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Discussion Starter #1
83 Stang, 3.8L C-5.

Transmission has no shift out of 1st unless you hit 45 mph or simply move the shifter to 2 from D once rolling, and no shift out of 2nd into 3rd until 78 MPH no matter what I do.

Is that still an valve body issue or something else? I ran it for a couple hours with some trans conditioner (not Trans-X like I normally use, it's off the shelf)
 

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Upshifts are controlled by engine vacuum, throttle position, shift valves and governor.


Make sure you have good vacuum at the modulator valve and the inner valve is moving freely and in the correct way.

See that the TV rod isn't jammed in an apply position. (passing gear)

If those check out my next suspect would be the governor.

You can do an aircheck on the governor once the valve body is removed.

Blowing air into the 2 holes in the rear of the case.

One will sound as a thunk, the other will sound like a fart.

If everything else is good look at the valve body.
 

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The TV rod is for increasing shift points and passing gear.

If there is no modulator the shifts will be very very high.

You can do without the tv rod but not the modulator unless you have a manual valve body.
 

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FE my brother-in-law , now dead but I remember alot I heard him say. This may work for ya. I have seen him jack a car up in rear, place car in reverse and that allowed the fluid in trans to back flow in the tranny. He stated a ford fluid would run backwards, not in a chevy. I am sure someone will post if I am wrong but it may work. Trash in fluid gets in the little balls and slows the fluid. Back flow allows fluid to flush that trash and shift again. If not ya no worse off.
 

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Putting a tranny in reverse makes the fluid go backwards? Seems improbable.

I never had this car apart it sat for 6 or 7 years.

And where is the Guvna? I can pull the modulator tomorrow and apply vacuum to see if it's working.

The "guvna" is in the extension housing.
 

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He was saying the TV rod (Throttle Valve - the carb rod) could be bent. It should be adjusted where WOT has the trans lever .030-.050" from maxed, and verify the lever returns when the throttle does.

Check the vacuum modulator for leaks.

The gubna is tested through the case after pulling the valve body.

I suspect that sediments have solidified while sitting for years. If the governor tests good, then I'd pull the VB apart for a good cleaning. The C5 has more busy stuff in the VB than the C4 and a bit easier to muck-up. That said, so many years of sitting shouldn't be a big deal, but the internal seals may have hardened and it just can't get enough pressure behind the seals (without max rpm/pressure/flow) to do their thing.

Worst case is around $25 to re-seal, about $50 to overhaul with clutches, plus any other iffy parts while you're in there. It doesn't sound like you'd need more than that.

David
 

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Yup, what I said.

"You can do an aircheck on the governor once the valve body is removed.

Blowing air into the 2 holes in the rear of the case.

One will sound as a thunk, the other will sound like a fart.

If everything else is good look at the valve body."
 

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Yeah, I was just recapping and added tidbits what you already said so FE had a clear plan.
:tup:
David
 

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Discussion Starter #17
I found the issue.

There was a 1 5/8" drill bit used as the pin for the vacuum module, but the pin was TOO FAT on the Module side to sit in the less than 1/8" hole in the module so it was behaving as if it was too long and not letting the piston in the tranny move at all.

So I ground the tip that goes into the module so it fit to the bottom and viollah, she shifts perfectly. :)


Thanks guy's and PSIG also!
 

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Woohoo! I was your eagle eye that caught that - take a bow!

David
 

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Found the problem

Way to go.
I use a piece of coat hanger.
 
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