Fragile FWD's

[aa35199]

How come front wheel drive transmissions are so much more fragile then rear wheel drive, I used to have a 2000 saturn with a 5 speed and 30k miles and I trashed not one, but 2 transmissions! Now I'm in my camaro with 155,000 mi. and the bullet proof 4l60e still runs strong despite a very abusive previous owner. It's not just the saturn, but my friends ford escort GT (manual) then again on his 98 nissan altima (replacement for the ford) and my other friends neon (auto) all trashed their trannies too. Each and every time the differential pin punched a hole through the tranny case. When I complained, the saturn mechanic said that durning wither he see's alot of cars come in with the same thing because the wheels will slip on ice and then abruptly gain traction resulting in a blown tranny. I just can't comprehend how fraile these are, a worn syncro, or a gear faliure on a boosted car I can understand, but this was absolutly ridiculous! Any mechanics or engineers out there know what is behind this?

[HokieBird]

The transmissions just aren't built as strong. You are talking about transmissions in small low end cars. Of course they don't beef up the parts as much.

[JohnD.]

Even in the stronger cars(like mine) the fwd trannies are weak. It's just inherent to the design of them. Without some major part strengthening they just can't take it.

[V6Bob]

The 4L60E is also used by the V8, I don't know if there's any internal difference between the V6 and V8 transmissions, but, if not, that's why your trans is "bulletproof". It's designed for a lot more power. Autos also take a lot less abuse than manuals because it's much harder to shock them with an abrupt load.

It's pretty much a car specific thing, not "FWD". I autocrossed and roadraced (Showroom Stock) a VW Scirocco for 4 years with no transmission problems.

[aa35199]

I forgot to metion another one of my friends blew the tranny on his 98 grand prix

[shenanigans]

Yeah I love our indestructable drivetrains... ohh wait... :(

[SpeedingFirebird]

I think the sideways motor has something to do with it as well. The front tires do all of the work (steering, braking, and accelerating) so it puts more stress on the tranny. Just a theory of mine.

[rhouse21]

V6Bob touched on it. Our 4L60E's were designed for big, torquey V8 engines. Our little v6's barely stress them, so they are pretty bullet proof in our cars (although I am on my second). On the other hand, V8 tuners always point to out stock 4L60E's as a likely point of failure because they run so much more torque than we do. That's usually one of the components they go out of their way to beef up before doing any major mods.

The transverse mounted transmissions in most cars are really trans-axles containing the transmision, the diff, and all the gearing needed to rotate the engines rotational energy 90 degrees to the wheels. They have to put a lot of stuff in a very small amount of space, so they tend to be built just strong enough to get by with the required amount of reliability. Most consumers do not hop up their engines, so it is not cost effective for most companies to build these units any stronger than the average consumer requires. For example, the reason GM only boosted the S/C 3800 SII engines to 240 hp was not because of engine any limits. (They can actually produce over 300 with just moderate boost.) The stock tranny's for the FWD cars just couldn't handle any more torque withough killing their reliability and it wasn't cost effective for GM to build a new, stronger transmission just for these cars.

You are starting to see more FWD cars makng big Hp now, and these cars have much beefier trannies.

[3.4 slow to go]

just change the "L" to a "T" and there's your fwd derivative. A tranny will last proportionate to your beating it (usually).

[Vracer111]

Originally posted by V6Bob:
The 4L60E is also used by the V8, I don't know if there's any internal difference between the V6 and V8 transmissions, but, if not, that's why your trans is "bulletproof". It's designed for a lot more power. Autos also take a lot less abuse than manuals because it's much harder to shock them with an abrupt load.

It's pretty much a car specific thing, not "FWD". I autocrossed and roadraced (Showroom Stock) a VW Scirocco for 4 years with no transmission problems.

I agree with V6Bob - it's the car not the layout that makes a car fragile. FWD and some Mid-engine sports cars have the same engine/transaxle transverse positioning...it's just the mid-engines are behind the driver and the FWD are infront. I will say that the 2nd Gen Acura Integra is a pretty stout FWD car that doesn't have tranny issues (other than CV shaft that need to be changed every so often - one reason I don't like FWD). Still, it's amazing how well a FWD 2nd Gen Integra handles when you set it up for autocrossing.