How close together for rear wheels before diff not needed ?

[Compo_Simmonite]

I'm adapting a small Yamaha quad to a 100% legal & registered with DVLA mobility buggy. Yes - it can be done if you follow the rules "to the letter"
The huge current balloon wheels and tyres will need replacing with something more sensible like trailer items. I would like to keep the solid rear axle and two wheels instead of making into a trike for traction in snow and gentle off road use. In the past I've had a road legal quad and the solid rear axle made it horrendous to ride on the road so the intention is to respline the axle so the wheels are closer together - like the 4 wheeler Isetta.
The Isetta rear track is 52cm and it managed without a diff so do you think that is a "benchmark" figue to work with or should I have them closer together / they can be a little further apart ?

Thanks.

Paul H

[one eyed mick]

It will be just like running with a locked diff rather squirilly!!

[Compo_Simmonite]

one eyed mick said:

It will be just like running with a locked diff rather squirilly!!

Exactly. Quads feel like they are going to tip over when you turn if on solid surface.
However when you have the wheels close together then the difference between the turning circle of each wheel is so small as to not be noticable. The further apart the wheels are with a locked diff then the worse it gets. BWM DIDN'T use a diff on the rear axle of the Isetta as the wheels were close together (52cm)so I'm going to do the same. Also max speed will be 8mph

Paul H

[KDIcarmad]

If the wheels are under 16" they count as one wheel, if total under 1000kg. Not really the question you asked but interesting.

[ChrisJ.]

Frazer Nashes have no a chain driven rear with no diff.

See here:
http://www.blakeneymotorsport.com/images/stories/d...