Was reading in another thread that if you swap diffs from different year Legacys, you might have to change the ECU. I don't even know what an ECU does and I am extremely untrusting of electronics and computers in cars. What aspects of AWD are controlled by computer and how is AWD different than fulltime 4WD with a center diff? I might be needing a "family" car soon and the 1990-1994 Legacy looks like the best choice, but I can't have breakdown caused by silly little electric things. So, I guess my final question is: How reliable is early AWD technology? If and when it breaks, how much $$ to fix various things?

a manual trans in general is a better bet for reliability assuming the clutch and associated throw out bearing, pilot bearing and pressure plate are in good condition. and they have the added bonus of being "startable" if the battery ever fails.

 

the older AWD trans are fine for reliability. change the ATF and install an aftermarket trans cooler and you're golden. i see more problems with the newer trans, the clutchpacks - search on torque bind and you'll see what i mean, than the older 4EAT's that don't typically have that issue. the auto's are sensitive to proper maintenance, overheating and tire sizes so they are more prone to being in worse shape due to poor maintenance of previous owner than a manual trans. check the fluid (smell it, look at it), check the tires, check the radiator (since the ATF coolant lines run through it), look for leakage and install an aftermarket cooler.

 

i've seen more auto trans fail than manual trans that's for sure. but in that time a manual trans will need a clutch job anyway, so for someone like me that does their own labor and has extra parts it doesn't make much difference. but i would consider the 4EAT to have significant failure rates. i abused mine and had to replace the trans at 156,000 miles. i'm guessing my tire choices probably did it in as in college i would buy used tires on a regular basis.

Regarding the diff swap question. No you don't need to worry about swapping the computer if you change final drive ratios. Just remember that the front and rear final drive ratio need to match.

Was reading in another thread that if you swap diffs from different year Legacys, you might have to change the ECU. I don't even know what an ECU does and I am extremely untrusting of electronics and computers in cars. What aspects of AWD are controlled by computer and how is AWD different than fulltime 4WD with a center diff? I might be needing a "family" car soon and the 1990-1994 Legacy looks like the best choice, but I can't have breakdown caused by silly little electric things. So, I guess my final question is: How reliable is early AWD technology? If and when it breaks, how much $$ to fix various things?

 

A lot of people don't trust computers and electronics in cars because they don't understand them. The reality is they are likely the most reliable parts on your car.

 

If they do fail they are also the easiest parts to change. They are light, easy to get at and usually only require a screwdriver and unplugging a connector to change.

 

I'd much rather change an ECU then a lower ball joint anyday.

 

My advice would be find a well cared for car and don't worry. 1st gen Subaru's have a great rep for a reason.

With AWD are you basically in FWD until it senses slipping then engages the rear wheels? Or is it a constant variable split?

A big 10-4 on that guy. Sometimes you even get dust on you changing a computer.

It's easy to tell when a driveshaft or axle breaks, cause you can tell by looking at them (duhh) But when a computer goes out it's always some tiny circuit inside. I just imagine myself crawling under my car trying to figure out why something won't work when it's an invisible problem on the other side of the car I should be loking at. Did that make sense? I hear Sub folks talking about getting a "code #xxx" Is there a tool that comes with the car or for sale at a store that you plug in somewhere and it tells you what thingy is malfuntioning? I know virtually nothing about anything electronic beyond "positive + negative = power" so that's why I'm afraid of having to/trying to fix them.

With AWD are you basically in FWD until it senses slipping then engages the rear wheels? Or is it a constant variable split?

 

With MT transmissions, torque split is 50/50 all the time.

 

With AT transmissions, the torque split is 90/10 under "normal" driving conditions under a straight line highway driving. However that variance with torque split under day to day driving will vary all over the place.

With MT transmissions, torque split is 50/50 all the time.

 

With AT transmissions, the torque split is 90/10 under "normal" driving conditions under a straight line highway driving. However that variance with torque split under day to day driving will vary all over the place.

 

That's really cool about the 50/50. I will definately try to pick up a 5MT when I move. Thanks.