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#16
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Vexed question
Johnny
Lwin asked who drove in D, who drove in 3. Might have been better served by a poll, but most took the trouble to answer and say why they use whichever method. You are "new" to the Forum, long after, I think, the technical discussion Trevor mentions. Two philosophically opposing arguments apply here: (1) The box is auto. It is optimised to make changes at the best possible times for progress/longevity/consumption/smoothness/torque/your mother/etc (2) I want it to do what I require when I want/need it. I fall into bracket (2), even though I bought this, my fiirst automatic, to take the stress out of urban gridlock driving. Most people in bracket (2) will drive floor shifts, as I have done, but the millions of declutching actions in city traffic is playing hell with my left leg and hip. So I want an auto that will push on the car when I require it, not too much to ask. Interesting some of the respondents use D to allow the T/C to slip and heat up the oil in cold climates, would not be needed here. So you see which method you use will be dictated by what response you want, as you note yourself, and what the ambient temp is in your local climate. Not really a black and white argument, but depending on where you are, what you expect your car to do. Both methods are valid, but I stand with Trevor in saying top [4] is a really high gear, and the tranny should not select it till 60+ comes up on the clock. The shift map is optimised for different reasons than those that caused me to buy a 230 hp car. Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#17
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Re: Re: Re: Who drive in 'D' and who drive in '3'?
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I note that you have not answered my simple questions so that we can have an informed debate. You should not have taken my words harshly as my concern is simply that others could be given a bum steer and I wish to gaurd against this. It is apparent that transmission problems in respect of the SVX are endemic in your part of the world and this problem is best avoided by taking all possible precautions. I will be polite as I value the good will set by many here and will answer your questions as requested -- " with a miniscule amount of clarity and accuracy ". But also please take note of the preceding post by Joe which contains further facts and a great deal of common sense. The TCU does not have human intelligence and can be assisted with some of this in the form of driver input as others have pointed out here to their credit. When left to its own devices it will hunt up and down from D to 3, when the car is driven at slow speeds, causing wear and tear which CAN be avoided. This fact is not limited to the SVX. Manufacturers manuals or sales blurb will naturally not disclose any of this as the information would devalue the hype attached to selling the feature of automatic transmission. If you require a " Guru " on the SVX transmission, please refer yourself to Harvey and his posts as he has done a great deal of research and is fully qualified. Meantime please answer my original questions, standing upright , so that we are aware of the reasons for your choice in order that an interesting debate may continue.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#18
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For the RPM to stay the same, the torque converter has to be locked. It will only lock above 160F on my SVX, which it now almost never does in winter because of the tranny coolers. Even when I had normal cooling and the tranny could reach lockup temps, once I've gotten up to 45MPH, I am either still in 3rd and on the gas to accelerate to 65MPH, or I am ready to let off the gas and cruise at the city speed limit. In the city, there is little need for continuous acceleration above 45MPH that would cause additional heat due to a locked TC. Most of the heat and wear is generated during stop and go rather than low to moderate acceleration with the TC locked.
KuoH |
#19
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Re: Re: Re: Re: Who drive in 'D' and who drive in '3'?
You should also take note that the common sense Joe refers to does not automatically dictate that all SVX drivers use 3 or D. Rather, the choice depends on your preferred response from the car. Driving in D does not automatically cause the tranny to "hunt", as you described. Your driving habits have a lot to do with what the tranny does.
In the end, the conclusion is the same as before. There is no clearly demonstrated fact that tranny wear will be reduced for everyone driving in 3 versus D. KuoH Quote:
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#20
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Why do I do, what I do?
I drive the car in 3rd unless I am cruising at over 60MPH/2000rpm.
Why? I want the auto to last as long as possible. This car was designed to be a high speed tourer, to run at sustained speeds of over 100MPH. To this end it runs an overall top gear ratio of 2.44:1, or 30MPH per 1000rpm. Driving in 4th gear around town, has the engine turning less than 2000rpm. The engine has not even started to climb the torque curve, it's output is so low, that the torque converter has to work over time, to increase the torque to accelerate the car. If it had a 4speed manual box, no one would drive it at 2000 rpm in 4th gear, so why do it just because it has an auto? Some say, "the box will use the right gear for the situation" and so it will, as long as you are using the car for the designed use, as a high speed tourer. If you use it as a shopping trolley or a 10 minute commuter then you will have to change your ways to compensate for misuse. Driving in 3rd drops the overall gearing to 3.545:1, or 20MPH/1000rpm, so 2000rpm comes up at 40MPH, by the time you are doing 60 the engine is at 3000rpm and well into the torque peak, provided by the Inertia Inlet system. This provides ample torque to accelerate the car without too much torque converter action. It also keeps the alternator charge high. The last and most important point is that in 3rd gear, the gears in the box are all locked together, as a solid unit, no gears are running against any other gear, gear box load and wear is totally removed. The way I see it is, two problems arise in this gearbox, heat and low line pressure. Driving in 3rd helps to avoid both problems, the torque converter does not have to work as hard to provide the necessary torque and the oil pump runs faster to maintain enough pressure to keep bands and clutches from slipping. This last point is why most autos self destroy. Trying to tramsmit the high torque loads, with the low line pressure caused by low speed driving in 4th gear. The line pressure is controlled by the throttle sensor, the more it is open the higher the pressure, the safer the gear box. If you don't want to use the car for what it was designed for, compromise use 3rd, or get different car. Apart from the early facings problem, there is nothing wrong with this auto box, it is just abused in it's use. I tried to keep this as short and to the point as possible didn't work did it? Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#21
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Those are some good points, but I honestly don't believe that the car was "designed" to run at sustained speeds over 100MPH without consideration for normal driving 90% of the time. For one thing, the wheel bearings seem deterioate considerably faster after prolonged high speed driving from my experience. I suppose it's just my driving habits but around the city, which is mostly flat here in KC, there is rarely a need for the car to provide more torque than necessary to keep the car at 40MPH.
KuoH |
#22
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Quote:
40 mph in D is 1300 rpm, the engine is at a fast idle and you expect it to perform. Every time you ease the pedal down at that rpm, the high clutch and the front Planetary gear set transmit very high loads, with a much lower line pressure. Apart from the bearings the rest was designed for high speed touring, oh and the fuel gauge. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#23
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I may as well insert my less than technical nose into this one. I asked this question somewhere in a galaxy long, long ago, but got no reply. It's the, "What's happenin' down there after it shifts from 3rd to 4th, but hasn't locked up" question. Is this "grey area" that says "Let's make lotsa' heat & make the fluid turn brown"?
I put mine in Drive & leave it there unless I want to go backward, at which time I use "R", meaning Ram. My '92 lives in a garage, so in the morning it's never below freezing. I don't really idle to warm it up, but drive about 1.5 miles through residential streets before it hits the 6 laner for about 10 miles at the usual 60-75 mph. The car has a small B & M cooler. It shifts through the gears & into 4th after only 2 minutes of driving. After hitting 4th, it seems to lock up rather easily at speeds over 50mph. Oh...what was the question? Uh... If I'm cruising at around 60 mph (locked up) on level terrain & want to "briskly" accelerate, if I semi-floor it, should it simply un-lock, or drop to third"? I'd like it to hit third, but the car seems pokey. If I really mash it at 60, it drops to second which is afterburner time. I could manually drop it to third, but that takes planning, & I'm into laziness. Now I've really lost the point. Oh... back to "unlocked" 4th gear. Is this the twilight zone that's the biggest contributor to smoked trannies? Ron (really beatin' around the bush).
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Good s**t happened. 69 was worth the wait. '92 stock semi-pristine ebony - 160K '96 Grand Caravan - 240K '01 Miata SE - 79K '07 Chrysler Pacifica - 60k - future money pit. |
#24
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[QUOTE]Originally posted by oab_au
40 mph in D is 1300 rpm, the engine is at a fast idle and you expect it to perform. Every time you ease the pedal down at that rpm, the high clutch and the front Planetary gear set transmit very high loads, with a much lower line pressure. Harvey. [/QUOTE And it will hunt down when you ask for some added acceleration and up again when you back off. Give it a break by staying in 3 ! Thanks for your informed input Harvey. Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#25
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Its great to read all this info.
before I answer: My trany is not 100%, so to save it I use it differently. I drive in "3" in the city, all the time, the rpm's can go above 3000 once in a while, and I know where my torque is in my car with the fuel I'm using so it works great for me. Once I get on the highway, I pop it into D. Now for the gratuatus babble: I have found that in the city, my trany seems to find 4th gear very quickly, and spend a lot of time slipping, and almost never locks up. when I drive in "3" the trany feels solid, and the engine more responsive( I like that), and I'm told that the TC will also lock in 3rd, but I can't really tell, it feels like its always locked for me when I'm in 3rd. Another note to all, the shifter will go from "P" all the way to "3" when slid, it does not stop at "D" but stops at "3" Why is that? a) Because its broken, b) Because it was designed that way. Hmmm
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Chris G 92 Pearlie, sold @ ~209k miles. Now owned by Tim. Current Ride, 1985 Honda Aero 80, stock 3024 klms |
#26
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3
I drive in 3 these days (a few months now) and the car feels so much more responsive and fun to drive.
I knock it into D once I intend to sit above a 100 for more than a few minutes. Just lately I've also been slipping it in to 2 manually when getting ready to stop at lights. I slip it bak into 3 before takeoff. When I'm in a traffic jam, trying to avoid coming to a total halt, I leave it in 2 and also engage the manual button so it stays in 2. I find the constant transitions between 1 & 2 when moving at a slow pace in traffic annoying. I hope I'm treating my baby ok? Cheers, Pete. p.s. moving between D and 3 definitely does not require the lever button to be pressed.. It's all in the handbook. |
#27
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Quote:
They are all this way. Except maybe, it is meant to snick into D first, if it is slipping back to 3 very easily, maybe the cable mechanism needs tightening up. It stops at 3 to make it difficult to downshift to 2 at high speed, and break up the internals. I use this feature a lot when about to overtake. It is designed to allow you to pull back the lever to 3 and stop there, knowing you will not select 2 and do damage. If you use this method, remember not to squeeze the button, just pull the shifter. Interesting that Ron has the same problem, only he is too lazy to pull the shifter. I checked out mine this morning on the school run. Driving in D on a light throttle, it upshifts to D4 at about 45mph [tops out Lwin?] My clock is in kms, but roughly 45 all right. This is too low a speed as our antipodean duo are suggesting. For the high final drive I believe it should not select 4 till the car is doing more than 60mph. Mine are more for reasons of driveability than the technical reasons Harvey has explained so well. Of course the technical operational features underpin the way the car gets the power to the road. Joe
__________________
Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#28
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Re: 3
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The very latest 5 speed smart aleck auto for the Ford Mondeo does exactly what you say for city driving, i.e. locks out 1 and starts in 2 all the time to minimise shifts. Two things strike me about this; it will make a lot of use of the torque convertor and create heat, which would not be good in a hot climate, don't know how hot it is in Queensland. Second, in saving many shifts, it must also save on clutch pack wear, so this would be a good thing for longevity. I suppose the bottom line would be this is OK, maybe even the correct thing to do, provided your ATF is sufficiently cooled. Joe
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Black Betty [Bam a Lam!] '93 UK spec, still languishing Betty Jersey Girl Silver '92 UK [Channel Isles] 40K Jersey Girl @ Mersea Candy Purple Honda Blackbird Plum Dangerous White X2 RVR Mitsubishi 1800GDI. Vantastic 40,000 miles Jersey Girl |
#29
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QLD
I think Queensland is pretty well what you'd call a 'tropical' climate. Humidity can be quite high, and summer temperatures are around 30 C average I guess. How does that sound?
The coolest it gets is probably about 10-15C during the day in winter. CHeers, Pete. |
#30
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Re: Re: Re: Re: Who drive in 'D' and who drive in '3'?
Quote:
Your next statement seemed a little arrogant and even a little condescending to me, especially when what you said had no clarity or accuracy as to why you use third other than a vague reference to old posts on the subject. ("It would appear that some do not have the technical knowledge to understand what is sound logic even when this has been expressed in simple terms. Any rejections should be expressed with equal clarity and accuracy.") That is what originally got my dander up and I apologise if that was not your intent but it did seem a little snotty to me at the time. As far as answering your original questions (which, by the way, you never asked any questions), standing upright , so that you are aware of the reasons for my choice in order that an interesting debate may continue, I believe I already had given the reason I use "D" in a previous post in this very thread. "I leave mine in "D" since I am not worried about responsiveness. If my speed and throttle position do not warrant being in a position to go quickly then why not let it go into overdrive to drop the RPM's and maybe save a little fuel." I would like to thank Joe and Harvey for their excellent, clear and accurate reasons for choosing third over "D". I admit to being ignorant to the working of an automatic transmission as I have ever had one open nor devoted much time to the study of them (I've only worked on manuals in the past) and their explainations have helped me quite a bit and it does make sound sense. My only remaining question is, considering the extremely cold temps we are experiencing in my locale, whether to use "D" to help my tranny warm up properly on a cold morning or to just stick with third. Considering I only live less than a mile and a half from my job I doubt it would make that much difference but when running errands or just enjoying my SVX I believe I will switch to saving "D" for highways runs from now on. Thanks for the informed discussion guys!
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Pearl '92 LS-L 179K (Historic 1st 5-speed SVX) Mods: 5-speed, 4.11's, Group-N motor mounts, dual Magnaflows, cone air filter, Kenwood MP-228 CD/Receiver, white-faced gauges, '97 grill, custom window tinting. Ebony Mica '92 LS 80K Oct 2002 - Dec 2004: Victim of theft. She served me well. You can tell the lack of craftsmanship by the wrinkles in the duct tape. |
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