Trans problems...

[CowPunk]

Hi everyone, just joined the site today in hopes that some of you more experienced mustang lovers would be willing and able to help me out with some issues I'm having with my car.

I have a 1966, has the 289 in it. I -think- it has a c4 transmission, (3 speed, auto). I haven't found out yet how to determine the difference between the c4, c6, and fmx900.

Nevertheless, a friend of mine, about a month ago, told me I should replace the transmission vacuum modulator on the car as it would probably help with the hard shift I had been experiencing when I really get on the gas. So I went to autozone (mistake #1 probably) and picked up a new one. Replaced it, ever since that point it felt like it would kick into neutral for 2 or 3 seconds before shifting from 1st gear to 2nd gear. I tried adjusting it (mistake #2 probably) to see if I could clear it up a little. It didn't do much, and now I'm afraid I might have over adjusted it and damaged the transmission.

Today I went to the car to go to work, put it in drive.. and it never moved. I put it in overdrive, and it never moved. I put it in low, and it inched forward, I gave it gas.. up to about 3000RPM is what I would guess, considering I don't have a tach, and it moved forward just like it would if it were at an idle. Thinking of the last thing I replaced, I walked to the nearest auto parts store, picked up a new module, replaced the module and the o-ring, and left the adjustments alone. I replaced the vacuum line that runs to the module the first time I replaced it.

Any idea what could be causing the lack of movement? I never had any problems with the transmission before replacing the original module, and because I broke the first one, I could never put it back on.

I'm desperate, this is my daily driver and I can't afford a transmission shop right now. Any suggestions?

[SpectorV]

fluid low? if fluid is low it wont engage right

[CowPunk]

Oops, forgot to mention that. I checked the fluid level right after I put the module on to make sure it didn't leak much out. Didn't think it did, but I checked it anyway. It's right between the add and full marks. So the level is good.

[CowPunk]

Also..

I just took a look at the line the runs from the back of the module to the intake on the back of the motor. Replaced both rubber vacuum hoses from line to module, and from line to motor. So both of the rubber lines are now also brand new. Also checked for tightness on the fitting to the intake.

This is confusing me.. it shifts from park, to reverse, to neutral, just fine. I have no problems in reverse, it's only forward gears that don't seem to engage.

[Pony Gaz]

Just a thought. What color is your trans fluid? If it's not cherry red but brown & smells burned then the clutches & bands are worn. Sounds like you have either a valve body or clutch pack problem. I will check in my tech literature & let you know in more detail.

[Pony Gaz]

Just checked thru my C4 Bible. Could well be a problem with the foreward clutch not engaging or slipping due to wear, as this is the only component that is common to all foreward gears irrespective of shifter position, i.e D, 2, or 1. If that is the case the trans will have to come out & be overhauled.

[Cobra GT]

Dextron III oil is brown if he does not have the Ford oil in it. And it sounds like your tranny has expired. It’s probably a coincident after changing the module too. When you took the first module off did any oil come out of it? Does your tranny have a shift kit in it that could explain the hard shifts? Also the pump could have gone out, in that case you will have to recycle it.

[CowPunk]

Trans fluid in the car is still the normal shade of red that it's supposed to be.

The car doesn't take DexIII, It takes Type F.

Fluid did come out of the back of the transmission when the module was changed, I've pretty much determined that I'm just gonna replace the transmission altogether. I'll probably just say screw it and put a c6 in it, if I'm gonna replace, may as well upgrade in the process.

As for now, I'm off to the lot tomorrow to buy a motorcycle, I'll fix the mustang as time and money see fit, instead of relying on something over double my age.

[CowPunk]

Quote: Originally Posted by Cobra GT Dextron III oil is brown if he does not have the Ford oil in it. And it sounds like your tranny has expired. It’s probably a coincident after changing the module too. When you took the first module off did any oil come out of it? Does your tranny have a shift kit in it that could explain the hard shifts? Also the pump could have gone out, in that case you will have to recycle it.

Oops, sorry. The tranny is probably the original, or at least a replacement of the original. There was no special shift kits or anything. It wasn't a hard shift unless I floored it, then I had to back off before it would shift.