Hi folks, I'm new here but I'm sure I'll be a regular in no time. Sorry if there's already an answer buried in the site somewhere, but I've searched and can't find it. Here's the deal - I just bought a 1965 Comet and it runs fine except this one problem - it won't shift up until I let off the gas. I hope this doesn't mean I need to rebuild the whole C4 transmission...any help is greatly appreciated!
how old is the modulator valve?whens the last time the fluid/filter has been changed?has the bands ever been adjusted?
Unfortunately I have no answers to any of those questions. I'll definitely change the fluid and filter, and from what I've gathered, the modulator valve is easy to replace...but I have no idea what to look for or where to start. Also, is it easy to adjust the bands? Sorry if my questions seem novice; the most experience I've had with transmissions consists of changing the fluid/filter. I'll be getting the Haynes manual soon but I'd like to start enjoying my car asap! Thanks for the help...
James, Changing fluid - type "F" only - drain the converter if it has a drain plug. You can clean the screen in a C4 - change it only if it is damaged There are two bands to adjust but I doubt it will solve the shift problem: 1. jack the car up and block it or use stands - high enough that you can get under it to the transmission on both sides. 2. You will need a 3/8 12 point socket (or a 5/16" square or eight point), a torque wrench that will work at 10 foot pounds, and a 3/4" box end wrench. 3. Loosen the front lock nut (3/4") and tighten the adjusting screw (5/16" square) to 10 foot pounds. Back it out 1 1/2 turns. Tighten the locknut while you hold the adjuster so it doesn't turn. (about 35 foot pounds for the lock nut) 4. Loosen the rear locknut (3/4") and tighten the adjusting screw (5/16" square) to 10 foot pounds. Back it out 3 turns. Tighten the locknut while you hold the adjuster so it doesn't turn. (about 35 foot pounds for the locknut) For the modulator: Get a white stripe modulator. You will need a thin wrench to fit the modulator (I don't remember what size but it has to be thin to fit). Jack the car up from the rear as high as you can. Place blocks or stands. On the rear - passenger side is the modulator. Disconnect the vacuum line and unscrew the modulator from the case. the pin will come out with the modulator - remove the pin and install it in the new modulator. Place the gasket on the new modulator and screw the modulator and pin into the case. Connect the vacuum line. Fill the C4: put two to three quarts of type "F" fluid in the transmission. Start the car and let it idle in drive. finish filling the transmission with type "F" fluid by adding a quart and checking the level untill it is half way between the ADD and FILL marks on the dipstick. shift it through the gears a few times and then put it back in Park. Check the fluid and fill to 1/2 way between the ADD and FULL marks. The C4 should NEVER be over filled - it will puke oil all over if you do. The only time the oil level should be at the FULL mark is when it is hot.
