c4 woes

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by DangerousII, Sep 20, 2011.


  1. DangerousII

    DangerousII New Member

    Joined:
    May 17, 2011
    Messages:
    21
    Likes Received:
    1
    Trophy Points:
    0
    Alrighty, So I think my tranny is on its last leg...

    here are my symptoms,

    When car is cold, hasnt been driven for atleast 4 hours, when put into drive, if i hit a bump, or step on the brakes, the transmssion looses line pressure and comes out of gear.. (transmission is full of fluid)

    When sitting at a stop light in drive, or 1'st i have to put excessive pressure on the pedal to hold the car stopped, normal pressure can be applied if i have the car stopped in 2nd gear (idle is set to 850 in park)

    When shifting from 2nd - third it will give me a big slip..

    I know the slipping third gear shift is a typical c4 issue, what about the other 2?

    i have a fully built reverse manual valvebody C4 mated to my other high horsepower motor but it has a 3500 stall, so i am reluctant to swap those two trannys untill i can afford another converter..

    Is there anyhting i can do to prolong the life of this tranny, or deal with mainly the loosing line pressure when cold issue?
    I just want to limp it into winter...
  2. James75

    James75 Member

    Joined:
    Jan 14, 2008
    Messages:
    60
    Likes Received:
    0
    Trophy Points:
    6
    Hey DangerousII, do the symptoms go away after it's warmed up? If so I suspect the clutches are worn out. How does the fluid look, normal pinkish/red or tan/brownish? Is the pan bent upwards into the pickup? Is the screen clogged? I've burnt up many c4's and they slip like hell cold, but never had a problem holding it stopped in 1st or drive, that ones a mystery to me too.
  3. DangerousII

    DangerousII New Member

    Joined:
    May 17, 2011
    Messages:
    21
    Likes Received:
    1
    Trophy Points:
    0
    fluid is a red, no smell of burnt, it dosent slip out of gear, it looses line pressure and dis'engages out of drive/2nd/1st, you bring the rmp up a couple times and clunk back into gear.. engine/tranny are on solid mounts..

    it slips into third almost all the time, sometimes it will have a good day and shift hard for a bit..
  4. COBRA 7

    COBRA 7 Founding Member

    Joined:
    May 19, 2000
    Messages:
    454
    Likes Received:
    3
    Trophy Points:
    19
    In cold weather, My c-4 likes to be a little over full on the dipstick.

    Add 1/2 a quart and see if it helps.

    Maybe dipstick not real accurate.
  5. DangerousII

    DangerousII New Member

    Joined:
    May 17, 2011
    Messages:
    21
    Likes Received:
    1
    Trophy Points:
    0
    sorry guys, added a buncha lucas tranny fix type **** and it stopped loosing pressure cold, but it still slips going into 3rd horribly, and feels like seccond dosent quite have the grab anymore.. its on its way out..

    So, I want to build a c4 That rattles my teeth, breaks my back, and and knocks my head off the roll bar when it hits seccond and third gear.. what do you guys reccomend internals wise?
  6. MUSTANG J

    MUSTANG J Member

    Joined:
    Dec 29, 2006
    Messages:
    357
    Likes Received:
    0
    Trophy Points:
    16
    The B&M "Transkit" works good. I managed to rebuild it myself with the great instructions in the kit. The C4 is easier then most Automatics to rebuild. No special tools required. A C-clip removal tool is the only "special" tool required. Make sure you get the proper filter, last time I got lazy, had a shop rebuild it and they used a generic C4 filter. The fluid pick-up was pressed up against the pan, how it got any fluid I will never know. Note: getting someone to rebuild your automatic transmission cost a lot of money for a reason, it is a BIG time consuming job. Took me a couple of days just to clean all the burnt clutch off of everything, I have more time then money though LOL.

    B&M 50231 - B&M Transkits - Overview - SummitRacing.com
  7. cobraii351

    cobraii351 Founding Member

    Joined:
    Jan 10, 2000
    Messages:
    1,102
    Likes Received:
    0
    Trophy Points:
    37
    Yeah the c4 is a simple trans to do. And fairly easy to make hold more power. Extra clutches and a good servo a C4 will live a happy life behind a stout small block. Good job on the rebuild.

    Tim
  8. MUSTANG J

    MUSTANG J Member

    Joined:
    Dec 29, 2006
    Messages:
    357
    Likes Received:
    0
    Trophy Points:
    16
    Opps I forgot that part. If it is an actual Mustang II trans, make sure you get a forward clutch drum that holds more frictions. With 139HP on tap Ford got stingy with the poor Mustang II C4. I bought the drum for peanuts @ a local transmission repair shop.

Share This Page