C4 shift points?

Dugan

New Member

Mar 21, 2007

47

0

0

Portage Mi

Jan 13, 2008

#1

• Jan 13, 2008

• #1

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

Member

Jun 20, 2006

418

2

16

Jan 13, 2008

#2

• Jan 13, 2008

• #2

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

New Member

Mar 21, 2007

47

0

0

Portage Mi

Jan 13, 2008

#3

• Jan 13, 2008

• #3

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

New Member

Nov 1, 2003

408

0

0

Tyler, TX

Jan 13, 2008

#4

• Jan 13, 2008

• #4

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.

 

3

351vic

New Member

Jun 13, 2007

33

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0

Pierz, MN

Jan 23, 2008

#5

• Jan 23, 2008

• #5

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

Member

Jun 20, 2006

418

2

16

Jan 23, 2008

#6

• Jan 23, 2008

• #6

351vic said:

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

Click to expand...

sure it's not in second?

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

 

Cobain03

Active Member

Aug 27, 2003

996

0

36

Lexington, Ky

Jan 23, 2008

#7

• Jan 23, 2008

• #7

mine shifted at around 4300 under WOT

now it shifts whereever i want it to

 

Fast63

New Member

Sep 20, 2007

717

0

0

Jan 24, 2008

#8

• Jan 24, 2008

• #8

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.

 

3

351vic

New Member

Jun 13, 2007

33

0

0

Pierz, MN

Jan 25, 2008

#9

• Jan 25, 2008

• #9

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

New Member

Mar 21, 2007

47

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0

Portage Mi

Jan 26, 2008

#10

• Jan 26, 2008

• #10

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.

 

N

neverhit

New Member

Oct 30, 2007

2

0

0

Jan 26, 2008

#11

• Jan 26, 2008

• #11

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

New Member

Mar 21, 2007

47

0

0

Portage Mi

Jan 27, 2008

#12

• Jan 27, 2008

• #12

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

 

N

neverhit

New Member

Oct 30, 2007

2

0

0

Jan 28, 2008

#13

• Jan 28, 2008

• #13

I turned it clockwise.