M40 adjustments

[John Brown]

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You can also buy aftermarket kits with different weights - similar to distributor advance weights - that will alter shift points.

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I take it that you're talking about the weights in the governor assy.

[RPOLS3]

Correct - I have a "CD" coded low perf M40 in my 72. By adding a shift improver kit (not a full blown shift kit) and tweaking these weights I was able to get it to shift where and how I wanted it to. It is a little bit of a trial and error process but is not overly difficult. It has performed flawlessly behind a GM crate 454/425 for 8 years now.

[TimG]

Thank you for the information. It is the original CW transmission and it shifts very well now. If it is adjustable, I was going to play with it to see if I could make it bang a bit harder.

[Mr70]

Tim
Which posi rearend ratio are you running...3:73...4:10?

[TimG]

The original 4.10, it's kind of a beast.

[Chevy454]

LOL...all these guys wanting firmer shifts from there 400s, and I'm going the opposite direction...

[WILMASBOYL78]

I don't htink the governor will have a big impact on normal driving upshifts....adjusting the modulator or modifying internal pressure with a shift kit will work better. The governor has more of an impact on WOT shift points and down shift for passing gear.

Tim, I would try using an adjustable modualtor(aftermarket) and not mess with the factory unit. The more you restrict the vacuum....the firmer the shift and it will hold a little longer.

CW tranny and 4.10 gears are a trip...we have that setup in our 70 L78 car and it really works ...and, with the stock modulator.