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Thread ID: 70604	2006-07-09 05:47:00	Automatic transmission	Lizard (2409)	PC World Chat

Post ID	Timestamp	Content	User
469613	2006-07-09 05:47:00	Having never owned an auto before, I'm not 100% sure of this, hence the asking: Should an automatic in Drive, facing up a moderate hill, ever move backwards (i.e. foot off both brake or accelerator)? It's not all the time, but I've noticed that when I pull into a friend's driveway, which is on a moderate gradient, and take my foot of the brake, the car would roll backwards slowly. However, when I stop at the lights, and leave it in Drive, it's fine (admittedly, not too many hills in Palmerston North...) I wonder if it's a problem with the ATF, or possibly the auto clutch - but not knowing too much about this, I'm at a loss to explain it - or is it normal for an auto? Cheers Lizard	Lizard (2409)
469614	2006-07-09 05:58:00	With the foot off the brake and accellerator, it may indeed move backwards. Think of it as a manual gearbox being in a forward gear, but you have your foot on the clutch and no brake on - could it roll backwards? Yes of course. That is the situation here. The "torque converter" (acts like an auto clutch) is applying almost no connection between the motor and the gearbox at idle, on the flat it may "creep" forwards, but on a hill it could roll backwards. What were you anticipating could happen?	godfather (25)
469615	2006-07-09 06:04:00	With the foot off the brake and accellerator, it may indeed move backwards. Think of it as a manual gearbox being in a forward gear, but you have your foot on the clutch and no brake on - could it roll backwards? Yes of course. That is the situation here. The "torque converter" (acts like an auto clutch) is applying almost no connection between the motor and the gearbox at idle, on the flat it may "creep" forwards, but on a hill it could roll backwards. What were you anticipating could happen? Thanks for the info Godfather I guess I always envisaged the auto "balancing" the gearbox the way you do in a manual, but with a slight positive load creating the "creep forward" - on a hill I imagined it would adjust the balance accordingly. It's good to know this is normal - in every other repsect, the Altezza has been an incredibly good buy. Cheers Lizard	Lizard (2409)
469616	2006-07-09 07:29:00	Think of the creep forward as a light slipping of the clutch, it would still roll backwards on a hill. There is no "balancing" involved, that is what Park is for, it locks up the transmission (never apply Park while you are moving, unless you really want a new gearbox...). On a particularly steep place I visit and have to turn round reversing downhill, I use Drive to control the speed at which it rolls backwards, to stop it going too fast. Gives nice control, accellerate a bit to slow the reverse speed. An Altezza in auto? That takes the fun away. They are best in 6 speed manual form.	godfather (25)
469617	2006-07-09 08:01:00	DO NOT USE the transmission to "hold" your position on a hill! Your grandfather might have gotten away with it, but you probably will not . :annoyed: Use the brakes . . . . . that is what their job is! You'd never use a manual clutch to hold on a hill . . . would you? :groan: I love to rebuild them when people do that . :p The only real heat generator in an automatic transmission is the torque convertor, and making it hold you and your car on a hill is not part of it's design . People have the strange notion that the fluid allows the clutches to slip in the clutch packs; that is not the case! They hit and hold fiercely and if they slide at all, then they get replaced very soon . Clutches are only made of paper-like material on a steel backing . . . some a little heavier than others, but they do not accept abuse for more than a few times . Early autos used cork for the friction material and it worked very well . . . but it got torn off as horsepower increased . Shortening the life of the fluid is the least of your problems if you do slip the convertor on a hill . Bands though, are typically used as brakes in an automatic transmission, ie: when you downshift to help keep the vehicle from speeding up on a downhill . . . they then apply if you drop the lever a click or so . They lock up the freewheeling drums and hold them stationary . The spragues don't hold except on acceleration, locking at the shift to that clutch pack . You'd love to work on an E4ODE or a THM7004R! The newer 4L80E's are neat too . . . all computer controlled . Manually upshifting is useless, as most start in the lowest range anyway . . again an exception . . . Ford C3, C4, C6 and the very ugly FMX or any with a Green Dot will start in 2nd if you put it in that range . There are exceptions in the band count and purpose . . . . . . . like the MOPAR UltraDrive with underdrive and overdrive bands that never allow direct drive . . . it's just not in the ratios, but you'd think so! There may be others . . . I have not experienced all the automatic transmissions out there . Subarus had that little hill-holder on the clutch pedal that held the brake until you let out the clutch . . . . . . but I don't think there are any others that had or have that little gem since .	SurferJoe46 (51)
469618	2006-07-09 08:09:00	You'd never use a manual clutch to hold on a hill . . . would you? :groan: . Yes . For a low speed manouvre that only lasts a few seconds, I doubt it would add to the repair bill that I would ever have to face (the next owner may perhaps) . But I also thought this would "flush out" a few comments . . . . and am not disappointed . By the way, you really have to see this turning spot to appreciate why I would consider doing it . . . .	godfather (25)
469619	2006-07-09 08:17:00	Yes . For a low speed manouvre that only lasts a few seconds, I doubt it would add to the repair bill that I would ever have to face (the next owner may perhaps) . But I also thought this would "flush out" a few comments . . . . and am not disappointed . By the way, you really have to see this turning spot to appreciate why I would consider doing it . . . . Well . . . necessity is the mother of invention . . . even if it's cross-purposes to design . Was I baited? :confused:	SurferJoe46 (51)
469620	2006-07-09 09:50:00	Heh, in Dunedin you will do more than roll back gently. Kind of a good idea to use the brake pedal at intersections, so people can see your brake lights and not run into the back of you. ;) I use the hand brake for the bigger hills...	gibler (49)
469621	2006-07-09 09:56:00	You'd never use a manual clutch to hold on a hill . . . would you? :groan: Actually I did that sort of thing all the time in our Cambridge . Went through one or two thrust bearings but the clutch itself was fine . And (not relevantbut fun) taking off in 2nd and changing to 4th . For ages my brother thought Cambridges only had 2 gears . :D But autos suck . They're for girls . Oh hang on, I mean children .	pctek (84)
469622	2006-07-09 10:00:00	Heh, in Dunedin you will do more than roll back gently. Kind of a good idea to use the brake pedal at intersections, so people can see your brake lights and not run into the back of you. ;) I use the hand brake for the bigger hills... Do you use handbrake on the steep slope? Before continue accelerating pull the handbrake and release the brake before accelerating. This can save you from rolling back and hit the behind car. 1st thing accelerate a little make sure the car in hold position then release the handbrake. ;) Don't forget this. lol.	PedalSlammer (8511)
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