Pan installation must happen...
Pan installation must happen by the book to prevent leaks. Never use sealer on a transmission pan gasket. Transmission fluid is a thin detergent type that finds its way past every seal and gasket if you're not careful.
Never overtighten pan bolts....
Never overtighten pan bolts. Tighten to torque specifications as directed by the Ford Shop Manual. Overtighten can distort the pan, causing leaks. Use a synthetic gasket, not cork, and evenly tighten the bolts. This is a new reproduction pan from National Parts Depot.
When you change fluid, drain...
When you change fluid, drain the torque converter every other fluid change to avoid shocking transmission seals. Never drain the converter completely. Leave some fluid to keep the front pump primed. Stick with the same brand and type of fluid each time. This is suggested for fluid, friction, and seal compatibility and the sensitive nature of your transmission's hydraulic control system.
Follow Ford's instructions...
Follow Ford's instructions for band adjustment to the letter for optimum results. The tighter you adjust bands, the firmer the shift. However, this is not always advised because everyone has a different opinion of what "tight" is.
This is the low-reverse band...
This is the low-reverse band adjustment located on the right rear side, just ahead of the crossmember. Loosen the locknut, tighten the band 10-12 ft-lbs, then back off the adjustment two full turns. Tighten the locknut. Torquing the adjustment 10-12 ft-lbs seats the band; backing off relaxes the band to proper drum clearance.
Intermediate band adjustment...
Intermediate band adjustment is at the left front portion of the case. Loosen the locknut, tighten adjustment 10-12 ft-lbs, then back off 1 to 1-1/2 turns and retighten the locknut. Adjustments are best performed with a warm transmission.
These are the C4's two bands-...
These are the C4's two bands- low-reverse band is on top with the intermediate band on the bottom. The bands work like clutches, holding and releasing clutch drums. They are activated by hydraulic servos fore and aft in the case.
The C4 was equipped with two...
The C4 was equipped with two basic types of valve bodies-first generation "Dual Range" for '64-'66 and second generation P-R-N-D-2-1 from '67-'82. If you're not concerned about originality, it is suggested you opt for the '67-'82 valve body along with a corresponding change in shifters because detent location is different.
When performing transmission...
When performing transmission service or a complete rebuild, it is suggested you install a B&M shift improvement kit, which is simple to install. The kits firm upshifts, not only for increased performance but also to provide longer transmission life because they reduce or eliminate clutch and band slippage, which creates heat and puts friction material in the fluid to risk damage to the clutch piston seals.
This is the vacuum modulator,...
This is the vacuum modulator, which either screws in or is retained with a clamp depending the C4's vintage. To adjust the vacuum modulator, which controls shift points, remove the vacuum hose and use a small common screwdriver to make adjustments clockwise or counterclockwise, but never more than one-quarter turn at a time. Never go more than four turns in either direction. Clockwise, you increase diaphragm spring pressure, which delays upshifts and makes them firm. Counterclockwise makes shifts softer and earlier. Check the vacuum hose for leaks, which can cause both engine and transmission performance issues.
Here's the neutral safety...
Here's the neutral safety switch and kick-down cable. If you experience a no-start condition and have to cycle the shifter to get a start, the neutral safety switch is to blame and should be either adjusted or replaced.
If your classic Mustang is...
If your classic Mustang is a weekend cruiser or daily driver, a stock steel pan is adequate for both cooling and fluid capacity. If you're going racing or operating in a harsh environment, opt for a deep sump finned aluminum pan (right) for added capacity and improved cooling. Never change fluid without changing the filter.
Typical C4 leakage points...
Typical C4 leakage points are the pan gasket along with front pump and output shaft yoke seals. Whenever you rebuild a C4, make sure these seals get abundant lubrication. Transmission assembly lube is perfect for these seals.
This keeps them pliable for...
This keeps them pliable for dry start-up. What kills seals more than anything is long storage periods followed by dry start-ups. Mixing transmission fluid types can also damage seals. Drive your Mustang at least once a week on the open road to keep everything happy.
Fluid Servicing Facts
Always use Type F in a C4 transmission (as long as you can find it) and stick with one brand. If you cannot find Type F, go with Mercon V, a synthetic automatic transmission fluid designed to work with all types of automatics and fluids.
With the torque converter and pan empty, the C4 requires eight quarts of fluid. Add five quarts first, then check the dipstick reading with the car on a level surface. With fluid showing on the dipstick at or below the "ADD" mark, start the engine. With the engine at idle, check fluid level, which should be well below the ADD mark. With the engine at operating temperature, check the fluid level again. It should have expanded to the ADD mark. Add fluid one quart at a time until it reaches the FULL mark. It is suggested you not overfill, but instead add until fluid is between the ADD and FULL marks. Take a spin and get your C4 to operating temperature, then check fluid level again. Add fluid to the FULL mark. After an open road drive, examine fluid consistency and color. If it is foamy, the transmission is overfilled. It's always best to underfill, then add as necessary. If you overfill, you will have to either siphon fluid out or loosen the pan. Never check transmission fluid level cold; always check at operating temperature.
Remember, your Mustang's torque converter holds nearly four quarts, or half of the transmission's fluid capacity. If you haven't drained the torque converter, all you will need is approximately four quarts.