Shift kits.. do you really need one????

I'm not sure you guys have this all correct. Based on my experience doing them since the late 80s...

"the cup plug is not for applying but for timing the release of the previous gear, so that you don't end up with a flare between gears."
"Flare" is the rise in rpms that happens when the release of one holding mechanism and the apply of another. Normally when you increase line pressure there is less flare, and in the case of the 2/3 shift, it's overlap, not flare that's the problem. In the case of the cupped plug - it slows down the 3rd gear apply to give the 2nd gear band a chance to release. The cupped plug goes into the high gear apply passage.

"I have the pressure raised and the separator plate drilled for quicker firmer shifts and a spring on my TP rod to delay the shift a little."
The enlarging of the plate passages, the removal of the casting wall, the removal of the check balls, and the removal of the spring from the accumulator all decrease the time it takes for the trans to shift. The firmness comes from the combinations of line pressure, kickdown pressure, the changes in the shift circuits, and the forces opposing the holding mechanisms - those being the Belville spring in the forward clutch, the multiple springs in the high gear clutch, and the ratio of the kickdown (2nd gear) lever. It's not a couple things - it's all of it working together.

"In the Torqueflite, the release of the bands is very important to speeding up and firming up shifts."

I disagree. The rear band is not applied in stock valve bodies in Drive ("D"). It does get engaged in Break-a-way first ("1") but there's a very stiff spring to release it, and it's a smaller diameter (smaller surface area) so it pulls off very quickly as soon as the pressure is dumped. When it shifts up into second (in "D" or "2") the low/reserve band loses pressure and releases but not as fast as the kickdown band can apply. So it's common to have overlap (feels like a shudder) when going 1st to 2nd at part throttle (less rpm than a WOT upshift). When it goes from 2nd to 3rd the kickdown band servo loses pressure and the large spring works against the kickdown lever's ratio to releasee the band. While that's hapening the high gear clutch pack is getting pressure. That pressure acts against the return springs in the clutch pack. By installing that cupped plug the volume of fluid allowed to pressurize that clutch pack is reduced, and the affect is a slower 3rd gear apply. The biggest affects on 2nd gear release is not the band, but the spring and that lever ratio. That's why most good builders don't use the 5.0 lever. The best compromise is the 3.6 or 4.2 levers. If you get the return spring count, line pressure, and lever ratio right - the 2/3 shift feels instantaneous and precise. Doesn't matter what band is used really. The lighter double wrap is fine for most cars but does not have the holding capacity of the 1-piece. The 1-piece can hold anything but can slow down the apply. Trucks and heavy towing applications would normally use the 1-piece.


I'd like to here Fishy's opinion on these. Maybe I'm completely off...lol.