First off, I am going to use what I have, a Jetaway. Now I am looking for advice on which to use, a lockup or non-lockup. I have each. My engine is a mild 330 (.030 0verbore, mild cam, #4 heads). The rear is a 8.5 inch POSI from an 86 442 with 3:73 gears. Going into a street rod that weighs about 3200. It will be mostly street driven with some short highway trips. Mileage isn't important because it will not be a DD. Is there any advantage to the lockup trans over the non-lockup in this build?

 

To the best of my knowledge there is no lockup on a jetaway trans. There is a switch pitch and non switch pitch and if you have both AND a good converter for it I would use the switch pitch because it will get you off the line better due to the high stall it goes into at idle/low speed.

 

I'd use the SP because the higher stall will help with your cam.

 

First, as noted, there's no such thing as a lockup Jetaway. The JT trans wend out of production in the 1969 model year and lockup converters didn't happen until 1980 or so. Your choices are switch-pitch converter (1964-67) or fixed pitch converter 1968-69). The front pump is different depending on which you use.

Second, the fact that you have something doesn't make it the right choice. If your rod really is 3200 lbs, that's not exactly lightweight (my 62 F-85 wagon is 2700 lbs). You can likely buy a built TH350 for less than the cost of setting up a JT trans, especially if you want the switch-pitch version. The lower first gear will be a welcome addition.

 

Joe, I have been a member here for many years and I hold your opinion in high regard, but for other reasons, I am going to use the Jetaway. I know all of the reasons not to use it, but regardless of those reasons I will use the trans of my choice. I'm only guessing at the weight of my car. It is a 46 Ford fat fender coupe and the title weight shows 2800 with a flathead V8 engine. I'm adding the extra weight because of the chassis modifications I have made.

 

Certainly use what you want, but "because I have one" is not the best reason. I'm guessing your car is heavier than you think. Olds certainly used the switch pitch JT in heavy cars, and even behind the 400 motor in the 65-66 442s. In those case, it was a switch pitch version. The added torque multiplication in the converter will help with the otherwise lethargic response off the line.

 

I'm curious, is it easy to tell the difference between the two transmissions by looking at them?

 

My guess would be with the electrical connector on the side of the trans, unless it used the TCS like the TH400 did.