Corner Weighting
You have fitted a lovey shiny new set of coilovers to your car to improve the ride and handling. So how do you know how to set up them up to get the most from them? You have the benefits of height adjustment, simply lowering the ride height might have some benefits, but to achieve the best balance with the car ideally you need to corner weight it.
Corner weighting is for race cars I hear you cry, and it is, but hear me out because there are benefits to corner weighting road cars too, particularly if you changed the suspension set up as we talked about in the August 2023 edition of the Jaguar Enthusiast when we spoke about AVO suspension kits. To gain the maximum benefit from coilovers you would have also poly-bushed the car too, again if you go back to the January edition of the Jaguar Enthusiast we covered this topic too.
Now you are in position to unlock the handling and performance of your Jaguar. One of the main reasons for fitting aftermarket suspension is to have the ability to adjust the suspension ride height. Coilovers also give you the capability to adjust the way weight is distributed around the car, altering its balance. Corner weighting, sometimes called corner balancing, is the method of equalling the weight distributed over all four wheels. Having your Jaguar weighted equally can lead to some major handling improvements and is a great way of boosting the performance gains offered by aftermarket suspension. This also leads to benefits in tyre performance, maximising grip and wear. You will also accomplish more predictable handling with less oversteer and understeer.
Generally speaking, and ideally you will want to achieve equal weight balance between the front and rear axles. Theoretically, this leads to a better balance between understeer and oversteer. The reality is on the majority of road cars, that is not entirely feasible. Most of the weight is over the front axle due to the engine and gearbox sitting forward of the front axle. Controlling this front-to-rear divide will inevitably be a balancing act against your car’s front and rear roll stiffness. To some extent it will also be a compromise to reach the target amount of understeer or oversteer to suit your driving style. It’s rather particular to the driver and the car, and you’ll need a fair amount of test driving, along with a certain amount of adjustment to get it right. Our experience with racing, chassis dynamics and setting up of race cars can help enormously here.
It’s not just front to rear balance we are trying to achieve, but as importantly side-to-side balance too. If a car has a weight bias to one side or the other, then it won’t corner evenly. From a driving perspective, a car that isn’t equal left-to-right would be unpredictable and a lot more challenging to drive. Consequently, you will battle to get the most out of your set up and the best from your coilovers. We can also get a diagonal cross weight reading. This will show a percentage of the total vehicle across the cross axle, so front right to left rear and front left to right rear, the target being fifty percent.
Our corner weighting system has four scales or pads that the wheels sit on, and they connect to a display panel. To get correct readings we need to make sure that the car boot isn’t full, granny isn’t sat in the back seat and that the fuel tank isn’t empty. If we were setting the car up for racing or track days, we would have fuel in the tank and the driver strapped in the seat. We would also make sure that the tyres are set to the pressure we’d be running. Anti-roll bars should also be disconnected to prevent the roll bar affecting the result.
To begin the process, we roll the car onto the scales and allow it to settle. Once the numbers have settled, we take a note of the readings. In order to reduce the weight on a wheel we begin to lower the ride height, this done by winding the spring seat downwards. You may think that this would be doing the opposite as it’s lowering that wheel down and making the car lean more that way, but spring seat is actually decreasing the preload on the spring and shortening the spring and damper assembly. To increase the load, you naturally do the opposite. Make small adjustments to try and balance the weight cross axle, so if the right rear is too light adjusting the left front lowering it to balance the right rear. The best analogy I was given on chassis dynamics course is, the wonky pub table, you correct by putting beer mat under one leg, the principle here is the same. This isn’t a short or simple process especially when you are trying to achieve a certain ride height. Corner weighting is often seen as a bit of a ‘Dark Art’, and it takes some perseverance to get it right.
With race cars we often have to shift some of the mass around and relocate things like batteries and fire extinguishers to achieve a perfect balance. This is less achievable with a road car so their will often be a slight compromise. Some cars have a naturally good balance and then this becomes a good bit easier, you will often read car reviews, and they talk about how well balanced the cars is.
Corner weighting may seem a bit extreme and unnecessary and for cars that remain factory standard, and it probably is. For cars however with modified and uprated suspension then it’s well worth considering especially if you plan to do regular track days.
