If you drive a smaller FWD vehicle, you’ve probably wondered how everything can fit under such a tiny hood. Engine bays on compact vehicles barely have any room to spare, so it’s hard to imagine how an engine and transmission can
comfortably fit inside. That’s where a transaxle comes into play. For all intents and purposes, a transaxle is just
a smaller and more versatile transmission bundled together with a final drive differential.
While the transaxle and the transmission do fulfill very similar functions in a car, there are some key differences
between the two. Understanding the distinctions between car parts can not only expand your automotive
knowledge, but can also give you valuable insight into the way certain cars are designed and how they function.
What is a Transaxle?
A transaxle is a smaller version of a transmission, found primarily in FWD vehicles with automatic transmissions.
Unlike a transmission, a transaxle has the axle integrated into its assembly allowing for a much smaller overall
Instead of having the differential in the rear of the vehicle, it is immediately attached to the transaxle itself.
This greatly simplifies the vehicle's driveline as the driveshaft doesn’t have to connect to a differential before
power is sent to the wheels.
A lot of the key differences between a transaxle and a transmission overlap with the differences between transverse
and longitudinally mounted engines; transaxles are easier to package on transversely mounted engines. Instead of
having to connect the transmission to the differential and the differential to the wheels, the power can go directly
from the transaxle to the wheels themselves. Talk about convenient! That being said, transaxles are also a common
occurrence on all-wheel drive cars, as the integrated final drive differential makes packaging easier.
Performance Differences Between Transmissions and Transaxles
Transaxles aren’t perfect for every vehicle, however. There are plenty of situations where a transaxle is either an
ill-advised design choice, or just flat out unnecessary.
For one, the added weight in the engine bay can really disrupt the performance of a rear-wheel-drive vehicle. The
less weight there is on the driven wheels, the less traction the car can attain. When a transmission is mounted
behind the engine, it brings more of the vehicle’s weight towards the rear.
Additionally, there are more ways to bolster the strength of a transmission than a transaxle. While there
theoretically are transaxle designs that could handle ultra-powerful engines, their compact design poses some
serious engineering challenges. Transmissions, on the other hand, have more room for careful design. Additionally,
the separate rear differential means that you can easily swap it out for an upgraded one.
There are RWD vehicles with transaxles too. Instead of being mounted directly beside the engine, the transaxle is
placed in the rear where the rear differential would be. This isn’t a common way of designing cars, but it does
allow for better weight distribution while eliminating the need for a rear differential as well.
Transaxles generally don’t come as a manual transmission. Given the way that it is packaged, a transaxle will almost
always be an automatic transmission, with the CVT being an increasingly popular option. If you wanted a performance
car with a manual transmission, it’d likely be RWD anyway.
Sources: CarID | Carthrottle
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