Roto-Hydramatic

[RShepherd]

Does anyone know why Oldsmobile didn't put the four-speed Jetaway Hydramatic in at least the Ninety-Eights from 1961 to 1964 instead of the god-awful Roto/Slim Jim disastermatic? Pontiac put it in the long-wheelbase B-bodied Bonnevilles and Star Chiefs, while Olds put the Roto in the C-bodied Ninety-Eights. And after suffering with it for three years, they could have put the Turbo-Hydramatic in the '64 Ninety-Eight like Buick did with the Electra. My parents (always Olds people) had a '64 98 and I had forgotten how lousy that transmission was until I came across some posts on this board.

I remember first being very low and then there was a huge gap between first and second with a slow, slippy-sloppy shift (when it wasn't jerky and abrupt..you never knew for sure what was going to happen)which left the 394 flat-footed and often detonating until it could get going again. It had to be rebuilt at 50,000 miles and it performed marginally better afterwards. My dad hated it until we traded it in with 80,000 miles on a '69 with TH400..talk about night and day.

[rocketraider]

Probably the same reason they used Rottenchester 4GC carbs when everyone else was using Holleys and Carters.

You have to understand about Oldsmobile. They invented HydraMatic, and they were pretty proud of it. They designed the Roto for low transmission tunnels, and they stuck with it. I'm not 100% sure, but I think senior Pontiacs had a different trans tunnel. I don't see how they could have made the Super HydraMatic fit otherwise. Always thought it was kinda ridiculous that they stuck Slim Jims behind 421's in Catalinas and Grand Prixs too.

Turbo HydraMatic. Yup. A great improvement over fluid coupling HydraMatics, and descended from a Buick Triple Turbine Dynaflow- which pretty much established Oldsmobile wasn't going to have anything to do with it. Buick snubbed HydraMatic way back when, saying it wasn't smooth enough for a Buick. Hmm- it was smooth enough for a Cadillac, but not for a Buick. What Buick meant was they didn't design and build it, so they weren't having it, and Olds never really forgot or forgave.

The biggest reason Olds adapted to it in 1965 was federal standards for shift patterns if a carmaker wanted to bid on federal motor pools. Chrysler dropped the pushbutton shifter for the same reason. Cadillac Commercial Chassis still used the Super HydraMatic thru 1965; of course they were still using 1959-60 cowl and roof shells too.

[RShepherd]

Thanks for the interesting and knowledgeable reply. The reason I've always seen for Buick not wanting Hydra-Matic was that their torque tube drive was not nearly as forgiving of the HM's somewhat abrupt shifts as the Oldsmobile's and Cadillac's Hotchkiss. Some time ago, I inquired about the Automatic Safety Transmission and someone who owned a Buick with it and had driven an Olds with it said the shifting was acceptable in the Olds, but too jerky in the Buick. Some people preferred the sluggish Dynaflow because of its smoothness compared to Hydra-Matic, but most people who ended up with a Cadillac or Oldsmobile with "Turbine Drive" aka Twin-Turbine Dynaflow hated the slippy take-offs. One man who had bought a Dynflow equipped Cadillac in 1953 (after the HM fire) wanted to trade it for a '55, but when he found he couldn't get Dynaflow on it, bought a Roadmaster instead.