SHO Transaxle Drain Plug Installation

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This modification will allow you easily drain all the fluid from the MTX-IV manual transaxle. All information contained herein as well as the location drawing was provided by Gary Morrell Senior Test Engineer Ford Motor Company Colorado Springs, Colorado



The modification is performed entirely at the vehicle owner's risk and will not be warranteed by Ford Motor Company, its subsidiaries, the Ford Dealer Service Organization, or any Ford Motor Company employee. Damage resulting to the vehicle as a direct or indirect result of this modification is the responsibility of the vehicle owner.

Parts/tools required:

  • an 1/4"-18 NPT brass hex head pipe plug
  • an 1/4"-18 NPT pipe tap
  • a 7/16" drill bit and a drill (3/8" drill recommended)
  • some teflon thread tape or teflon pipe dope


  1. Chock the rear wheels and raise the front end of the SHO a sufficient distance to allow the length of the drill bit plus the drill motor to fit comfortably between the lower transaxle surface and the garage floor. Allow some additional room for a shallow drain pan, there will be a slight mess. The car should be level side-to-side and supported by safety stands.
  2. (Optional) Drain as much transaxle fluid as possible by removing the fork interlock retaining pin bolt (13mm) on the lower front face of the transaxle. CAUTION: be sure not to move the shift linkage while this pin is removed, as transmission internals will be dislocated. Shop manual recommends that the threads be coated with a teflon containing pipe dope, torque the pin to 12 to 15 lb-ft.
  3. Using the drawing provided, locate and mark the drain plug location on the raised area on the transaxle's lower surface. This area is the lowest part of the transaxle case, contains no reinforcements, and is relatively far away from any of the transmission internals.
  4. (This is the messy part... You may want to wrap a rag around the drill motor and have your drain pan ready, when the bit breaks thru the case you're going the get 3 quarts of ATF in your face, 1 and 1/2 quarts if you performed step 2). Drill the 7/16" hole perpendicular to the case surface at the mark, don't push too hard, the aluminum drills rather easily and you don't want the bit to go up inside the transaxle when it breaks thru. Now remove the transaxle fill plug.
    Don't worry about the small aluminum filings that may end up on the inside of the hole that you drilled; they won't damage the steel internals of the transaxle, and are far softer than the fragments of steel that chip off of the internals during normal use!
  5. Allow the fluid to drain.
  6. Tap the drilled hole with the 1/4-18 pipe tap, don't tap too deep, pipe taps are tapered and will enlarge the hole too much to get a good seal with the plug. Tap just deep enough that 4 or 5 threads are showing when the plug is threaded in by hand.
  7. Put a few wraps of teflon thread tape or some teflon pipe dope on the brass plug and thread it in, tighten to about 10 ft-lbs, no more.
  8. Refill the transaxle with 3.1 quarts, US, (6.2 pints, or 2.95 liters) of your favorite fluid, such as Redline MTL or MOBIL 1 ATF. The fill plug is toward the top of the transaxle, facing the front of the vehicle. It is a 3/8" square recessed drive plug. You will need to purchase or fabricate an appropriate funnel in order to reach the fill plug.
  9. Install the fill plug and check for leaks. Lower the car and go out and enjoy some nice crisp shifts.
  • Avoid using low friction additives in the MTX-IV transaxle such as PTFE or molybdenum disulphide compounds. These will reduce friction so much that the synchronizers will not function and shifting may become quite difficult.

Helpful Hints

  • Take an old antifreeze jug and cut it about four inches deep. On one end of the bottom cut a hole about 3/4 in. in diameter, on the other put a piece of duct tape and drill a hole thru the tape and bottom of the jug. The tape helps stop fluid from running down into the drill. Then place the oil draining bucket so the 3/4 hole is over the bucket and the drill bit in the proper location on the transmission. Then drill the hole, and watch the 1.5 qts. of fluid drain into the bucket instead of into your face, and thinking "Damn, I'm smart :)".
  • Find a piece of aluminum and drill a test hole. Tap it and test the plug to get a feel for how deep you need to tap the hole in the transmission to make the plug go in as deep as you want it to.