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Old 10-01-2003, 05:48 PM   #1
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Default Chassis flex - or not to flex

I've heard a bunch of theories on car tuning, especially since I purchased a xray, that having a flexible chassis will make the car grip better in corners.

Having run a stock (non-graphite) tc3, factory graphite chassis and an IRS chassis, the IRS chassis was much more predictable in the corners, and also much more stiff.

I'm in doubt on this and I wanted to see what you all think.

My thinking Goes:
Chassis flex is bad. It modifies the camper change in the compression of the car's suspension in unpredictable ways. Esentially the tires will not maintain the correct camber angle to the road during cornering because the chassis is flexing and changing the geometry of the suspension.

This might make it easier to drive, similar to a shorter link with a lower inside camber link pivot point, but not faster.

Basically make the suspension do what you baught it for, control tire contact patch.
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Old 10-01-2003, 11:00 PM   #2
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chassis flex is the hardest suspension component to judge,bcos it will affect ur car setups n u have no control over how much u wan or dun wan.

i feel tat chassis flex would b gd for a beginner as the car is much easily to drive.it's also better if the surface terrain is not smooth as it will help 2 absorb the bumps tat is minor 2 us,but major to the moving RC car...
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Old 10-01-2003, 11:04 PM   #3
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Ideally a completely rigid chassis would allow the suspension to function exactly as it was designed to. I think having a stiff chassis is paramount for racing on carpet, especially with foams.

On ashfault, I would think a small amount of flex would be acceptable, as it would help the car grip a little bit more. Personally, I would still go for a rigid chassis for ashfault, but I don't think the rigidity affects the car so much as on carpet.

I agree with what you said - a flexible chassis will make the car feel easier to driver, but it will not actually be faster. In my opinion, if you want to make your car easier to drive, you should make changes to the suspension. This is just what I would do, because I know what changes I made and how they affect the car.

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Old 10-02-2003, 01:03 PM   #4
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Default Chassis flex - or not to flex

Guys;

From personal experience with my HPI Pro-3, having a flexable Chassis, is like running too soft of a suspension for the conditions. The Car will definately scrub off more speed in the corners than it would with a stiffer Chassis. Easier to drive yes, but not as fast as it can be and less consistant.

One more thing I've noticed over the years. A flexable Chassis structure will tend to Tweek after a crash and can take several laps to settle back in. A nice stiff Chassis assembly will recover instantly.
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Old 10-02-2003, 03:21 PM   #5
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I agree. I have found a more flexible chassis to make the car stick better to the surface, but it doesn't carry speed through the turns. Therefore it also wastes more battery energy.
A stiffer chassis feels more loose and responsive and can need more experience to drive as it need a more gentle touch. This is often also faster, especially on high byte tracks.
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Old 10-03-2003, 07:13 AM   #6
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What i'm curious is that in the example of the Xrays, :
The EVO is super stiff and well suited for high traction surfaces
However:
The T1r with the composite chassis is a little more flexy and well suited for low to medium traction surfaces...

Why is that?
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Old 10-03-2003, 09:21 AM   #7
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Just a tip from full size racing.

A stiffer chassis will work better if it is set-up properly given a consistent racing surface. The set-up "window" where the car works is smaller because suspension changes have more affect on the car.

A more flexible chassis will often work better when the track is slick or inconsistent because spring and shock changes have less affect. The set-up window is larger but the chassis won't ever be "perfect". Sometimes this can make the lap times faster.
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Old 10-03-2003, 12:02 PM   #8
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Default Chassis flex - or not to flex

Quote:
Originally posted by Unregistered
Just a tip from full size racing.

A stiffer chassis will work better if it is set-up properly given a consistent racing surface. The set-up "window" where the car works is smaller because suspension changes have more affect on the car.

A more flexible chassis will often work better when the track is slick or inconsistent because spring and shock changes have less affect. The set-up window is larger but the chassis won't ever be "perfect". Sometimes this can make the lap times faster.
This is a VERY true statement. I don't think anyone could have stated it better.

Thank you.
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Old 10-03-2003, 12:11 PM   #9
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i cant have said any better unregisterd dude !
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Old 10-03-2003, 01:15 PM   #10
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I'll second Unregistrered and JesseT.
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Old 10-03-2003, 01:30 PM   #11
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Nice way of saying what I've observed. I guess that I'm lucky to run on very consistent track surfaces. Sealed parking lot, ozite carpet, and a concrete super-speedway road course.

It took about 3 race weekends to dial in the car for each surface. Once I hit it, my car was very fast and very predictable. Just loose enough to rotate fast but just tight enough to turn in well and accelerate well out of the turn.

So stiff is good, if you know how to set up your car. Also explains why real cars run softer setting in the rain then in the dry.

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Quote:
Originally posted by Unregistered
Just a tip from full size racing.

A stiffer chassis will work better if it is set-up properly given a consistent racing surface. The set-up "window" where the car works is smaller because suspension changes have more affect on the car.

A more flexible chassis will often work better when the track is slick or inconsistent because spring and shock changes have less affect. The set-up window is larger but the chassis won't ever be "perfect". Sometimes this can make the lap times faster.
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Old 10-03-2003, 01:36 PM   #12
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Quote:
Originally posted by sands
Just loose enough to rotate fast but just tight enough to turn in well and accelerate well out of the turn.
Oooohh yeah, it's nice when all the work with setup give these results. What's complicating it is, that these setup also should fit driving style and track layout.

I like the way you phrase it above, it's this balance it's about to find.
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