AJS & Matchless Owners Club

Duncan wrote: ↑Sun Dec 31, 2023 6:33 pm I'm not following this if the roller is 1 thou over, it sits between the crank pin and conrod liner so surely that is 0.5 thou off of each to make the roller fit?

Two rollers, diametrically opposite each other, are each 1 thou bigger in diameter, so you have to make room for the extra 2 thou. Assuming the con rod liner is unaltered, that 2 thou has to come off the diameter of the crank pin.

Pharisee wrote: ↑Mon Jan 01, 2024 10:19 am Two rollers, diametrically opposite each other, are each 1 thou bigger in diameter, so you have to make room for the extra 2 thou. Assuming the con rod liner is unaltered, that 2 thou has to come off the diameter of the crank pin.

I don't know the process by which the sleeve on the two-piece crankpin is hardened but by turning down its diameter isn't there the risk of removing the hardened running surface? I would guess that if the whole sleeve was hardened it would be too brittle.

Here's one knackered pin that I removed...........

Pharisee wrote: ↑Mon Jan 01, 2024 10:19 am

Duncan wrote: ↑Sun Dec 31, 2023 6:33 pm I'm not following this if the roller is 1 thou over, it sits between the crank pin and conrod liner so surely that is 0.5 thou off of each to make the roller fit?

Two rollers, diametrically opposite each other, are each 1 thou bigger in diameter, so you have to make room for the extra 2 thou. Assuming the con rod liner is unaltered, that 2 thou has to come off the diameter of the crank pin.

Yes 2 thou off the diameter of the crankpin but only a skim of the surface of the crankpin of 1 thou. Or am I misunderstanding? Having said that I thou might still be enough to get through the hardening. So the idea of 0.5 off both the crankpin and the conrod holds. 0.5 skim of the conrod would increase its diameter by 1thou, 0.5 off the crankpin would reduce its diameter by 1 thou.??

Pharisee wrote: ↑Mon Jan 01, 2024 10:19 am

Duncan wrote: ↑Sun Dec 31, 2023 6:33 pm I'm not following this if the roller is 1 thou over, it sits between the crank pin and conrod liner so surely that is 0.5 thou off of each to make the roller fit?

Two rollers, diametrically opposite each other, are each 1 thou bigger in diameter, so you have to make room for the extra 2 thou. Assuming the con rod liner is unaltered, that 2 thou has to come off the diameter of the crank pin.

Ping! light bulb moment, thanks.

I don't think you'll be able to skim either the crankpin or the conrod sleeve, they will be hardened through. The most you'll achieve is scratched surfaces. The pin needs to be ground, or the conrod eye honed out. I suspect the grinding would be easier, most good engineering workshops should be able to do the job, but I have no idea of the cost. Best of luck, Andy

Hi Duncan. Let me try this way. There are two rollers across the diameter of the assembly. So to allow for the increase of 2 thou, one thou has to be taken off the radius of the crank pin, which equals 2 thou off the diameter.

Andy51 wrote: ↑Mon Jan 01, 2024 7:58 pm I don't think you'll be able to skim either the crankpin or the conrod sleeve, they will be hardened through. The most you'll achieve is scratched surfaces. The pin needs to be ground, or the conrod eye honed out. I suspect the grinding would be easier, most good engineering workshops should be able to do the job, but I have no idea of the cost. Best of luck, Andy

Agree. This would be a cylindrical grinding job.

Happy New Year all. This is an update on the project.
The first photo shows painted and chromed fork shrouds and a chromed mag platform done locally.
The next shows the jampots before dismantling. They were seized solid but one of the local engineering shops made up a special tool comprising a steel ring with a slit and a clamp bolt with a big tube welded to it. The next photo shows one of the units dismantled. We are looking at metal spraying and grinding the damper tubes. Let's see.
The next photo is a frame stud I renewed and the final shot is the lower rail in the drill for drilling and tapping for the new stud.

The fork stanchions are (I think) scrap because they are 3mm bent and very corroded.

Anyway......plodding on.
I am awaiting delivery of a parcel of spares from the club shop.

Is there any non corroded sections on the front stanchions? I say this because I couldn't get any rear jampot stanchions, but there was just enough clean material on the 1 1/8 front stanchions to make up a pair of rear ones on my last project. Easy enough to turn them up in a home lathe, the correct high tensile material too. The only difficult bit was turning the Whitform thread which attaches to the jampot top casting.

Worth a look anyhow..

Adam

Sad looking fork stanchions. I did consider grinding the length of the seal landings undersize then under size seals and bronze or plastic sliders. But I think the pitting in one of them is too deep.