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View Full Version : What's wrong with the gearboxes of some cars?



Ralph B
28-03-2016, 10:28
Well, some cars have strange gearing since the times of developement. One of them is the Mitsubishe Lancer ST Evolution XFQ 400. While the first 4 gears are fine, the gap to the 5th feels to big. Ok, feels odd somehow, but still driveable. This weekend had the opportunity to be passenger in this (real) car. Mmh, the fifth is indeed a bit like an overdrive, but the jump from 4th to 5th doesn't feel half as wide in reality than in pCars. A subjective feeling, but still in green range.

Annother example is the Escort Mk1 RS 1600. I drove the MK1 RS2000, when it was on the market in the 70th. Maybe the gearbox differed from the RS1600 and my remembrance is blured, but I never felt the big gap from 3rd to 4th such negative as I do with our model. However, still driveable, even it doesn't feel exactly as real one.

But it goes worse. Lets take out the Ford Mustang GT for a spin on a track, where reaching the topspeed should be possible - let's say the Nordschleife or Le Mans. All fine with the first 5 gears. But shifting into the 6th, the RPM instantly drops to a level, where the car isn't able to accellerate anymore, even isn't able to keep up its current speed, no matter how short you have choosen the final drive. Well, you may say it's an overdrive to spare fuel. Maybe that's the intention of Ford and working like this in reality. But that the engine starves after a few hundred meters even with full throttle - like it does ingame - makes no sense and doesn't seem very realistic.

Annother example: the Audi R8 V10 Plus. It has a 7 speed gearbox. Here even the 6th is already such long, that the car can hardly keep it's speed. And the 7th is useless as a goiter. What should that be good for?

And a last example, slightly better than the last two, but still pretty strange - the Ruf CTR3. It has a close-ratio 7 speed gearbox. It's not adjustable and the final gear is fixed, too. The gaps between the gears are fine, but in the overall performance it's still a bit to long for the engine. The 7th is totally lame and the engine has problems to manage it.

This are the cars I excessively tested. Maybe there are annother ones with similar odd behavior.

Of course I did a comparison to the real car datas. I wasn't really surprised, that SMS had done a good job and the numbers are more the less identical with the original technical specs. So what the hell is wrong? I'm shure, that manufacturers like Ford or RUF are not to stupid to build a functional gearbox, which matches the power of the used engines. And even the idea of saving fuel doesn't justify such long gears, that the engine starves. That makes no sense and I have some doubts, that it would be a good marketing argument.
So I'd say, there must be some mistake in the calculations of pCars. Power- or torque curve of the engines? To much drag, wrong rolling resistance allgorithm? I have no idea. But there's definitively something wrong. I'd really appreciate some explanations or even better - an overhaul. And if not for this game, at least for pCars2!

Mahjik
28-03-2016, 13:10
For the most part, any current standard production car uses the last gear as a "fuel saving/overdrive gear". They aren't designed to achieve top speeds. Most of the time, the vehicle top speeds are quoted theoretically based on power and drag. However, you also need to the gearing to achieve such speeds and most standard production cars do not ship with gears designed for top speed runs. In most of those cars on a race track, you'll never use the final gear.

Ralph B
28-03-2016, 15:54
The "fuel saving / overdrive" idea was the first thing, that came into my mind. Would make sense - no doubts. But don't you think, it's some kind of contraproductive, when the gearing is such long, that you can retain some speed only with full throttle? Or even worse - like with the Audi R8 or Mustang GT - if you can't keep the engine allive at all and it starves after some hundred meters. That makes no sense - even for a fuel-saving overdrive. And I don't think, the manufacturers of the real cars waste their knowlege and resources for developing gear ratios, that don't work at all.
My father once owned an Audi 200 (standart engine with 136 hp I think, not the Turbo) with an overdrive gearbox. I drove this car a several times myself and have to agree to your explanations above: it didn't reach its topspeed in the longest gear. But at least it was able to keep up a good speed with a moderate amount of throttle. It didn't slow down so much, that you had to shift down again after a few seconds. I've also driven some Mercedes of the 70th, which were known for their long last gear and the big gap between the last two gears. They didn't drive very sportive, but even here the long overdrive was useable.
So I'm sorry to say, this time your answer doesn't really convince me. For the real cars you are basically right of course - but somehow it doesn't work this way in pCars. If you don't belive, try out if you can use the 7th gear of the Audi in any senseful way. I promise, you can't - exept running down a step hill. And for the Mustang it's not much better.

Mahjik
28-03-2016, 15:59
The "fuel saving / overdrive" idea was the first thing, that came into my mind. Would make sense - no doubts. But don't you think, it's some kind of contraproductive, when the gearing is such long, that you can retain some speed only with full throttle?

That's because those gears are designed to maintain around the car fuel efficiency window which will likely be around 60-70mph (highway cruising speeds). They aren't designed to maintain or propel the car at 140mph. Most newer cars when switched into their sport modes disable those "overdrive" gears from being available.

ramm21
28-03-2016, 16:20
Yeah, you can't look at gearing now like you did even a decade ago. With the fuel/emission requirements, most manuals have one or two overdrive gears.
Look at any car with decent horsepower and a manual- they have tall gears, usually second gear is good for around 80mph. You can't have short geared manual cars with a lot of horsepower. They would be unmanageable at low speeds trying to put the power down and shift at any decent rate.
When I have cars that have overdrive gears, I just ignore them. Look at a 6speed like a 5speed, set your gearing so that youre redlining fifth on the longest straight.

Ralph B
28-03-2016, 17:28
Ok guys - you won! ;)
Did the ultimate test and sneaked arround Le Mans with the mentioned cars in the longest gear and with about 80mph. It felt horrible and like riding on a snail, but showed an interesting result. Against all expectations the engines didn't stall and even a slight acceleration with a small amount of throttle was possible. Now I know, how the manufacturers come to those incredible low fuel consums, that a customer never can reproduce. :p
So it's no bug, it's a feature! :highly_amused:

WTF - who buys such a car for saving fuel .... but that's not the problem of SMS I assume.

ramm21
28-03-2016, 21:04
WTF - who buys such a car for saving fuel .... but that's not the problem of SMS I assume.

Yeah if it was solely up to the manufacturers, they would never put overdrive gears on sports cars. It all stems from government emission/fuel standards.
IRL I put a heavier engine oil into my car because I found out the only reason the manufacturer uses the thinner oil is because it saves like .5MPG. It makes the car a little less reliable, but I guess to them its worth it.