Ford C6/NP205 removal and re-installation guide

By John Bauer

Disclaimer: The following document outlines procedures
for removing and installing a Ford C6 with New Process 205 transmission
and transfer case. The author assumes no liability for any direct
or indirect damage, injury, loss of property or life resulting
from the use of these instructions. The author assumes no liability
for the contents of this document or its accuracy. Follow these
procedures at your own risk.

Credits: I wish to thank Jason K. Schechner, Gary
Peters, and Drew Beatty for project technical advice.

Goal of this document:

Provide a straight forward method of allowing a single
individual to remove and reinstall a Ford C6 transmission and
New Process 205 transfer case for diagnostic/repair of unit by
expert service technician.

Vehicle used as model to create this document:

Heavily customized 1977 Ford E250 4wd drive van with
460/C6/NP205 + dana 60 front and rear axles. Unless otherwise
noted, any van specific terminology has been avoided in order
to provide as universal a guide as possible.

Tools required:

  • general collection of automotive wrenches, sockets,
    screwdrivers, etc.

  • general automotive rolling floor jack with removable
    jack top plate for use with transmission adapter

  • general transmission jack adapter to fit above
    rolling floor jack (see Note 1)

    • OR
  • transmission specific jack designed especially
    for automotive transmission removal

  • large catch basin for old transmission fluid
    (bigger the better, it goes everywhere)

  • two bolts approx. 4" long that match the
    threads of the top two bolts holding the C6 bell housing to the
    block (used in re-installation as helpers)

  • two bolts approx. 3-4" long with plenty
    of thread that match the threads of the top two bolts that hold
    the NP205 to the rear of the C6 (used in re-installation as helpers)

  • small ¼" blocks of wood or pieces of
    metal to act as shims/spacers if your transmission jack or adapter
    does not allow left/right movement (mine didn’t)

  • heavy chain or bar that can span the distance
    between both frame members and fully support the weight of transmission
    if need be. The ability to clamp or bolt this support item is
    a must since it will be used to support most of the weight of
    the transmission at a few points in the removal and installation
    process.

  • Kitty Litter or other such oil spill clean up
    agent.

  • RTV Gasket Maker type product, comes in a toothpaste
    like tube from your basic parts store.

Removal Process:

  • Disconnect negative cable from battery.
  • Depending on the height of the frame of your
    vehicle you may need to raise and support a comfortable working
    height. Remember that the transmission jack must be able to reach
    the height of the raised vehicle. Also, the vehicle must be raised
    high enough to get the transmission out from under it. When you
    are comfortable your vehicle is securely lifted and supported,
    the actual removal process can begin.

  • If the vehicle is a van, remove the engine "dog
    house" cover for access to bolts, etc.

  • Remove both front and rear drive shafts and set
    aside. May wish to be careful with universal joint caps for they
    tend to fall off at the most inconvenient times.

  • Remove the electrical connection for the reverse
    lights and neutral start switch near the transmission shift arm
    approximately under the drivers seat.

  • Using a 7/16" wrench, remove the bolt that
    holds the speedometer cable/gear in the transfer case. It may
    be a good idea to put the bolt back into the transfer case for
    safe keeping.

  • Disconnect shift lever coming from column (or
    added floor shifter, etc.) to the transmission shift arm. It
    maybe handy to put the retaining bolt right back on the arm to
    keep from losing it.

  • Unbolt the transmission tube holding bolt from
    the passenger side engine block. Then lift complete tube out
    of vehicle. Bottom of the tube has an o ring that may require
    a bit of twisting and jiggling to break loose.

  • Disconnect the vacuum line that goes from the
    rear of the engine intake manifold to the vacuum modulator on
    the rear of the C6′s main body, passenger side just past the end
    of the fluid pan. I removed whole vacuum line to avoid getting
    it caught on anything during removal.

  • Remove the two bolts (top bolt head points to
    the rear of the vehicle, bottom bolt head points to the front)
    that connect the starter motor to the C6 bell housing. Set away
    from the transmission area. The power lead from the starter solenoid
    may need to be disconnected if the starter motor can’t be moved
    away from the work area.

  • Now the messy part. Prepare to drain fluid from
    C6 fluid pan. Prepare large catch basin underneath fluid pan.
    Note: when the vehicle used as a model for this document was
    secured for this removal process, the C6 was naturally tilting
    down towards the rear of the vehicle. Thus, gravity would cause
    most of the fluid to drain from the rear of the pan in this instance
    proved best. With this in mind, positioning the catch basin towards
    the rear of the pan, in this example, proved best. Now, using
    ½" socket, slowly loosen bolts around pan approximately
    one half turn. Once all bolts are broke loose, loosen the bolts
    on the rear half of the pan so that the fluid begins to spill
    out between the pan and the transmission. Keep working all the
    bolts loose while the pan continues to spill out fluid. Once
    most of the pan fluid has spilled into the basin, remove all bolts
    from the pan, lower pan, pour remaining pan fluid into basin.
    At this point, I was running for the Kitty Litter for I just
    made a massive mess during this process. Have no fear if the
    cork gasket between the pan and the C6 gets cut/torn, replacements
    are cheap and provide piece of mind.

  • After relaxing from the cleanup of the work area,
    the pan can be re-attached to the C6 somewhat solidly (use all
    the bolts, don’t put just one or two to hold it in place) for
    the pan will be used as the holding spot for the transmission
    jack/adapter in future steps.

  • Now locate the transmission cooler lines on the
    passenger side of the transmission. One close to the bell housing
    the other at the rear of the body of the C6 just before the rear
    shaft housing. Loosen the fittings and pull metal tube and fitting
    away from the C6. Be prepared for the fluid in the cooler lines
    to start slowly running out both ends. Drip pan helpful underneath
    to catch the mess.

  • The next step is to drain the fluid from the
    torque converter. I made the mistake of not draining it, makes
    the removal process much messier and the torque converter is 4-5
    quarts of fluid heavier.

  • At the base of the front of the bell housing
    is a plate held in place by two small bolts. This plate is to
    allow access to the torque converter and flex plate. Remove these
    two bolts and the plate. The below graphic may be helpful, for
    my explanation may be poor:

  • Figure 1
  • (Graphic looking from front of vehicle towards
    rear)

    • A = starter motor mount location
    • B = cover plate in question
    • C = bolts holding cover plate in place
  • Once plate B is removed, the engine side of the
    flex plate will be visible.

  • The donut shaped (more technically, torus shaped)
    torque converter has four threaded studs as part of the unit that
    go through the flex plate. The 9/16′s nuts that attach the converter
    to the flex plate are on the engine side of the flex plate, accessible
    through the small cover plate (B in above graphic). Engine rotation
    will be required to expose all four bolts as well as the drain
    plug. See Note 2 for possible engine rotation method.

  • Rotate the engine to expose the torque converter
    drain plug. It is usually found through a hole in the flex plate
    approximately one inch from one of the four bolts, but drain location
    may vary.

  • Prepare to catch the few quarts of fluid left
    in the converter and remove the drain plug.

  • Replace the drain plug
  • Rotate the engine and remove the four nuts holding
    the converter to the flex plate. Save nuts for later reinstallation.

  • Now time to remove the transfer case.
  • There is a rod and cotter pin that connects the
    shift arm to the actuating arm, remove the pin and rod so the
    shift lever can hang free and the transfer case is only connected
    to the vehicle by the bolts between the transfer case and the
    C6 rear shaft case.

  • Locate transmission jack/adapter just below transfer
    case.

  • Remove mounting bracket between frame and NP205
    if one is present.

  • Using a 9/16th socket or wrench, remove
    all the bolts that connect the transfer case to the C6 rear shaft
    case. Note any movement between the transfer case and the C6,
    the RTV gasket sealant and friction should keep the two together
    after all the bolts are removed. If they begin to separate, prepare
    to pull transfer case back from the transmission about 2 inches
    and set onto jack after last bolt is removed. Otherwise, pull
    transfer case back from the transmission about 2 inches and set
    onto jack, some light prying maybe required to loosen RTV gasket
    sealant.

  • Store transfer case at similar angle to installed
    position so the fluid remains in the transfer case and not all
    over a workbench, etc.

  • Position jack under C6 fluid pan, raise till
    just meets fluid pan, then attach chains or other safety options.
    Apply just a slight bit of upward tension for, in the next step,
    the holding bolts are removed thus the jack will support most
    of the weight of the C6.

  • Remove all bolts and completely remove the frame
    crossmember that supports the rear of the C6.

  • Loosen and remove bolts that connect the C6 to
    the engine. There should be two bolts facing the rear on the
    top, two facing the front on the bottom (near the removed small
    cover plate), and two on each side of the C6 facing the rear.

  • Begin to roll the jack towards the rear of the
    vehicle. Raise or lower the jack if there appears to be any tension
    between the flex plate and the torque converter. Moving the C6
    back from the engine about 2.5 inches should be enough to completely
    separate the transmission and the engine to where you can now
    move the transmission freely.

  • Feel free to remove the torque converter from
    the C6 by just pulling straight out. This will lighten the C6
    just a bit and reduce chances of the torque converter falling
    out and crashing to the floor at a later time.

  • If the jack can be lowered to allow rolling the
    C6 out from under the vehicle, skip to the end of this section,
    otherwise, the following are tips to not break your back when
    getting the C6 out from under the vehicle.

  • If the C6 and jack can’t be rolled from under
    the vehicle, try this option:

    • Raise the jack so the rear end of the C6 is above
      the bottom of the vehicle frame.

    • Connect a chain or strong steel bar between the
      two vehicle frame rails just under the rear shaft housing of the
      C6 butted up again the bolt hole flange at the very rear of the
      C6. You may wish to clamp the chain or bar to the frame to keep
      it from slipping.

    • Roll the jack so the bell housing or front of
      the C6 is close to one of the frame rails while the tail or rear
      end of the C6 is still in the center of the vehicle just above
      the steel bar or chain.

    • Place blocks under the bell housing of the C6
      so the jack can be lowered and the transmission is now resting
      on the bar/chain in the rear and the blocks in front.

    • Move the floor jack to the opposite frame rail,
      parallel with the C6, raise to approximately the height of the
      blocks holding the C6.

    • NOTE: the following step assumes the vehicle
      is a van, if a truck is involved, this procedure will need some
      modification.

    • Enter the vehicle, the engine "dog house"
      cover should expose the top of the C6 bell housing.

    • Grab the top of the bell housing, lift and swivel
      over above the floor jack. Set bell housing down on top of the
      floor jack.

    • Return underneath vehicle and lower jack to lowest
      point and remove blocks.

    • Return to the inside of the vehicle, grab bell
      housing, lift and swivel over to side of vehicle where blocks
      were and set on the ground. Bar/chain should still be supporting
      the rear weight of the C6.

    • Return underneath vehicle, position floor just
      at rear of C6 just before bar/chain. Lift jack to take the weight
      of the C6. Remove the bar/chain. Lower jack.

    • C6 should now be flat on the ground ready to
      be slid out from under vehicle.

Trip to the Shop:

  • Take your C6, torque converter and some fluid
    with you. Silver metal filings or other chunks can give the shop
    a good clue as to what is going on with your transmission/transfer
    case.

Return from the Shop:

  • Ask the shop to put the torque converter on while
    you watch.

  • Place a flat piece of steel or yard stick across
    the opening of the bell housing and measure the distance between
    the "yard stick" and the bolts that go into the flex
    plate on the torque converter. They should be about ¼"
    to 1/8" distance between the two. This is important for
    inevitably, the torque converter will slip out during reinstallation.

  • It may be worth testing the torque converter
    to verify it will mate correctly with the flex plate. The shop
    should be able to visibly compare the old and new torque converters,
    but a final check before installation may prove valuable. Follow
    Note 3 to re-install the converter.

Installation Process:

  • First step is to get the C6 with the torque converter
    installed back up on the jack. Use your favorite method or repeat
    in reverse the steps mentioned in the removal section of this
    document.

  • Spin the engine to ensure the torque converter
    drain plug hole in the flex place is on the bottom.

  • Elevate and position the C6 so that it is at
    the approximate height for installation and the same angle in
    both directions to the rear of the engine. If the transmission
    jack does not support left/right movement, you may need to use
    metal or wood shims to achieve the correct angle.

    • The above listed 4" bolts may be used to
      aid in this alignment process. If the vehicle in question is
      a van, the removed "dog house" should provide for easy
      access to the top two bolts between the C6 and engine. If the
      vehicle is not a van, some acrobatics may be required to align
      the bolts through the engine compartment.

    • One untested method recommended was to grind
      the heads off the bolts to a point, install the special bolts
      prior to lining up the C6 with the engine. Theoretically, the
      ground bolts would allow the bell housing to slide right into
      place.
  • Before proceeding, return to the "yard stick"
    and check the distance between the bell housing and the torque
    converter bolts. Ensure that they are the same distance as previously
    discovered at the shop. If the torque converter has slipped out,
    have no fear, check Note 3 on how to get it back in place.

  • WARNING! With extensive movement of the C6 prior
    to installation, the torque converter can disengage from the pump
    and be approximately one inch from fully seating in the transmission.
    At first glance, it may appear that everything is in place, but
    the "yard stick" is the best way to ensure the torque
    converter is fully installed. If it is not fully installed, then
    when the final tightening of the bolts that hold the C6 to the
    engine occurs, the torque converter circular flange with be pressed
    up against the C6 pump gear and cause both to be gouged and thus
    ruined.

  • Slide the C6 up to the flex plate but leave just
    enough distance to allow the torque converter to be rotated.
    The bell housing of the C6 will almost come in contact with the
    engine in this step.

  • Spin the torque converter so the drain plug is
    on the bottom.

  • By looking through the opening created by the
    removal of the small plate depicted by Figure 1 from the removal
    process, one of the holes in the flex plate for which the torque
    converter bolts pass through should be visible. Reach through
    the removed small plate opening and spin the converter to line
    up the bolt with the hole in the flex plate and ensure the drain
    plug is also going to pass through the designated hole in the
    flex plate.

  • If all is visibly lined up, feel free to push
    the C6 up to engine. The bolts on the top as well as the studs
    on the engine should aid in verifying complete mating of the C6
    and engine.

    • If the C6 and the engine are off slightly, it
      may be difficult to complete this process. If there is any binding
      during this process, pull the C6 back from the engine, perform
      the "yard stick" test on the converter, re-align and
      try again.

    • If everything is aligned correctly, there should
      be no noticeable binding during this process.
  • Return to where the torque converter can be seen
    through the removed small plate from Figure 1 above. With the
    C6 fully against the engine and the converter pushed all the way
    against the back of the bell housing, the bolts in the converter
    would be protruding through the flex plate, but not enough for
    the bolts to grab. Push the C6 back away from the engine just
    enough so the converter can be pulled out about ½" from
    its fully installed against the bell housing position. Then,
    slide the C6 back up against the engine, verifying the converter
    bolts extend through the flex enough for the bolts to grab. NOTE:
    There is some discrepancy regarding the need to pull the converter
    towards the flex plate the additional ½". Please consult
    your expert repair technician for input on this procedure.

  • With the C6 against the engine, loosely install
    the bolts between the C6 and the engine to keep the C6 in place.

  • Return to where the torque converter can be seen
    through the removed small plate from Figure 1 above. Final verification
    that the torque converter is properly installed, the converter
    studs should be just smaller than the stud hole in the flex plate.
    With fingers, the stud should be able to be moved left and right
    within the flex plate stud hole.

  • Repeat the process discussed in the removal process
    of this document for installing the four bolts that hold the converter
    to the flex plate.

  • Reinstall the small cover plate outlined in Figure
    1.

  • Torque transmission mounting bolts.
  • Plug back in the electrical connection for reverse
    lights and neutral safety switch.

  • Reconnect the shift lever mechanism.
  • Reconnect the transmission cooler lines.
  • Reconnect the vacuum diaphragm hose.
  • Reconnect the transmission filler tube, including
    bolting it back into the engine block. A new o ring should always
    be used and tt may be helpful to lubricate the o ring on the bottom
    of the filler tube with some automatic transmission fluid to allow
    it to slide into the C6.

  • Reinstall the rear cross member that supports
    the rear of the transmission.

  • Should be safe now to remove the transmission
    jack.

  • Now on to re-installing the transfer case (NP205)
  • Using the floor jack with regular circular adapter,
    place the NP205 on the jack and roll it in to position right behind
    the C6 in line for mounting.

  • Now position NP205 as close to original angled
    position on the jack. Might feel like three arms are needed to
    pull this off, but it can be done.

  • Slowly raise the jack to get the NP205 right
    behind the C6 rear shaft ready to slide into place.

  • Take two of the 3-4" bolts and slide them
    through the two top most holes of the C6 rear shaft and into the
    corresponding two bolt holes in the NP205. Turn a few times to
    ensure the two bolts will be able to support most of the weight
    of the NP205.

  • Rest for a few minutes and consider why one chooses
    to abuse themselves with these tasks before continuing.

  • Use the RTV gasket maker to cover the surface
    of the C6/NP205 mating area as indicated by the RTV usage directions.

  • Using a 9/16" socket, turn the bolts to
    pull the NP205 against the C6 rear shaft while pulling the jack
    with the NP205 to provide support.

  • As the NP205 nears the C6 rear shaft, ensure
    the studs on the NP205 are correctly lined up with the holes in
    the C6 rear shaft.

  • As the turning of the 3-4" bolts finally
    brings the C6 rear shaft into the NP205, general turning right/left
    of the rear output shaft of the NP205 may be needed to allow the
    splines to line up and provide complete mating of the NP205 and
    the C6.

  • Install the remaining bolts, then remove the
    extra long bolts, replacing with regular bolts. Do not tighten
    100%, leave a bit of slack to allow the RTV material to turn into
    a gasket. Return after indicated time by RTV usage directions
    to re-apply final bolt torque.

  • Reconnect speedometer cable/gear to NP205 using
    7/16" wrench.

  • Reconnect mounting bracket between frame and
    NP205 if one existed.

  • Remove jack.
  • Reconnect front and rear drive shafts.
  • Reinstall starter motor.

First Startup after Installation:

  • Fill transmission with 5-6 quarts of automatic
    transmission fluid.

  • Ensure vehicle is in Park
  • Startup vehicle
  • If possible grinding sound is heard, proceed
    to Note 4.

  • Otherwise, continue to add fluid until correct
    level.

    • 1976 Ford Truck Service manual lists C6 contains
      13.6 quarts of fluid.
  • Hopefully, stand back and admire a job well done
    and wonder why you went through all the effort.

NOTES:

Notes 1 – I had a 3 ton Sears rolling floor jack
and purchased a transmission adapter plate from mail order tool
house Northern Hydraulics for approx. $60. It was designed for
a 2 ton jack because the adapter dowel that came with the adapter
was smaller that the hole in the floor jack. It worked when the
weight of the transmission was applied to the adapter but you
may want to make sure your floor jack and adapter are designed
to work together. Included is a simple graphic of what it looks
like (not to scale):

Labels:

A = chains that wrap around the transmission body
and hold it securely to the adapter.

B = dowel that goes into the floor jack hole after
the jack plate is removed.

C = knob that turns the yellow screw drive that
allows tilting of transmission front to back

Note 2 – One method for engine rotation (others may
work better depending on application) is to remove all the spark
plugs, loosen accessory belts (alternator, power steering, etc.),
then use a 11/16′s socket and wrench on the center bolt in the
harmonic balancer. Turn the bolt clockwise (when looking at the
engine from the front of the vehicle). The socket wrench should
give you enough leverage to turn the engine without backbreaking
effort.

Note 3 – To ensure the torque converter is fully
installed and engages the C6 pump, then complete the following
steps:

  • Place torque converter inside bell housing on
    input shaft, slight rotating of jiggling may be required.

  • Start spinning the torque converter with one
    hand, while applying pressure to get the converter to go deeper
    into the bell housing. Without warning, the converter should
    go deeper into the bell housing by about an inch with any audible
    "clunk". The converter should be almost parallel with
    the outer edge of the bell housing with the bolts protruding out
    past the bell housing by a small degree.

  • Grab one of the bolts and begin to spin the converter
    at a comfortable speed (can be sped fairly quickly). Apply very
    slight pressure to encourage the converter to go further into
    the bell housing. May take 10-20 revolutions before completion.
    Again, but this time with an audible higher pitched "click"
    sound, the converter should engage the pump in the C6 and go deeper
    into the bell housing by another inch.

  • Using the original yard stick, check the distance
    between the bolts and the bell housing.

  • If original distance still is not achieved, fully
    remove the torque converter and repeat process. The finally step
    is the most critical for when the pump engages, the torque converter
    should be fully installed and confirmed by the yard stick test.

Note 4 – If a grinding sound it heard and it is coming
from the front of the C6/rear of the engine area, turn off the
engine. Remove starter and check ring gear on flex plate and
starter motor gear for possible new wear marks. If found, place
washer on starter bolts to pull the start back from the flex plate
by the width of the washer. Potential movement from the removal/reinstallation
process may have caused a slight change in distances that the
washer/spacer can correct. If this does not correct the problem,
contact transmission repair shop for other options.

Comments ()