Rear sway bar

[Buzzsaw]

I configured my kit with a front sway bar and IRS suspension. I am not going to track the car and my thinking at the time was with IRS it isn’t necessary to have a rear swat bar. I still have time before my final configuration and final payment since my completion date is 10-21. Did I make a mistake not order ice rear sway bar option? Please let me know your thoughts.

[rich grsc]

Adding a front bar without a rear can increase push (understeer) in a turn

[danmas]

I went back and forth on this and ultimately decided to add both front and rear as the cost was relatively negligible. If I decide I don't like the way it drives with the sway bars it take very little to disconnect. Adding after the fact is not impossible either. It is easier to install it at the beginning of your build however.

Dan

[Jeff Kleiner]

Either both or none. With the factory spring rates these cars have a moderate understeer; as Rich pointed out adding a front bar without a corresponding change to the rear will exacerbate that and the car will push even more.

Jeff

[RoadRacer]

Agree 100% with all above... but worth noting that for novice drivers of these cars, understeer is where you want to start out for a good few months.. WAY safer. :)

[Jeff Kleiner]

Agree 100% with all above... but worth noting that for novice drivers of these cars, understeer is where you want to start out for a good few months.. WAY safer. :)

This is true but with a caveat. Moderate understeer is safer than loose HOWEVER when you get into heavier understeer what happens is when the car is pushing and doesn't turn the driver's instinct is to abruptly lift off the throttle or worse yet brake---this loads the front and unloads the rear inducing a snap oversteer and the driver finds himself looking at where he just came from :eek:

Jeff

[Indy Shu]

Or... don't install any sway bars. Personally, for street driving I don't think they are necessary.

[Buzzsaw]

To all responders,
Thank you for taking the time to respond. I certainly know more about the steering characteristic I can expect depending on my decision. I will be adding the rear sway bar to my configuration! I never enjoyed a car that pushed in a corner
Ross

[GoDadGo]

Here is an interesting observation from: The Dark Side!

My pal Heath has a 3-Link MK-4 that has no sway bars, and understeers a pretty good bit.
He's got power steering so his caster angle is is at 7.5 with a .5 camber setting
His tire sizes are 245/45-17 and 315/35-17.

My car is also have a 3-Link MK-4, but has a small .75" front sway bar with no rear and it does not push and is very neutral.
I don't have power steering so my caster angle is 3.5 with a .5 camber setting.
My tire sizes are 245/45-17 and 285/40-17.

My takeaways are listed below:

1. Heath's car has far more rubber out back than I do.
2. My driveline is heavier than his and is roughly 6" further forward yielding a 50/50 weight distribution.
3. The weight distribution difference, combined with the smaller rear tires, combined with the small sway bar makes my car feel balanced.

What I wonder is if I went stepped up to 315's in the rear, would my car also begin to push (understeer) or not?

By the way, this is a great forum thread regarding sway bars and IRS cars.

[RoadRacer]

GoDadGo, I have this bookmarked because it's so handy: Understeer / Oversteer Tuning (https://www.elephantracing.com/tech-topics/understeer-oversteer/)

Here's a teaser..

190035

[GoDadGo]

GoDadGo, I have this bookmarked because it's so handy: Understeer / Oversteer Tuning (https://www.elephantracing.com/tech-topics/understeer-oversteer/)

Here's a teaser..

190035

Thank You!

[Jeff Kleiner]

GoDadGo, I have this bookmarked because it's so handy: Understeer / Oversteer Tuning (https://www.elephantracing.com/tech-topics/understeer-oversteer/)

Here's a teaser..

190035

Plus, to a large extent the driver also comes into play.

Jeff

[nucjd19]

Here is an interesting observation from: The Dark Side!

My pal Heath has a 3-Link MK-4 that has no sway bars, and understeers a pretty good bit.
He's got power steering so his caster angle is is at 7.5 with a .5 camber setting
His tire sizes are 245/45-17 and 315/35-17.

My car is also have a 3-Link MK-4, but has a small .75" front sway bar with no rear and it does not push and is very neutral.
I don't have power steering so my caster angle is 3.5 with a .5 camber setting.
My tire sizes are 245/45-17 and 285/40-17.

My takeaways are listed below:

1. Heath's car has far more rubber out back than I do.
2. My driveline is heavier than his and is roughly 6" further forward yielding a 50/50 weight distribution.
3. The weight distribution difference, combined with the smaller rear tires, combined with the small sway bar makes my car feel balanced.

What I wonder is if I went stepped up to 315's in the rear, would my car also begin to push (understeer) or not?

By the way, this is a great forum thread regarding sway bars and IRS cars.

I wonder sometimes is the over/understeer influenced by corner balance of the rig. I followed edwardb process for ride height but have never truly corner balanced my roadster. When neutral it really felt like there was oversteer built into mine when pushing it in a circular test pad I had access to testing the limits safely. Installed a front sway bar on mine and that made it neutral to me. It allowed me to control power slide my roadster with throttle modulation ( again a safe circular test pad I had access to ). As said before I tracked Porsche 911s for years and I am quite intimate with over steer. Reading Jeff's post about it over the years tells me my corner balancing might be off and I am offsetting it with a front sway bar.

[GoDadGo]

I wonder sometimes is the over/understeer influenced by corner balance of the rig. .

Unlike everyone else, I fell into a 50/50 front to rear and a 50/50 side to side balance by sheer luck...It seems that my engine placement, tire size choices along with counting threads on my coil overs got my car where it needed to be...With that said, I can tell you that I'm much happier on curvy roads when I've a person of equal weight in the passenger seat...To avoid divorce, especially since I'm 60 years of age, I won't ask my wife to match my 180 pound weight.

[CraigS]

I wonder sometimes is the over/understeer influenced by corner balance of the rig.....
Go back to your skid pad and run it in both directions. If the balance is the same both ways, your corner weights are really close if not perfect. BTW, watch your oil pressure gauge.

[GoDadGo]

James,

I found the link from your earlier post:

https://www.elephantracing.com/tech-topics/understeer-oversteer/

Thanks Again!

Steve