by Jonathan » Sun May 08, 2005 7:34 pm
"In reply to to what Jonathan said, I must speculate that FWD is actually more expensive to engineer and produce than RWD because of the cramped space in which the engine, the driveaxle, and all other components that must fit."
It can be cheaper since you do not have to machine a driveshaft, differential, axle housing, then there are other issues such as engineering the chassis to be strong enough to hold the axle's torque, plus the transmission mounts and chassis strength in that area, plus the cost of a beefier suspension in the rear and all sway bars etc. to have to put in place. With FWD you have a transaxle that integrates all duties in one space and is directly connected with the CV axles. It's not that much more difficult to engineer than a RWD transmission, as most RWD transmissions you'll see (especially manuals) have a lot of unused length to them that simply contains a shaft housing. It's kind of like looking at a laptop computer thinking "wow, look at how much they crammed into that" and then cracking a desktop and seeing that hardly any of that space is used to begin with anyway. RWD is generally built more rugged than FWD and it still introduces it's own engineering issues, especially in today's cars since you're dealing with a smaller car, more crash regulation, and you'll give up interior space, working around that in a modern vehicle is a big challenge since you have more engine length and layout problems to have to fight, plus the dreaded transmission hump. Engineering may or may not be more expensive for FWD, dependant upon who is doing it, but it's been done for so many years now that all cars using them will be based upon a common platform and a common engine family. The internals of these transaxles are cheaper than the internals of a RWD typically (to produce, not to buy), and they are made as modular parts that are somewhat easy to change out, at least easier than it could be. Where in a RWD car you have a transmission, driveshaft, axle housing, differential, and the axle shafts, with a FWD car you simply have the transaxle and the CV axles. All a similar number of parts used, but less steel to get it done in the case of FWD.
"In reply to to what Jonathan said, I must speculate that FWD is actually more expensive to engineer and produce than RWD because of the cramped space in which the engine, the driveaxle, and all other components that must fit."
It can be cheaper since you do not have to machine a driveshaft, differential, axle housing, then there are other issues such as engineering the chassis to be strong enough to hold the axle's torque, plus the transmission mounts and chassis strength in that area, plus the cost of a beefier suspension in the rear and all sway bars etc. to have to put in place. With FWD you have a transaxle that integrates all duties in one space and is directly connected with the CV axles. It's not that much more difficult to engineer than a RWD transmission, as most RWD transmissions you'll see (especially manuals) have a lot of unused length to them that simply contains a shaft housing. It's kind of like looking at a laptop computer thinking "wow, look at how much they crammed into that" and then cracking a desktop and seeing that hardly any of that space is used to begin with anyway. RWD is generally built more rugged than FWD and it still introduces it's own engineering issues, especially in today's cars since you're dealing with a smaller car, more crash regulation, and you'll give up interior space, working around that in a modern vehicle is a big challenge since you have more engine length and layout problems to have to fight, plus the dreaded transmission hump. Engineering may or may not be more expensive for FWD, dependant upon who is doing it, but it's been done for so many years now that all cars using them will be based upon a common platform and a common engine family. The internals of these transaxles are cheaper than the internals of a RWD typically (to produce, not to buy), and they are made as modular parts that are somewhat easy to change out, at least easier than it could be. Where in a RWD car you have a transmission, driveshaft, axle housing, differential, and the axle shafts, with a FWD car you simply have the transaxle and the CV axles. All a similar number of parts used, but less steel to get it done in the case of FWD.