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1967 With Rebuilt C4

 
wayla_k
New User
Posts: 2
Joined: 12/13
Posted: 12/13/13 07:20 PM

Need help with this...

Rebuilt C4 put in approx. 15 years ago very little day to day driving done with it.  Then bought a new truck and Mustang went into storage...now it will not shift out of first gear.  Any suggestions out there for what to try next?  

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wayne712222
New User
Posts: 18
Joined: 10/13
Posted: 12/13/13 10:19 PM

replace the hoses to the modulator...

there is a rubber hose section between the back of the intake.. and the modulator tube... then at the modulator there is usually a modulator elbow..   its a molded 90 degree bend that most transmission parts suppliers and you might even get one from a transmission rebuilder...  they are less than 2 bucks at the whole sale level.. so under 4 bucks is a great deal..
won't shift out of first gear is usually that problem..


thats where to start.. there is a chance the governor is stuck.. or one of the valves in the valve body.. i have heard and i don't recommend this..  jamming the gear shift into park with the wheel up in the air spinning at 15 MPH.. this makes a hammering noise.. that can free the governor..  as the parking prawl is next to the governor..

again.. i don't recommend it..  

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wayla_k
New User
Posts: 2
Joined: 12/13
Posted: 12/14/13 02:10 PM

Thank you for the information, however I guess I was wrong, it does shift out of first gear it just takes getting up to approx. 40 mph to be able to shift out of gear, my dad said it does shift just takes spend and a jamming effect.  

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wayne712222
New User
Posts: 18
Joined: 10/13
Posted: 12/15/13 07:02 AM

if it hangs in first gear..'
but when you take your foot off the gas while rolling..
and it seems to drop into neutral..

its the modulator.. or the vacuum supply to it..


if you disconnected the modulator tube at the back of the intake manifold..

applied vacuum and released vacuum.. and applied again.... you should hear the modulator move..  if its quiet where you are..

once vacuum is applied.. you should not have any leaks..

once you prove there are no leaks..

start the engine and with the modulator tube disconnected.. you should have a tremendous vacuum leak.. this indicates that the vacuum passage is open..

hook up the modulator tube to the intake..

climb under car and disconnect the vacuum hose at the modulator..  you should again have a tremendous vacuum leak..

this proves that the vacuum is enough to move the modulator in response to throttle and load changes...  

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