240 track?

Hi Dave

Nice to meet you at the weekend. Despite your phenominal Volvo knowledge, I beg to differ on this (I think!).

Bear with me... in normal driving the whole axle stays parallel to the road with a live axle. The roll stiffness is provided by the strength & position of the springs and the anti-roll bar. Neither of these change with spacers.

So with a live axle I think the NORMAL roll stiffness is a function of factors other than track UNLESS you get to extreme forces where an inside wheel could lift off the ground. And in such circumstances a narrow track would give the mass of the body more leverage to lift the inside wheel, hence less rear grip, hence more sudden oversteer (old term: "roll-oversteer", because of wheel lift).

An example to illustrate the point. The original late '50s Jaguar 2.4 (subsequently referred to as the "Mk 1") had a very narrow live axle due to fully enclosed rear wheels. I believe this car suffered sudden roll-oversteer at the limit, not understeer, with the narrow track. This was addressed in the Mk2 which had a wider axle and gave less oversteer. Another example was the old Commer van (narrow axle, high centre of mass if loaded, roll oversteer). I don't think they ever bothered to fix this one!

So on my logic I don't think spacers in isolation would make much difference to roll stiffness or handling, but if there was a difference it would be more rear grip and less oversteer (= more understeer) in extreme situations.

But you're the engineer and I stand to be corrected!

(And anyway a 240 handles like a Lotus compared with my last Volvo... you want understeer? ... try a 164 with 50% more engine weight up front!)

Cheers

John