Weird Ways to Make FWD Cars Fast - Part 4

Celebrating 6 years of Racing Secrets with more FF speed secrets

Posted by Roger on February 01, 2021

The very first article on this StudioVRM Racing Secrets blog was a list of tips and tricks to make FWD cars fast around a racetrack. 6 years later, it remains one of the most read and visited articles on the site.

So for the blog's sixth birthday, I thought we would keep the series going with three more tips and tricks to get the most out of your FWD track or race car.

Use Rear Toe-Out on Newer Cars

As many of you know, we at StudioVRM recommend running small amounts of toe-out in the back of FWD Honda racecars. It keeps the rear end from dragging through the entry and middle phases of corners, helping with cornering speed and keeping tyre wear more even.

What we haven't talked about is how this has become the standard for pro-class FWD Touring cars.

The main reason for this is that almost all new sporty front wheel drive cars use a Macpherson strut layout up front. Despite all of their advances, these front suspension systems are still camber challenged compared to the double A-arm setups on FWD cars from the 80's and 90's. To make matters worse, many Touring Car classes limit the amount of camber you can add to the wheels. This is all bad news for cornering grip on a front-driven racecar.

Fortunately, the engineers at pro touring car teams are resourceful. They realized that if they can't add grip to the front, they need to make the rear tyres work for them. So that's what they did. By adding more rear camber and dialing in extraordinarily high amounts of rear toe-out, they effectively use the rear tyres to help steer the car through the first few two phases of a corner. This takes some work away from the already overworked front tyres while allowing the driver to rely on load transfer rather than steering lock to rotate the car.

How high is "extraordinarily high"? Well, just to give you an idea, reliable sources at several TC America teams have admitted to running over a full degree of rear total toe-out.

Of course, this is something that applies to newer (2012+) cars with limited front suspension geometry and very small rubber bushings. If your FWD racecar was built in the 80s, 90s, or early 2000s, start with a lot less, say 0.1 degrees of rear total toe-out. Don't attempt anything more than 0.4 degrees of total rear toe out unless you have replaced your squishy stock suspension bushings with spherical bearings.

Add a Rear Wing

In the early 2000's, big wings on front wheel drive cars were regarded as a bit of a joke amongst car enthusiasts. In 2021, nearly all fast FWD track cars have a big, downforce-producing rear wing.

So what changed?

The answer is that racers and track day drivers started setting up their cars for corner entry oversteer. In the 1990's, only the fastest and most aggressive racers would use a big rear anti-roll bar, stiff rear springs, run narrow rear tyre, or run extreme-looking alignment settings in pursuit of that razer-sharp cornering performance. In the 2020's, it's common knowledge that you need to do one or more of these things to get the best possible lap time out of a FWD track or race car.

However, all of these setup changes come with a drawback - corner entry oversteer through high-speed corners. And yes, that is a bad thing. Unlike in the world of autocross and stage rally, high-speed oversteer is both slow and scary on a road course. If only there was a way to retain that tail-happy behavior through slow corners while keeping the car stable through fast sweepers.

That's where a good, downforce-producing rear wing comes in. A well-designed, well-set up rear wing will give you that much needed stability through the fast sections without sacrificing that low-speed cornering agility you worked so hard for. You also don't need anything exotic. A 9Lives wing or an APR GTC-200 mounted a few inches below roof height is more than enough to make a significant difference in how the car handles.   

Use a Softer Rear Tyre for Sprint Races

I learned about this counter-intuitive trick from a fellow Honda racer, Fusion Works Fabrication's Brett Whisenant.

As we all know, it takes a little while to warm up the rear tyres of a front wheel drive racecar. If your FWD track car runs on DOT R-compound or full racing slicks, you're probably already used to wrangling the car during the first few laps of a race due to tons of corner-entry oversteer from cold rear tyres. A rear wing does wonders to fix this behavior, but there are many racing classes out there that won't allow you to run one. So what can you do?

Brett's solution to this problem is to swap the road-race oriented Hoosier "R" DOT racing tyres on the rear end of his Integra with the softer autocross-focused "A" compound of the same size. These softer Hoosier As are designed to come up to operating temperature within a few corners instead of within a few laps. This means he can aggressively push the car from the very first lap without worrying about spinning the car.

As the race goes on and the rear tyres get hotter, that extra grip will fade away. On a rear wheel drive car, that would be annoying. But in a front wheel drive race car, you can use that to your advantage. A 30-40 minute sprint race will generate enough heat into your front tyres that their grip will start to fade, resulting in more and more corner exit understeer.

If you play with the tyre pressures on the rear tyres, you can get the rears to fade at the same time as the fronts, neutralizing that late-race understeer and keeping the handling of the car consistent through an entire session.

While this strategy might not be necessary for those of you living in warmer climates, it's something to consider for sprint races during the cool autumn months.

 

That's all I have for today. Thank you very much for reading.

I will see you at the track.

~R