New Anti-Roll Bar Stiffness Calculator so you can compare different bar sizes to your original bars, and also compare different adjustments on the bar. Then work out your preferred upgrade from Whiteline, Eibach and H&R,
Uprated anti-roll bars are one of the most effective ways of improving not only the handling of a car, but also outright grip levels. The majority of cars produced today have some form of anti-roll bar. The biggest advantage of the anti-roll bar is that you can limit roll in corners whilst still retaining suspension travel and a good ride. Uprating the anti-roll bar for a larger one increases the roll stiffness at that end of the car (Eibach & H&R kits generally contain front and rear bars). If the roll stiffness is increased so is the weight transfer on that axle.
Uprating the bar at one end only means that pair of tyres will attract more weight transfer through a corner. Depending on the handling balance of front to rear this will either increase or decrease outright grip. For example on a Mk4 Golf if you uprate the front bar only the car will reduce it's outright grip level as it already has too much front roll stiffness and not enough rear. Some cars require a stiffer rear bar only.
This is the case for many front wheel drive cars - uprate the rear bar first - which makes the rear of the car work more and prevents understeer. If you bought front and rear you would tend to run the front soft and the back hard. In a rear wheel drive car depending on the original balance you'd tend to uprate both bars by a similar amount and then fine tune using adjustment. Four wheel drive vary between these two depending on a number of factors including torque split. Another factor to consider is feel - body roll can be nauseating so adding anti-roll bars makes the drive more pleasant, again without ruining the ride. However please note this is general wisdom - some cars may benefit from increased front and rear roll stiffness.
Go too far on the bar which is connected to the driven wheels and you will run into traction problems.
However do bear in mind that increased grip can come not only by optimising the tyre loads front to rear but also by better geometry underload. Excessive body roll on most macpherson strut cars causes unfavourable geometry change - eg loss of camber and caster. A stiff anti-roll bar combination will keep the wheel closer to it's optimum angles..
The Whiteline bars which are available separately give you more freedom of choice depending on what you need from your car. .
Another big plus of the anti-roll bar is they are often easily adjustable. You may have spent a lot of time and effort setting up coilovers to ensure the best weight distribution, you then find for instance the front end is understeering on a tight circuit you’ve not visited before. It is much easier to adjust an anti-roll bar than change the springs.
Work out current bar stiffness, then upgrade to suit .