How big is \"too big\" for anti-sway bars

Steampunk · Postby **Steampunk** » Fri Nov 30, 2007 10:09 pm

I would like some informed opinions about this.
I know stock sizes, and I know what most manufacturers like Racing Beat and Flyin' Miata makes, but is there such thing as \"too big\" or \"too stiff\"?

There is a set I know of, the front bar is hollow (I think) and is a whopping 32cm in diameter.
The rear bar is also quite hefty, a solid 16mm.

Would this cause adverse effects for a car with stock suspension? What about a car that has decent dampers/springs/coilovers and upgraded end-links?

Fatty · Postby **Fatty** » Fri Nov 30, 2007 10:19 pm

i'm certainly no expert, but the first thing that come to my mind is that you can say goodbye to any steering \"feel\", feedback, whatever. which is one of my favourite things about the mx5.

Boags · Postby **Boags** » Fri Nov 30, 2007 10:29 pm

And you can say hello to lifting the inside wheel off the ground.

Mr_Q · Postby **Mr_Q** » Fri Nov 30, 2007 10:30 pm

1red5 wrote:the front bar is hollow (I think) and is a whopping 32cm in diameter

That'll stop any body roll.

Woo · Postby **Woo** » Sat Dec 01, 2007 12:13 am

Mr_Q wrote:

That'll stop any body roll.

Not quite, but just about. Imho it's a really good combo, makes it very cart-like

Hellmun · Postby **Hellmun** » Sat Dec 01, 2007 11:03 am

The hollow bar is not as rigid. There's a rough formula on whitelines site. I believe the 32mm hollow racing beat bar is equivalent stiffness to a 24mm solid bar.

I have a 16mm rear bar arriving any day now and I've already got a 24mm front in the car. Not a track day though until feb to test.... The rear is the biggest change. The NB8B atleast already had a 22mm front sway. The 16mm is a big step up from a standard 11mm rear. I believe SE's got 14mm rears standard though. It seems large but I'm hoping with pre-load adjustment and adjustable shocks I can hit neutral with it. I was rather torn between 14 and 16mm rear bars. Decided Whiteline only offering 16mm's with their 24mm solids hopefully had a lot of research behind it.....

Slugoid · Postby **Slugoid** » Sat Dec 01, 2007 2:25 pm

As mentioned, 32mm hollow bar isn't all that stiff due to being hollow, but it weighs a lot lighter than a solid bar of the same stiffness.

I had a 16mm rear bar and 24mm front bar, with Koni and Kings. Kings were rated at 165-215lb/inch front and 105-160lb/inch rear, which were relatively soft compared to my Tein SS now (6kg/5kg or 336lb/280lb). This setup gave a neutral to slight oversteer setup depending on how you've set the rear bar. I had mine on the middle setting front and rear and I quite liked now it went. On track you can soften up the rear to give it more mid corner stability.

I now have Tein SS with the same 24mm front bar but I've now gone back to the 12mm stock rear bar cos I worried that the stiff 5kg rear springs and 16mm rear bar will cause massive oversteer. With this setup, it feels more stable with high speed corners with only a tad of understeer at tight hairpins.

The key to choosing swaybars is the balance between front and rear stiffness. With my limited experience, having a big front sway isn't a problem as long as there is a bigger rear sway to much. However, having too big of a rear sway will require a huge front sway. For my current setup, if I was to keep my 16mm rear sway, I would need a front sway of at least 27mm (solid too) to keep the same general feel as I have now. That's something which I'm not repaired or want to do at all. Plus stiff spings and big sways mean lack of suspension independence, which is also a problem

SteveS1 · Postby **SteveS1** » Sat Dec 01, 2007 4:59 pm

using the calculation method in the fatcatmotorsports spreadsheet, the racing beat hollow bar (1.125\" outer (29mm), 0.125\" thickness) is about 1.25 times the stiffness of a 24mm solid bar.

their larger hollow bar (1.25\" outer (32mm), 0.1875\" thick) is 2.3 times the stiffness of a 24mm solid bar - but not recommended for NA models.

according to the racing beat website, the 1.125\" hollow bar weighs 5.5lb (2.5kg) whereas their 0.93\" (24mm) solid bar weighs 10lb (4.5kg). So 2kg lighter.

so how much is a us$150 bar in Australia?

Cheers
Steve

Steampunk · Postby **Steampunk** » Sat Dec 01, 2007 8:20 pm

HA!

ANOTHER post from you ... you are beginning to slip Steve :mrgreen:

$150USD = approx $170AUD, shipping will be approx $65USD.
Ask RB if they have a used set. Fair chance they would.

I'll race you to Racing Beat

..... GO!

Garry · Postby **Garry** » Sat Dec 01, 2007 10:05 pm

For street driving in an NB8B with stock springs and Koni's I have a 24mm front solid bar and I had a 16mm adjustable rear Whiteline bar. I found that setup a little bit tailly even on the softest setting on the rear bar. I switched back to the stock bar and had plough understeer in the wet, so got a 14mm rear bar made up. That combination and my alignment setup suits me perfectly.

If you go to a really thick front bar you will need to stiffen up the mounting brackets on the chassis rails. Apparently they have a tendency to crack if you use a bar over about 25mm thick (solid). There are a couple of manufacturers that make the upgraded brackets.

But to answer your question, yes it is possible to have to much roll stiffness.

Steampunk · Postby **Steampunk** » Sun Dec 02, 2007 1:34 pm

The 32mm and 16mm anti-swat bar set was actually for an NB, so for that, and other reasons, I didn't get it.
But it did weigh less than a 22mm solid stock NB front bar.
Garry is spot on with beefing up the standard bracing, but the kit sold by Racing Beat looks to be easily copi .... errr .... custom fabricated. :mrgreen: