amrcnmscle

i have a 1969 oldsmobile cutlass 'S' with a 350 v8 and a 2 speed powerglide, the time has come where it needs rebuilt or replaced. my question is do i rebuild it or put in a 3 or 4 speed transmission. money is somewhat an issue and also this is my daily driver/cruise car so i am looking for gas mileage as well as low price? please help with any advice...

joe_padavano

Contrary to popular belief, your trans is not a Powerglide (which was never used by Olds). It is a Super Turbine 300 (ST300, also called the Jetaway by Olds). A TH350 is almost a bolt-in (the cable kickdown is the only difference) but won't help gas mileage since it also has a 1:1 top gear. The overdrive four speed 200-4R can be installed with not much more work than the TH350, but to get one that's been sufficiently beefed to survive behind your 350, you'll spend somewhat more than you will for the TH350.

markowyo

I have a '64 Jetaway in a Cutlass which has never given me a lick of trouble, and odd as it seems, 2 speeds work great behind that 330. I've considered it, and I don't care to trade it for a turbohydramatic.

Also, at 65 mph I get about 21mpg.

wmachine

The Jetaway is definitely a weak transmission, especially compared to a TH350 even. I wouldn't even consider replacing it with another Jetaway, expecially considering the availability and ease of a swap to a TH350.

amrcnmscle

thanks guys for the advice and information about my transmission, much appreciated

f-85

I dont know about you guys, but i have had real good luck with the jetaway. About a year and a half ago i put in a 455 in my 64 F-85 at the same time i pulled the 2 speed and put in the th350. I loved the th350. The gear ratio was much better. 2.56 1st, i was loving it. It lasted me about 3 weeks before i blew it. Back to the 2 speed until i found another th350 . After a month or so i got another th350. Man i was loving it. It lasted 5 weeks. Back to the 2 speed again. Then over the winter i bought a built th350, and a stronger motor (1970 455) Now i was really flying! The trans really shifted firm! That one only lasted about 6 weeks. And this time it really blew. Man it was loud! Bang-klunk- crunch. Had to drive home almost a mile in reverse. LOL back to the 2 speed for a couple months. Now i finally have a good trans. I bought a built th700r4. Now im really happy! 3.06 1st gear and 4th in O.D. plus the lockup so its like a 5 speed. I couldnt be more pleased. But i still have that old 2 speed in the shed just in case. I had the 2 speed behind a BB for at least 4 months total. And i dont baby it. It has been the most dependable trans ive had with this car. I wouldnt say its weak. Yes the 1.70something 1st does suck. But i just couldnt brake that son of a gun! Just my experience.

Josh

markowyo

I did forget to say about the Jetaway ... smoo-ooth ... an Oldsmobile hallmark!

nonhog

Thinking about leaving in the 2spd when I go to the 455 swap . Its lived behind the 425 for who knows how long. My reason is Ilike the column shifter. I know I could replace my column with a 3 speed column but it scares me to think of the down time finding parts and pieces .
And putting the floor shifter (Hurst) wont look right (to me)
Are the Jetaways equal to powerglides in terms of strength ?
I toasted a powerglide behind a stock 427 390hp maybe it was the 460 ft. lbs. Yikes the 455 will have more than that . Hmmmm better rethink my plan.

Jamesbo

Good idea

matt69olds

I’m not interested in starting or being in a pissing match, but they did cast a PowerGlide in a BOP and unibell bolt pattern. I have personally seen dozens. They aren’t common, but out there.

joe_padavano

Correct. Pontiac used them. They were never installed in an Old.

matt69olds

I assumed they used them behind any and all of the BOP engines. Did Pontiac use the Jetaway trans?

When I worked at Coan 25 plus years ago they had several dozen core BOP Powerglide transmissions. Considering there were probably 5000 core chevy Powerglide transmissions in the warehouse, the BOP Powerglide was a pretty rare trans.

rocketraider

What years, Joe? I had a 64 Tempest 4d sedan for a work beater in the 80s and it definitely had ST300. About every oil change I learned to squirt some WD40 into the downshift switch plunger. The damn thing would stick when you set the automatic choke and then wouldn't shift out of Low.

olds 307 and 403

Holy old thread but some interesting facts. I like the one guy who blew up 3 TH350's, kept switching back to the ST300 and talked about how he finally had a strong built trans that would last, a 700R4 trans🤣.

edzolz

There was also an ST300 with dual bolt pattern. Came in 67 F85 with six cylinder. The six was Chevy design 250 cu in. but the tranny was Olds 2 speed.

Killian_Mörder

Buick was likely using them also. My dad had one in his 4-door F-85. Had I known it his had both patterns, I would have kept it before he had the car junked. I don't even remember if there was even anything wrong with the car, before he junked it

Nothing like having a boring THD 400 behind the mill

Killian_Mörder

Interesting to note, besides the Powerglide, a Chevy boltpattern bellhousing was once cast onto a Buick unit. Whoever bags one of these, he or she will have earned a collector's item. I've never known that these things to even happen, until this video came out overnight :

rocketraider

1957-61 Turboglide/Triple Turbine Dynaflow was a disaster for both Chevrolet and Buick. As bad as or worse than RotoHydraMatic. Its only saving grace was it laid the groundwork for TurboHydraMatic.

Chevy used it to offer buyers an alternative to heavy, noisy cast iron Powerglide but mainly to help Buick amortize TTD's enormous R&D costs. Olds, Pontiac and Cadillac had HydraMatic and weren't interested. They were still smarting from the 1953 HydraMatic plant fire which forced them to use Dynaflows and Powerglides till the HMT plant got rebuilt.

You'll notice that Turboglide had a separate bellhousing to adapt TTD to the Chevrolet block bolt pattern. HydraMatic also used that, making the transmission adaptable to each GM Division's engines as well as the many independents who bought HMT from GM including Lincoln and Rolls Royce. A HydraMatic could easily be attached to a Chevrolet block as well, which is what Chevrolet itself did in its 50s trucks.

Killian_Mörder

It must have been humiliating for Chevrolet Division engineers to find out that their division had become GM's garbage disposal. Especially, if they themselves were ordered to design the toiletbellhousingbowl for the Dynaflush with the Chevy bolt pattern. I suppose, that Black Swan tranny would have been trouble free, when hooked up to an Iron Duke

d2_willys

Even though Chevy's Turboglide and Buick's Flight Pitch (triple turbine) dynaflows functions were very similar, they were TWO different transmissions. Turboglide went thru several changes due to clutch problems, where Flight Pitch dynaflow was built remarkably well. The big issues were the Engineering costs that were in excess of 86 million dollars. Chevy Turboglide was only used on 283 and 348 engines in full size vehicles. Corvette went with Powerglide or a manual transmission. Turboglide never had a bell housing for a Buick Nailhead, and Buick Flight Pitch dynaflow never had a bell housing for the Chevy V8's.

My father bought a new 1959 Chevy Parkwood wagon with 283 and Turboglide. He quickly regretted getting the Turboglide, as the torque converter failed at 10000 miles. I changed the transmission out to a 3 speed stick after getting to driving age. A few years ago I bought a 1958 Buick Roadmaster with Flight Pitch Dynaflow. The Buick has much better takeoff than the Chevy did, due to the large torque Nailhead engine.

Killian_Mörder

86 million was alot of money, back then. Infact, it was still real money and not that Monopoly Tee Pea of which they're printing nowadays. That's probably the main reason for bean-counting on GM's important projects