fe c6

[evolutioneng]

what determines the shift point on the transmission?

[Donnie]

Hi, the shift points are controlled by the governor & the engine vacuum. This is explained in more detail in one of my earlier posts..
Check there to see if your questioned is answered, if not post back & ask a direct question & I will explain .........Donnie

[evolutioneng]

explain it to me brother.

[Donnie]

The shift points are determined as I said by the gov. & engine vac.-----
At engine idle, truck not moving==engine vac is high & the gov, is not spinning as it is connected to the drive shaft, so gov. pressure is low
As you start to press the throttle the engine vac will drop, relative to how hard you throttle it, the modulator relays this data to the valve body
This we'll call throttle pressure
As the truck starts moving, the gov. is now turning, creating gov. pressure..the faster U go, the gov. pressure will increase
These 2 pressures are working against each other, when the gov. pressure overcomes throttle pressure, a series of valves in the control body stroke against their springs & allow fluid to move the shift valve, thus the shift will occur..
If you are in 1st gear----the 1/2 shift valve will stroke allowing 2nd gear to happen, in most of our trucks, a band is applied for 2nd gear
The same thing happens when in 2nd gear, as the gov pressure increases & overcomes throttle pressure=the 2/3 valve strokes allowing the rev/hi clutch to apply, now you have 3rd gear
When you are into the throttle hard or wide open, the vac is low so the throttle pressure is high, that is the reason that the shifts are late, as the gov pressure has to elevate a lot to overcome the throttle pressure....when it does the shift will occur.....HTH...........Donnie

[ponyexpress]

I don't mean to hijack this thread but could someone post a picture of where the the vacuum line from the modulator connects to the motor. When I purchased my truck the motor and tranny were removed from the truck. I know where the modulator is but not quite sure where to get the vacuum from the motor. Currently 360 FE with 2 barrel motorcraft carb. Thanks

[BobbyFord]

I don't mean to hijack this thread but could someone post a picture of where the the vacuum line from the modulator connects to the motor. When I purchased my truck the motor and tranny were removed from the truck. I know where the modulator is but not quite sure where to get the vacuum from the motor. Currently 360 FE with 2 barrel motorcraft carb. Thanks

There should be a vacuum tee screwed in the intake near the #3 runner.