Replacing Roundhouse cranks

[tom_tom_go]

I suspect I have answered my own question but if I want to replace the standard ones already fitted with the darjleering cranks Roundhouse produce I am going to mess up the timing?

The return cranks are pinned by the factory.

[GTB]

I suspect I have answered my own question but if I want to replace the standard ones already fitted with the darjleering cranks Roundhouse produce I am going to mess up the timing?

The return cranks are pinned by the factory.

You surmise correctly, you'll lose the valve timing if you change the driving axle cranks to new ones. Changing the others won't make any difference though.

The new axle cranks won't come with pre-drilled crankpins AFAIK.

If you are careful the valves won't move on the valve rod during the changeover, but the valve timing will need checking afterwards to position the return cranks correctly. The new crank pins can then be drilled using the holes in the existing return cranks as a guide.

Personally I don't pin return cranks, but that's a different discussion........

Graeme

[tom_tom_go]

Is it enough to just bolt the return cranks, or do you do something else?

[GTB]

Is it enough to just bolt the return cranks, or do you do something else?

I fettle the return crank to ensure the clamping screw seats flat when tightened, make sure the gap is wide enough that it doesn't close before the crank is fully clamped and replace the screw supplied by Roundhouse with a hex head steel one with a matching nut.

I'm not advocating that everyone should do it this way. I just dislike pinning things.

I haven't had a return crank move after setting it up properly. Once clamped tightly, I can't move them by hand. They might move after a severe knock in a derailment, but it isn't difficult to reset them in that hopefully very rare event.

Regards,
Graeme

[tom_tom_go]

Thanks Graeme for the advice.