commando/amc gearbox options/compatability

acotrel said:

I'm pretty sure any AMC box will fit into a commando and the internals are all similar, except for the mainshaft. On my bike, I use a TTI gearbox with a single row primary chain with a Manx clutch. The TTI is intended to be used with the diaphragm clutch, so the mainshaft is too long. I get around it by using Jawa Speedway engine sprockets floating on a splined carrier I had manufactured. It depends on what you use the bike for - I would not do that on a road bike.

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acotrel said:

I'm pretty sure any AMC box will fit into a commando and the internals are all similar, except for the mainshaft. On my bike, I use a TTI gearbox with a single row primary chain with a Manx clutch. The TTI is intended to be used with the diaphragm clutch, so the mainshaft is too long. I get around it by using Jawa Speedway engine sprockets floating on a splined carrier I had manufactured. It depends on what you use the bike for - I would not do that on a road bike.

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To mount a Commando clutch to the earlier gearboxes either the mainshaft must be changed to the later version or a modified Commando clutch center must be used.

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modified Commando Clutch Center The simplest and least expensive way to fit a Commando clutch to a Featherbed gearbox - $105.00

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acotrel said:

Many of the pre-1960 Matchless and AJS had AMC boxes which can be used in a commando, if you change the mainshaft or use an early clutch .. If you don't change the mainshaft in the earlier box and use the diaphragm clutch, there is an alignment problem of about 6mm.

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hobot said:

Rest assured Atlas shell is identical to Commando except the Atlas shell does not force ya to fart with the stupid thick wedge spacer, just fit gearbox align holes, shove in bolt nip up done. Atlas shells are about 1/2 cheaper last time I shopped 15 yr ago. I've a Qualfe shell that Icrken Canaga did a bolt hole weld up repair for me. I like its beefy looks. Did not use as eventually afforded a New Zealand ITT 4 spd.

So far no cost effective way to restore wallowed out AMC bearing bores so eventually will run out. About 15 yr ago called world wide looking for Commando gb to learn the major shops each had a big pile of cases that by now likely scraped out. The only place I know that still has piles of good Commando and Atlas shells, plus other Commando items, is Baxters Cycles.

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All inner gearbox covers are the same for Atlas, Commando, N15/P11.

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All inner gearbox covers are the same for Atlas, Commando, N15/P11.

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pierodn said:

You cannot use the very early Atlas inner gearbox that had not the dowel spring hook location to stop the KICKSTART RETURN SPRING.
The spring was located directly into a hole in the inner gearbox covers and the spring was thin.
Ciao.
Piero

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baz said:

I think all atlas gearboxes had that type of return spring right up to when they stopped production and changed to commando ,but I'm not certain

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baz said:

I think all atlas gearboxes had that type of return spring right up to when they stopped production and changed to commando ,but I'm not certain
I assume the earlier return spring was not as good as a commando one?

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pierodn said:

Hi.
Not at all, only the early year.
Piero

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baz said:

I wouldn't know
I have an atlas gearbox that I thought was from a late model atlas gearbox but maybe an early one
This has the spring retained with a hole

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