How does this work?

Howard Jones

Here's a picture of the front suspension on a WSC. It's really not that important what the manufacturer is as I have seen a lot of modern prototypes using this type of anti roll bar.

It appears to use a single torsion bar that is driven by push rods that are actuated from the bell cranks. I just can't see how the forces coming from the two sides of the car don't cancel themselves out. Also how does this work when there is equal bump on both sides? Can anybody clue me in on how this works.


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Hi Howard,

Firstly the torsion bar at the front is the anti roll bar, all the cars weight is taken by the springs and dampers (seen at the back of your picture)

I think the bit you are missing is where the anti roll bar is fixed to the chassis (out of sight inside the monocoque) it is on a pivot so it can move forwards and backwards.

The anti roll bar is driven from the rockers, so when one wheel is in bump and the other wheel is in droop the rockers apply a twisting motion to the anti roll bar.

when the car is in bump or droop there is no twisting to the anti roll bar and as it is on a pivot just swings back and forward.

I hope this helps?

Howard Jones

Brian, So the bottom of the torsion bar is fixed in the housing and the housing is allowed to swing fore and aft on pillow blocks or something like that. The flat arms coming from both sides of the housing must be held in place in the pillow blocks and ride on bushings. Maybe even bearings. Hum.........Ya, I see that. Thanks buddy.

Thinking about mods to my SLC anti roll bars. I think the rear will end up with something like this one. It's a bit more conventional.


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I will try and dig out a picture to show it more clearly....

when designing your anti roll bar for your SLC be careful.
There are a few things to consider when designing anti roll bars. Firstly make sure your linkage is a minimum of 3 times stiffer that the torsion bar part, or you will start using the linkage as the flexing member, and also check that the torsion bar part of your linkage does not go beyond the yield point of the material when one wheel is in full bump and one in full droop, or it will snap.



Brian, one can see the rotating housing for balancing out equal side bumps down in the chassis. I´m with you on that. But in cornering this works like a "controlled roll" bar ( even if the levers are not pivoting on the torsion bar). if the outer turn wheel goes in it will push his bell crank towards to passenger ( loading the spring) but the other side wheel will be pulled out by the same amount. Due to the pivoting of the housing the car will still be sprung. Don´t even think that the upright bar is a torsion bar. It looks like the lever is mounted rotating on that upright bar. THe length of the lever and the mounting point of the rods to the bellcrank are defining the roll ( one can see two more inwards mounting points for less roll).

A classical anti roll bar is flexing and is moving both wheels in the same direction ( Howards second pic).

Here is a similar system,

The only way I can see that it works, would be that where the rod connects to the central spider it must move up and down for the suspension to move when both wheels compress at the same time

Howard, heres a pic of the set up i used on the front of a sports car i built, its ex Reynard, if you look at the bottom mounts you can see how it can pivot back and forth, then at the top is the arm which takes the links from either side which activate the blade.
the wire you can see is for the potentiometer, for data logging and the little bracket bottom right is for the adjuster cable, so with the blade at 3 O clock you have max resistance,and blade at 12 oclock min resistance,
hope that helps
cheers John
Howard and I have been scratching our heads over how this type system works ..... as we plan our swaybar solution.....

Thanks for the explanations.
One of the first cars i saw with a "tunable" blade ARB was the JBL Cobra.JBL Motorsports - Home Page
Wander through their web site, there is a lot of good info on these systems. They have since upgraded the chassis, but there was an argument at one time, that the blades were not that tunable in that the blade was either vertical or horizontal and that the inbetween angles were not that predictable or were really soft settings in the long run. I know that a lot of cars are using this technology, but I have always wondered whether it really worked that well. Suposedly the soft was for wet track conditions and the hard was for dry. I am no expert, just bringing up questions that I have heard for many years since I first saw them. Always thought a cockpit adjustable setup would be great as you could change it on the fly to suit track conditions. Especially in the endurance races.