Layshaft idea, hit ot miss

[Marty ULC]

I'm no engineer nor metallurgy expert so please don't shoot me down in flames if this is a daft thought...
Would cryo treatment work on layshafts?

[Scooterslag]

I'm no engineer nor metallurgy expert so please don't shoot me down in flames if this is a daft thought...
Would cryo treatment work on layshafts?

That's not a crazy idea at all, I remember reading about Stuart Owen Cryo-treating his gearboxes on his sprint machine due to chewing too many up, might work on layshafts. Paul

[Jim Rose]

Tornado,

You seem convinced that it's the cones causing layshaft failure. Fair enough.

The one that failed me was the original layshaft / cone and hub as it came out of the factory all those years ago. At the time it went the only changes from factory spec was a soft tune on the top end a bigger carb and exhaust.

You may well be right that the more modern cones are of lessers quality than Mr Innocenti produced but it is only part of the whole setup.

If layshafts are failing and we want to find out why then we have to maintain an open mind and look at all factors. Hence independent expert with no pre conceived idea on whats going on.

That said if you do get a hardness test done on the cones it would be interesting to hear the findings.

Cheers Jim

[Toot]

.. with people who were running R1 shocks on their machines? (could be wrong here) but I thought that the extra stiffness of the shockers were passing the bangs and crashes of the road impact onto the layshaft causing a guillotine effect? Paul

I've often wondered if an R1 shock sits 'true' between frame and engine?

There are lots of riders that use R1 shocks on Lambretta's, and a few that have turned up nylon spacers (different thicknesses top and bottom) to ensure that the R1 shock sits 'true'. However every frame/engine combo could be slightly different as I know when I look at my rear tyre it suggests it sits slightly right of the centre of the frame??

I have R1 shocks suitable for a Lambretta. and haven't yet fitted one to one of my scoots, I've run a Escort shocker for the last few years and not have any issues with the weight of baggage and/ or pillion that I've carried.

[Jim Rose]

Toot
I fitted an R1 shock to my last project (the euro one) and have lost several shock bolts on it, last one when I went on the Derbyshire run. It's likely that its slightly off centre which is why i'm loosing the bolts. I've never had an issue with this before.
Jim

[rossclark]

Jim, Do you mean nuts rather than bolts?

[Warkton Tornado No.1]

You seem convinced that it's the cones causing layshaft failure. Fair enough.

That said if you do get a hardness test done on the cones it would be interesting to hear the findings.

WT No.2 buzzed around to me yesterday…

Unfortunately, the hardness tester that was @ his place of work evaporated. Obviously, not in ‘our’ direction….

I found another cone to add to my list. Yet another old but shallow taper cone with signs of use in the bore & on the coned part, but not significantly marked in the bore like the newer ones that I have.

There are four more fitted to bikes/engines in the garage that I hope to get to in the next few days.

My theory looks like it’s only mine, though.

Nobody has yet to disclose their own findings concerning cones so I’m guessing that there are no concerns with the new cones burring up in the bore, other than those that I have….

[Angry Bloke]

I stripped a rear hub yesterday - Spanish with cone ( Both NOS and previously unused when fitted ) which have now done 5000 miles and was pleased to see that the cone is unmarked or burred

I had used an original rear hub nut but in light of the comments in this thread re overtorquing and as I have no knowledge as to the torque this nut was tightened up to by the previous owner ,I think I'll replace it

[Warkton Tornado No.1]

Angry Bloke

Thank you for that information!

Did you buy the hub & cone as a matched set? I’ve been in the habit of buying individual cones. Are you thinking what I am thinking?

It’s also worth mentioning that I use Copaslip.

It would be great if you nip the hub off again in a week or two to examine the effect of the correct torque that you will apply.

[Angry Bloke]

Did you buy the hub & cone as a matched set? - Yes
I’ve been in the habit of buying individual cones. Are you thinking what I am thinking? - I Think So

It’s also worth mentioning that I use Copaslip.

It would be great if you nip the hub off again in a week or two to examine the effect of the correct torque that you will apply. It was me that fitted this hub ( to correct torque 5000 miles ago ) so I'm sure that the result will be the same

The nut came with the bike and I changed the layshaft and hub hence my lack of knowledge of the nut's history

Hope this helps

[Warkton Tornado No.1]

as I have no knowledge as to the torque this nut was tightened up to by the previous owner

Yes, that all makes sense now that I understand you were questioning the nut (quality) rather than the torque (quantity)

Thanks for the information.

My hub cones came from Scooter Restorations, but I'm only adding that as an aim to be transparent in any information. I'm not pointing a finger or stating anything controversial without validating what is a hunch.

Given the opportunity, I will get some cones tested for hardness, but I don't know when that will be.

As an apprentice served engineer, I do have some idea of the dangers of allowing critical components to deviate from specification, & the pre-load of a fastener is an area where the parameters are misjudged or simply misunderstood, to the detriment of the assembly in which their key role is to ensure integrity.

In the mean time, it would be appreciated if there were to be further feedback.

[gaz_powell]

In respect of R1 shocker comments from Toot - I would agree. I fitted an R1 with nylon bushes, 225lb spring, half nyloc nuts backed off. Kickstart engine was shot within a couple of 1000s miles. When I replaced the mount it was evident that the geometry (it been "true") was out. I spaced it but was never totally happy - it did about 4k tops and shot another sil mount. So new mounts and r1 removed for the new year. Brand new Escort fitted at minute but will change for something better (?) that is lambretta specific. It's funny because as was replacing the mounts I was thinking about the likley hood of stres on the layshaft if the geometry was wrong. I have done a visual check and all seems well (hub/layshaft/cone etc).

[Dazts1]

Another thing which can chuck out the alignment at the rear of your bike is offset cones. I too was doing the right side engine mount. This was down to the cone spinning round. Thus chucking everything out of alignment and stressing parts. Yes I used locktite on the cones and left them a day before engine fitment. Spinning cones stresses mounts , shocks and probably layshafts.
I only mention this because of my own findings. Also the mass use of offset cones nowadays.

[gaz_powell]

Another good point.
We are often quick to move to things that haven't really been tested in the traditional R&D respect for road going parts on a lambretta.
A combination of two what are really non lambretta tried and tested items has the potential for a knock on effect elsewhere.
My experience was with normal cones.

[coaster]

...........Kickstart engine was shot within a couple of 1000s miles

Gaz, I wouldn't leap to the conclusion that the R1 mount was to blame for the kickstart side mount failing after 2k miles, that's about the going rate i'd say. In fact I've had a set from a well known tuner that lasted a LOT less than that. My experience has mainly been on Escort shocks although there is an R1 on there at the moment. I have now fitted one of Andy Francis long mounts on that side

[gaz_powell]

Apology to the OP that this has gone on a tangent.
I was just basing the mounts on the longevity of the SIL ones in my GP which runs a GAZ shocker.
We'll see what happens this year on the SX with new UNI mounts and an Escort shock.
I would say that I was never totally happy with the fitment of the R1 shock.
Would happily swap the R1 for a decent Hagon/GAZ or similar.

[jonw]

Sorry but Warkton Tornado No.1's Butt Plug joke was hilarious!