Scooterotica

Both min 40 years old?

On my lammies, I'd say one layshaft is 45 years old and the other probably now in its 50th year. Would be useful for this subject to appear in scootering bringing in a materials scientist and testing to show how the original ones compare to newly made. Anyone have a view on which ones are bulletproof from SIL, Casa or MB ?

Only way would be to x-ray a cross sample of new and old parts and subject layshafts to destructive testing. Boasting that this or that layshaft is the strongest or better hardened would then be backed up scientifically.

Other than that consider changing half century old layshafts to something newer as they do get some hammer and it can't always be spotted by the naked eye.

My friend had one break last September on a 1966 Spanish special.The wheel came off at about 40mph,he was two up at the time,luckily the back wheel wedged itself under the panels and he skidded to a stop.......very scary.

I've no doubt that it's an extremely terrifying and very dangerous part to have let go.

All the weight on the bike and all the power from the engine is transferred through that part. How many times has the hub been on and off? How careful were the other people who worked on it over the years? It is shocked by bumps in the road and under torque loading and stress it's whole working life.

I think you're expecting a lot from a part that age if you refit an old one.

As to which is best, I'd say a genuinely manufactured to spec new part would be better than and aged unknown one any day.

I was talking to Tim at Dyrons (Home of the Dyrospeed special) a while ago (they used to be a Servetta dealer back in the 70's) and He said they had a few scooters break the rear axle when they were still within warranty.

Personally I use Indian SIL items, but that's not because I know they are stronger, I just feel that new is better due to fatigue issues.

ok decision made to change layshaft then.......

old or new why do they always snap at the end of the thread?

It's probably the thinnest part that's unsupported. If the hub or wheel gets a jar it will put pressure against the the nut.

If you ever snapped a stud they always go at the point where the thread stops.

I had a layshaft snap on me a few years ago (2009)
It was a "new" at the time SIL layshaft . The engine it was in was a TS1 used for rallies and euros so had about 15,000 miles on it.
It snapped at the bit where the O ring goes.

Luckily I was on a quiet country back road so no traffic to fly into. I ended up in hospital with a busted shoulder with needed a plate and six screws to sort it!!

Anyway when I build my engines I use the MBD layshafts.

I've done a fair amount of miles on them and had no problems!!