C-4 WOT UPSHIFT TOO LOW

red · 07-27-1999, 09:11 AM

I just went through this with my '65, c4 trans, 302 engine combo.

Make sure the kickdown is hooked up.

Switch the vacuum from your carb to the manifold and plug the carb vacuum port, if your EFI then get a vacuum gauge and check to see that your pulling around 15 psi at Idle and pressure goes down when you hit the gas.

Since you have the screw in type modulator, if these don't work you will probably have to drop the valve body and change the springs. Probably best left to the transmission shop since I have never seen spring assortments available. We went through 4 stock valve bodies and two shift kits, all had different springs, before we got a combo that performed as desired. My stall is not that high though (around 2500). If it comes to this let me know and I'll find out which spring to change from my trans guy and see if I missed any steps.

P.S.
If this is a street driven car, you probably should not let the trans shift automatically at that high of an rpm (5500). Manual shifting engages the bands simultaniously and gives a stronger shift (read will not dammage the trans as much).

-JON

[This message has been edited by red (edited 07-27-1999).]

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07-27-1999, 09:11 AM	#3
red Registered Member Join Date: Sep 1998 Location: Millburn, NJ Posts: 310	I just went through this with my '65, c4 trans, 302 engine combo. Make sure the kickdown is hooked up. Switch the vacuum from your carb to the manifold and plug the carb vacuum port, if your EFI then get a vacuum gauge and check to see that your pulling around 15 psi at Idle and pressure goes down when you hit the gas. Since you have the screw in type modulator, if these don't work you will probably have to drop the valve body and change the springs. Probably best left to the transmission shop since I have never seen spring assortments available. We went through 4 stock valve bodies and two shift kits, all had different springs, before we got a combo that performed as desired. My stall is not that high though (around 2500). If it comes to this let me know and I'll find out which spring to change from my trans guy and see if I missed any steps. P.S. If this is a street driven car, you probably should not let the trans shift automatically at that high of an rpm (5500). Manual shifting engages the bands simultaniously and gives a stronger shift (read will not dammage the trans as much). -JON [This message has been edited by red (edited 07-27-1999).]