1971 Frame for a 1974 MK2A

I need a new or used frame, and I'm told a 1971 Commando frame will fit my 1974 Mk2A. Only difference are the gussets that reinforce the rear loop near the rear shocks. I have no reason to doubt this; just looking for potential future issues.

Thoughts?

Thanks

The 750 frame steering head angle is also (1.0 degree) different to the 850 frame. The 71 frame side stand pivot lug will be different unless it has been upgraded.

L.A.B. said:

The 750 frame steering head angle is also (1.0 degree) different to the 850 frame. The 71 frame side stand pivot lug will be different unless it has been upgraded.

Click to expand...

Thanks,

What does this mean in practical terms?

The 1 degree difference, how does that affect the ride?
How difficult is it to modiify the side stand pivot lug?

Is this something you would avoid?

MCP said:

Is this something you would avoid?

Click to expand...

Yes

Don't go this route, the 850 geometry is more stable than the 750.

If you go with a used frame take it to a frame guy and make sure it is in proper alignment.
Someone from NA will have to help with who is the go to on this.

MCP said:

What does this mean in practical terms?

The 1 degree difference, how does that affect the ride?
How difficult is it to modiify the side stand pivot lug?

Click to expand...

Your 850's yokes/trees should both be marked 'ANG' on the underside?
ANG yokes are for 850 frames.
Section G, Note.

Whether the 1.0-degree change in head angle makes a significant difference or whether ANG yokes can be used with a 750 frame has been the subject of discussion and as I have no personal experience of this then I can't offer you advice but would be preferable in my opinion to find an 850 frame if you can.

You could find a pair (must be a pair) of 750 yokes to use with a 750 frame but the 750 geometry will be less stable as kommando mentioned.

MCP said:

How difficult is it to modiify the side stand pivot lug?

Click to expand...

Thank you everyone for your expertise,

I've scratched the 750 frame option.

Well, I have a '71 750 and a '73 850, so may be able to weigh in. I prefer the '71's fork angle steering to the 850's. It steers quicker in the twisties, the 850 slightly less so. I didn't think it made much difference on the highway, even when taken to the top end, but that's lower on a 750 due to the 19 tooth gearbox output sprocket.
You will want to fix the sidestand mount. Rear shock reinforcement too. Both were available from Old Britts, but you better hurry, they're selling everything off for their retirement.
A '72 frame would be my choice if you wanted to use a 750 frame.