The Dallara F3 cars have been running a front monoshock for a while now. They achieve roll stiffness by using a couple of bellville washers. I'm not sure how successful the design is but Dallara totally dominates F3.

If you don't have any damping in roll then a) your car will oscillate undamped in roll
and b) you lose a significant element of transient u/s o/s tuning.

Aaron Johnston
University of Waterloo FSAE

www.eng.uwaterloo.ca/~fsae

A steering damper from a motorbike could be used (in conjunction with some sort of linkage for adjustability) to do the job for the roll damping...they still use pressurised nitrogen to reduce oil cavitation etc, but since the shaft is a 'through' type, they dont have the preload normally associated with regular shockys.

Then both the roll and bump systems would be fully independent of each other, yet still fulfill their roles completely..

just a thought.

Sam.

Dammit! Stop wasting time thinking outside the box, and just do a conventional setup like everyone else ! ! !

I don't see enough people using Gas-Struts - as in the thing holding up your bonnet or boot/tailgate. Cheap and readily available, it's a spring AND a damper in one ! ! I don't quite understand why you'd chase a lower roll resistance: I'd be chasing Zero roll with maximum wheel independance - like the de-coupling Anti-Roll bars mentioned before. I've seen these done with hydraulic rotary coupling IN the A.R.B, and hydraulic A.R.B. MOUNTS - coupled to another hydraulic mount on the car's opposite corner.

BMW also do Active de-coupling of roll bars in their "Dynamic pack" for the 5/6 series Luxo-barges.

Hell - just blow the entire S.A.E. Budget on doing fully active suspension ! ! !

OK... but you can't design a suspension with a half dozen random thoughts.

Will,

Just a little more background info, if you would like to know. As both you and Clausen mentioned, FVee's utilized "zero-roll" rear suspension...which means that almost no roll stiffness is provided by the rear suspension. The reasoning behind this is most likely a solution to an altogether different problem: the differential.

FVee's are open differential cars, which as you know can exhibit noticeable inner wheelspin during corner exit on slow/med speed corners. By allowing the front suspension to provide nearly all of the roll resistance, the rear inner wheel will always remain loaded by at least the unsprung weight at that corner. This might not be much weight, but it may be enough for an underpowered car (like a FVee) to prevent open differentail wheelspin.

Anyway, just my $.02......but I'm just a drivetrain guy, so don't take my word as gospel! Hope that provides some more insight.

We ran a front monoshock on our '05 car. Works great, don't have roll dampening yet but the car has incredible turn-in and handles slaloms extremely well. I'm currently working on a way to include roll dampening. Hopefully the car will handle even better.

quote:

Originally posted by jayhawk_electrical:
We ran a front monoshock on our '05 car. Works great, don't have roll dampening yet but the car has incredible turn-in and handles slaloms extremely well. I'm currently working on a way to include roll dampening. Hopefully the car will handle even better.

Think about running the front A.R.B. damping similar to that supplied by the regular dampers in the rear end. Otherwise you'll get a massive imbalance in effective roll resistance under dynamic loads between front and rear ends. i.e. when you turn-in. Has anyone ever tried running a monoshock, with active roll control? Think Williams FW14B, which can be seen here LEANING IN to a corner!


I personally would run a conventional twin-shock/spring system, with no A.R.B. to interfere with wheel independance. To negate body roll, I'd mount the inboard ends of the springs&shocks on a common shaft, which can be moved via worm drive or a threaded shaft.

Mmmmm.. . . Anchovies . . .

Jason,

Re: Formula Vee. These have, as a result of using the Beetle suspension, a ground level "roll-centre" at the front, and an ~axle-height RC at the rear (approx at the centre of the diff). If they had conventional springing at both ends then they would have way too much lateral-load-transfer at the rear, and hence be prone to oversteer in corners. This is because LLT = elastic-anti-roll (from the springs & ARBs) + viscous-anti-roll (from the dampers) + kinematic-anti-roll (from the slope of the line from wheelprint to RC). With the "zero-roll-stiffness" arrangement at the rear, their front/rear LLT's are about equal - all front LLT comes from the springs & dampers, all rear LLT comes from the high RC - hence reasonable handling.


Erich,

The monoshock Dallaras don't have front roll damping because it works better that way! I posted on this in "Anyone else run a Monoshock?" thread.

Z