Rockabilly Hooligan Posted January 24, 2019 Share Posted January 24, 2019 Hello...I believe I might have an bad/cracked Flexplate. I purchased a new PRW SFI Flexplate P/N 1845505. Before I bought it, I spoke to the PRW tech support and verified the P/N to be for my transmission. When it arrived, the the label states 1968-90 Olds V8 260, 307, 350, 400, 403 166 Teeth OEM T-450, T-400 compatible. Have not dropped transmission and removed old flexplate to compare. Before I do I like to make sure new one will fit/work. Do you know if this flex plate will fit my transmission and work with my starter? Thanks Link to comment Share on other sites More sharing options...
Pfeil Posted January 25, 2019 Share Posted January 25, 2019 Flex plate for Olds 260, 307, 350 Etc. Jetaway below Link to comment Share on other sites More sharing options...
Rockabilly Hooligan Posted January 26, 2019 Author Share Posted January 26, 2019 Got it. How rare does these break/crack and cause noise when rotating at low RPMs? Link to comment Share on other sites More sharing options...
Pfeil Posted January 26, 2019 Share Posted January 26, 2019 Link to comment Share on other sites More sharing options...
Rockabilly Hooligan Posted January 26, 2019 Author Share Posted January 26, 2019 (edited) OK. I am confused. Where does the flexplate you show mount and connect to transmission? Behind this cover Edited January 26, 2019 by Rockabilly Hooligan (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted January 27, 2019 Share Posted January 27, 2019 (edited) 57 and 58 Oldsmobile’s came with Hydra-Matic, right? Why picture of Jetaway, a 64 or so transmission. Or is Jetaway just wrong word for correct picture? Ah ha! Further research found the term Jetaway was used for the second generation of Hydramatic that came out in 1956 in Pontiacs, Oldsmobiles and Cadillacs ( plus those sold to American Motors). So, picture right, term right. And I learned another new fact! i do not remember the Jetaway term being used in the 1956 Pontiac shop manual. But that was 40 years ago...😉 The engine I rebuilt was connected to the old style Hydramatic, with those 30 bolts to remove from the torque converter to remove the engine! The 1956 shop manual also showed the newer Hydramatic that did not need 30 bolts removed. Edited January 27, 2019 by Frank DuVal More info. (see edit history) Link to comment Share on other sites More sharing options...
Pfeil Posted January 27, 2019 Share Posted January 27, 2019 (edited) 12 hours ago, Frank DuVal said: 57 and 58 Oldsmobile’s came with Hydra-Matic, right? Why picture of Jetaway, a 64 or so transmission. Or is Jetaway just wrong word for correct picture? Ah ha! Further research found the term Jetaway was used for the second generation of Hydramatic that came out in 1956 in Pontiacs, Oldsmobiles and Cadillacs ( plus those sold to American Motors). So, picture right, term right. And I learned another new fact! i do not remember the Jetaway term being used in the 1956 Pontiac shop manual. But that was 40 years ago...😉 The engine I rebuilt was connected to the old style Hydramatic, with those 30 bolts to remove from the torque converter to remove the engine! The 1956 shop manual also showed the newer Hydramatic that did not need 30 bolts removed. A little history here will help. G.M.'s Detroit Gear, later Hydra-Matic - Division the maker of Hydra-Matic's wanted a replacement for the older single coupling Hydra-Matic because of harsh shift quality. A new Hydra-Matic was introduced in all 1956 Cadillac, Olds 98, Pontiac Starchief. The Olds 88 and the Pontiac Chieftain 860 and 870 models retained the old unit. In 1957 all Cadillac like before, and all Oldsmobile's and all Pontiac's received the new Hydra-Matic . Hydra-Matic division called the transmission "Dual Coupling Hydra-Matic", or sometimes called it "Controlled Coupling Hydra-Matic" Cadillac called the same transmission "315 Hydra-Matic" or sometimes "P 315 Hydra-Matic" Oldsmobile called the same transmission " Jetaway " Pontiac called the same transmission " Strato-Flight " ( 1956-57 ) and later 1958-1964 Pontiac called the same transmission " Super Hydra-Matic " Oldsmobile used this Jetaway until 1960 and replaced it in 1961 with " Roto Hydra-Matic Cadillac used 315 Hydra-Matic until 1963, in 1964 some models still used it, but some models used the new ST400 or "Turbo Hydra-Matic 400 Pontiac used the Strato- Flight - "Super Hydra-Matic from 1956 to 1964, however in 1961 Pontiac Catalina, Ventura and Grand Prix used the Roto Hydra-Matic while Star Chief and Bonneville continued with "Super Hydra-Matic" through 1964. In 1965 all full size Pontiac's use Turbo Hydra-Matic 400. Why did Pontiac have both Super Hydra-Matic and Roto? My assumption is Pontiac never wanted Roto, but was forced to take it because Oldsmobile didn't make enough cars to go it alone with Roto for the unit to be profitable. Edited January 27, 2019 by Pfeil (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted January 27, 2019 Share Posted January 27, 2019 Excellent history lesson. Clears up a lot. That original Hydramatic in that 56 Pontiac looked a lot more like an industrial gearbox than later Hydramatics, etc. It was not a Star Chief, so that makes sense, I think it was an 870, California car that ended up in Virginia. My first "old" car without rust to work on, belonged to a friend, he bought it for $150 with most of the engine in the trunk, only bare block still under the hood. He still owns it, almost 40 years later. Link to comment Share on other sites More sharing options...
Pfeil Posted January 27, 2019 Share Posted January 27, 2019 9 minutes ago, Frank DuVal said: Excellent history lesson. Clears up a lot. That original Hydramatic in that 56 Pontiac looked a lot more like an industrial gearbox than later Hydramatics, etc. It was not a Star Chief, so that makes sense, I think it was an 870, California car that ended up in Virginia. My first "old" car without rust to work on, belonged to a friend, he bought it for $150 with most of the engine in the trunk, only bare block still under the hood. He still owns it, almost 40 years later. Frank, I don't know about industrial, however the 1955-56 last version of the original ( back to 1940) Hydra-Matic design because they were referred to by enthusiast as "Slant Pans" ( because the trans was cocked to the side and required a slant oil pan ) were very robust units and they did jerk shifting gears. For us racers a fast shifting Hydra-Matic is what we wanted! Those slant pans found their way into many "Gassers" and early "Funny Cars" of the 50's and 60's. I had a slant pan behind a 421" Pontiac punched out to 480" with a G.M.C. 671 Blower and Hilborn injection about or near 1,000 HP in a 64 Tempest that ran 8.80's 168MPH and it could take all the punishment you could give it! BTW, those older units were bought by other car companies too, Rolls Royce, Hudson, Nash, Lincoln etc. Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted January 31, 2019 Share Posted January 31, 2019 On 1/24/2019 at 4:29 AM, Rockabilly Hooligan said: Do you know if this flex plate will fit my transmission and work with my starter? Thanks No, it will not. The correct flex plate is shown on the second picture from Pfeil. On his first picture, he is showing the transmission you have. The flex plate from your Olds is attached to the crankshaft and with 4 nuts at the flywheel. If you don't have a shop manual, I would suggest you are looking for one. Olds manuals are well done with a lot of drawings or pictures. Link to comment Share on other sites More sharing options...
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