Transmissions and Drivetrain Need help with your trans? Problems with your axle?

700r4 governer mod w/rear end swap?

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Old 04-16-2018, 10:27 AM
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Car: 1988 Pontiac Firebird Formula
Engine: 305 TBI, Hedman shorties
Transmission: 700R4
Axle/Gears: 3.23, non-posi drum
700r4 governer mod w/rear end swap?

Hey guys,

I'm planning out my upcoming 700r4 rebuild and rear end swap. I'll be going from my stock 2.73 rear to a 3.23 rear.

I've got the right speedometer gear to do the swap, but the guy I bought the rear from suggested I might want to get my governor modified so that the shift points are appropriate. He included a modified governor (read: lighter weights inside) that he had on-hand that was modded by a local trans shop.

Is the governor swap really needed? I'm concerned the car will shift too soon with the heavier weights in a 2.73 governor and that it'll ride around feeling like a cement truck.

Thanks in advance for any advice!
Old 04-17-2018, 09:11 AM
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Re: 700r4 governer mod w/rear end swap?

Is the governor swap really needed?
Well, ... is the gear swap "really needed"? REALLY? or what?

Define "needed".

That said, the transmission has exactly 2 eyes looking at the world around it. Each is looking at 1 specific thing the transmission needs to know in order to do its job right.

The TV cable is giving it information about driver demand.

The governor is giving it information about road speed.

Those are THE ONLY ways is has to evaluate what it needs to do next.

If either of those inputs is distorted, the transmission's behavior will be distorted as well.

Whether the governor you are being offered is "right", "good", "correct", "better", or anything else, I couldn't begin to guess. It does sound like it's been adjusted in the right direction however, but only driving it will tell. Won't hurt anything to try both the original and this one, and see which matches the situation more to your liking.

2.73 -> 3.23 isn't a totally radical change or anything; significant yes, radical no. 2.73 -> 3.73 for example would be a MAJOR change. But I suspect that you'll want to do all sorts of things to make the transmission act more "peppy" in a general way, since overall the effect of adding more gear is to make every event the transmission needs to deal with, to arrive sooner; while at the same time, engine RPM under any given circumstance will tend to always be higher. Higher line pressure at all times and faster clutch/band action will help make it respond correctly. Might want to try the simple stuff you can do to it without much effort or risk of screwing something else up; a Vette servo and a larger boost valve for example, in addition to governor reprogramming. A whole shift kit (more risk) may not be necessary.
Old 04-17-2018, 11:45 PM
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Re: 700r4 governer mod w/rear end swap?

Make sure the TV cable is adjusted correctly (tight at WOT). If you find the part throttle shifts are a little early, remove the governor and remove the weaker of the two springs in the governor. This will make part throttle shifts slightly later.
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