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Thread ID: 95585	2008-12-11 01:13:00	Manual or Automatic	Roscoe (6288)	PC World Chat

Post ID	Timestamp	Content	User
727660	2008-12-12 01:50:00	One of our newer cars which has ECM, etc etc.. It is automatic and tiptronic. It doesn't even have the feature of OD switch. The airconditioner for example don't have AC switch .. it just goes by itself I guess. I've read that tiptronic never used yet, if you forget to change gears after a while it will do it for you. They say you could come to a stand still at gear 4 or 5 in tip mode or over accelrate from 1. Manual get a real manual car if you want that kinda thing...	Nomad (952)
727661	2008-12-12 01:52:00	The OD is only a forth gear on most all transmissions made after . . . . uh . . . . . 1988 . . . . . or so . Does it make any difference overall if the auto has a 4th gear that isn't an OD ie 1:1?	PaulD (232)
727662	2008-12-12 02:01:00	Joe, is it ok for OD to be on all the time?	Nomad (952)
727663	2008-12-12 02:10:00	I concede PC that you are a great IT-person, but that isn't true what you said about overdrive . Like IT is your game, transmission are MY game . It was simple . OD on, put car in drive and take off . Slug . This was how it was when I bought, took me a week to discover it had this silly button on the side . OD off, put in drive, take off . Noticeable difference in performance . I drew my own conclusions .	pctek (84)
727664	2008-12-12 02:21:00	Joe, is it ok for OD to be on all the time? OD should be on all the time as it won't go into that mode until the ECM confirms it . It is a great fuel-saving device, but like I said, it keeps the trans temps down . The reason? The torque converter is really the only part of the transmission that makes heat, and if it's locked (and/or allowed to go ) into TCC, then things cool off . This is one of the greatest areas of misunderstanding in transmissions worldwide .	SurferJoe46 (51)
727665	2008-12-12 02:47:00	Joe: Just the type of thing us non-mechanical people need to know . Thanks . A big help . Have to agree: each to his own and I have noticed that anyone with any motoring related posts tend to receive and excellent reply from you . We need someone to sort out the uninitiated and you do that very well . :thanks Even the best soothsayer in the business would have difficulty predicting where an F1 thread would end up . At least we stayed, sort of, on the right track this time . You did not tell us your preference and why? We'd all be interested to know your opinion, Joe . :) § Well . . . I have a THM700R4 in my 1986 K5 Blazer (95,000miles/152,887km) which is GM's best 4-speed w/OD transmission of it's day . I have modified it to be a 7-speed (it's technical, but it was indeed fun to convert!) and I tow 10,000 lbs/4500kg+ with it at freeway speeds all day long and at very good fuel mileage . I twist it with a stroked 5 . 7L/350CI engine out to 383ci with a 400 crank . It gets about 28 MPG unloaded, and 16-19 MPG towing, which is the reason I built it in the first place . Gas mileage and the metric equiv escape me for this factor at the moment . § My wife's 2002 AstroVan with a 4 . 3L V6 (120,000+miles/193,121+km) has about the same 4-speed w/OD transmission, called the 4L60-E or basically another version of the THM700R4 although a lot later model and as of yet, I have not had to touch it . It works well and is fully electronically controlled . Funny thing about this vehicle - it gets 18 . 8 MPG religiously, until you start to open it up to over 100 MPH/160 KPH, and then it gets even better! Must be the aerodynamics taking over . § My 1989 Isuzu Amigo, 2 . 6L, with the 5-speed manual gets a work-out by me as I drive it like a madman . With 300,000+miles/482,803+km on it, it has the original transmission and still works fine . I have installed one (1) clutch in all that time . This vehicle gets better with age (and the new engine) and now gets over 26 MPG, although I keep the speed down to 90 MPH/145 KPH since it gets "unstable" at higher speeds . I love to drive them all, although the AstroVan isn't my favorite . . . . but don't tell the wife that! Automatics can be driven well; almost as well as a stick, and even though there's always the manual-mode that I employ, it's true that the automatic transmission is designed to factor OUT the nut behind the wheel . Interesting enough, I use the K5 Blazer for my serious off-road activity with the automatic transmission . It seems to have a broader range for torque as I don't have to think about power/gears and let the trans take care of the small stuff whilst I concentrate on the path of least- or more- depending on my mood - resistance .	SurferJoe46 (51)
727666	2008-12-12 02:56:00	It was simple . OD on, put car in drive and take off . Slug . This was how it was when I bought, took me a week to discover it had this silly button on the side . OD off, put in drive, take off . Noticeable difference in performance . I drew my own conclusions . Was this a Toyota? They have a unique idea on what a transmission should do, and it is a little strange to some people too . I see WHY they did it, but don't have any idea what it accomplished in the long run . They (some Toyotas) don't only have an OD-ON, OD-OFF mode, but they also incorporate it with the POWER-ECONOMY button to really confuse things . In the ECONOMY-Mode, the trans is indeed a dog . It starts up in second-gear and then makes a sloppy shift to 3rd and almost un-discernibly instantly into OD, if THAT button is not turned OFF . So . . you might be right about you car . . . but there are a few other vehicles that use/used this "ECONO-Mode" for a while . One was the Ford "Green-Dot" C3, or C4 "Cruis-O-Matic" that when in the GREEN-Dot mode had all three forward gears, but when not in that position started in 2nd and then quickly shifted into 3rd . They had no TCC in those days, so it was a bad idea as the converter would get very hot after a few boulevard starts in that position and the trans was quickly rendered a smoking cinder .	SurferJoe46 (51)
727667	2008-12-12 02:58:00	Funny - I was told that OD should never be used around town - only on the motorway. Something to do with placing excessive strain on the gearbox/convertor or something :(	Zippity (58)
727668	2008-12-12 03:06:00	Does it make any difference overall if the auto has a 4th gear that isn't an OD ie 1:1? I think I see what you're asking here, Paul . Again, it's a little confusing about OD and TCC and all, but there are indeed, some vehicles with just 1:1 for top/fourth gear, and they aren't really a true OD at all . They may however, have a real TCC in them anyway . If it's an AT, then running in 4th is fine . . but like all other things, there are exceptions . If you feel the transmission is a lot "busy" and shuttling between 3rd and 4th or 3rd and OD, and it bothers you . . . then YES, take it out of OD to settle it down . It's only really bothering you, and the trans is well equipped to handle this if it doesn't get to go on for miles or many kliks . What's happening is that the ECM or even the fluid controls are trying to find the best gear ratio for the conditions at hand . It might not be able to look over your shoulder and see that the road's gonna level out soon and keeps up with the shuttle-shifting until you get nervous and shift out of OD . That's OK . . we are humans after all, and we are (sorta) masters of our own fates . . . at least in the pocketbook or purse . If your trans does NOT have a true OD to it, and we are still talking automatic units here, then use the 4th gear position as much as you can . It's designed to run there as much as it can .	SurferJoe46 (51)
727669	2008-12-12 03:06:00	Funny - I was told that OD should never be used around town - only on the motorway. Something to do with placing excessive strain on the gearbox/convertor or something :( I was told I should only down shift away from D when I am on the motorway from my instructor ... :p	Nomad (952)
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