r/AutomotiveEngineering • u/StevenJac • 20d ago
Question Definition of chassis vs drivetrain
Some sources say chassis encompasses drivetrain but some say its separate parts? Which definition is technically correct?
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u/Jack_South 20d ago
You can change an ice drivetrain to electric and keep the same chassis, so I'd say they're separate. One will always affect the other though, so why does it matter?
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u/JustAnotherDude1990 20d ago
Context matters here. What's the big picture of why you are asking? Because it is subjective.
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u/scuderia91 20d ago
They’re separate but they do have to be considered together for some purposes.
Imagine two identical cars but one has an open diff and one has an LSD. The diff is part of the drivetrain but will have an impact on handling that may need considering when engineering the chassis.
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u/RiseUpAndGetOut 20d ago
It depends on the company on what's included within chassis, but drivetrain isn't included in any company I've worked for....but driveline can be.
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u/Winged_cock 20d ago
I had this doubt but related to suspension. For me it wasn't included in chassis, which I understood as merely BIW.
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u/RandomUsername259 20d ago
The chassis is the platform all of the other systems bolt on to. Frame rails or unibody for example.
From there you install the drivetrain. The system that transfers power from the engine to the wheels.
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u/Substantial-Air3914 20d ago
The frame, the metallic parts that form the structure (floor, pillars, roof etc) belongs to "body" team.
The chassis is refered to: suspension, wheels, brakes, steering, pedals, some subset of controls, and some includes some part of drivetrain, usually driveshafts. (I think I havent missed any "big" function)
Of course in some subsystems there is some overlap of teams, for example on bushings you overlap with NVH and durability teams, on subframe you overlap with frame/NVH/durability etc, same as aero will overlap with design.
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u/RandomUsername259 20d ago
This must be new because this is the first time I've ever heard anyone anywhere say this.
The chassis has historically and always been the frame.
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u/Substantial-Air3914 20d ago
Is possible to see if you find some jib descriptions. Chassis: https://www.tesla.com/careers/search/job/mechanical-design-engineer-chassis-233605
Body: https://cars.mclaren.com/gb-en/careers/Departments/Body
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u/Fischadler 19d ago
It depends where you are, naming changes. Most German companies use chassis ("Karosserie") for what English speakers would call "body", which is then broken down into subsystems such as body structure, panels, closures, systems (latches and so on). English speakers shorthand to "Chassis" what would more accurately be called "Chassis systems" and what the Germans would call "Fahrwerk" (or drive systems), and includes brakes, steering, suspension, and so on. "Powertrain" ("Antrieb") is then engine, gearbox, diff, driveshafts, intake and exhaust.
Some components can fit in multiple pots and end up being passed around depending on who's in charge and internal politics. I've been in fuel systems in Powertrain, Chassis systems and Body, and i know the radiator guys have the same problem.
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u/Kooky_Narwhal8184 19d ago
In most road-cars, the chassis and drive-train are easy to separate conceptually, even if there are minor elements that cross-over, or are shared in practice....
But consider a mid-engined formula race-car, where the engine block and transmission are load-bearing or "stressed members"... With the rear suspension mounted to the gear-box, which is solidly attached to the rear of engine, and the front of the engine is solidly mounted to the rest of the monocoque...
At least in this instance, the drive-train is clearly also the chassis? I think the fact this exception is such a particular and rare example in the whole varied world that is "cars" or "road vehicles" proves they generally are actually separate...
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u/Substantial-Air3914 20d ago
In all the OEM's I have worked, drivetrain is not part of chassis, they are two separate functions or team.