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I don't underIstand everyone's hate for the Jetaway. It has a 1.76 to 1 first gear times a 2.45 hi stall variable pitch multiplication equals ~4.3 to 1, which is similar to 2.52 1st gear times a multiplication of 1.8 in a stock th350 (~2.5) tc. I understand that the torque multiplication factor would increase with an increase in engine torque, but the same would happen with the Jetaway.
I would like to see comparative times (both 0to60 and 1/4mi.) of a Jetaway and th350 in the same car, with the only change being the tranny swap.
They both have a 1:1 high gear, so similar there. The TH350 has a 1.52:1 second gear before getting to that 1:1 high gear. That means the TH350 would give better acceleration after shifting out of 1st.
Mine has the variable pitch jetaway. So many people are flabbergasted that it does in fact drive like any other car and has no problem keeping up with traffic. Hell I'll even tow with it
Mine has the variable pitch jetaway. So many people are flabbergasted that it does in fact drive like any other car and has no problem keeping up with traffic. Hell I'll even tow with it
But….but….butyou don’t have overdrive!!!
You don’t have 4 wheel disc brakes!!!!
You don’t have EFI. Or electronic ignition!! Or antilock brakes!!!
We have heard it all. There are people out there who obviously forgot that cars were around almost 100 years before that stuff was common. Grandpa didn’t stop halfway thru a cross country vacation to retune the family car. Grandma didn’t furiously pump the gas pedal to start here Cadillac before Wednesday night bingo. Life didn’t stop when the weather changed. These cars were expected to start easily, in any environment, without fuss or hassles.
Put a TH350 in the car and drive it, you will quickly understand. Regardless of the theory and math, the car will just perform much better.
I have done many Powerglide/Jetaway conversions, once completed the car feels like it has an extra 50hp with zero downside.
The only thing better than ditching the 2 speed trans for a 3 speed would be ditching the 2 speed for a 3 speed with overdrive.
Powerglide is a different transmission than the Jetaway and doesn't have a variable pitch strator, so you can't lump them into the same category.
Swapping a PG for a th350 might feel like you gained extra hp, but i want to see actual numbers for the difference in going from a Jetaway to a th350.
Mine has the variable pitch jetaway. So many people are flabbergasted that it does in fact drive like any other car and has no problem keeping up with traffic. Hell I'll even tow with it
I've had two F85's with Jetaway drive 1st one was a 330 2bll. I beat a 68 Caprice 327 4bll, to 80, mainly because the Jetaway held low gear to 70+ mph.
My 2nd is the 65 Cutlass in my avatar.
Last edited by Cutlass Fan; Dec 15, 2025 at 07:48 PM.
Not exactly if you have an old school way of thinking. If you are using all of the factory controls for the torque converter you have a variable - pitch torque converter. However if you leave all of the original parts in place and put in a separate wire and switch bypassing the original parts you can then control the torque converter. By doing this you basically create a 4 speed automatic. You can choose when to control the stall of the converter.
On my 65-442 with the Jetaway transmission doing this modification created alot of fun because they thought of the car as (just a 2 speed transmission). More than a few were surprised when they were beat by an appearing 4 speed automatic. Low stall work out to be about 1500 rpm and Hi stall was 2700 rpm.
Now for a little Trivia that many don't know. Later I use this setup with a Turbo 400 with switch pitch converter to basically create a 6 speed transmission. However with a 455 the Low stall was 1800 and Hi stall was then 3000 rpm using the same converter. It was incredible fun back then.. When I sold the car I kept the transmission for a later project.
If you look at 3rd part listing you will find the factory torque converter for a 65-442. If you then go down to the 13th entry you will find the that the torque converter for the 67-442 OAI used the exact same thing.
Powerglide is a different transmission than the Jetaway and doesn't have a variable pitch strator, so you can't lump them into the same category.
Swapping a PG for a th350 might feel like you gained extra hp, but i want to see actual numbers for the difference in going from a Jetaway to a th350.
I don’t know anyone that still has a Jetaway. I’ll admit, I’d be interested in trying a back to back comparison. Even with the switch pitch, my money would be on the TH350. It’s hard to beat the mechanical advantage of gearing.
Who wants to abuse their Jetaway equipped car for a real world test?!
I had a '64 Cutlass with a 330/290 and Jetaway SP. I swapped the Jetaway for a TH350. The TH was faster. As other posters asserted, the car felt like I'd added 50 HP.
I had a '64 Cutlass with a 330/290 and Jetaway SP. I swapped the Jetaway for a TH350. The TH was faster. As other posters asserted, the car felt like I'd added 50 HP.
Are you sure the SP was working? With virtually the same overall torque multiplication off the line(sp working) there shouldn't be that much difference.
Would still love to see some empirical numbers.
I don’t know anyone that still has a Jetaway. I’ll admit, I’d be interested in trying a back to back comparison. Even with the switch pitch, my money would be on the TH350. It’s hard to beat the mechanical advantage of gearing.
Who wants to abuse their Jetaway equipped car for a real world test?!
Not all Jetaways came w/ the switch-pitch TC. Stock, mine was a dog out of the hole, but once going, winding out 1st to 70 MPH (2.78 rear, foot to the floor keeping the kickdown switch engaged) was satisfying. Kicking it down into first at 50 MPH also netted a pretty good shove to the back. Compared to Powerglides I've driven, the Jetaway didn't jerk on kickdown, rather it just surged increased forward thrust after the downshift with no jerking (much smoother trans than the PG IMO). If you didn't press hard enough of the pedal and didn't engage the kickdown switch, it would shift ~50-55 MPH. Best MPG I ever recorded was 23 pure HWY driving ~70 MPH avg., but in city driving you're relying on TC torque multiplication 95% of the time and the MPGs struggled to reach 13. At minimum throttle, it would upshift around 12 MPH. So overall, a pretty good trans for grocery-getter 2bbl cars, but not a performance transmission by any means. When I swapped mine (after ~120K trouble-free miles other than leaks), I couldn't give my old Jetaway away, so ended up recycling it for scrap.
Last edited by JohnnyBs68S; Dec 17, 2025 at 05:13 AM.
Are you sure the SP was working? With virtually the same overall torque multiplication off the line(sp working) there shouldn't be that much difference.
Would still love to see some empirical numbers.
Having more gears makes a world of difference. If you look at RPM shift points, the TH350 will shift to second and pull harder with the 1.52:1 gear ratio at a much lower MPH than the JW shifting from 1st to the 1:1 final ratio. Kinda like how having a lower rear gear improves acceleration.
Then imagine a TH350 with a lower stall. It would outrun the Jetaway due to the better transmission gear ratios.
"Having more gears makes a world of difference. If you look at RPM shift points, the TH350 will shift to second and pull harder with the 1.52:1 gear ratio at a much lower MPH than the JW shifting from 1st to the 1:1 final ratio."
Except that the Jetaway is still in low with a 1.76 ratio and low stall until 70+ mph and pulling even stronger than the th350 with a 1.51 ratio that shifts to 3rd at 75.
The way I remeber it is that a th350 would beat a Jetaway until the th350 shifted into 2nd when the Jetaway would pull ahead.
Would still love to see an actual measured comparison. Doubt if that will happen so the debate will continue!
You’re talking crazy talk. The TH350 has a 2.52:1 first gear, so by the time it’s in its 1.52:1 second gear that you are saying is competitive with the JW, the TH 350 has already gained a commanding lead due to the lower first gear ratio.
In fact, only the 1964-67 Jetaways used switch pitch and only behind the V8s (six cylinder cars did not get the switch pitch). The 1968-69 Jetaways dropped switch pitch behind all engines.
We get it, you love your Jetaway. They work for what they were designed to do. For a good running street car, it’s the worst choice.
Years ago, I had a 78 Grand Prix with a swapped in 425 Olds, TH350 trans, and 2.41 gears. I use to bracket race the car at my local 1/8 mile track. The car was slow, but consistent. With tall stick tires, welded spider gears, and the lousy 2.41 gears, it was a money maker. The tires were 28 inches tall, with the welded spider gears and lousy gearing there was ZERO tire slip. I could run the entire 1/8 mile in 1st gear, if I remember correctly the car ran 74ish mph, with ET in the 9.70s. Embarrassing slow. As long as I could cut a decent light, the car ran the same number round after round.
I have no doubt with some 3.73 or 4.10 gears, the car would have run better. Yet, I would have had to use most of 2nd gear to reach that same 74-75mph trap speed.
I believe all pontiacs had a standard fixed converter, just in case someone reads this thread and is hunting for one.
The variable pitch is a neat gimmick, but there is a reason it only lasted a few years. Buick designed it as a band aid for the struggling nailhead of the time. Definitely some leftover dynaslush technology, or maybe better stated as methodology.
I believe all pontiacs had a standard fixed converter, just in case someone reads this thread and is hunting for one.
The variable pitch is a neat gimmick, but there is a reason it only lasted a few years. Buick designed it as a band aid for the struggling nailhead of the time. Definitely some leftover dynaslush technology, or maybe better stated as methodology.
Correct, only Buick and Olds used the switch pitch on the ST300
You’re talking crazy talk. The TH350 has a 2.52:1 first gear, so by the time it’s in its 1.52:1 second gear that you are saying is competitive with the JW, the TH 350 has already gained a commanding lead due to the lower first gear ratio.
You are forgetting about the high stall in the Jetaway which virtually makes low comparable to 1st in the th350 and that when the 350 shifts into 2nd (1.52:1) the Jetaway is still in low all the way to ~ 70 mph, advantage Jetaway.
I might be all wrong but that is why I would like to see actual numbers.
You are forgetting about the high stall in the Jetaway which virtually makes low comparable to 1st in the th350
I’m not buying that. The higher stall allows the engine to rev higher at the same vehicle speed, but the overall gearing is still the same. I’ve had several different stall speed converters in my car with the same rear gears, then swapped rear gears to a lower ratio and that was way more of a performance boost than the converter stall changes.
I’m not buying that. The higher stall allows the engine to rev higher at the same vehicle speed, but the overall gearing is still the same.
100 % accurate.
As 66_Jetstar stated its a gimmick. Similar to what I do at the track by not letting my car shift into 3rd as it hurts the ET so late in the run. By keeping her in 2nd she is spinning 4800 rpm at the finish line making her think the rear gear is aggressive. Rather than the 3000 it would be turning in 3rd. But it only helps halfway. My 60 foot is terrible because I do in fact have a highway gear no matter what. Trickery will only go so far. Now if she had a 3.55 rather than a 2.56 she's great on both ends. No trickery needed. And now she's potentially a 1/2 second quicker. While spinning 4300 rpm at the finish line in 3rd.
Yes, its beer goggles from being satisfied. Like being with a 7 who makes you happy and equating that to a 10 because of said satisfaction. She's still a 7 but the person is content.
Originally Posted by matt69olds
We get it, you love your Jetaway. They work for what they were designed to do.
Bingo !
Earlier this year the subject came up on this Facebook post.
Look at Ray and Keith, they are on fantasy island. Meanwhile Marcel laid out the truth.
Cutlass Fan, our cars are fundamentally a big science project that is fully calculable. The kinks were sorted out decades ago. There's no real guess work here, with factory components. It just comes down to the right combination for the quickest acceleration, and the ability of the driver to extract every bit of power via a ideal performing powertrain. Calculations alone can sort it all out. And the verdict has been in. The TH350 is a significant improvement over the Switch Pitch Jetaway. And if a Jetaway outperforms a TH350 all else equal, Its just because something was off with the TH350s run. Meaning, issues with the powertrain, weight imbalance, driver incompetence, etc. Scientifically stock to stock it cannot outperform or even perform as well, within the original vehicles.
1966 Cutlass Sport Coupe 310 hp Jetaway
1969 Cutlass S Coupe 310 hp TH350
66 test weight 3591 lbs
69 test weight 3674 lbs
1/4 mile for 66 = 16.5
1/4 mile for 69 = 15.3
69 Cutlass S 250 hp non switch pitch 2 sp.
69 Cutlass S 250 hp TH350
69 test weight 3643 lbs = 17.4 in the 1/4
69 test weight 3674 lbs = 16.4 in the 1/4
Automobile Catalog .
I hope the last et speaks loudly enough.
The 250 hp 3 speed auto Cutlass is quicker than the 66 310 hp 2 speed Cutlass. Gross to gross, while weighing more. Rendering a 60 hp difference worthless. That's how ineffective a SP Jetaway is compared to a TH350.
Automobile Catalog does not just guess, they run all the vital info through a computer program that calculates the ideal outcome relative to testing methods at the time. If the factory rated hp is accurate its good as gold. As that is the only variable, because they do not account for underrated engines, or tweaked ones... But our cars spec info from then could be stood on to a reasonable degree.
I understand you want concrete real evidence but that would take a lot of track time in order to try and sort out difference makers. But if you were to do it would be a fun follow. In the meanwhile the calculations will cut to the chase immediately. It took me 4 years and 150 passes to prove Automobile Catalog accurate with my 69... But my 50 year old ride at the time, needed dual exhaust to compensate for lost power since birth. (The original calculation is with single exhaust.) And then I needed every possible track advantage to take place in order to do it. And of course a healthy well running car. Often their calculations are a 1/2 second quicker than can casually be attained. Or the equivalent of the loss of time due to traction issues back then. For example they say the original 442 should run a 15 flat when new. However actual original road tests peaked at 15.5 but the speed attained says yes 15.0 was attainable. Others like the 66 W30 they say can run a 13.8 and it really did. While its tested mph indicates a 12.60 with full traction... Their Jetaway 442 performance is basically dead on as well when you balance out weight. 2 tenths quicker than reality because Auto Cats version weighs 200 lbs less. (They only account for 1 passenger(the driver)) Put another way its challenging for an original good running stock model to run as well as their calculations state in general. Tweaked cars do not count. If I advanced my timing it would not correlate or be representative to their test results.
Interesting conversations about the Jetaway trans...
Having one of these transmissions in my 66-442, I can attest to the performance limitations & the reason it was replaced by a TH400 in later years.
The switch pitch is a nice feature & greatly improves performance, but still not as much a more gear multiplication.
No need to defend your car, I'm just saying it would run better with an extra gear.
All the math of the additional stall torque ratio from the switch pitch is somewhat true, but there is no replacement for actual gear multiplication.
The multiplication of the converter only is at it's max output when slippage is also at it's maximum... this quickly diminishes as the output shaft rpm increases.
I put 4.33's in my car to improve the acceleration, but it's still lacking in off the line acceleration.
I considered a TH350 (which would be a definite improvement) but never went through with it as I would rather have OD also. If I could find a 200-4R, I would put the effort into the swap.
Last edited by Lonnies Performance; Dec 28, 2025 at 08:47 PM.
Interesting Lonnie, thank you for contributing. If you have a moment please review my next post. I put some time and effort into it. As I want it to stand up to scrutiny. Please let me know what you think.
On the w29 board I came across some interesting chatter.
The OP of a thread was looking into a sales pitch given to a friend, back in 2012. The seller of a GTO was telling his friend that a 2 speed was increasingly the way to go. The OP opened the thread to see how accurate the sellers words were. And after being presented with clear and obvious replies. He settled for confirmation bias that it was the way to go...
Intermixing performance Powerglides with Jetaways and seeing that 70 mph before shifting to 2nd was great. The problem is that you just accelerated from 0-70 in a glorified 2nd gear. A true first gear that shifts at 5000rpm into a true 2nd gear will perform better. Unless your ride is pushing 1 hp per 5 lbs or better. Meaning insanely not stock.
1963 Chevrolet SS409 340 hp Powerglide. (This is the famous road test where the car was shifted into 2nd at 76 mph.)
1965 Oldsmobile 442 345 hp SP Jetaway.
1968 Buick GS 400 345 hp TH400.
1963 test weight, 4120 lbs.
1965 test weight, 3890 lbs.
1968 test weight, 4030 lbs.
1963 SS409 0-70 = 9.2 seconds (still in 1st)
1965 A2442 0-70 = 9.8 seconds (auto shifted at 57 mph)
1968 GS400 0-70 = 7.7 seconds (shifted to 2nd at 42 mph)
Minus 100 lbs on the SS and rear gear match it to the GS and if it can handle the +1000 rpm 1-2 shift, it still gets smoked by the stock GS. (Car Life clearly stipulated that the 409 was force shifted at 5800 rpm into 2nd.)
I agree with the 70mph in first gear comment.... it's more of a bragging right than a performance benefit.
it pulls really nice from 40-70, but 0-40 is not impressive.
Also, I did not think a 63 Chevy would be that heavy.
Maybe a lazy first gear helped with traction in some cases since the old tests were on skinny bias tires.
The interesting part is that most tests of more modern cars show the autos being similar or faster than a manual trans, but look at the old 4 speed road tests & they show an advantage over the autos.
Try to find a Powerglide big block Vette vs a 4 speed... should be interesting.
Most cars successfully running a Powerglide in racing are typically very light and/or have over 700hp... and likely a 5000+ stall converter.
A drag car leaving on the trans brake against the converter is way more beneficial than the typical street situation.
The one thing I always disliked the most on my 442 was this trans.
I did like the feel of a full throttle downshift when the converter hit high stall at the same time as the downshift. That is when the trans was in its sweet spot to match the first gear ratio to the road speed.
Years ago I raced a 70 Chevelle with a 350/TH350... I likely had 100 more HP & 150 Ft.lb. more torque, but I watched him pull 2 cars on me when we left the red light.
Once he was in 2nd, I came around him & put cars 5 on him in the 1/4, but I realized what better performance I could have with the same trans.
