Radius Arm (road car): high or low?

[Austin David]

I'm fitting the radius arms on my 360S and noticed the higher "S" position vs lower "R".  I couldn't sort out the difference on my own.  Cruising some other forums it seems like the generally preferred option, road or not, is "lower" (R position).

 

Does anyone have direct experience?  Or does everyone pretty much just leave them in the "R" position?

[Pokey]

When researching for my build it seemed like the general consensus was upper for road, lower for track.  I went for the lower position and have left it there so can't compare, but the car seems fine on the road so no complaints.

[Austin David]

Thanks!  I moved them down to "R".  This old post seems to indicate some roll steer in the "S" setting, which I very much find annoying and definitely would not want in my 7.

 

If I get curious I may move them up to see what it's like; seems easy enough with wheels off.

[Austin David]

Josh @ RMC confirmed I should be using the "R" setup.  One of those checkboxes was "sport" suspension, so here's another exception to the Ikea installation guide.

[KnifeySpoony]

If you don't want roll steer, consider adding the watts linkage. I chose that for my recent build. 

[Austin David]

I've got the rear ARB.  How bad does it roll, and how much roll steer are we talking?  This is a street car...  

[KnifeySpoony]

Amount of body roll/suspension deflection with bump will also be determined by spring rates. From my reading, many Caterham drivers like the rear steer feeling that the deDeion with radius arms gives, maybe it's part of the 7 experience? I chose watts for my build as I want a more predictable/stable chassis. My car is primarily a track car. I can induce rear steer in other ways that are under my control (my philosophy anyways).

 

 

[Austin David]

Sounds like something I just need to play with for a bit before I make a bunch of changes.  Like the intake / ITBs 

[Austin David]

3500 miles in, some answers.  Mostly "stop thinking this behaves like a car."  For "spirited" street use, 2/4 seems about right; 1/4 is pushy / understeer, 3/4 is a little extra fun / oversteer.  I understand it's easy enough to induce oversteer at any setting, but 2/4 is natural.  I have not tested the higher "S" mounting locations.

 

There is very little body roll in this setting.  Roll steer is there, but not significant; I sort of have to hunt for it, honestly.  Certainly not enough roll action that I feel like I would want to add linkages to my rear arms.