Heartless

It seems reading thru the sway bar posts, many people run the 36.5 mm front Hotchkis sway bar (hollow) and a Spohn 22mm rear bar (solid)..... how does the Spohn 32 mm front bar (solid) stack up against the 36.5 mm Hotchkis sway bar ?

Bud M

iTrader: (1)

The Hotchkis 36.5 mm bar is significantly stiffer than the Spohn 32 mm bar. 32/22 bars will make the car tailhappy.
Strano's 35/22 is a better combo than Spohn's 32/22.

Urban Legend

iTrader: (5)

36.5 Hotchkis/22 Spohn does the job extremely well. Would not have it any other way.

FSUNole17

iTrader: (18)

im curious also, is the hotchkis rear bar not good or is the spohn just better?

DONAIMIAN

iTrader: (18)

Nothing wrong with it besides the fact that its too big for most peoples taste. That is unless you lower the PHB (not talking about the BMR kit) and thats a different animal.

Most people here when upgrading either run a 32mm bar or some sorts. If they run anything bigger than that its mostlikley a strano bar.

Heartless

Really..... I'm not a physicist, but I would have thought a 32 mm solid chrome moly bar that is heat treated and tempered would be significantly stiffer.... I would imagine without a second thought that the hollow bar would bend or distort much easier than the solid bar would......

Addicted

Bust out your Mechanics of Materials Book or Machine Design Book.. The Moment of inertia is:
I=(pi/64)*(D^4-d^4)
J=2*I
D=outer diameter
d=inter diameter

(angle of deflection)
theta=(T*l)/(G*J)
T=Torque
l=length
G=modulus of rigidity
J=polar second moment of area

if you play around you'll find that the outter diameter effects the stiffness (reduction in angular deflection) more the the inner diameter. This is why Al driveshafts are large diameter and hollow.. And G is nearly always almost the same even when heat treating occurs.

YellowToy/A

iTrader: (1)

Good data wins again

Captainofiron

iTrader: (1)

Good Job I was about to say something like that. and remember whenever something is tempered it increases the metals ducility which means not stiffening it.

Cumbias

How does the Hotchkis rear bar feel or compare to the spohn 22? Is it harder to control? Or too manuvaruble? (given the hotchkis front bar is used)

Cal

iTrader: (1)

As hinted at above, too big of a rear bar will make the car tail-happy. 21 mm solid or 22 mm hollow is best for the rear of these cars. On the front, get a big one (35 mm Strano or 36 mm Hotchkiss.)

Bud M

iTrader: (1)

I originally thought the same way but I've had both bars and the 35 hollow is obviously stiffer than the solid 32.

Cumbias

Tail-happy?
Forgive the questions, I keep learning new stuff everyday!!!

Bowtie Guy

Tail happy = Oversteer.

Sam Strano

iTrader: (41)

It's about the front vs. rear bar ratio..... 32/22 and 35-36/25 are both too damn stiff in the rear when compared to the front.

Aside from all the autocrossing, etc.... I sell a lot of brands. Hotchkis and Addco amont them (Addco makes 32/22 solid). And you can bet it would have been a lot easier for me to have just sold what was already out there. And I would have--had either worked the way I feel they should. They don't.

When I decided that a different set of bars was needed, I had Addco build them for me (not me in my shop bending metal). And I also decided I was going to keep them light so I didn't have to drag around weigh that was useless.....

Sam Strano

iTrader: (41)

BTW....... I race my stuff (and win).

Also Chrome-Moly and all that is of NO use on a swaybar. It's not any stronger. CM is stronger in tension and compression, but no more resistant to twisting force. Also, CM is more brittle in ways than more normal steels. Not what I really want on a part that is intended to flex to work.

Cal

iTrader: (1)

For maximum cornering speed, you want the lateral loads (sideways forces trying to push the car off the road) as equally split between the front and rear tires as possible. This is because each tire only has so much grip. Once you use up that grip, that end of the car slides. When you put too big of a bar on one end of the car, that end of the car is forced to bear more of the lateral load, so that end will slip first in a turn. Too big of a bar on the rear will make the rear end step out while still having grip on the front end = oversteer. Also, remember the rear tires are the ones that put power down on a corner exit, so a big bar back there will hinder that by putting less weight on the inside tire, allowing it to spin easier.

Cumbias

Oh, so if the rear bar is too big, the car will lose traction in a turn if youre going too fast possibly causing a tailspin?

Bud M

iTrader: (1)

That would be an extreme situation. More common would be loss of traction on the inside wheel as you try to accelerate out of a turn.

Cal

iTrader: (1)

Whether you just spin the inside tire on a turn exit or do a "tail spin" just depends on how hard you push the car, and what the surface conditions are like. I've looped my car several times on an autoX course, and my friend did over two rotations driving my car once! AutoX is a good drill for learning the limits of your car, and just how it behaves at those limits.

I think it is important to point out that you can easily spin a car of this type and HP level even with the suspension set up properly. All you have to do is push it until the tail steps out a little, then simply floor the gas pedal! Been there, done that! Always remember to steer with the throttle in a max effort turn.