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Old 09-02-2003, 07:00 PM   #1
oney01
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Question AT or MT? Which is better for off road abuse?

I have an 03 Baja with the AT and I go off road on the beach, upstate hunting and when ever I can find mud! Although the 2.5 is a little under powered the car has gotten stuck! When you go up-hill and the front tire or tires loose traction, the viscus limited slip can not deliver enough power to the rear. I think it pushes at best 9 foot-pounds per 1000 rpm. Not enough to move the car. When I am on the beach, the clutch cries as I try to get it rolling through the soft sand! Can the AT handel this any better? Does the clutch pack in the MT lock up all the way so you wont get stuck if the front looses traction? I plan to trade the car in for the turbo version in a few monthes and can not decide which tranny to get. Which one is or would be faster out ot the hole and or for passing "slow pokes" on the highway? Please answer as technical as you can in regards to the Viscus diff on the MT and the clutch pack on the AT. Can the AT handel off road abuse? Thank you!!!!!!
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Old 09-02-2003, 07:09 PM   #2
ciper
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The AT would be better in almost every way

For one the center differential locks (non VTD center)
Torque can be built without the vehicle being in motion (liquid coupling through the TC, plus torque mulitplication)
No loss of power as second gear is applied (two gears are engauged at once)

All of that and the benefit of shifting during VERY ruff terain without missing gears or dropping the clutch accidentally.
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Old 09-03-2003, 12:24 AM   #3
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Question Abuse? Performance?

Thanks for the info! Which is faster? Somebody once told me that the AT WRX was faster than the MT WRX, is it true and would it be true for the Baja? What about steep hills off road that my 165 hp MT baja can not get up, will a AT be able to "slip" its way up the hill? Which would you expect will last longer, the AT or MT? Wow, thats alot of questions! I hope I see alot of answeres Thanks in advance for the help!!!!!! (the banana is the best BTW)
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Old 09-03-2003, 01:52 AM   #4
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Faster, which way?

The AT would have a far better chance to get up the hill, 165 is probably 4 times the power you really need.

The MT will easily last longer. If shifted properly they can pretty much last forrever.
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Old 09-03-2003, 08:51 AM   #5
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Default Faster

Faster as in 0-60 and or 1\4 mile. When I do get the turbo version, will there be more turbo lag with the 4-speed? Also when you try to pass on the highway, will the 5 speed get into the power quicker?
As far as getting up the off road hill, its a lumpy bumpy one one so you cant go full speed. In first gear on the 5-speed at 3000 with your foot to the floor it just slows down until its hit the clutch or ping a little then stall in a rough jerking stop! Thanks. Now for the banana
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Old 09-03-2003, 09:04 AM   #6
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The wording of your origional post is a little confusing, however I will assume from your first line that your Baja is an Automatic. With that said, if you want better traction in the sand try putting the transmission in first or second gear. First locks the centre diff, second also locks the centre AND locks it IN second gear. I do not believe this is in the manual, but it is quite true. Drive and 3rd both split torque 90-10, with the 10 gong to the rear. In your situation what is probably happening is that; sand creates a very similar traction potential front and rear so you will be driving 90-10 until the front starts to dig. Once the front does start to gig and slip power will transfer to the rear, however it is probably too late by then.

The automatic only has two real benefits off-road. The locking differential is one, and the fact that you don't have to work the clutch on steep inclines is another. However, I much prefer the manual for off road for these reasons.

- It has a 50-50 split in all gears. This is what you want in the sand;
- The effective gear ratio for 1st and reverse are lower, so you have more torque available. Although ciper is correct that you have more than enough power, I find that the extra torque gives you more modulation, the same way larger brakes give better modulation...but in reverse. V8 pickups have more than enough power as well, but how often do you see them rock crawling or hill climbing while not in low-range;
- Although the center diff on the manual cannot lock, you have to ask yourself how often you are going to be in the situation where either the front or rear has drasically different traction situations. I personally have NEVER had any trouble with this;
- Although we are using gas engines, I still find there is some useful engine braking. This is not possible with the automatic.
- The manual is lighter;
- $800 is 4 really expensive tows, some sand ramps, and a good comalong.

As with most things Subaru, it is difficult to say which is better. There are benefits to both. I prefer the manual, but there you go. If you are interested in sand most specifically, I think the manual is the answer. The "secret" of sand is to keep moving; the maual has 50-50 in all gears which makes the "keeping moving" bit easier. Plus the lower 1st gives you more modulation when you need it.
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Old 09-03-2003, 09:20 AM   #7
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To answer your question on Speed. the Manual is almost always faster than the automatic. Except in cases where the auto is a squential tranny (like the option on the M3 for example.) In those cases the auto can be just as fast as the manual. But subaru just uses a "regular" automatic. Turbo lag will be less in the manual also since you can put it in the gear you want before you need/want to accelerate.

I think the manual would be just a capable off road as the auto. In my WRX I've gone all over the place: mud, gravel, sand (up a fairly big sand dune also). Be sure to take a lot of air out of your tires, and I dont think you'll have a big problem off road.
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Old 09-03-2003, 10:56 AM   #8
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IIRC, the Baja Turbo will have VTD. That should give you better traction. The improved torque will help as well.

The other issue is air pressure. Are you airing down when you're in sand? When I had a manual OB Sport, I took it in deep sand quite a bit. I got stuck three times in the beginning because I didn't air down enough. After airing down to 12-14 psi's, I never got stuck again. And the sand was deep enough in some place to touch the bumper.

In dirt and moderately deep sand (3-4 inches), 20 psi's or so should be ok.

-Dennis
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Old 09-03-2003, 02:23 PM   #9
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Thanks for the input. My Baja is a MT. I thought it was better, until I got stuck with it. Like I said, I was off road hunting going up a steep hill, as soon as the front tire (no front LS) hit snow and lost traction it just spun and the car stopped moving, the viscus center diff does not send enough torque to the rear, on a flat road it may be enough to keep the car moving but not up a steep incline.
Yes, I found that airing down to about 15 lbs will keep me from getting stuck in the sand but it is very abusive on the clutch getting going from a stop.
The STI tranny would answer all my problems, low first gear, ability to lock the center diff, fast with the turbo motor. Are they hard to get, and are they an easy swap? Thanks again!
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Old 09-03-2003, 02:28 PM   #10
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Unhappy I am a dumb ass!

Sorry! I Switched MT and AT in just about every spot on my first posting Sorry
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Old 09-03-2003, 03:00 PM   #11
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The automatic would have helped you out in that particular situation IF you had had it in 1st.
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Old 09-03-2003, 07:54 PM   #12
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brandon:

"It has a 50-50 split in all gears."
Not a benefit, you can still spin one front wheel at an incredible speed while the two rear wheels barely turn.

"The effective gear ratio for 1st and reverse are lower, so you have more torque available"
Wrong, the TORQUE CONVERTER is just that, it will not only INCREASE the amount of torque but allow you to put a load on the engine at a higher rpm producing more power from a stand still. This is a big reason why 1st in an auto is geared "higher"

Combine the above fact with a turbo and you are able to build boost and increase available power even while standing still

"- Although we are using gas engines, I still find there is some useful engine braking. This is not possible with the automatic."
Wrong, engine braking is active in every gear except first when in 2-3 or d and IS active in 1st when in the 1 selection.

"50-50 in all gears which makes the "keeping moving" bit easier. Plus the lower 1st gives you more modulation when you need it."
Wrong. 4 locked differentials would be the best for sand. The automatic comes far closer to this than the manual. You dont need more modulation to keep moving, you need precise control over the amount of power given to each wheel. With a fluid coupling its easy to hover at a certain amount of power even while CHANGING the throttle opening.

Sounds to me like you dont own an automatic subaru. Ive got TWO dedicated dirt subarus on the other hand (not driven on the street). I recently sold one to a buddy. It was a 5 speed turbo. A turbo manual transmission in low speed dirt situations sucks most of the time because the turbo slows down through the constant shifting and low load on the engine. The other is a 5 speed NA 6 cylinder. It has a rear LSD and a locking center differential. Its far better since I dont have to wait for spool up but trust me when I say Id much rather have the auto.

Ever try changing gears in a manual while flying over massive bumps? You'll try for second and ending in 4th while dropping the clutch or even hitting neutral and revving the engine for no reason.

The last disadvantage to the manual for dirt is your transmission will get trashed if you try to do anything half fun. The constantly changing load combined with changing speeds and the need to keep momentum usually results in some nasty shifts. It doesnt take long before synchros are worn and gears grind.

The auto on the other hand CANNOT grind gears, only clutches and bands wear out.

If the Baja turbo does have the VTD transmission then some of the stuf we mentioned might not be accurate. It isnt a simple clutch pack like the old automatics.
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Old 09-04-2003, 02:55 PM   #13
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Ciper: Thank you so much for the info, it helps alot! What is the VTD? If you tell me what it stands for Ill look in to it. Thanks again for your help. I have written letters to Subaru NA asking technical Qs and all they give me is nonsence! Never hard numbers of factual stuff I can use. Thanks!
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Old 09-04-2003, 03:36 PM   #14
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Veriable torque distribution. The Automatic US WRX, the VDC outback and the STI 6 speed manual use this center differential. In an oversimplified definition think of it as a planetery LSD that is electronically controlled.

Check these threads for some useful information http://forums.nasioc.com/forums/show...hreadid=358602
http://forums.nasioc.com/forums/show...hreadid=296350
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Old 09-04-2003, 05:37 PM   #15
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ciper:
Quote:
Not a benefit, you can still spin one front wheel at an incredible speed while the two rear wheels barely turn.
I agree you can spin one wheel if there is a LARGE difference in the available traction front/back. The origional author of this thread was asking about driving in sand. On a consistently sandy surface the available traction at all four wheels will be almost exactly the same. So unless you lift a wheel, having a 50-50 split is a huge benefit. If 90% is going to the front in really soft stuff, you are going to dig a hole with the front wheels...and then the rears "kicking in" isn't going to do you much good. Of coarse you can get aroung this by putting the auto in 1st or 2nd as I said earlier.

Quote:
Wrong, the TORQUE CONVERTER is just that, it will not only INCREASE the amount of torque but allow you to put a load on the engine at a higher rpm producing more power from a stand still. This is a big reason why 1st in an auto is geared "higher
Perhaps you missed the bit I wrote about modulation. Why don't you go back and read it again. A torque converter converts the mecanical (rotational) torque to a hydraulic equivalent, and then back. THAT'S what the torque converter does. It does NOT increase torque in any way. In fact, if anything it loses torque through the process of converting. I've never seen a 100% efficient torque converter before, which is one of the reasons AT cars don't get as good fuel mileage! Your statement about raising the RPM is correct, but you are not applying as much as you think. If an engine puts out 100ft-lbs @ 2000 RPM, and that is where your stall speed is, the transmission gears won't see the full 100ft-lbs, because a whole bunch of it is being wasted as heat by the slipping of the hydraulics. BTW, you can create this exact situation in a MT by slipping the clutch, it just smells a little worse. The big reason 1st is taller in an auto, is because there's less gears, not because the TQ magically creates more torque.
Quote:
Wrong, engine braking is active in every gear except first when in 2-3 or d and IS active in 1st when in the 1 selection.
Once again, the torque converter is a slipping device. You will NOT get the same engine braking as you will with a manual which is "locked" to the drivetrain. And given how minimal engine braking in a gas engine is, the loss through slipping in th AT makes it almost worthless. I can't imagine you drive down too many steep hills in 1st in your auto without using the brakes.
Quote:
Wrong. 4 locked differentials would be the best for sand. The automatic comes far closer to this than the manual.
Of couse 4 locked differentials would be better (at low speeds). But the auto doesn't have that either so it's a moot point.
Quote:
You dont need more modulation to keep moving, you need precise control over the amount of power given to each wheel
I want you to read over this sentence again really carefully, and then tell me what's wrong with it. If you need a hint, try opening a thesaurus. And by the way, this completely conflicts with your previous statement that "all 4 wheels locked" is better. So please make up your mind!
Quote:
Sounds to me like you dont own an automatic subaru. Ive got TWO dedicated dirt subarus on the other hand (not driven on the street). I recently sold one to a buddy. It was a 5 speed turbo. A turbo manual transmission in low speed dirt situations sucks most of the time because the turbo slows down through the constant shifting and low load on the engine. The other is a 5 speed NA 6 cylinder. It has a rear LSD and a locking center differential. Its far better since I dont have to wait for spool up but trust me when I say Id much rather have the auto.
If you recently sold one to a buddy, then you would have ONE "dedicated dirt subaru". That is unless my kindergarten math fails me. No I don't own an Auto Subaru, but my parents do, and my brother does, and my uncle. I've driven only one of them in the sand, and I much preferred my MT 2.5RS. I've driven ALL of them in deep snow, and I much prefer all the MTs I've owned over the autos as well. I feel they give significantly more control. However, that's only my OPINION given the off roading I've done, which seems quite similar to the off roading oney01 stated he does. I've owned 5 Subarus since 1992, one of them being the one you must own right now...an XT6. There have never been any other H6 MTs, and it was one of very few to have a manually locking center. However, they made a reasonable number of XT6 autos, so why don't you just pick one of those up instead?? Personally, I've always found Turbos rather useless off road, that pesky modulation thing again. Of corse that statement refers to most car turbos which don't spool up until later. Low spooling turbos fitted to diesels, and very small turbos on gas engines (like the the Forrester XT) don't have the same problem.
Quote:
Ever try changing gears in a manual while flying over massive bumps? You'll try for second and ending in 4th while dropping the clutch or even hitting neutral and revving the engine for no reason.
Yes I have in fact, and it's never been a problem for me. It's also never been a problem for all those people racing in the infamous WRC or the far more "hard core, drive over everything" Dakkar rally. So maybe you might want to brush up on your shifting technique a bit, too much time in the autos might be the problem. You may also want to try not shifting while in the air, as I can't imagine needing to do that. Further, I don't remember that the author of this post said anything about flying over bumps.
Quote:
The auto on the other hand CANNOT grind gears, only clutches and bands wear out
Aha, there we go you've got one right. Bully for you!!!

If I seem a bit hard on you I appologize. However the tone of your post (that I quoted) was hardly friendly. You may want to consider that next time. I also can't understand your harshness towards me, given I didn't "trash" the ATs at all. I thought I did a fine job of explaining the advantages and disadvantages of both, and then just stating my preference.

oney01, if you're planning to spend a bit of money for off roading, you may want to consider importing a dual range 5MT from Australia, South Africa or the UK. It will bolt right up to your car if it's already MT. That will do FAR better off road than either of the transmissions we've been discussing so far. If you do buy a Baha turbo though, I don't think the dual range will hold the power, but you never know. I've been planning on importing one myself, but it costs money, which I don't have a lot of.
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Old 09-04-2003, 06:08 PM   #16
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I offroad my truck often, and in the offroad world, AT is golden. I don't know how many people have been saved from being stuck due to having an AT.

I'd look into putting a little lift on the Baja for heavy duty offroading.

If you wanna see some pics of subies offroad in NJ. (blue subie is in here)

http://Isuzu-suvs.com/events

-mike
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Old 09-04-2003, 06:22 PM   #17
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Quote:
Originally posted by AZP Installs
I offroad my truck often, and in the offroad world, AT is golden. I don't know how many people have been saved from being stuck due to having an AT.

You may want to mention that to the people who buy Rovers/Land Cruisers/ Tatras etc. in countries where it matters. I don't remember seeing too many diesel AT Land Cruisers in Africa.
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Old 09-04-2003, 09:22 PM   #18
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brandon:
"On a consistently sandy surface the available traction at all four wheels will be almost exactly the same."

Thats if you are driving at a constant speed. Any type of agressive accelleration will cause one wheel to start spinning and its downhill from that point. Its the same problem during autocross events, look up how many people "light up" the inside tire, its a common discussion on this board.

"It does NOT increase torque in any way"
You are loosing your credability fast. You dont even know what your talking about. Look up what a Stator does

Here is a qoute from that site we all love so much, Howstuffworks.com


Quote:
the torque converter actually gives your car more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times.
http://auto.howstuffworks.com/torque-converter3.htm

"But the auto doesn't have that either so it's a moot point."
Dude. Any non VTD Auto has a LOCKING center differential. This means its not possible to spin only one wheel like the 5 speed does.

"If you recently sold one to a buddy, then you would have ONE "dedicated dirt subaru". "
Okay you win Its not like he is across the state or something. Just today I went with him to kragen to get a clutch return spring. After bending it and installing it we both went for a quick spin in the dirt near our office. Meaning I still drive it. We also went to pick and pull, can you believe they wanted 28 dollars for an 18 year old TWO CHANNEL 20 WATT radio!

"Yes I have in fact, and it's never been a problem for me. It's also never been a problem for all those people racing in the infamous WRC"
The tracks they follow are smooth. If he is taking the car off road its going to be bumpy. If you are in the middle of a long stretch that you can easily get stuck in once you reach say 30 mph in first you will want to shift. Its not always at a convinient time.

"So maybe you might want to brush up on your shifting technique a bit, too much time in the autos might be the problem"
Thats not even fair. I currently own 3 autos and two manuals. Previously though the only automatic vehicles I had was a carburated escort and an econoline 250. My most recent previous car was a Supra 5 speed turbo and I wasnt half bad shifting.



The tone of my message may seem seem rude, but it was because you gave the person incorrect information.
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Old 09-05-2003, 12:26 AM   #19
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Angry Fight nice kids!

Please tell me more about the DR 5MT! It won't solve my problem with the center viscus diff not suppling enough power to the rear will it? My worst problem is getting stuck going up a steep hill and the front hits snow and a wheel spins and I no longer travel forward, it sucks. Thanks again, Keep it coming! Konrad
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Old 09-05-2003, 01:36 AM   #20
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ciper, I can't believe I'm having to stay up and revisit these things.
Quote:
Thats if you are driving at a constant speed. Any type of agressive accelleration will cause one wheel to start spinning and its downhill from that point. Its the same problem during autocross events, look up how many people "light up" the inside tire, its a common discussion on this board.
First of all lets get something straight. Oney01 never said that he was driving agressively. Therefore my more steady state answers apply quite well to his situation thankyouverymuch. However, even under hard acceleration (in even a reasonably straight line) on soft sand, you aren't going to have this dreaded one wheel spinning "problem". You just can't create enough of a traction difference front to back. The only time you get the "lighting up" of the front tire in autocross is under hard, fast cornering and heavy throttle, at which point that front tire is almost lifting off the ground. All of which would hardly be a wise thing to do in soft sand, whether the center diff was locked or not. From more than enough personal experience I can safely say that the MT viscous centered Subaru is quite unlikely to spin only one wheel, unless it has already dig itself in so deep that one wheel has little to not traction. If you decide not to drive smoothly in the sand, well then you takes your chances. Subarus actually have a VERY good reputation for driving in the sand (both MT and AT), in other parts of the world where they actually think of subarus as off road vehicles (think australia).
Quote:
You are loosing your credability fast. You dont even know what your talking about. Look up what a Stator does
I will resist the temptation to verbally lambaste you on this, in an attempt to keep the thread civilized. You'll be happy to know that I followed your link, and read ALL the sections on torque converters, just to make sure I wasn't missing anything. I am happy to say I wasn't. I will post that entire section though instead of just the parts that, when taken out of context, prove your point.
Quote:
By Howstuffworks - In addition to the very important job of allowing your car come to a complete stop without stalling the engine, the torque converter actually gives your car more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission. At higher speeds, the transmission catches up to the engine, eventually moving at almost the same speed. Ideally, though, the transmission would move at exactly the same speed as the engine, because this difference in speed wastes power. This is part of the reason why cars with automatic transmissions get worse gas mileage than cars with manual transmissions.To counter this effect, some cars have a torque converter with a lockup clutch. When the two halves of the torque converter get up to speed, this clutch locks them together, eliminating the slippage and improving efficiency.
I'll admit that I've never read all that much from "howitworks" given that I learnt most of it through school, and practical experience. I will say though that I have found a few places on that site where they use terms slightly incorrectly to get things across to the layman. Thier use of the term "multiply" is one of those cases. If you read the next sentence - after the multiply 2 - 3 times bit- you'll notice that they say "only when the engine is turning much faster than the transmission". That is the key! If the engine and shaft out of the TC were spinning at the same speed, it would be the same torque in and out. Well actually, it would be less torque out than in, because of the heat being created. This is "conservation of energy" at its most elegant. The "multiplication" of torque; is only because the engine is creating more since it is spinning much faster (or more accurately it is further into its torque curve) than it normally would be if it was connected directly to the transmission. As I said previously though, you can do the same thing in a MT by slipping the clutch. The clutch just isn't quite as good at it. In other words, the torque converter doesn't produce more power at a standstill, it just allows more power to be available. Those are two VERY different things, and what I found so misleading about your origional statement. You also made it sound like more torque and higher engine RPM were mutually independant, which they are definitely not, as even the howitworks site clearly states. Really though, this whole thing is avoiding my origional point, because I wasn't referring to the lower ratio being beneficial at a standstill. I was referring to hill climbing, and the available torque at speed. Since the TC does not work as a "multiplier" once it's past its stall speed, the lower gearing provides more torque to the wheels at anything above that stall speed. Now realistically, how much time do you spend driving below the stall speed?
Quote:
Dude. Any non VTD Auto has a LOCKING center differential. This means its not possible to spin only one wheel like the 5 speed does.
I was referring to the fact that niether the AT nor the MT have locking front or rear diffs, so you are taking my statement out of context. Since you brought it up though, the AT does not normally drive around in a locked condition (obviously). The front wheel(s) do have to slip before the center locks up. And with the car in D, it does not do this willingly. I have read more than a few cases on this board where people have complained that thier ATs got stuck without sending as much power to the rear as they needed. And I can personally attest to the MT working MUCH better in the snow when compared to the AT in Drive. Our Legacy and my Uncles are the exact same car (even the colour), except his is automatic. Last year after a snow storm he couldn't even make it up our street until I showed him the 1st, 2nd trick. Our car drove up the road no trouble at all. My parents car is an Outbact Sport, and does the SAME thing. As I clearly stated in my very first post, the ability to lock the center is a benefit of the AT.
Quote:
The tracks they follow are smooth. If he is taking the car off road its going to be bumpy. If you are in the middle of a long stretch that you can easily get stuck in once you reach say 30 mph in first you will want to shift. Its not always at a convinient time.
First of all I think you are under rating the difficulty of SOME of the WRC courses. There are a couple that get really muddy and sandy. They don't show it on TV, but if you read rallylive, you'll see that the conditions are bad enough that the get stuck sometimes. The roads in the African and Australian WRCs are hardly smooth. But you also neglected to acknowledge my Dakkar reference. If you try to call the Dakkar smooth and not "off road" enough you're going to get giggled at by a lot of people other than me...guaranteed.
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Thats not even fair. I currently own 3 autos and two manuals. Previously though the only automatic vehicles I had was a carburated escort and an econoline 250. My most recent previous car was a Supra 5 speed turbo and I wasnt half bad shifting.
No it wasn't fair, and I didn't actually mean it. But when you post such rude replies, you should expect to have a few shots fired. If you can't take it, then don't dish it out. And I would prefer that you didn't try to dish it out, whether you can take it or not.
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The tone of my message may seem seem rude, but it was because you gave the person incorrect information.
I believe I have sufficiently defended my points to prove that they were not incorrect. If there is anything left of my comments which you think are incorrect (and not that you have just a slightly different opinion), please point them out and I will attempt to either correct or explain them. Even if there were things which were incorrect, that was still no excuse to be rude. You can question peoples comments perfectly well without acting like a (fill in the blank). There are people on this board smarter than you or I who occasionaly post something wrong. So give it a rest!
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Old 09-05-2003, 01:55 AM   #21
brandon
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Originally posted by oney01
Please tell me more about the DR 5MT! It won't solve my problem with the center viscus diff not suppling enough power to the rear will it? My worst problem is getting stuck going up a steep hill and the front hits snow and a wheel spins and I no longer travel forward, it sucks. Thanks again, Keep it coming! Konrad
The manual does have the problem that when there is a significant difference between the available traction in the front vs the rear (or vice versa) it cannot lock. So unless you can get a locking center, you're always going to have the trouble with the snow and the VC. The auto will be better in that particular situation, especially if you lock the center by putting it in 1st.
I cannot, unfortunately, answer the question for the newer AWD VC dual range. I have tried to get some info about whether or not it has a lockable center, but have got conflicting answers. I would presume though, that if you're going to make an off road dual range tranny, that you would have a locking center. Especially since the locking center VC existed in the mid 80s in the XT6, and in the RX Turbo. In fact the RX turbo had a dual range AWD VC 5MT for sure. With a rear limited slip and everything. I would love to have one of those cars!
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Old 09-05-2003, 07:33 AM   #22
ducktapeguy
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In general, an AT and MT each have advantages off road, but if you are only comparing the Subaru AT to the Subaru MT, then for off road use the AT has a greater advantage. Why? Because the MT is missing one very important thing in a Subaru, and that's a low range transfer case. So the U.S Subaru's are missing the main off-road advantage of an MT. If you had a dual range tranny on the other hand....then things start to get more fun.

The main advantage of the Auto is the torque converter. The torque converter does MULTIPLY the torque during the low speeds, and it has nothing to do with the engine being further up in the torque range. Do a search on torque multiplication and there hundreds of sites that can explain it better than I can without breaking out my textbooks. But essentially it is sort of like gearing it lower (not really, but you get the picture) You gain torque, but you have to sacrifice engine speed. You can NOT do the same thing by slipping the clutch. You just end up with a lot of wasted energy and a burnt clutch.

Other reasons for an AT:

Smoother shifting - Depending on the type of terrain and other factors, having a smooth shift can prevent losing traction in the first place. Especially when going up a slippery hill, trying to start smoothly with a MT will probably cause you to lose traction. Even though theoretically you can shift a MT as smooth as an auto under certain circumstances, in real life things change.

Longevity - As long as the tranny isn't abused, I think the auto would probably last longer. No clutches to burn. If you have to constantly slip the clutch, you'll end up having to replace them eventually. Plus, the torque converter acts as a buffer for the rest of the drivetrain. If you're travelling off road, then obviously the traction will vary depending on the surface. If one wheel loses traction, then all of a sudden catches on something, that's a lot of stress on the drivetrain. Since the torque converter isn't mechanically connected, all that shock is absorbed by the fluid instead of gears. So I think a AT would handle the abuse better. But if you do have to fix it, it's gonna cost you some $$$$

Easier to drive - Pretty simple to understand. Just step on the gas until you get up to speed. No pedals, handbrakes, slipping the clutch, etc to worry about. Not many of us have the driving skills of a WRC or Dakar driver, so even though they use a Manual, doesn't mean everyone else should.


Advantages of a MT

Simple and Cheap - Much cheaper to repair, cheaper to buy, and easier to fix. Which is probably why you see mostly MT in other countries. I doubt if they have the ability to diagnose and repair something as complex as an Auto transmission in some remote village, or would even have the parts. Not only that, most of the Rovers/Land Cruisers/ Tatras have a low range, which is completely different than a Subaru MT

Engine braking - Useful to control your speed, but since subaru's don't have the low range, the engine braking as useful as it could be. Depends on the situation. May or may not be helpful

More efficient - Yes, it's more efficient because there is a direct connection between engine and drivetrain, but who cares? So what if you get 1mpg less.

Constant velocity. Since there is a direct connection between the engine and drivetrain, when your engine is turning at a certain rpm, your wheels will be turning at a certain rpm, no matter if you're going uphill, downhill, over a rock. So you have more control over your speed.

Able to jumpstart - That's a big advantage for some people who leave their lights sometimes. And if you're off-roading somewhere remote, then that might be useful.

One more thing, the MT is a 50:50 split, when all 4 wheels have traction. Once one wheel starts to slip, you don't have that nice even torque distribution anymore.

These may or may not apply to your situation, so take it with a grain of salt. This might be completely wrong for your situation. And this doesn't even take into account the different LSDs and all that. But all this stuff about transmissions and locking center diffs or viscous diffs is pretty minor compared to other things. No matter which drivetrain you choose, in the end, they're going to perform about the same, meaning no one transmission is going to be able to take you places where the other one won't. It sounds like you'd be much better off 1) airing down the tires for more traction 2) getting new tires or 3) getting a more capable SUV, than worrying about which transmission would be better.
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Old 09-05-2003, 08:26 AM   #23
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Hmm, I am willing to concede that I may not know as much about TCs as I thought, at least for the time being. I'm going to have to do some more research into it. However, it seems obvious that this torque multiplication thing only happens until the stall speed, at which point the gearing is the gearing. So once again, if it's past the stall, the MT has a lower ratio.
I would like to point out that I made no reference in my origional post about TCs. So I still don't see where I was so wrong in that post to warrent cipers response. I don't have the time to respond to anything else at the moment, but I'll be back later today hopefully. Weekends I'm rarely online.
Ciper, please look to ducktapeguys post to see how you can discuss without insulting.
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Old 09-05-2003, 09:24 AM   #24
bluesubie
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Quote:
Originally posted by AZP Installs

If you wanna see some pics of subies offroad in NJ. (blue subie is in here)
http://Isuzu-suvs.com/events

-mike
Oh yeah, forgot about those pics.
Here's me in the manual OBS. I miss that slow car sometimes.
No way would I drive the Rex in water deep enough to come over the hood.
http://isuzu-suvs.com/events/pb02-17...cs/index_6.htm

The new Baja will have an inch more clearance than the current model, so it's already lifted.

-Dennis
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Old 09-05-2003, 05:38 PM   #25
ciper
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You are right, I was getting mean in my posts. Lets drop it down a notch and keep the discussion going. I enjoy going back and forth with you.



"You just can't create enough of a traction difference front to back"
You can. Imagine an open differential, even on the street its easy to overcome the amount of available traction. You may not believe it but the center differential in the 5 speed is very soft. Combine that with the fact that one wheel spinning on either front or rear differential has a 2:1 advantage over the other differential. In other words if you had equal load on each rear wheel and zero speed difference between the front and rear outputs of the center differential one front wheel could spin twice as fast.

The Torque converter multiplies torque at any time below about 4500 rpm, the stall speed is variable, if you are stopped and your stall is 3000 rpm then you start moving at 10 mph and it takes an additional 1000rpm to move at this speed the new stall speed is 4000 rpm (does that make sense?).
You get a double benefit. Not only are you higher in the RPM range so the engine is producing more power but the torque converter is also increasing the amount of power.


Something that everyone has forgotten is the ability to gradually apply power. Im going to search for a posting I made but basically I was able to get a AWD (always 4wd) expedition with a 5.4 liter and LSD stuck real bad. If it wasnt for the automatic transmission in my legacy I wouldnt have been able to get it out.

"I was referring to the fact that niether the AT nor the MT have locking front or rear diffs, so you are taking my statement out of context."
Let me reexplain. 3 open diffs is the worst case, 3 locking are the best. One locking and two open would be better that one loose lsd and two open. If the auto had an LSD then it would be one locking, one open and one LSD compared to two lsd and one open.

The WRC drivers are tightly fastened to the vehicle. They also have suspension set not to bounce all over. In a normal off road vehicle you end up all over the place.

Id be willing to bet that most dedicated 4wd dirt vehicle with a manual transmsision I see has a bad second gear syncro.....


ducktapeguy:
"More efficient "
I dont agree entirely. In theory an auto should be considerably more efficent than a manual. One problem with a manual is that every single gear is alwas spinning. Not so in an auto. A planetery gear set has less loss because of this. The locking TC helps to bring the highway mileage up while the torque multiplication helps to reduce the need to open the throttle more when the engine is below its optimum rpm range. The controls of the transmission also help to keep the car in the correct gear, the majority of drivers keep their engine too low in the rpm range.

Just look at the MPG of the Scion XA with auto and with manual, you will be surprised

"Constant velocity"
I dont agree that you have better control over speed. With a manual very small changes in throttle position make a large change in speed. Under low load/traction its easy to brake traction. With an automatic you can slowly reach the peak, including applying the brakes at the same time to even further control the vehicle. Every try to parralel park on a steep hill in a very small parking space? Talk about freaking hard with a manual. An automatic can do it with ease.
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