Thread: 1965 Biscayne/5 speed conversion

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Don there is another overdrive option although it is a 4 speed not a 5 speed and as such the gear splits are not optimal.

That is the Chevrolet version of the New Process A833 overdrive transmission (based on the NP A833 that Chrysler used for years behind all their big and Small block engines).

I have the Chrysler version in my 57 Plymouth with the 354 Hemi and 4.10 gears (the OD ratio makes the final ratio equivalent to a 3.00 ratio). I’m running 235/70/15 tires. The car probably weighs about the same or maybe just a bit more than your 65.

FWIW here are my impressions of the transmission.

It’s has given me a very good service life so far and yeah, I “shown off” a bit with the car (with a HEMI, Tri Power and 4 Speed who can really resist).

The transmission comes with a 3.09 low gear and with the 4.10s low is really about useless when you jump on it. That being said, I have a pretty healthy cam in the car and for normal driving around town it really make the car well street mannered leaving stop signs and such. If I were to do it again I would probably step down to something in the 3.75 ratio area in the rear end. There is a pretty good jump in ratios between 2nd and 3rd (which is the 1:1 Ratio), but with the rear end gears and torque the Hemi makes it’s not all that noticeable. The OD ratio on the transmission is .73. Overall with the gear ratios I do enjoy driving it on the street but if I were to ever get serious about drag racing the Plymouth I would go to a conventional non OD transmission for the better ratio splits.

I’m using the Inland (Chrysler factory) shifter on mine and it shifts really nice. It has defiantly got a old school feel to it with the long throws but you’re going to run into that anytime you have the long shifter handles necessary with the 50-60s cars. The throws could be shortened by re-drilling shift arms, but it’s something I haven’t bothered with.

I got lucky with my overall combination, at 75 MPH the car is running at 2600 RPM, and the engine is in a happy place and gets 20 MPG (with the AC on).

These transmissions were used in some 70s-80 Chevrolet trucks and are not very well know or sought after so it usually take a bit of looking to find one. The plus side is they usually don’t command a high price.

Here’s a link to one that was put in a 65 Impala.

The New Process A-833 an Alternative to a Muncie Borg Warner


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