What's The Deal With Chassis Flex?

[MotoObscura]

I keep hearing that the reason modern buggies are so narrow is to give the chassis more flex for more grip. Why is that?
My dad used to race full sized cars and he always told me that a chassis should be as stiff as possible to let the suspension do it's work properly. That seems to make much more sense to me. With all of the tuning options you have in the suspension, why rely on chassis flex for added grip? It seems like that is the least tunable part of the car, and if anything, could cause unpredictable handling characteristics.
Can anybody enlighten me?

[Wicked6]

Sure seems like a good way to go bald faster trying to dial in your suspension.

[Jay Dub]

The reason given was an overly simplified, and mis-understood notion. The biggest reason chassis flex is believed to "give you more traction" is that it helps to even out discrepencies between front and rear spring and damping rates. I really flexible car will usually feel great first time on the track. However, as time is spent tuning, one will learn that really drastic changes need to be made in setup to become significantly faster on the track. Now one of the benefits of a flexible car is that they are less sensitive to track changes and more consistent. The biggest issue however is that ultimately their potential for getting to that fine tuned line (that world and national class drivers require) is limited and rarely achieved. Now there is benefit from a little flex (because of reasons mentioned previously) and because this allows the "suspension" to move in a manner that one cannot achieve with shock/spring movement alone -our shock/spring packages just are not sophisticaed enough. IT is a compromise, and chassis flex (and type) has become as tuning aid in order to mitigate some of those short comings. So, depending on the type of surface encountered chassis flex (in various forms) can be a valuable tool but by no means is a simple solution like "CHASSIS FLEX = TRACTION".

[MotoObscura]

I see. Thank you for that very informative post. That clears things up quite well

[integra22t]

My dad used to race full sized cars and he always told me that a chassis should be as stiff as possible to let the suspension do it's work properly.

nicholasdivitto im with you .. back in the day we all tryed to elemanate flex and now i hear its good ... sounds like eggs,bacon,fat,smokes or anything else that was good is now not

[jwscab]

when all other tuning options fail, make the chassis floppy and drive through it!

Jay Dub is correct in that the scale of the vehicle makes it difficult to achieve 100% desired chassis dynamics, so adding some flex can help.

[janaya]

Yes that's a great explanation. Some flex is good but too much is bad for you.

[RichieRich]

I thought this was going to be a list of Seinfeld jokes.

[Coelacanth]

Yes that's a great explanation. Some flex is good but too much is bad for you.

I thought this was going to be a list of Seinfeld jokes.

But can your chassis be too stiff?

[RC10th]

They always say a loose sloppy car is a fast one....

A car that is too tight can be too darty and a bit unpredictable. Arm flex and other factors can actually cause the suspension to bind up under operating conditions but work fine on the bench leaving you scratching your head.

In my opinion most fast drivers can tune a chassis 80%-85% of its full potential but the factory guys can get 90-95% of the way there. It's all a balancing act which only a few can master.

[AscotConversion]

It probably depends on what type of racing you are doing as well. The trend in on road has been more and more flex. Rumor has it that Ronald Volker of Yokomo has been running a super flexible chassis beyond even what they are selling to the consumer, and he has been kicking butt wherever he roams. At the same time, a flexible graphite chassis is a lot different than a plastic tub. I have had tub cars that go into the crapper when the traction comes up, but putting a graphite chassis on the car and everything is fine. On asphalt though, that tub car would be awesome.

Beyond that, how the chassis flexes is also important. Front to back vs. torsional flex makes a big difference in the handling of a car. That is why you will see the length of the top deck and bulkheads changing as the new models come out. Even where on the length of the chassis the top deck is tied in or not tied in makes a bit of difference.

In offroad, I'm sure things are different. I don't run offroad much at all, but I would think that there has to be a lot different dynamics affecting the car.

[cautrell05]

The general consensus when i was racing full scale stock cars was that flexible cars were easy to get close with the setup. The rigid cars were a little harder to get set up but would be faster one you get there. Hopefully that makes sense. all of my cars were built as rigid as possible.

[Brandon G]

I thought this was going to be a list of Seinfeld jokes.

Haha!

[edwin pibal]

we call the shuy mi5 "the wet noodle" over here because of the flex it has.

ed