Fiesta ST autocross accident

[RAAM]

I see a few issues with the car setup.

1) They do not need a rear sway bar, not sure without digging into my old chassis setup books but it could likely of been a factor. As I recall a rear sway bar would transfer weight to the opposite side front tire.
2) Tires, OK, love sticky tires but....air pressure might of been to low and the next item on the list can be very critical.
3) Wheels, should be 8" wide for proper sidewall support, compounded again by air pressure.
4) Springs, I do not know the rates or if linear or progressive but could be a serious issue.
5) Dampers, also do not know how well they are valved to work with those springs.

Then the course layout and surface as well as driving style not being very smooth, all mitigating factors.

The main problem is most have very little understanding of proper geometry, the more one lowers a car the closer one gets to being to low, if the springs compress enough it can result in the majority if not all the weight being transferred to the outside tires like it does on a properly spring rate setup but lowered to much. The inner pickup points HAVE TO BE HIGHER than the ball joints center of rotation, simple physics.

The vast majority of modded cars are not setup properly, especially the absurd stance ones, cartoon setups that work for nothing about actual performance and most are quite dangerous, fact, not fiction.

Rick

 

[Snrub]

I like that RAAM has suggested multiple ways of how to be safer. I know others have eluded to it as well, there has yet to be an explicit recipe to reducing rollover risk, rather than simply not increasing it.

For instance, there was discussion of roll centers but how would one know how low is too low? Most lowering spring are progressive, is this a bad idea?

What if one wants to make the car safer than OEM? Would the safest be an adjustable coilover, or DIY setup like Dialcalipers where he used standard racing coils at a higher spring rate while maintaining ride height?

Montotune's (presumably one of the best funded engineering) springs drop the car, but barely adjust the rate. The fronts look linear, the rears look progressive.

Lots of people had dropped to 16 or 15" tires sizes with taller sidewall. Should they make different considerations than those with 17" tires?

There is another thread with shock dynos. What are the safest spring/shock matches?

I know when I've done emergency swerves, the body roll of the car makes the car far less easy to control than say my old RX-8, or my old NA Miata race car. At one point I lowered the Miata so low the control arms angled up when sitting (double wishbone front/rear, height adjustable sleeves) and I couldn't notice the mistake on the track.

 

[WannabeST]

I like that RAAM has suggested multiple ways of how to be safer. I know others have eluded to it as well, there has yet to be an explicit recipe to reducing rollover risk, rather than simply not increasing it.

For instance, there was discussion of roll centers but how would one know how low is too low? Most lowering spring are progressive, is this a bad idea?

What if one wants to make the car safer than OEM? Would the safest be an adjustable coilover, or DIY setup like Dialcalipers where he used standard racing coils at a higher spring rate while maintaining ride height?

Montotune's (presumably one of the best funded engineering) springs drop the car, but barely adjust the rate. The fronts look linear, the rears look progressive.

Lots of people had dropped to 16 or 15" tires sizes with taller sidewall. Should they make different considerations than those with 17" tires?

There is another thread with shock dynos. What are the safest spring/shock matches?

I know when I've done emergency swerves, the body roll of the car makes the car far less easy to control than say my old RX-8, or my old NA Miata race car. At one point I lowered the Miata so low the control arms angled up when sitting (double wishbone front/rear, height adjustable sleeves) and I couldn't notice the mistake on the track.

Track day insurance is always an option, but motorsports by nature are very risky and unsafe. We can obviously mitigate risk with modifications and safety equipment but no amount of modifications or equipment will change the fact that you are still tossing around a big chunk of metal. Rollover risk aside, any car can have a failure from stress or fatigue at any moment, which can lead to a bad accident. The Fiesta is still one of the worst cars (safety rating wise) to own. If one cars that much about their safety they should consider a different chassis or they should consider the fact that motorsports is not for them.

 

[Snrub]

^ That amounts to saying trying is the first step towards failure. It's common when building a racer car to consider things that make the car safer, so why not consider it as part of this discussion?

 

[foodtruck]

Well, if you want to race your car but make it safe,

1) Use high-treadware tires (300+)
2) Make sure car has a significantly wider average wheel track than it is higher (main SCCA solo eligibility rule criteria)
3) Make sure it has more traction in the rear than in the front so that it understeers rather than oversteers at the limit

But you have to make peace with the fact that it wont be the most exciting car to race 🤷🏻‍♂️

For everything else, you probably need a team of engineers and complex simulation software to be certain (which is probably why the common advice is to not mess with the formula provided by, you know, a team of engineers and complex simulation software at the company that built the car)