Not too long ago here on PRC.net, we ran a lengthy Reader Submission from an anonymous yet respectable sim racing community member, who kindly took time out of his day to break down the inherent lack of simulation value in most popular third party mods, and why corners are cut during a project’s development. Our resident science teacher has returned on this Wednesday afternoonwith another reader submission, this time detailing the five most prominent mistakes sim racing mod teams make. While his explanations may fly over the heads of some individuals, consider this a rare glimpse into an element of sim racing that most people will never think twice about.
Hello, readers of PRC.net! I’d like to follow up on my previous submission with a significantly more technical piece. I wanted to list five of the most common mistakes sim racing mod teams make in regards to how car physics are handled within the isiMotor engine. Beware, this might get a little complicated.
- Weird Tire Values – This one isn’t a surprise. Tires are still somewhat of a mystery to even the most advanced engineers among us. If you’re able to get most numbers within a reasonable range, that might not necessarily yield the expected results when in-game. Yes, there are a few tire characteristics that are scientific fact, such as slip angles or load sensitivities, but it’s not uncommon to see totally wild values for these elements, due to the fact that they “feel better” on a subjective basis. What I’m saying is that tire values end up being fudged to appeal to those beta testing the mod, and what they prefer from their sim racing experience.
- Botched Suspension – Suspensions are hard, don’t kid yourselves. If it wasn’t for carFactory or other modding tools, it would be almost impossible to get right if you don’t have experience in designing them in the first place. Now, the safe modding teams either copy/paste some suspension designs, or make a generic suspension in carFactory. This isn’t a very realistic depiction of the particular car, but if they copy something that was done right the first time, at least it will generate proper suspension behavior. However, most people don’t even know, for example, that a BMW M3 E30 has semi-trailing arms in the back, and behaves completely different compared to most modern cars. This is a mistake many mod teams, and even probably some first party sim racing developers, have made. The brave modding teams that try to design an entire suspension from the ground up, usually don’t have enough knowledge to get it right, so we end up with suspensions featuring massive bump steer, totally wrong ackerman components, too small travel values, weird camber variations, and other suspension oddities.
- Ultra Stiff Suspension Settings – This here is what most modders use to hide what I just stated above in the previous element. If you make the suspension hard as a rock, it won’t move much, and therefore it won’t show all those nasty characteristics of wrong suspension geometry. It also “feels more responsive” to beta testers who have no clue that even a Group 6 Porsche 936 actually exhibited a bit of body roll while cornering. This, coupled with the wrong tire values, turns a car into what I like to call “skateboarding physics”, where your steering wheels seems to control how much the rear of your giant go-kart is sliding.
- Low Inertia or Center of Gravity Height Values – Copied once, twice, maybe even three times from the very first Image Space Incorporated vanilla content, all the way back from the days of F1 Challenge 99-02. It’s not uncommon to see anything with wheels slapped together with values better suited to a Formula Ford. This helps to make the skateboard effect described above even worse, making cars that roll much less and therefore more twitchy, but your average sim racer will rave how “responsive” and “dangerous” these cars are to drive.
- Excessive Downforce – Cars with strange tires, rock solid suspension components, and low inertia values can be a bit tricky in high speed corners. So the solution for most modders is to just add more downforce. If we’re comparing building a car in an isiMotor title to baking a cake, Downforce is comparable to sugar. It makes everything “good” again, and your giant go-kart will now blast through medium and fast corners as if it’s on rails, but it will be twitchy and nervous in slow bends. Sound familiar? In the world of sim racing, some modders believe even touring cars or 1970’s Formula One entries must behave like some high downforce ground effects prototype.
These are the most common issues off the top of my head, and in all my years of working with the isiMotor engine, I can safely say that only a handful of mods got every aspect right.
I work for an extremely large rental car company as what’s essentially an inventory guy, and we have pretty much every North American car you can think of, from lowly shitboxes to high-end muscle cars reserved for longtime customers. During the summer months last year, we received a fleet of convertible Chevrolet Camaro’s, as well as a huge array of brand new 2015 Ford Mustangs. At the time, the rental car company were a bit short staffed on the customer service side, so us inventory guys got to take on the role of shuttle drivers – a position traditionally reserved for the older gentlemen. Basically, there were days at work where I didn’t do a whole lot other than drive new Mustangs and Camaro’s from our lot to the airport and back again. Sure, it isn’t track day experience
aside from that one time I took a rental Charger to the drag strip, but I sort of know what both of these cars feel like.
The Camaro has shitty visibility & heavy steering, while the Mustang is pretty much perfect. The end.
Anyways, for those who have been around this place for more than a few months, at one point I uploaded a revised 2015 Ford Mustang for Assetto Corsa. The source material came from a shady Russian modder, and I claimed that I’d made a few adjustments to the car based on my own personal experience driving it around in traffic.To my surprise, a lot of people praised the revised car, including a certain Assetto Corsa shill with over 8,500 posts on the official forum. I have no modding experience – none – so it was pretty hilarious to receive any positive feedback at all. Yet the general consensus among those who downloaded it, was that whatever I did under the hood, it was pretty damn good.
Would you like to know what I did?
This was enough to earn the approval of those who downloaded the revised mod, so it’s no surprise that extremely unrealistic car physics are flying over the heads of other sim racing community members.