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Racing car without swaybars?

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sierra4000

sierra4000

Automotive
Oct 17, 2013
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Hello,

is a good idea?
with low center of gravity 4WD racing car without swaybars? (maybe only small rear bar for balance)

some other reason swaybar for use in racing?(than corner balancing)

thanks for your opinion!


Radek



 
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I'm not aware that a swaybar does anything useful when traveling straight ahead.

ISTR that when the highway up Pikes Peak was paved only with gravel, the fast racers would remove swaybars, or at least use thinner bars. I think their operating theory/guess was that increased body roll would put more weight on the outside tires, causing them to dig deeper in the gravel, forming a dynamic/transient berm and allowing increased corner speed.

If they were right, your answer depends on the surface you're racing on.
If you have a mix of surfaces, maybe you need a dynamically disconnectable swaybar, which you can clutch/declutch with whatever time you can free up from other driving tasks...



Mike Halloran
Pembroke Pines, FL, USA
 
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I mean:
If we can achieve an acceptable body roll and good corner balance without swaybars, there is no reasons for swaybar use?

Radek
 
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Right, I think. Stiffen the springs enough to limit body roll, and remove the swaybars. Ride quality will suffer, but you don't care about that unless the track is bumpy, and maybe not then, depending on how old you are. ;-)





Mike Halloran
Pembroke Pines, FL, USA
 
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sierra said:
is a good idea?
with low center of gravity 4WD racing car without swaybars? (maybe only small rear bar for balance)
Click to expand...

Adding a sta-bar increases wheel rate - making that end of the car less compliant, resulting in greater variation of wheel loads over whatever suspension movement occurs. It also reduces the "independence" of wheels on a nominally independent suspension. I think years ago it was Porsche whose opinion was that avoiding the need for a sta-bar was a goal to be sought, reasonable perhaps in the days of low, 1500 lb sports roadsters with horizontally opposed engines and no other single item of substantial mass other than the driver.

Powerful RWD solid axle cars may not use a rear sta-bar at all; this is normal at least in oval track racing whether on asphalt or on dirt.


Mike said:
I'm not aware that a swaybar does anything useful when traveling straight ahead.
Click to expand...

There is a clear advantage to having a rear stabilizer bar in the very narrow situation of drag racing a car with a solid rear axle. What you're trying to do there is use roll stiffness distribution to oppose driveline torque and equalize the rear tire loading for maximum total longitudinal grip. Rear sta-bars used in this manner tend to be far stiffer than would be sensible for street driving, and may even be coupled with the removal of the front sta-bar.


Norm
 
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OK Norm,
I have now a stiff front spring for travel limitations and 0.7" front sway bar for body roll limitations
Also very stiff rear springs and big bar for understeer compensation - this causing inner rear wheel traction loss during acceleration out of slow corners

I mean ,when swaybars stiffness decrease the same values front and rear - I get better acceleration out of slow corners

BUT - what will be the impact on the corner balance - when I have the front rollcenter low than the rear?
will to more oversteer?
is correctly?

482397_661543320543659_722082957_n.jpg
 
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Are you talking about load transfer distribution?

You need to keep load on the inside rear, this means reducing rear roll stiffness or increasing front roll stiffness. Unfortunately this means an increase in understeer.

I have a load transfer calculator that may be of use to you for this purpose?
 
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It is here: Best viewed on a desktop/laptop with Chrome or Firefox. It is not Internet Explorer friendly.

Default inputs are Mazda MX5, you'll need to know a fair amount of detail to fill it in for a Sierra, but most of it should be available if you don't already know it.

At the moment the ARB calculation is only a basic straight, right angled arm one, I've not yet got round to angled arms or anything else. Should still be useful as a comparison between two different setups on the same car, just not between cars with different suspension designs.

Ideally you want the LTD being within a few percent of the weight distribution for a RWD car.

Roll angle is defined as that generated by suspension movement alone. Tyre deflection is not accounted for.

Erm, any more questions, give me a shout!
 
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"Ideally you want the LTD being within a few percent of the weight distribution for a RWD car."

This thread is mostly about AWD, but I think a slightly more robust rule of thumb would be LLTD should be biased towards the undriven axle, and towards the front of the car. A good rule of thumb for RWD road cars would be LLTD on front axle = WD+5%


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
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Greg, yes you are correct on the LLTD being WD+5% for RWD.

On FWD Honda's, they worked best at around 46% LLTD when the WD was around 62%.

I have to disagree on the LTD being the roll stiffness distribution. As you change the lateral acceleration, the LTD changes, the RSD does not.

Norm, good to hear it works on the latest version. I'm not all that bothered about re-scripting it for the older versions, people should be well away from them now but I still need to mention it as there are a few dinosaurs lurking that are still using IE6-9!

The unsprung mass is that in each corner.

How do you quote on this horrible forum software?
 
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LTD / LLTD / FLLTD = Front Lateral Load Transfer Distribution. The percentage of the total load transfer which is taken across the front axle. A higher number typically means more understeer bias. Changes with lateral acceleration as the stiffer axle transfers load at a faster rate.

RSD = Roll stiffness distribution. The percentage of the total roll stiffness taken by each axle. This is fixed.
 
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I only know the syntax, but there is an icon for inserting quotes about 6th from the right that I've never tried.

[quot name]paste text here[/quot] . . . misspellings of the word "quote" are intentional else you won't see it. Including the name is optional.


Norm
 
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