wcbcruzer

First off, I'd like to say that I just re-did the shift kit in my VB and WOW what a difference! The truck is a whole different animal now. THIS is how I've been wanting to get it. Shifts are nice and smooth, no jerks, no hard down shifts, ahh... I dont' want to jinx it though. I've only driven it about a day. Anyway, the weird thing is... I feel like the truck is faster now. Like the throttle is even a little more sensitive than it was after I installed the GSK. I did lower the drive pressure in the valve body from the max of 5 turns on the PR screw to about 2.75 turns. Could tranny drive pressure cause the engine to have more power? Or is it just me? I thought maybe lower pressures won't put as much load on the engine or something.

By the way, does anyone know which band (front/rear) controls which shifts? Which affects the 3rd-4th gear shift?

JD730

This I can answer. There are 2 clutches and 2 bands in the front section and there's also 2 clutches in the overdrive section. One of these is applied by a heavy spring and is only released when it is in 4th.

1st gear in D, is the rear clutch only, the rear roller clutch holds the drum from turning. 1st gear in 1 is the rear clutch and the rear band applied.

2nd gear in D, is the rear clutch and the front band engaged.

3rd gear which is D, The front and rear clutches are engaged.

The direct clutch is applied in all of the above gears, as I mentioned before its applied by a large spring to its applied all the time unless its released by hydraulic pressure when 4th gear is applied.

The 3rd to 4th gear shift occurs when the trans is in 3rd or direct drive, so the front and rear clutches are engaged. The overdrive piston applies the overdrive clutch and releases the direct clutch.

AlpineRAM

I don't think that the VB pressures will make moe engine HP, but the shift timing (esp. 2-3) is crucial to not burning up engine power in the tranny.
Getting the shift points to the rpm that fit for the modified engine (GSK) will net you more usable horsepower, so it will be zippier.

Just my 2c

AlpineRAM

wcbcruzer

Thanks, I read that 8 times. I kinda get it. Is the overdrive piston the accumulator piston? Does 4th gear have less holding power than the rest of the gears and is that why they say it's bad to tow in O/D?

With my shift kit now, the 3rd-4th gear shift is a little harder than the other two, especially under light throttle. I'm trying to figure out if it has to do with the separator plate or something else. Transgo did include another spring for the accumulator piston and I upgraded the piston to a double ring aluminum one.

AlpineRAM

The OD piston is not the accumulator piston. The shifts get a little harder because the pressure is higher.

AlpineRAM

justme-

My mechanic is a tranny specialist - according to them when I first bought my ram the OD is a weak link because it is only that spring that holds it on. Line pressure can be increased but the spring will only get weaker with age.
They recommended leaving OD off until I was doing 40+MPH consistently because of the poor factory line pressure settings at the rpm when the OD engages. OD off makes a huge improvement in acceleration and responsiveness in driving but did seem to cut my mileage. I just went back to leaving the OD on last week to see what mileage difference there really is. FWIW, that's over 70K miles on a mildly modified factory auto with OD off most of the time.

BTW line pressure is critical in the holding power and life span of the clutched/bands and has no effect at all on engine power (or engine anything) Higher pressure (to a point) makes for faster and firmer engagements which creates the firm or hard shifting. Firm shifting holds more torque- if the transmission shifts smoothly it means the clutches/bands are slipping a little on engagement and any slip is detrimental to the life of the clutch/band the amount of power it handles at that point is related to the life.

The improvement you're seeing in acceleration is from moving the shift points from the shift kit. I would suggest upping the line pressure a little- mine was done several years ago- with light pedal it shifts smooth but under heavy throttle the shifts are nice and firm (not harsh or hard)- I feel them. you should feel each shift.