News Physics Update: Touring Classics, DTM 1992, Group 4, Procar

Before anything, the #1 rule here is that old setups will not work with any updated cars. Trying to use these setups will result in a very poor handling car. They must be deleted!



Touring Classics are based around the Group A series, which takes production road cars and allows some modifications. The exception here is the Skyline R32 with which we decided to make the Group-N version, because it's a fairer fight. A Group A Skyline did exist but totally wiped the floor with the opposition in the early 90s. Group N allows fewer modifications, which brings it down to similar performance as the others in Touring Classics.

As with the other updated classes, everything here is brand new. It's a ground up rebuild with no stone left un-turned. That means any setups you may have created before this update won't work and will need to go in the bin.

Downforce is none existent across the board, with all the cars actually exhibiting slight lift at high speed, although far less than a modern road car. Drag coefficients are fairly high so top speeds aren't too high, but that may be a good thing considering high speed lift! Tyres and suspension have both received a lot of attention and are up to date with all of the latest features - see other thread detailing general developments here.

BMW 635i
Has a long wheelbase, a relatively high centre of gravity and soft suspension. If you're used to driving GT3s, take a deep breath and slow yourself down - nothing will feel like it's happening quickly when you first hop in. When you get in the zone, driving this is one constant slide which is super rewarding when it clicks.

BMW E30 M3
This one is probably the simplest to drive out of the box with very few quirks. It's engine likes to rev but it only has five gears, so you'll need to stay on top of the revs.

Volvo 240 Turbo
Affectionately known as the flying brick, this one will probably take the most getting used to. It has a solid rear axle, so rear suspension is not independent. To help traction and rear end grip, the rear suspension is very soft, but that means it will lift it's front inside wheel off the ground when cornering. So, if you're thinking about going near the brakes as you turn, you've got quite a high chance of locking that unloaded front up. Turbo technology was still very much in development in the mid 80s, so turbo lag is very much something to wrestle with. There is one saving grace though: from 1986 the car raced with traction control. So that's one less thing to trouble you.

Nissan Skyline R32
This car is four wheel drive, which means it has an incredible launch off turns, particularly slow ones. However, you have to drive it correctly in order to make the most out of it. The correct technique is very much like the front-wheel-drive approach of slow in, fast out. Mashing the power too soon can result in chronic understeer which will see you ploughing off track in the worse of cases. It's also the heaviest car in this class, but brakes are no bigger than it's opponents, so watch those braking distances as it can't stop as quickly.



The 1992 DTM series was also run to Group A regulations, but they're a generation on from our Touring Classics. The cars are lighter, they have more power, better brakes with ABS, and sticker tyres, so lap times are quite a bit quicker.
Considering how popular and loved this car set is, the decision to update every aspect of their handling wasn't taken lightly. However liked the previous version was, they were a throwback to old thinking regarding car handling. The way cars would hold a constant yaw angle in every turn and pretty much hold on forever reminded me more of a slot car than anything I've ever been strapped in to. Handling like that does have a time and place in gaming, but we're being a sim here.
We can be a lot more accurate now in all areas. Aerodynamics, engine behaviour, suspension geometry, tyres, dampers etc have all had hours and hours of development time.




Group 4 existed under several different guises over the years. The version we're representing here in RaceRoom began in 1970 and was contested by production based exotica such as the Ferrari 365 GTB/4, De Tomaso Pantera, BMW M1 and the Porsche 934. It was replaced by the new Group B GT class in 1983, where several Group 4 cars were allowed to run, hence we have included some liveries from that era too.

The class features manual gearboxes, lots of power, very little downforce and in the case of the Porsche, a LOT of turbo lag. Back in the late 70s/early 80s crossply tyres were the norm, with radials only starting to appear in high end motorsport from around 1983. A crossply tyre uses a stiff sidewall to support the tyre, with a relatively flexible tread section in the middle. This gives them a distinctive difference in feel to a modern radial. They typically operate at much wider slip angles and are more forgiving at the limit without the dreaded snap-back a radial can give you. Due to the stiff sidewalls they do not respond well to camber, and much prefer to sit perpendicular to the road surface. Big camber angles with a crossply tyre will only serve to overheat the sidewall and reduce grip.

In the damper department, they're a much simpler affair than a modern unit. Separate high speed damping has not been invented yet, so all you get it a low speed adjuster. This means you have to consider behaviour over bumps as much as general handling needs when adjusting them as you can't separate the two elements out.





The BMW M1 Procar series took identical cars, Formula One drivers and pitted them against each other on international circuits in support of Grand Prixs. The Procar is lighter than the Group 4 version as sprint-type components are used. The engine's rev limit has also been raised, allowing for a bit more power to be freed up. All these changes together mean that can lap a few seconds quicker than the Group 4 car, even though both use the same tyres.

 

The AWD loads the front tires much more, so it’s normal yes