1 simple question...

[fty]

Torsion bars eliminate body roll..correct? They basically restrict the struts from playing around correct? Thanks-chris

[944pete]

Nope..torsion bars are basically springs, anti-roll bars (aka "sway bars") are what you're thinking of.
BTW, your website looks great, thanks for putting a pic of my car on it.

Pete

[Lawrence Coppari]

Torsion bars are an alternative to coil springs. They do affect body roll as do sway bars.

When vehicle corners, centrifugal force causes compression of the outer suspension parts and extension of inner suspension parts. Therefore if you stiffen the torsion bars, you will have less body roll because the spring effect of the torsion bar is stiffened. A corning centrifugal load will cause less movement of stiffer springs. The movement is just enough so that the difference in spring (torsion bar) force equals the centrifugal loading - the inner radius spring unloads while the outer loads. Stiffer springs mean the deflection would have to be less with less body roll.

Stiffening the torsion bars will always cause a rougher ride. Stiffening the sway bars will not when both left and right opposing wheels are stimulated by the same bump. Sway bars limit body roll by acting as a torsion bar. In order for body to roll, the sway bar must be twisted.

Hope this helps.

[fty]

Thanks guys...looks like its time to order some torsion bars..anyone know where they ahve the best price......I want 28-30mm bars...how hard is the procedure anyways..i heard it was tough...-appreciate it-chris

[slevy951]

My understanding is that the whole rear suspension has to be dropped from the car to change the torsion bars.

[Lawrence Coppari]

Why not just increase the size of the sway bars? You can get adjustable ones, and they are relatively easy to install compared to changing torsion bars. A sway bar change really affects handling yet leaves the car without the bone jarring ride that stiffer springs cause. Guess it depends on what you're after.

[fty]

Call me crazy but i want the car to break loose at the tires before any body roll is apparent..can i get there with a sway bar..I mean i want nasty nasty handling I dont care about body roll....thanks-chris

[Lawrence Coppari]

Don't know about that. All I know is if I tighten my rear sway bar too much the car gets tail happy, very tail happy.

[eligunn]

So how do the adjustable drop links work?

[Lawrence Coppari]

The bar goes across the bottom of the car. At the ends of it there are 90 degree bends with a short portion pointing to the rear of the vehicle although the direction does not matter (so long as both ends point in same direction). The bar may have some other bends in it to clear obstacles under the car.

The bar is attached to the frame of the car by two bearings. Thus if the ends of the bar are disconnected, the bar can rotate freely in the bearings. The ends are put in a horizontal position and attached to the body via what are called drop links. Usually there is a collar that slips over the end of the bar. Each collar has a clamp so it can be moved closer and further from the end of the sway bar. The collar attaches to the body of the car by a drop link. The drop links are mounted vertically, one on each side.

What happens is that when the body tries to roll in relation to the frame (chassis), the side on the outside of the road curve pushes the end of the sway bar down as the body compresses the outside spring. This rotates the bar. But remember, the other end of the bar is attached to body on the other side of the car via the other drop link. Because the body wants to lift there, the bar is twisted in the opposite direction. The resistance of the bar against the twisting lessens the body roll.

If you slide the collers closer to the 90 degree bend in the bar, it stiffens the setup because your moment arm is shorter. It's like using a wrench with a short length versus using one that is longer. You have to exert more force with the short wrench to get the same torque. The torque is what twists the bar.

Note that the bar does nothing if both sides of the car move up or down in unison. In that case the bar merely rotates in its bearings.

A small increase in bar diameter causes a big difference in its resistance to twist. It has to do with the polar moment of inertia which is 4th power.

[PrerYDoG]

fty: I want the same thing you do! I've been looking into it over at Rennlist and talking with Skip of Paragon Products. Not only does he know his stuff about the issue, they have some of the best prices I've seen for this stuff. Check out paragonproducts.com and on page 2 of the 944/951 stuff you'll see the torsion bars. I'm going to get the 28 or 30mm bars with 300# springs for my 951S here soon.

Personally, I don't like it when my car "dives" under hard braking or "squats" under hard acceleration, I must get rid of that!

[fty]

ahhhh excellent muhhahaha...19mm sway bar with 28mm torsion bar.....I think Ill purchase the beefed up sway bar shortly..oh and by the way anyone know how thick the stock rear sway bar is? Thanks....-chris 1.2g here I come.....

[macreel]

Be sure to check the "Excellence" article beginning on pg.139
in the December 2001 issue. Good description & photos.

G'luck.