# PLEASE HELP - - Shifting Problem is a Pain in the @$$



## 70455goat (Nov 5, 2007)

Looking for any ideas?????

My 70 GTO has had a shifting problem since I purchased it (455 with 400 auto). When driving it normally (like a grandma), it shifts perfect, both up and down. When you romp on it, it downshifts fine, then won't shift back into the next gear until you completely let off of the gas. Even if you only hold it down like half throttle and the car catches up to the speed of the engine, it won't shift until you let off of the gas.

I had other issues more pressing so I have been putting off the problem, but now I'm finally getting around to the working on the shifting issue. Today I replaced the Vacuum Modulator. It made no difference. I checked the vacuum at the carb and modulator and it is 19-20 in.

Any ideas????

I appreciate any and all help.

Dale


----------



## wytnyt (May 17, 2008)

70455goat said:


> Looking for any ideas?????
> 
> My 70 GTO has had a shifting problem since I purchased it (455 with 400 auto). When driving it normally (like a grandma), it shifts perfect, both up and down. When you romp on it, it downshifts fine, then won't shift back into the next gear until you completely let off of the gas. Even if you only hold it down like half throttle and the car catches up to the speed of the engine, it won't shift until you let off of the gas.
> 
> ...


incorrect modulator or adjustment
where vacumn line hooks to it,,inside there you can adjust it
test try a few adjustments


----------



## Rukee (Feb 8, 2007)

Check the operation of the kick down switch by the gas pedal, make sure it`s working and adjusted right.


*edit*
It should turn 'on' only at WOT and turn 'off' as soon as you let up off the gas.


----------



## geeteeohguy (Feb 2, 2008)

Ditto on the pedal kickdown switch. Throttle valve pressure must overcome governor pressure for the upshift to take place. Good luck.
Jeff


----------



## 70455goat (Nov 5, 2007)

geeteeohguy said:


> Ditto on the pedal kickdown switch. Throttle valve pressure must overcome governor pressure for the upshift to take place. Good luck.
> Jeff


Thanks,

Both you and Rukee seem to be focusing on the same area. I know abosolutely nothing about the pedal kickdown switch. Where is the switch located and what do I need to check?


----------



## Rukee (Feb 8, 2007)

It should be under the dash and make contact with the gas pedal rod close to the firewall there. Checking with the key on there should be power to just one side of the switch until the gas pedal is floored, then both sides should have power. As soon as the pedal is let off the floor the one side of the switch should loose power.


----------



## 70455goat (Nov 5, 2007)

Rukee said:


> Check the operation of the kick down switch by the gas pedal, make sure it`s working and adjusted right.
> 
> 
> *edit*
> It should turn 'on' only at WOT and turn 'off' as soon as you let up off the gas.


Thanks Rukee,

I'll bet this is my problem. Where do I check the opreration of the kick down switch? You said it's by the gas pedal? How do I verify that it is turned on only at WOT and back off when I let off the gas? I will look by the gas pedal tonight and see if I can find the switch.

Dale

You're too quick for me. I didn't know you were online and already answering my question!!!!


----------



## 70455goat (Nov 5, 2007)

Rukee said:


> It should be under the dash and make contact with the gas pedal rod close to the firewall there. Checking with the key on there should be power to just one side of the switch until the gas pedal is floored, then both sides should have power. As soon as the pedal is let off the floor the one side of the switch should loose power.


Thanks Rukee,

You were too quick. I didn't know you were online and already answering my question!!!

Any idea what the power should be??? 12 VDC?

I have all of the GTO's original problems fixed except this one.

The car had major exhaust manifold leaks on both sides when I bought it. I was able to get the passenger side off and replaced the gasket, but could not get the driver side off. I had resorted to vice grips on two bolts!! Not good!! I had pretty much decided to pull the engine to get the manifold off. 

The other night when I had the starter out replacing the solenoid, I tried one last time to get the manifold off. I got all but one bolts out. So I cut the head of the last bolt off with a cutting wheel, then pulled the manifold off with the bolt still in the head. Then used a pair of vice grips on the bolt and it came right out. Boy does it sound better! No more pop pop pop when you let off the gas or loud ticking under the hood!!!

I would love to get the shifting problem fixed. I still haven't been able to get a real idea of what it will do because it won't shift until I let off the gas. I will be checking into the kick down switch as soon as I get home.

Dale


----------



## 70455goat (Nov 5, 2007)

wytnyt said:


> incorrect modulator or adjustment
> where vacumn line hooks to it,,inside there you can adjust it
> test try a few adjustments


My first thought was the modulator. I replaced it and no change. The aftermarket one I replaced it with doesn't have an adjustment screw. I am thinking about putting the original vacuum modulator back on. What do you think? Is the original one with the adjustment screw better?

Dale


----------



## Rukee (Feb 8, 2007)

Yes, battery voltage is what your looking for.


----------



## 70455goat (Nov 5, 2007)

*UPDATE on shifting problem*



Rukee said:


> Yes, battery voltage is what your looking for.


IT'S FIXED!!!!!!!!!!!!!!!

Thanks guys for the help. I found the kickdown switch. There wasn't any way to adjust it though. The switch bolts to the bracket and there isn't any adjustment. 

When I first looked at it, the 12 vdc was present on both pins when you barely push on the gas and didn't go away on the one pin until you nearly let off of the gas. Not good huh! So I just bent the bracket away from the firewall.

Fixed the problem!!!!

Now I need to decide whether to put the original vacuum modulator back in and take the aftermarket one back to Autozone. There probably wasn't anything wrong with the original one, plus it is the original one for the car, with the adjustment screw. What do you guys think????

Thanks again guys. I knew someone would know what to do.

Dale


----------



## Rukee (Feb 8, 2007)

Unless you have a reason to adjust it, I`d prolly just leave the new one in there. They have a rubber diaphram in there that can fail. Replacing the original one isn`t such a bad thing to do.


----------



## 70455goat (Nov 5, 2007)

Rukee said:


> Unless you have a reason to adjust it, I`d prolly just leave the new one in there. They have a rubber diaphram in there that can fail. Replacing the original one isn`t such a bad thing to do.


Thanks, sounds like good advice.

Dale


----------

