C4 shift points?

[Dugan]

What should a C4 shift at? I am asking because mine seems to shift rather low, usually 3000 RPM's or lower. Is this right?

 

[enferno]

just cursing around, i set mine to shift between 1800 and 2000 rpm.

at WOT, it should shift a lot higher than that though

 

[Dugan]

hmmm. when i take mine out of storage after winter i will have to see, don't think i ever looked at the tach at WOT.

 

[jcp123]

I've seen it shift as low as ~1100rpm on my '68. Normal driving for me, it'll shift at 1400-1600, and on medium-hard driving anywhere from 1800-2500. Rarely does it ever even get to 3000. WOT shift point for a stock setup is 4400.

 

[351vic]

Mine will shift at idle. It's in third before i get to the end of my driveway if it's warm but on WOT it typically runs to about 4700 before it shifts i think

 

[enferno]

Mine will shift at idle. It's in third before i get to the end of my driveway if it's warm but on WOT it typically runs to about 4700 before it shifts i think

sure it's not in second?

some early c4's start off in second for better traction, then shift normally from there

 

[Cobain03]

mine shifted at around 4300 under WOT

now it shifts whereever i want it to

 

[Fast63]

mine shifts at about 6000 in "D" at WOT but it was modified some by the previous owner so I have no idea what has been done to it.

 

[351vic]

Yes sir I'm positive. I can see it on the tach and feel it. It's VERY minute but if I'm nice to it outta the driveway i can wind it up to highway speed and it never shifts again lol

 

[Dugan]

Ok. Another question, can the gears in the rear end affect when it shifts?
Sorry I am still new to this, as it is my first classic car, well and my first ever car.

 

[neverhit]

On the back of my 69 C4 is a vacuum modulator which is cylindrical in shape. From the modulator is rubber tube that goes to a steel tube and runs toward the engine. At about the firewall it switches back to a rubber tube that goes to the vacuum on the intake manifold. The vacuum causes the modulator valve to shift. A light pull on the rubber hose that goes to the modulator on the back of the tranny will reveal a small screwdriver slot. I turned mine a couple of turns in and it increased my shift point under hard throttle. Under light throttle, it shift at low speed still. I put a vacuum pump at the intake manifold end and verified it was holding a vacuum. I saw on another forum that you shouldn't go much past two turns as it may cause damage, but I can't confirm (Maybe someone else can..). For my 69 with the cross member to support the tranny, I needed a long flat blade screw drive and started the screw driver behind teh tranny support and guided it straigh into the modulator. Hope that helps.

 

[Dugan]

which way do you turn it to increase shift points, clockwise or counter clockwise

 

[neverhit]

I turned it clockwise.