Rear sway bar- how big is too big?

[PLee]

Been doing some reading/searching on the forum, but can't seem to find a definitive answer. For road course racing, how much bar is too much? I'm pulling these numbers from memory, but I believe my stock 05 gt rear bar was approx 20mm in diameter. I now have the rear bar from the Ford Racing FR3 handling pack on the car, which I believe is 22mm. I know too much bar is not good, but have noticed the stock 2011 5.0 bars are even thicker (haven't measured it yet, but I have one). I have a whole host of other supporting suspension mods that we can discuss if need be too... Any help appreciated!!

 

[pcdrj]

I think you're headed in the wrong direction for a road racing setup. Bigger rear bars are rarely better. Some AI guys run V6 bars and others even run no bar. Do a search on here as there is a ton of info on sway bars. Sam Strano has more posts on this than I can count.

 

[frank s]

I have used the H&R 26mm rear bar with Steeda adjustable front on two different S197s.

2009 GT/CS coupe with the front bar on full stiff, FRPP "P" springs and Koni yellows at full stiff, the car is a good autocross rotater at 10/10, under- or over-steers at your bidding. Inexpensive Goodyear Eagle F1 285-40s on GT500 18x9.5 wheels all around.

Pretty much the same story on a 2006 V6 convertible, D-Specs, Steeda Sports, Saleen Parnelli Jones 19x9/10 wheels, 275-35 Michelin PS2s, no limited slip.

I ran the coupe at Chuckwalla Raceway (clockwise) for a few sessions, with the Konis at 1/4 from full soft in front, 1/4 from full hard, rear. The car stuck well with mild full-throttle oversteer from slow corners, pretty much neutral elsewhere, all at 7-8/10ths. The back end almost got away from me after a hump, but came back pretty well without drama. I must confess to being pretty conservative, what with no rollover or personal fire protection; can't really speak to behavior at competition speeds. My impression is that the 26mm bar is close to the limit of what would be useful with a streetable setup. I really like the way it squats and scoots at corner-out.

 

[kevinatfms]

i run the FRPP bars(eibach) but ran an h&r front on full stiff with a stock rear bar before cutting my track time down and trying more auto-x lately. for the auto-x i like to run the front in the middle setting and use the frpp rear bar.

i think its more of a personal preference, the big thing would be the adjustablity of the strano bars. too thick for one person may be different for someone else.
im not saying going wild on the bars as there are guidelines but i think for the off-the-shelf bars you can buy today you cant go wrong with them. just choosing and trying what you like and want....

 

[STEVE_POE]

we run 18 19 mm rear bars with the steeda adjustable front . depending on the track and what the car does determines what bar we run .

sometimes we run no rear bar .

tire sizes and spring rates can also play into sway bar sizes and what the car does or needs . Driving style also can determine sway bars .

these car are push happy and putting more rear bar on them usually makes it worse .

 

[PLee]

Thanks for the insight guys!

I'll keep doing some reading and see what I can find as well.

 

[Sam Strano]

It's dependent on the situation. The front bar, the tires, the alignment, the springs, how you drive and what you are seeing from the car, etc. etc. etc.

This is s big reason that my bars are not only adjustable, but that I have 3 different sized rears. I can't help with an answer without a lot more information.

 

[fdjizm]

Hmmm, so for a DD do I really care or want my rear sway bar? I already don't have a front one.

 

[Norm Peterson]

Depends on what your daily driving is like. The easier you drive, the lower the need for either bar in the first place (they wouldn't be doing very much). But if you drive easy enough to where they could both be ditched and you not really notice that they're gone - then you pretty much ALWAYS have to drive that way, since you won't have time to re-install them if you suddenly find yourself in a situation where they'd be helpful.

Without a front bar as it is, you certainly don't need a rear bar as far as handling balance is concerned, and a stock rear bar by itself isn't going to reduce body roll in a corner enough to notice.

But it still helps as far as trying to keep your rear tire loadings closer to being the same under acceleration. Not nearly as much as a dedicated drag race "anti-roll bar" would, but still better than not having one at all.


Norm