Zero Droop Front Suspension Setup

[TVH 0]

Latest trend in (track racing) front suspension setup seems to be 'Zero Droop' where the spring is pre-loaded accurately to match the corresponding corner weight. This should increase grip on inside front wheel when cornering and improve weight transfer between front and rear. But I'm not so sure if it works on a FWD car, has anyone tried it? Any opinions?

[C_W 3 1 Cars]

I would have thought it'd make things worse and increase the chance of lifting a front inside wheel if it can't droop down at all?

[Batfink 201]

isn't that just standard cornerweighting???

[TVH 0]

Well, I'm just a suspension n00b but some people insist that zero droop is good, at least they use it on Formula Fords, Radicals and Caterhams.

 

People say that droop is not needed on inside front because the outside front will compress and therefore the whole front will dive by some amount. Zero droop should give a go-kart like steering response because the spring rate is infinite until the weight that the spring supports becomes greater than the amount of preload applied.

 

But the thing is, preload is difficult to adjust without losing ride height adjustment on coil-overs and after hours of googling, I still haven't found any information if zero droop is good on a FWD car. Looks like all the serious racers and suspension gurus drive and tune RWDs only

[nick 3]

On a std coilover you can't preload the spring ,only alter the ride height. The only way to get zero droop is to have zero spring compression, because as soon as the cars weight compresses the spring, this becomes droop when the weight is taken off the spring. The weight of the car sets the preload (the adjustable collars then become the fixed pan) To truly preload the spring you would need a fixed spring pan on top of the spring and the adjustable collar below it.

 

Nick

[James_R 3]

The alternative is to have suitable short damper bodies that at full damper extension are the "right" ride height, then you can go with zero droop. I've not tried it yet on 205's so can't comment if it works. But my old 306 had this the dmapers were so short that you effectilve had to wind some preload in to them to make the car not sink too much when you dropped it off the jack as it was very very low, and that had awesome amounts of traction open diff aswell, drive like it had a diff, but then it didnt' really have enough power to break the traction (400lbs springs 25/30 rear beam solid mounted)But my last set of coilovers on my 205 had dual springs in them so the above as true, but the second spring rate was pretty low, some 30lbs/inch or so which took up the slack between the 285 spring and the end of the damper travel, and it certainly worked well like that with the diff in.

 

If the spring goes free so the inside wheel is effectively floating then it's not going to contribute a great amount to the grip of the car, normally means make the tail stiffer so the car keeps more weight over the front.

 

I'm running Gaz Gold or whatever they are on the 205 with 300lbs springs and have put some preload in to them like the 306 used to run, won't be till early next year till I test it, likely to be with a bigger ARB front and back aswell, failign that no front ARB and 350lbs springs. (25/30 rear beam)

[Paintguy 0]

Well, I'm just a suspension n00b but some people insist that zero droop is good, at least they use it on Formula Fords, Radicals and Caterhams.

Which are all Rear Wheel Drive.

 

As C_W says, it'll make things worse rather than better on a FWD car I would expect., where zero rear droop would be a better idea

 

Remember, as a general rule you want the most roll stiffness at the opposite end of the car to the driven wheels.

[bobob 0]

Remember, as a general rule you want the most roll stiffness at the opposite end of the car to the driven wheels.

 

So a bigger ARB in a 205/ 306 case then?

[welshpug 1,626]

So a bigger ARB in a 205/ 306 case then?

 

 

in the Rear yep that or just larger torsion bars.

[Tom Fenton 1,526]

I'm going to resurrect this.

 

Me and my mate Phil have a track 205 between us which a few of you may have seen at Pugfest. Its in a continual state of improvement as we alter things in the attempt to make it better.

 

A recent addition has been some AVO coilovers and eccentric to mounts to get some negative camber on the front. However the dampers were second hand so we don't know the rate of the springs that came with them, but on comparison with the 225lb springs on my other 205 they are definitely a lot stiffer than this. Coupled with the 309 GTI ARB that was misguidedly fitted a while ago in a bid to improve it, 21mm rear torsion bars, and a standard ARB the handling is really not great at all!

 

SO, the plan at the moment is as such.

 

1) Establish front spring rate. Change springs to a more sensible rate if reqd TBC. 275-300lb perhaps? Suggestions welcome.

2) Change rear ARB to a cut down 306 24mm item.

3) Have rear dampers modified to limit travel in droop, to effectively achieve zero droop on the rear.

4) Experiment with front ARB. Potentially refit 19mm 205 GTI one.

 

Thoughts behind this are:

 

Front spring rate at the moment coupled with the 309 ARB is causing a loss of traction to the inner front wheel.

By increasing the rear roll resistance along with zero droop will cause the inside rear wheel to lift in cornering, this then stops this tyre dragging/scrubbing in cornering, reducing drag, and also will load up the outer rear tyre to get some heat into it and make it work.

Hopefully this should also make the car more balanced and stop the loss of traction to the inside front.

 

Any input welcome please.

[Rippthrough 98]

The first step I'd take if the springs are so stiff is to drop the front anti-roll bar completely Tom, disconnect a droplink and see what you think, I don't run one on the front of the 306 any more and springs are far softer than yours.

Edited September 9, 2008 by Rippthrough