4.2 kickdown lever

RustyRatRod said
Sorta. As long as you use a wide band, the 5.0 lever is a big plus. Otherwise, it really doesn't do much. No 904 ever came with the 5.0. That was a Hemi only option and they used a wider band than all the rest of the 727s. That's why you need the widest 904 band you can fit in if you use the 5.0 lever. I believe the widest that will fit is 2" wide in the 904.

Well I can tell you that my Tranzact pro nitro brake was set at 170 psi for use with a 904. The instructions clearly recommend either a 3.8 or a 4.2 . The line pressures are set higher for a 904 because it has less clutch surface than a 727. That increased line pressure speeds up the application of the front drum aggravating the shift overlap.
Increasing the spring pressure and plate clearance in the front drum
Is done to slow down the piston application and give the band more time to release.
Paul Forte of Turbo action sets his brake at 190 psi and he recommends a 3.8 lever. The band width has nothing to do with it.
I have the widest band made for a 904. This band is not usually recommended any more because the apply lugs are not centered
and causes uneven wear. At these kinds of pressures clamping force
Is not an issue for the bands. Harshness and speed of apply/release
Is the problem. Afaik