Hard Shifting.

[athuhts]

Hi, I’m new to forums, account wise. I have been reading them for a long time. I have been having some hard shifting with my 1985 cucv. I replaced the rubber lines, replaced the vaccuum valve regulator on the side of the injection pump with on off of Hill Billy Wizard. I have bypassed said vaccuum valve regulator, and when I do the truck shifts really early and soft like I’m pretty sure it should with bypassed regulator. Im not sure where to go from here. With the new vaccuum valve regulator it still shifts hard from first to second at around 25 and then from second to third at 35, adjusting it does nothing. Vacuum off the hard line at modulator on the tranny reads 8-10hg? whatever the measure is for vaccuum is. Any ideas what to do?

Thank you.

 

[CenterMass762]

How hard is really hard? What are the shift MPHs? Is this truck new to you or did you see a change in the way it shifts?

I ask because every CUCV I've driven from when I was a green-suiter until now shifts pretty firmly. Just want to first make sure you aren't chasing a false problem.

 

[CenterMass762]

EDIT- Double Tap.

 

[Barrman]

The IP mounted regulator is adjustable and it really should make a difference you can feel when you move it around. Have you changed the vacuum part on the transmission? One of my trucks wouldn’t shift at all with the IP valve hooked up and was in 3rd by 10 mph if I bypassed it. Turns out the unit on the transmission had a rust hole in it and was my problem.

Another thought is how are you driving? If you are more than 50% into the throttle the IP regulator just isn’t going to send any vacuum to the transmission because it is designed to replicate a quadrajet vacuum signal. Which would be 0 vacuum at that much throttle.

 

[WWRD99]

Hi, I’m new to forums, account wise. I have been reading them for a long time. I have been having some hard shifting with my 1985 cucv. I replaced the rubber lines, replaced the vaccuum valve regulator on the side of the injection pump with on off of Hill Billy Wizard. I have bypassed said vaccuum valve regulator, and when I do the truck shifts really early and soft like I’m pretty sure it should with bypassed regulator. Im not sure where to go from here. With the new vaccuum valve regulator it still shifts hard from first to second at around 25 and then from second to third at 35, adjusting it does nothing. Vacuum off the hard line at modulator on the tranny reads 8-10hg? whatever the measure is for vaccuum is. Any ideas what to do?

Thank you.

Replacing the VRV on the side of the Injection pump IP there is a spec for arm travel for it and of course a special tool to do so...I don't have that stuff and I doubt many do...I set the vacuum at 11 to 12 pounds off the trans side of the VRV at idle which is the top hose on the VRV...can plug your vacuum gage right on it. It should be a stable vacuum and not bouncing up or down...if it's not stable then go to the pump and make sure it has no leaking Ts and such. Once you get that straight the vacuum modulator on the trans is next. You posted it has 8-10 down there, it should be a stable number at idle and not jumping around. I usually replace them with a adjustable one so I can tune in the shift where I want it. If you have a vacuum pump you can check it and see if it holds vacuum...that's about all you can do to those without getting into a trans diag sheet. If it does hold vacuum it should be ok...usually when you pull the hose of it if it is bad it will leak a touch of trans fluid out...there should be none there.

 

[athuhts]

Thank you guys!! It was the modulator! Didn’t have any rust and wasn’t leaking but it must have failed because replacing it did the trick.

Again, thank you.