Snap oversteer

[Alonso]

Hey guys i wounder if you could help me. I am running formula volkswagen caes and we are battling with snap oversteer threw fast corners. What could this be or what should i look for to overcome this problem?. We are running on radial slick tyres and aero.
Thanks brett

[Jersey Tom]

Check to make sure your rear suspension isn't bottoming out.

Also, try different tires (different brand, construction, or compound).

[Alonso]

Thanks for your reply. We are only allowed one tyre make wich is a dunlop radial tyre. When you say bottoming out what are you reffering to. Would to much droop on the rear suspension cause it so be rolling to much wich then would result in the bottoming effect. I was running 23 mm droop for the event i dont think that it is to much. I also ran alot of pree load on the front springs and found that it was a little better. My driver is wesligh Orr the rookie driver for A1 team South Africa so he has good knowlege of what the car is doing. I was really bad threw fast stuff with a big snap on the rear. He also compalined of the front steering being very heavy.
Thanks Brett

[RacingManiac]

is the front caster adjustable? maybe try less caster as it should reduce the steering effort and get rid of some cross-jacking related to steering input, which could make the car harder to managed in a snap oversteer situation...

[Alonso]

Yes the castor in front is adjustable. Would taking castor away in front make the steering lighter? Would that have played a roll in the snap oversteer.

[donskar]

Is your suspension hitting the bump stops through the corner?

[fatburner]

Hey guys i wounder if you could help me. I am running formula volkswagen caes and we are battling with snap oversteer threw fast corners. What could this be or what should i look for to overcome this problem?. We are running on radial slick tyres and aero.
Thanks brett

Could you reveal what "remedies" you have already tried and what the driver felt then?Also,is it off/on-throttle,long corners only or this problem occurs also when turning sharply(but we are still talking about some fast corner,as you said).Is it more difficult when turning in,mid-corner or corner exit?.

So far it is not easy to decide,what to do.When the car is acceptable in most corners,but gets nervous when running through long fast ones on-power,I would re- check camber settings.Probably I would try more camber for rear(or less front).Still,more information would be helpful.

[marcush.]

snap oversteer is refering to a situation where the car is going from a understeer/neutral situation into a sudden oversteer situation at corner exit.
very often ,this is a tyre temp issue.
Having the fronts below optimum temp and the rears at maximum temp at corner entrance will cause sudden corner exit oversteer :As you push into the corner the temps front and rear will rise,the fronts gaining grip as they reach optimum temps ,the rears loosing grip as they exceed optimum temp.additionally you will exagerrate this with applying throttle at corner exit.
In case of the Formula V how is this in terms of Suspension layout? I correlate this to rear swing axle and front swingarm suspension.On the rear you face huge camber change in bump /rebound ,the front will give you zero camber change in bump but 100%camber change in roll -the only solution here is to get rid of most of suspension travel at all ,because the radials are not compliant to huge camber changes.You could try to get rid of the roll with a lot of anti rollbar front and rear.restricting droop at the rear would certainly help with the swing axle going into positive camber but at the expense of nervousness under braking.(and corner entry,but of course you may refer to corner entry nervousness as snap oversteer ,so I suspect one would need more detailed debriefing before actually changing setup or layout of the car)
Diagonals/bias ply tyres are more forgiving with geometry ,and this might be one of the issues you are facing.
For sure temperature measuring is the first step to get a clue.Best is to have as many infrared sensors on the tyres during cornering as possible and look into that data (front rear inside middle outside temps)

[alexbarwell]

For a stripped down FWD series, are you allowed to address weight distribution and brake balance that could affect the behaviour of the tail, also is a heavy duty anti-roll bar allowed on the back if the rear suspension is compressing too much and giving undesirable camber change some of this would be reduced by transference to the unloaded side of the car.

[Jersey Tom]

snap oversteer is refering to a situation where the car is going from a understeer/neutral situation into a sudden oversteer situation at corner exit.
very often ,this is a tyre temp issue.

I find this questionable.

[flynfrog]

Welcome to formula vee

They have a worse suspension design than the corvairs

[RacingManiac]

I find this questionable.

I tend to agree, I think tire temp is more of a result of car's handling traits, it would more likely manifast itself as the car's handling gets worse over time because the balance is shifting over time(say a car is exhibiting chronic oversteer, building up more tire temp at the rear). Anything "snap" I think would tend to suggest to something immediate, which results in more sudden balance shift. Bumpstop would do that as it will produce sudden increase of a wheelrate. Caster I think is more of a function of driver's ability to control that since it affects crossweight jacking and if do run a lot of it, any steering input(or correction in this case) may be amplified because of the cornerweight shifting caused by steering.

[Alonso]

Hey guys thank you very much for your input. I Founf a problem some time ago were the shop top is bottoming on the bell crank causing the shock to bend and wearing the shock top out bad. Would this have any effect on the reaction of the rear of the car. The car is really snappy threw the mid part of the fast sweep type corner and also exiting the slow corners power on. The rear cambers are 3,6 and the front camber is 2,6 the droop is 23mm and no matter what we did with the roll bars and squat angles on the rear wish bones it made no diffrence. Even full wing was not any better on the rear. I hate running to much wing because it really is telling me that there is a machanical set up problem. Caster is neg 7 degrees The tyre we using is a radial dunlop 13inch tyre. The heavy steering was just before the snap oversteer would accure.
Thanks Brett

[Alonso]

hey guys just wanna clear things up the car i am running is a formula volkswagen its a monocog chassis with full wishbone suspension and indivedual shocks fully adjustable bump and rebound. it has wings rear and front with a difusser.
Shot

[RacingManiac]

If your shock is bottoming out on the bellcrack its going to give you issue as at that point your spring rate is your bending stiffness of the shock rod(sounds like a pretty poor design on the chassis constructor's part, lol). Does this happen on droop or compression? One way or another it cannot be good at those condition...