles the www of vendors told me about were collected over several decades in Europe, N. America, Pacific and Asia regions prior to my decade ago shopping spree to find Atlas shells are a better deal for Commandos. Next most amazing thing to me on the P!! was lack of issues with its AMC tranny. Alloy does have a fatigue life if built w/o reserves such as Norton connecting rods. The isolastics go a long way to ease sense of over doing power loads only meant to take 35 hp and torque.
 
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