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I'm wanting got setup the suspension on a FWD golf track day/road car...
The car will have adjustable ride height and adjustable dampers front and rear.
I've had a look on the net and can find some information but its always about RWD cars.
Other than traction are the concepts the same?
At the moment the car is on standard suspension and seems very under damped, understeers from turn in to exit and is VERY sensitive to coming on and off the throttle.
I would like a neutral turn in and neutral to oversteer balance on the apex and way out if possible!
I hope some of our more knowledgeable members will help, but here's a starting point.
I have FWD 1998 Nissan 200SX SE-R. Independent front with struts; solid rear axle. My handling went from fair to MUCH better after these changes:
1- Solid front sway bar (Suspension Techniques) replaced the hollow original.
2 - Rear had some excuse for a sway bar (a torsion bar inside the hollow axle), but I added an additional sway bar (Suspension Techniques)in back. Adding a rear bar reduced understeer a LOT.
3 - Tein coil-overs all around.
4 - Upper strut tower braces added front and rear.
5 - Added lower brace connecting mounting points of lower front suspension arms.
6 - Lowered the rear about 1 inch.
7 - Lowered the front about 1.5 inches. Lower front than rear because more weight up front and better aero. Re-aligned to stock settings.
8 - 1 inch wider 15 inch wheels all around with 205-50 Nitto NeoGens instead of stock 195-65 Falkens. (NeoGens are designed for lowered cars with more camber)
Result: car used to handle adequately. Now I'm not brave enough to know what its limits are!
Basics - a stiffer rear sway bar will reduce understeer.
Lower the car moderately (1-2 inches.)
Stiffer springs reduce roll, but go to stiffer shocks, too!
Put more and better rubber on the ground.
CAVEAT: I was good enough to get into General Motors Institute, but NOT good enough to graduate!
Enzo Ferrari was a great man. But he was not a good man. -- Phil Hill
You don't want oversteer on exit if you want to be quick. Loose can be fast in, but not out. In any event you would be hard pressed to get the car to O/S on-throttle. Weight transfer to the rear will tighten any car up on-throttle. RWD cars with enough power can overdrive the rear tires to rotate the car around. FWD cars, overdriving the fronts on exit will be ridiculous U/S.
Only way to get the car to really rotate would be something like a real sharp lift-off on entry, or handbrake, Scandinavian flick, etc.
As has been said, spring and bar changes will give the most noticeable balance change. Stiffen the rear with respect to the front and the balance will be a lot more neutral. Lowering the front rideheight with respect to the rear (or raising the rear with respect to the front) will also shift the balance toward O/S a bit.
If the car is severely undersprung it will feel lazy and probably snap oversteer in esses and chicanes. Car will feel good going in the first direction but if you try to change directions rapidly the response will be nonlinear.
Given that the car is going to understeer like all hell on exit, this may be the kind of car that benefits from a "pitch and catch" style driving, over-rotating the car on entry (easy with load sensitive tires) to get pointed quickly and then the understeer out won't be as big a deal.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.
A FWD car will tend to have power on understear tendency ,just because you will have to transmit longitudinal (traction) and side force on the front tyres and only side forces rear.
Assuming same tyres front rear ,the car and driver will have difficulty to get the rear tyre temps up,wheras the fronts will tend to overheat.
free regulations would call for different compounds at least ,better yet even different tyre width to get that balance back.
Generally to be fast with a FWD car you desperately need to get rid of the understeer as a priority.So increase front track width as much as possible,transfer
weight to the rear ,between axles.
Make sure to really get the front suspension working (avoid stiction,especially with strut dampers,and make sure to avoid too much body roll to make the inside front stick and do its share of the front workload.
So low CG will help a lot as does suspension geometry.
A quick fwd car does have power on and off oversteer characteristic just manageable with cold tyres and will detoriate towards neutral over time.
I bet a current WTCC SEAT or chevy will not be controllable on cold tyres,luckily they got heat blankets there.
O/S just so much that you don´t need as much steering lock as when driving slow,I don´t propagate a no grip rear,of course,just enogh to help the car take the turn with very lttle steering lock but a lot of throttle.
Belatti wrote:A real challenge would be to develop a suspension for an Argentine Super TC2000 racing car.
430HP on the front is quite a thing...
i´m sure you don´t want the same tyre size/construction/compound front rear for these or you need to setup the car to three wheel around the corners ?
Is the Argentine series allowing for front -mid engine installation- or is your engine position fixed in the oriinal position?
I remember Ricardo Divila did some wonders to RMLs Nissan S2000 primeras a while ago ...tying the engine in for structural integrity of the whole front for example and playing around with swingarm lengths .
there is trick stuff around to optimise Macpherson struts -especially the top mount is a critical area in my view ..
Well considering BTCC cars are a mix of FWD and RWD and its not always the RWD that win. Also some of the Group A WRC cars beat the 4WD stuff on tarmac stages in the past, such as the Citroen Xsara. FWD can work with a good set up. The problems are Torque steer with high power outputs so a good diff can help. Also moving the battery is not always an advantage as weight on the front axle gives traction.
'Point' is useful on a FWD car getting fast turn in so the front is normally lowered more than the rear. Although track setups can be quite firm suspension wise i was always led to believe that teams go as soft as they can for grip whilst trying to avoid bottoming out??
I know this is an old thread, periodically updated, and highly ancillary to the main thrust of this board, but no point in not adding to the repository...
Every front wheel drive car is the same: they all need higher roll stiffness in the rear than in the front.
Every front wheel drive car is different: they all have design idiosyncrasies that must be appreciated.
One of the key idiosyncrasies of production front wheel drive cars is passive rear steering (typically towing the rear wheels IN under lateral and/or longitudinal load). If of sufficient magnitude, and left unaddressed, this can render an otherwise adequate setup maddeningly uncooperative. Another key idiosyncrasy is limited front wheel travel, requiring adequate front spring / bar / compression damping (and maybe even ride height!) Lots of people believe in deleting the front bar, some of whom even win that way - that doesn't make it right (ie optimal).
Also, a front wheel drive car, setup to get the most out of it, will require pretty strict adherence to the sequence of operation (exactly how you drive it), and be pretty intolerant of deviation.
Front wheel drive is interesting, but in the absence of a compelling reason for it there are better choices you can make.
RR98ITR wrote:Every front wheel drive car is the same: they all need higher roll stiffness in the rear than in the front.
Forgive me, but I don't think that is a correct statement. I have rig tested many front drive cars. If I recall correctly, most have had a very similar roll stiffness split since 1995, when the advantage(s) of a high rear roll centre became apparent.
