No forward gears

[Dugan]

I've been on the site for a few months now but haven't posted anything. i have a 67 mustang with a 302 from a 68 and a c4 tranny. now to the problem.. i was driving around town with a friend and we stoped to switch drivers, when my friend put it in D it wouldn't move. there is a tube (vacuum?) that runs from the intake to the tranny it was disconnected, reconnected it and while i still had it jacked up i started it and put it in D and the wheels spun but after i let the car down i tried to drive it and it wouldn't move... any ideas?


i don't know if it makes a difference but..
it also has a manual/automatic valve body and a B&M quicksilver shifter

 

[rbohm]

that tube goes to a vacuum operated modulator valve. if that valve is dieing, you wont get any forward gears. reverse for that matter. also check you fluid level.

 

[brianj5600]

I am not sure that is true. The modulator valve lowers fluid pressure under high vacuum. When they fail, you get full pressure all the time. It could cause a low fluid level since a ruptured diaphram will allow fluid to be sucked into the motor. The car would be smoking badly if this was happening. Low fluid could cause you symtoms.

 

[10secgoal]

That's right. The modulator controls the line pressure in the tranny and the shift points. The forward drum is not locking up. Whether it be from old clutches or a broken seal. No forward clutch pack means no forward gears at all. It's fixable in the garage if you can turn a wrench and read a book.

 

[mustangdave]

check your fluid while car is running.

 

[p0prcksandc0ke]

if you have money just buy a new transmision and while your at it you mite as well put a bigger engine in

 

[enferno]

if you have money just buy a new transmision and while your at it you mite as well put a bigger engine in

he might as well buy a car that's complete so he doesn't have to **** with it anymore then huh?

 

[p0prcksandc0ke]

no thats the whole fun you and that would cost more

 

[Dugan]

i was leaking transmission fluid before the problem began. i overfilled it by a little on accident and have since checked it. it is still a little over full. it does smoke somewhat out of the exhaust on startups and the higher you rev the engine

 

[brianj5600]

If it was pulling fluid out of the mudulator it would be under high vacuum. With the throttle wide open it should all but go away. I think a rebuild is in your future.

 

[mustangmike6996]

you said you overfill it???? is the fluid cavitating? (bubbling)??? thats not good to be over full

 

[Dugan]

i over filled it on accident, just the once no its not bubbling.

 

[Dugan]

so i figured i might as well just replace the modulator valve since it was so cheap. i put it on started it up and still won't go forward

 

[10secgoal]

That's because your forward clutches are still fried.
You generally lose first gear first. Here's what mine looked like. But I still had 2nd and 3rd gear.