650 SS vs Early Commando Triple Trees

[Stephen Hill]

I am about to look through my stash of Norton bits to find a set of triple trees for a friend's 650 SS.
I think I have a mix or featherbed and early Commando triple trees.
Are they interchangeable, and if not how do I identify the differences?

 

[elefantrider]

The thread on the stem is slightly different, Domi vs Commando. 26tpi vs 28tpi.

 

[Stephen Hill]

Thanks elefantrider. Does that mean if I have a matched pair, top and bottom, an Atlas and early Commando set is interchangeable?

 

[jan nelder]

Thanks elefantrider. Does that mean if I have a matched pair, top and bottom, an Atlas and early Commando set is interchangeable?

yes, as far as I know. Though the internal headstock spacer may not be same length.

 

[marinatlas]

Top tree have different threads for the handlebars mount , BSF for the domie/atlas , UNF for the Cdo , bottom tree as said 26tpi vs 28 tpi , plus you could have different steering lock stop .....

 

[acotrel]

The yoke offsets are important because too much offset reduces the trail. It causes the bike to understeer, and can cause a mishandle - the bike can stand-up under brakes and suddenly turn in the wrong direction. The trail on the steering is a combination of rake, wheel size and yoke offset. I think a Commando would have about 26 degree rake, and would use yokes with less offset than those from a featherbed. The worst yokes would be those from a Garden Gate Norton. They have a lot of offset. For a bike which is going to be ridden fast - nearly 100mm of trail with 26 degree rake and 18 inch wheels is good - but not on a two-stroke with a peaky power-band. I think the rake on a featherbed is usually 24.5 degrees, with 19 inch wheels. With 18 inch wheels, they are useless.