This original article was previously published by Seven Enterprises in our Winter 2011-12 mailer.
Using a Rear Sway Bar to Reduce Understeer
by Mike Kearney
Seven’s Service Shop Manager
Although it is technically an anti-roll bar, in the USA this component is commonly called a “sway bar”. A rear sway bar is a torsion bar mounted laterally on the rear suspension, and is designed to reduce body roll. On a Mini, drop links are used to connect the rear control arms to the sway bar.
So what is the advantage of a sway bar? For those of us that like to drive our Minis in an enthusiastic manner, it is a good way to help control the car’s natural tendency to understeer. On a front wheel drive car, the driving wheels and steering are combined to do both functions. With a weight distribution close to 70-30 to the front, a rear bar is really helpful to get the rear of the car to rotate. Almost every modern car that is front wheel drive has a rear sway bar installed from the factory and every aftermarket manufacturer makes a bigger (stiffer) one for those cars. Race Minis have used rear sway bars for 50 years to improve the handling in competition.
The sway bar we recommend for both function and quality on a street-driven Mini is FOR013. This sway bar has been tested on the Seven Enterprises’ vintage race Mini and several of our shop-built Minis, and has been found to be very good at controlling understeer and producing a neutral steering car.
For a more aggressive approach, we recommend the solid 5/8” rear bar made by KAD, part number KADARB9219. This is the sway bar widely used on vintage race Minis and in the very competitive “Mini Miglia” series in the U.K.
To optimize your Mini’s new rear sway bar, we suggest several additional suspension modifications. Good-quality adjustable shocks are a must for anyone serious about improving handling. Adding front negative camber arms along with adjustable caster/tie rods is always a great modification. Stock rubber suspension bushings should be replaced with updated ones in rubber, polyurethane or combinations of both. We would also add to the list of improvements two-way adjustable rear suspension camber-toe brackets.
Give us a call to discuss your individual needs, and basic suspension specifications. The handling needs of a road-going Mini will be different than a track-only race car. Let’s talk about what level of performance you want out of your Mini. The performance experts at Seven are here to help!
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