Sway bar or not? 11

[indyracer]

I've raced IMCA Modifieds successfully for decades, both pavement and dirt tracks. I've NEVER used a sway bar on the car, front or rear. I look at the big hunk of steel (bar) and the added weight, so off they come when I buy a chassis. Am I wrong to dump the bar? What do I lose? I know the bar allows using the left spring rate to allow for a softer right spring, but is it worth the extra weight? In my mind, I just spring/shock the car based on tire temps, weight at wheel and wheel travel, and save the bar weight. Your info/advice is much appreciated, thank you.

 

[patprimmer]

Anti roll bars are easy to make adjustable from the drivers seat while the car is racing to adjust for changing track conditions and changing fuel load and even changes to handling from minor collisions due to argy bargy racing.

Regards
Pat
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[MikeHalloran]

"I've raced ... successfully..."

There's your answer.

I'm guessing that the mental effort of worrying about when to tweak the ARB and in what direction and how much might distract you from just racing with whatever car you have at the moment, and the weight savings therefore pays off.

... at least for you.

If you start losing, consider adding ARBs.

... or washing the car. ;-)





Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

On a circuit car, whatever works, works. The chances are you want traction from the driven end, and braking from the front. Both are helped by less sta bar than more. aero is fairly insensitive to sta bar.

But I bet you can't set up a typical road car without some front bar.





Cheers

Greg Locock


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[AlexEsteves]

My off road racing experience is limited to racing Score 7S; where sway bars arent desired due to the amount of suspension
articulation and, to a lesser extent, sway bars increase the chance of rollover if one experiences unwanted bit when drifting through a high speed corner. Now I believe that 7S and IMCA are different primarily because IMCA is not requiring 2 feet of suspension travel, and the terrain is nowhere near as unpredictable as in the desert racing world.

With all due respect to the previous posts- yes, one cannot argue with results, if you've been successful with your current suspension combination then you may consider leaving it as is. However, racing is not about remaining complacent with moderately good results (in my humble opinion). Sway bars can significantly improve the contact patch of the tire while cornering because it reduces the car from swaying like a boat. Your suspension becomes predictable and allows for fine tuning from one track to another.

That being said, the traction benefits a sway bar can offer far outweight the added weight to a 2,000-3,000 lb car. I say give it a shot, in the worst case scenario youll find that your first instict was right, but at least you fed your curiosity for a relatively low price.

Alex Esteves, Pasadena CA.

 

[dfoxengr]

"Sway bars can significantly improve the contact patch of the tire while cornering because it reduces the car from swaying like a boat. Your suspension becomes predictable and allows for fine tuning from one track to another."

Pretty sure the ARB will decrease the available grip at that axle by transferring more load laterally. If he can live with a softer car in roll then no bar could be beneficial.
As someone else mentioned, the ARB is good for adjusting the roll rate distribution with changing tracks and conditions.

 

[Tmoose]

A long time ago in a galaxy far, far away ADDCO claimed a front ARB actually increased First gen Camaro front grip because the OEM camber curve was so poor it induced big understeer by tilting the tires in a bad way. Sounded good when I read it the first time. And Chevy and FORD did change their front suspension geometry as soon as TransAm got serious.

 

[evelrod]

If you can manage without an ARB, by all means do so. They are just one of those necessary 'crutches' to making a street car handle and still not ride like a 'rock wagon' (as my dad said).

On race cars, any race car, the bars are their because they are just another tuning aid. If they were not necessary, trust me, they would not be there. If you are in a car that has acceptable cornering and transitional handling with springs only, you are the one that has the edge. Smooth tracks, big springs, fat tires...that's the ticket. However, in my little cars, smooth track is usually an oxymoron...I have a bar at the back of my Mini because otherwise I would need to dicker with toe out to get the darn thing to rotate into a corner under power and that makes powering out a problem. The bar corrects that little handling deficiency well enough. It can also be made cockpit adjustable to correct for little on track changes like less fuel or weather. Digging deeper into the question, what about putting a small damper as the connecting link of the ARB? It's done in some racing classes. Makes the bar "work" entering a corner but "go away" exiting. Just a tuning aid. Man, if I could do without one, I would!!!

Rod

 

[billytheshoe]

Based on my road course experience, body roll can be used to a distinct advantage. I ran front drive cars, so I'm just pulling a cart around.

The dynamic is stiff across the rear (less body roll) and little ARB or no ARB in the front give you a great sense & feel weght shift for steering with the throttle.

The rear being "loose" allows slide the rear turning in (less steering input) and to control that slide you apply throttle and transfer weight to the rear causing the tire to grip slowing the slip rate. This is modualted with the throttle. You are able to aim the car & throttle out of the turn sooner.

I removed the front bar & added more spring allowing the RT & LF to compress independently to manage weight shift balance front to rear. With this type of set up you must be on the throttle all the time in a turn or the cart beats the horse out of the turn.

You want about 30% to 50% less spring in the rear relative to the front to allow weight to swat the rear as the weight transfers on throttle up. Better dampening in the rear than the front.

 

[indyracer]

Thank you all for your input. My car weighs about 2300 lbs, low center of gravity, relatively small tire patch, 8 inch width rims.
track is only 8 deg bank, sweeping turn, so not a lot of side g's, but lots of speed around turns. I spring the car pretty soft.
only gotta turn left. about 60 pct left side weight, wheel travel on all corners I keep at about 2 inches..so there's not much body roll at all...car is nice wide track. With this info, If I follow some of the comments, seems like the sway bar is just along for the ride...extra weight. Likely why I've done fine without. With the additional info, I'd appreciate your comments, thank you.

 

[billytheshoe]

Hauling 10 to 15 pounds of ARB hardware is very well worth it if it makes you quick.

 

[murpia]

Even F1 cars can run successfully without any anti-roll bars. They are not essential and increase warp stiffness which hurts grip on uneven surfaces.

The key is to understand the right 'numbers' for your tyres: aero balance, roll balance & weight distribution.

Regards, Ian

 

[patprimmer]

F1 do not use anti roll bars because they have a very low centre of gravity and very hard suspension to control ride height with down force that changes greatly with speed, therefore they have very little roll to counteract.

Regards
Pat
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[indyracer]

Patprimmer,murpia & billyshoe: Thanks again. My car also has low c.o.g. with little chassis roll, which seems to confirm that the single track I race and the car characteristics can do w/o the ARB. Nonetheless, I'm gonna practice with and w/o..I'll report the results. Billy: if my car can move 15 pounds off the front and over to the left or completely off car, it would also corner faster, yes? Hey, it's the engineering fun of the sport! Which way is best to go? So many variables...

 

[evelrod]

Murphy's Law ... For a race car to be quickest in all conditions it must be infinitely adjustable.

Corollary to Murphy's Law..If a race car is infinitely adjustable, there is a 100% chance that something is always in need of adjustment!
AND...
Nothing is so out of adjustment that $$$ cannot fix. ;o)

Rod

 

[patprimmer]

Rod
Another jewel of wisdom.

Regards
Pat
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[billytheshoe]

I am over my head in this forum, I may be better off observing before I embarrass myself....

 

[TMcRally]

I'm not qualified to answer either so don't pay much attention. But just from my experience sway bars seem to dumb down the suspension and adjustments are easer to follow without them. I used to run a rear adjustable bar which was handy but the adjustments (a series of holes) where big steps, I considered making a slide arrangement to replace the holes but I found adjustments to rear ride height work for me. You can be as course or fine as you like within reasonable limits.

Someone mentioned F1 - did anyone else notice they run camber now. Maybe it's old news and I haven't noticed but it looked like 1.5 or so degrees.

 

[NormPeterson]

Why wouldn't they? Even if the suspension permits zero roll, vertical tire flexibility means that the tires will still undergo camber change, and you can't leave that on the table. Low CGH helps, high lateral-g hurts.


Norm

 

[murpia]

Someone mentioned F1 - did anyone else notice they run camber now. Maybe it's old news and I haven't noticed but it looked like 1.5 or so degrees.

0.5->1.5 deg at the rear, 1.0->3.0 deg at the front, depending on the track. Plus dynamic camber gain from the geometry.

Has been that way since 1998 at least...

Regards, Ian