Century 4 Speed?
Question:
Lockup converters were used as far back as the 50’s on Studebaker automatics, and Packard Ultramatics. The overdrive shift can occur before lockup depending on throttle position, and lockup is delayed when cold till the engine warms up. Roy – Hide quoted text — Show quoted text – > Yeah, but the diesel Buicks shift differently, right? ; ) > The lockup torque converter was a clever thing for eliminating the loss you > described. I’m wondering when the first one came out, if anyone knows… > Further, with the 3 speed shifting 1,2,3, and lockup, I always though the > OD trans did the same and shifted overdrive last. I think my old 84 olds > delta 88 did that. My 96 Buick however, seems to shift overdrive ahead of > lockup? Or at least when it’s cold and lockup is delayed. Otherwise, it > shift so smoothly, I can barely tell when it shifts anything… > What you have is a THM 125C, a 3 speed lockup auto transaxle. You made a > positive ID on that by saying you have D 2 1, instead of OD D 2 1. > Notice the C in the 125C, that stands for clutch. For better gas > mileage, all the non-od trannies had a lockup clutch converters > installed (BTW, most all OD trannies have lockup converters). So that > last gear you feel is the clutch engaging so it is a 1:1 connection > instead of the normal hydraulic slip (usually 5-10% slip, depending on > the load) of a non lockup converter. OD trannies can also have the > clutch engage in 3rd if it’s put into D instead of OD. > — > All Diesel Webring Manager, All Diesel Webring ezboard Administrator > http://pub25.ezboard.com/balldieselwebringezboard > Rev it up, Smokem’ out with 100% pure Dieselfumes! > Project vehicle 81 Regal Limited, LF9 5.7L http://www.Dieselfume.Com > Cheesehead by birth, Packer fan by Choice! Go Pack!
Response:
Hi!! My 93 Century with 3.3 Liter V6 and (what I thoght) was 3 speed auto (D 2 1) OK, when I was going up a hill today around 35, my car went into (what I thought was) third gear and the engine was running slow (just not enough power in this gear to keep up at 35 MPH). I gave it gas and it went up one gear, and then a second or two later, it shifted up again (it never went back to "3rd"). I gave it more gas and it went into first. When I got to the top and let up on the gas, i felt it shift down (is that the correct way to say?) from second to third to another gear…..but I only have drive. This is drivin me nuts. My friend counted it also and says I have a fourth gear……am I missing something…it only has D, 2, 1 on the shifter. Again, I feel stupid for asking this. Thanks!! Dave
Response:
What you have is a THM 125C, a 3 speed lockup auto transaxle. You made a positive ID on that by saying you have D 2 1, instead of OD D 2 1. Notice the C in the 125C, that stands for clutch. For better gas mileage, all the non-od trannies had a lockup clutch converters installed (BTW, most all OD trannies have lockup converters). So that last gear you feel is the clutch engaging so it is a 1:1 connection instead of the normal hydraulic slip (usually 5-10% slip, depending on the load) of a non lockup converter. OD trannies can also have the clutch engage in 3rd if it’s put into D instead of OD. — All Diesel Webring Manager, All Diesel Webring ezboard Administrator http://pub25.ezboard.com/balldieselwebringezboard Rev it up, Smokem’ out with 100% pure Dieselfumes! Project vehicle 81 Regal Limited, LF9 5.7L http://www.Dieselfume.Com Cheesehead by birth, Packer fan by Choice! Go Pack!
Response:
I know from the numbers on my 93 skylark my tranny is a 3T40 which is different too the 125C.
– Hide quoted text — Show quoted text -> What you have is a THM 125C, a 3 speed lockup auto transaxle. You made a > positive ID on that by saying you have D 2 1, instead of OD D 2 1. > Notice the C in the 125C, that stands for clutch. For better gas > mileage, all the non-od trannies had a lockup clutch converters > installed (BTW, most all OD trannies have lockup converters). So that > last gear you feel is the clutch engaging so it is a 1:1 connection > instead of the normal hydraulic slip (usually 5-10% slip, depending on > the load) of a non lockup converter. OD trannies can also have the > clutch engage in 3rd if it’s put into D instead of OD. > — > All Diesel Webring Manager, All Diesel Webring ezboard Administrator > http://pub25.ezboard.com/balldieselwebringezboard > Rev it up, Smokem’ out with 100% pure Dieselfumes! > Project vehicle 81 Regal Limited, LF9 5.7L http://www.Dieselfume.Com > Cheesehead by birth, Packer fan by Choice! Go Pack!
Response:
- Hide quoted text — Show quoted text – > My 93 Century with 3.3 Liter V6 and (what I thoght) was 3 speed auto (D 2 1) > OK, when I was going up a hill today around 35, my car went into (what I > thought was) third gear and the engine was running slow (just not enough > power in this gear to keep up at 35 MPH). I gave it gas and it went up one > gear, and then a second or two later, it shifted up again (it never went > back to "3rd"). I gave it more gas and it went into first. When I got to > the top and let up on the gas, i felt it shift down (is that the correct way > to say?) from second to third to another gear…..but I only have drive. > This is drivin me nuts. My friend counted it also and says I have a fourth > gear……am I missing something…it only has D, 2, 1 on the shifter.
4-speeds are usually overdrives, and overdrive gears are often labeled with a circle around the d. if you ever see one, you’ll know what i mean. i’ve seen cars with (D) – D – 2 – 1, where the (D) is a circled D (overdrive), and plain D is like operating a 3-speed. now that means yours is a three speed. lately, that circle around the d has been dropped and now it’s just D, 3, 2, 1, but still an overdrive. if you want the tranny to stop hunting for gears when climbing hills, kick it down into 2 or maybe even 1. you can do this while in third and it won’t harm the tranny and there’s no need to apply brakes while shifting. it’ll feel weird when it kicks down, but if it’s a good tranny, it should take it failrly easily. after all, we’re not talking about a chrysler tranny here. just kidding.
Response:
The main reason it was shifting so much was because I was forcing it to. Usually (going up the looooooooooong steeeep hill) going up the hill, it will go to won’t hunt for gears. Its MUCH better than my old (dead) 1990 Mercury Sable. thanks, Dave
– Hide quoted text — Show quoted text -> My 93 Century with 3.3 Liter V6 and (what I thoght) was 3 speed auto (D 2 > 1) > OK, when I was going up a hill today around 35, my car went into (what I > thought was) third gear and the engine was running slow (just not enough > power in this gear to keep up at 35 MPH). I gave it gas and it went up > one > gear, and then a second or two later, it shifted up again (it never went > back to "3rd"). I gave it more gas and it went into first. When I got to > the top and let up on the gas, i felt it shift down (is that the correct > way > to say?) from second to third to another gear…..but I only have drive. > This is drivin me nuts. My friend counted it also and says I have a > fourth > gear……am I missing something…it only has D, 2, 1 on the shifter. > 4-speeds are usually overdrives, and overdrive gears are often labeled with > a circle around the d. > if you ever see one, you’ll know what i mean. i’ve seen cars with (D) – D – > 2 – 1, where the (D) is a circled D (overdrive), and plain D is like > operating a 3-speed. > now that means yours is a three speed. lately, that circle around the d has > been dropped and now it’s just D, 3, 2, 1, but still an overdrive. if you > want the tranny to stop hunting for gears when climbing hills, kick it down > into 2 or maybe even 1. you can do this while in third and it won’t harm > the tranny and there’s no need to apply brakes while shifting. it’ll feel > weird when it kicks down, but if it’s a good tranny, it should take it > failrly easily. after all, we’re not talking about a chrysler tranny here. > just kidding.
Response:
>the top and let up on the gas, i felt it shift down (is that the correct way >to say?) from second to third to another gear…..but I only have drive. >This is drivin me nuts. My friend counted it also and says I have a fourth >gear……am I missing something…it only has D, 2, 1 on the shifter.
This is your transmission going into lockup.. It’s not physically a "Gear", although some people misinterperet it as one as you have done.. It’s simply your torque converter locking up for a 1:1 transmission to engine ratio… Better milage, lower RPM, less transmission heat buildup. — Mark – Oshawa, Ontario, Canada Chevy Astro / GMC Safari Message Board! Click Below! http://pub37.ezboard.com/bchevyastroandgmcsafari
Response:
Yeah, but the diesel Buicks shift differently, right? ; ) The lockup torque converter was a clever thing for eliminating the loss you described. I’m wondering when the first one came out, if anyone knows… Further, with the 3 speed shifting 1,2,3, and lockup, I always though the OD trans did the same and shifted overdrive last. I think my old 84 olds delta 88 did that. My 96 Buick however, seems to shift overdrive ahead of lockup? Or at least when it’s cold and lockup is delayed. Otherwise, it shift so smoothly, I can barely tell when it shifts anything…
– Hide quoted text — Show quoted text -> What you have is a THM 125C, a 3 speed lockup auto transaxle. You made a > positive ID on that by saying you have D 2 1, instead of OD D 2 1. > Notice the C in the 125C, that stands for clutch. For better gas > mileage, all the non-od trannies had a lockup clutch converters > installed (BTW, most all OD trannies have lockup converters). So that > last gear you feel is the clutch engaging so it is a 1:1 connection > instead of the normal hydraulic slip (usually 5-10% slip, depending on > the load) of a non lockup converter. OD trannies can also have the > clutch engage in 3rd if it’s put into D instead of OD. > — > All Diesel Webring Manager, All Diesel Webring ezboard Administrator > http://pub25.ezboard.com/balldieselwebringezboard > Rev it up, Smokem’ out with 100% pure Dieselfumes! > Project vehicle 81 Regal Limited, LF9 5.7L http://www.Dieselfume.Com > Cheesehead by birth, Packer fan by Choice! Go Pack!
Response:
> I know from the numbers on my 93 skylark my tranny is a 3T40 which is > different too the 125C.
I *Think* that the 3T40 is the same as a 125C, only using the newer labeling system. Sorta like the 700-R4 went to 4L60 and 4L60E (electronic cont) and the 440-t4 went to 4T60…4T60E…4T65E, th-400 to 3L80, and so on… — All Diesel Webring Manager, All Diesel Webring ezboard Administrator http://pub25.ezboard.com/balldieselwebringezboard Rev it up, Smokem’ out with 100% pure Dieselfumes! Project vehicle 81 Regal Limited, LF9 5.7L http://www.Dieselfume.Com Cheesehead by birth, Packer fan by Choice! Go Pack!
