Hey guys, I did some searching and it didn't really show up and I'm quite curious about this now. What I know... MT are 50/50 power distribution and AT are 90/10 distribution Question.... Which one is the better AWD system for daily driving plus the occasional off-road racing?
AT is NOT 90/10 dist. It is front wheel until it senses slip. In my experience - they're both really easy to drive daily, and almost no difference in feel behind the wheel day-to-day. However, my car is a manual, if that says anything.
I have driven both daily and rallycrossed both as well. For daily driving you won't even notice a difference. If you have a crap commute get an auto. As for racing anything but drag racing you will want the 5mt. You can lock the center transfer clutch to make an auto trans. locked front to rear but I wouldn't really recommend that on a daily driver. Too many pin turns and you start to smell clutch. (really weird in an auto) BTW my Tleg with the locked up auto has taken 2 overall wins this year with a National champ behind the wheel. I have podiumed a few times with this set up as well.
Shibbs, So before the slip it's a 90/10 then? I know after the slip it's power gets distributed accordingly and also with acceleration/decceleration but with normal driving w/ no accel/decel at at constant speed, it's 90/10 correct? If so, this is why I'm wondering about it because then it means there's must be a time lag of some mangitude v.s. a MT tranny. Boomer, if it's not noticable for a Daily driving, what about in conditions like snow/ice or heavy rain?
From what I have experienced there is a noticeable lag time before the power is transfered. Much less from other AWD systems I have driven but it is still there.
There isn't really a torque split on an auto. Without front wheel slippage, there is no pressure applied to the transfer clutch. The condition of the transfer clutch will determine how much drag there is between the disks and the steels. An older car will have less drag, and the duty C solenoid's condition can play a part as well. For all intents and purposes, consider it completely FWD until there is wheel slippage. As far as slippage goes, it depends on the car, and how hard you mash the pedal. I feel a lot of slippage in my mother's Forester, but my old '90 Legacy had very little delay. Dan, I don't know how you could possibly smell burnt clutch with the auto since the transfer clutch is fully contained within the transmission. With a locked tranfer clutch you can feel some torque bind around tight corners.
Not sure how we could smell the clutches (trans breather?) but it was a very distinctive clutch smell.
Typically you aren't going to even smell burnt tranny fluid from inside the car. Wet clutches from within the tranny would be even less likely. Did you pop the tail section off the tranny to see?
I do wonder if the newer AWD systems still run the 90/10 split. The ones with planetary gearset trannies are slightly rear biased. I also wonder if the ABS has anything to do with the transfer clutch as well if you where to dis-able the ABS via fuse in older models like 97-04. The automatics are MUCH better than the manual 5spd. However they come close if you're talking about '08+ Subaru models because they deploy traction control via brakes to slow the spinning wheel. I like my DCCD though because I can lock the center diff. THAT is the better. If you can lock the center diff and rear diff, your off-road capability is increased greatly.
The auto cars are dependant on the ABS for wheel speed. Disable the ABS and no AWD. One can easily make an auto car lock the transfer clutch. It takes about 3 minutes to wire up a switch.
I am not entirely convinced of this. At every Ice Race expect the last one I have run the 4EAT Automatic trans in my 95 w/ the ABS disabled. I am pretty sure that my AWD was still working, both since the wheels were spinning and also since I was putting up competitive times. (based upon past history of FWD cars at the ice race I wouldnt have been competitive at all) Onto the original question: I have driven both Auto and Manuals in my Subaru and there are only minor differences. So I would have to agree with what Boomer said about DDing. For every day stuff on drive pavement you will not notice a difference in how they handle. In the snow you will notice the small things. (the following is all my perception) The auto felt more stable to me at high speed in the snow (70mph down the highway in a snow storm before plows were out) than the 5spd does. However it is much easier to get the 5spd to bring the back end out. This is not to say that the Auto will not do that, it will do it just fine but I noticed that the 5spd does it alittle better. Probably due to the fixed tq split and also that there is less power loss in the 5mt than the auto. So my answer of which is best is..... anything with DCCD ;-)
No, not on all the autos. My wife's is an Auto AWD and it is not equipped with ABS. You can insert a fuse under the hood to disable the AWD though. I thought the VDC cars used the ABS sensors. I've owned two auto subarus and two manauls. I can really tell the difference on snow/ice. To me the delay on the auto tranny was really annoying, there would be a certain amount of front wheel spin before the center clutch pack would respond. I usually just put the auto down into first gear when taking off from a stop on snow since that would lock the center diff on the auto. On pavement the difference was not noticable for daily driving.
AHh ok, lots of good inputs, thanks guys, this will help me towards a decision between the AT's and the MT's.
I have heard of this however I do not think that it is true on all of the 4eats. Fuji and I were messing around with this trying to determine if it was true or not. That autos we saw did not do this, but there are so many variations of the 4eat that our small test cannot hold true for all of them. I have a feeling that what you will eventually find out (alteast this is my conclusion) The 4eat (automatic) is a giant mystery and it should not be questioned how it works so long as it does.
i have an automatic impreza with a blown up front diff that im running rwd for the time being. I just took out the front diff and axles and used outer axle stubs form bad axles in the front hubs.center diff locks up right away and i have no issues except speedo and park are inop.
I got the straight skinny from the man. There are also speed sensors on the shafts in the tranny that essentially act as a back-up. The TCU is slower to respond when relying on them, but it still works.
The 4EAT tranny out of a WRX acts differently than a 4eat in other cars in the lineup. The center diff is very similar to the DCCD found on STi's, and with a little knowledge of PWM electronics, one can adjust the diff exactly like a DCCD. IIRC, the WRX 4EAT's center diff by default is 60/40 (rear vs front) and depending on conditions can shift the power around automatically.
That might be true on the old stuff, but my 02 bugeye had the abs disabled for years and I can tell you with 100% fact that the AWD still worked (4eat). Russ
Nope, not at all what I was saying. I'm well aware of the advantages of short shifting a WRX while drag racing. I only suggest the auto for drag racing because properly built they can handle a ton of power. Not to mention the fact that most people can launch an Auto trans. much more consistently.
Depends on the power and perference of the driver. But an auto (built) would be a wise choice for those who are serious with drag racing.
And also don't forget that you don't have to let off the gas when you shift an auto. Very important when racing with a large turbo(30R or larger) as you dont loose boost when you shift. And a properly built auto can shift faster and more consistently than any person could ever dream. Not to mention a built 4eat will hold a 1000HP with ease.
I decided to go with a 4eat Forester XT, unless I'm wrong, auto transmission have better towing anyways and in the end, it suits my purposes much better then a MT would. Besides, to be quite honest, I may never get into rally or x-cross anyways so I wouldn't be able to tell the difference between either but an auto would make driving much more simple for every day anyhow and I really don't see myself buying a sedan/coupe in the future anyways (otherwise it would be a MT if I did buy a coupe/sedan)
If you're gonna do some towing with it, may I suggest an auxiliary cooler. There are soft lines which are easy to intercept to add a cooler before the radiator. A switch for the converter clutch may help too.
