Oldsmobile Diesels - Factory Transmissions

[ClassicTVMan1981X]

Is it true that most of the Oldsmobile diesels were coupled to the Turbo HydraMatic THM200 automatic transmission? I know that was the case with the 1979 Oldsmobile Cutlass coupes and sedans when they were specified with the LF7 4.3L V8 diesel.

In 1981, the 200-4R automatic, which addressed the issues associated with the older direct-drive THM200 by way of beefing up the internals as well as adding an overdriven 4th gear, was introduced. Its bellhousing was also compatible with engines from the Chevy and BOP (Buick, Oldsmobile, Pontiac) libraries.

My question is, wasn't the standard automatic transmission across the board for the LF9 5.7L V8 and LT6 4.3L V6 diesels the THM250(C) or THM350(C) for rear-drive cars? The front-drive E-body, formal-roof Riviera, Eldorado and Toronado coupes used the THM325 direct-drive transmission for 1979-81, while for 1982-85 the THM325-4L automatic overdrive was used.

I am asking this question so that I can help others here as to which transmissions were factory.

~Ben

[Tomko]

Interesting question.

[MCGARRETT]

Well since most of the cars that had the diesel first were large cars, they usually had a Turbo 350 or 400 through 1979-80 in the big B-C body diesel cars. You could have spec'd a manual diesel Cutlass with the 4.3 diesel V8, I have a C&D road test for one from 1979, though they probably only made about 4 of them, there was a base Cutlass on ebay about a year ago with the diesel and the manual trans.

[ClassicTVMan1981X]

So, I'd be thinking that the TH350 automatic was the standard auto used behind the 1978-80 Oldsmobile Delta 88, Custom Cruiser and Ninety-Eight diesels, with the beefier TH400 as the option. From 1981-85, it changed to the TH200-4R. Although, I did see in a few Consumer Guide 11-year car buying guides that some Cadillac C-bodies (rear-drive) did use the older direct-drive TH200 behind the LF9.

The Cutlass rear-drive mid-size went for the TH200 (LF7) or the TH250(C) (LF9) through 1980, and finally switched to the TH200-4R from 1981-85.

Cutlass Ciera and 1985 Ninety-Eight (front-drive) diesels likely used the TH125 since the engine layout was transverse as opposed to longitudinal. The Toronado, Eldorado and Riviera front-drives, like I said before, all used the TH325 (1979-81) or TH325-4L (1982-85) transmission.

~Ben

[Tomko]

You've caught my interest twice by referring to the THM200 as "direct drive". I don't recall seeing this before.

As the 200 was a lighter weight and duty derivation of the 350 I'm not sure what you mean by using this description?

[Lowboy]

You've caught my interest twice by referring to the THM200 as "direct drive". I don't recall seeing this before.

He probably is refering to it being a non-overdriven transmission with high gear being of a 1:1 ratio.

[MCGARRETT]

I think the FWD C-body diesel cars used the 440T 4 speed auto with overdrive that all the FWD C-body cars used.

[ClassicTVMan1981X]

I can point out that the 1981 Pontiac Catalina Safari and Bonneville Safari diesels could not be optioned with the 200-4R since it said explicitly that that transmission was only available with the 5.0L (Olds 307) gas V8 (or, until January 1981, the Pontiac 4.9 V8) engine. Therefore I'm under the assumption the diesel wagons of that year were stuck with the TH350C (the only viable transmission since the regular TH200C was rather weak for a car of this size), as the 200-4R wouldn't be made available in a big Pontiac until the Parisienne Safari showed up stateside in May 1983.

~Ben

[Smaart Aas Saabr]

Those engines though had very little power, I don't think the torque was very important either. A TH400 sounds like absurd overkill, but then again, a THM 200-anything was made of some kind of cheese no matter what engine was bolted to it (ugh)