Category Technical Talk

Note: we have moved the complete list to our new site, all future updates will be published there.

The torsional rigidity is a critical parameter for a vehicle, which measures how many force you need to apply to “twist” the car body frame by one degree. Of course the larger of this value, the better.

From the consumer’s perspective, what is the benefit of a high torsional rigidity car body? A vehicle with high torsion rigidity will give the driver and passenger a more “solid” feel when the car is running, especially when the road is bumpy and has lots of potholes on it...

Last time I showed you some interesting facts about the ZF 9HP transmission. Today I am going to talk about the latest GM 8L90 8-speed automatic transmission, which will be used on the 2015 Corvette.

Please do not be confused with the Cadillac CTS 3.6 V6 trim’s 8-speed transmission, that one is not the 8L90. Instead GM sourced it from Aisin and it is a completely different design.

First I would like to show you the structure diagram of the 8L90. The drawing is from the patent GM filed with the US Patent and Trademark Office several years ago. As expected in a patent document, the drawing looks terribly complicated...

The ZF 9HP is a 9-speed automatic transmission for transverse engine layout, which is used on the Jeep Cherokee and the upcoming Acura TLX. While there are plenty of technical analysis on this new ZF product, here I am not going to feed you with some PhD-thesis-type content. Instead I have some interesting facts you may find interesting.

First off, don’t be frightened by the below ZF 9HP internal structure image, it is for your reference only, you don’t try and memorize it all in one go. It takes time to learn.

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Since the data comes from different sources, there may be duplications or conflicts in the list. We will fix them later on.

Following data in kg:

Bugatti Veyron: 400kg
Cadillac Sixteen: 316kg
Chrysler Viper GTS: 295kg
Chevrolet Corvette C4: 281kg
McLaren F1: 266kg
Porsche 996 Turbo: 260kg
Porsche 928: 260kg
Mercedes-Benz SL65/CL65 AMG: 253kg
Pagani Zonda F: 250kg
BMW E60 M5: 240kg
Porsche 964C4: 238kg
Ferrari 456GT: 235kg
Maserati MC12: 232kg
Mercedes-Benz SLR McLaren: 232kg
Ferrari Enzo: 225kg
Audi S8 5.2: 220kg
655ci V8 From Indy: 220kg
Koenigsegg CCR: 215kg
Lexus LS400 (94): 210kg
BMW 740i (92): 210kg
Porsche Carrera GT: 205kg
Porsche 996 Carrera: 204kg
Porsche 997 Car...

In part 1, we reviewed some basic knowledge of AWD system, BMW xDrive and Mercedes-Benz 4Matic system. Now we continue our discussion on Lexus and Audi.

Lexus: the IS250/350 AWD and GS350 AWD are using a planetary-gear center differential, plus a wet-type multi-disc clutch control to act as slip control. This is a very advanced and complex design. Because the multi-disc clutch can be 100% locked, it means Lexus’ AWD can handle the case that even front or rear wheels completely lose traction, than the rest side of the two wheels still have full power. The disadvantage of this design is it is complicated and the parts take space...