C4 Question..what did I miss?

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by Turbo II, Dec 4, 2003.

  1. Well the C4 finally packed it in on the Ghia last weekend so I pulled it and did a quick dismantle on it.

    Symptoms were:

    1) overheating (even the shifter handle would get warm :( )
    2) when shifting into drive from either park or reverse the transmission would often not engage at all particularly after it had been driven for a while.
    3) reverse was never affected, always worked fine

    The rebuild consisted of new seals on the servos, new input and output shaft seals and bushings, new rings on the govenor and new clutches ands steels for both the reverse/high and forward clutches. As I suspected the forward clutches were cooked..almost no material on them at all. The valve body was dissasembled, cleaned and one of the two check balls replaced. The other was smaller and did not match any of the new ones in the kit. (of course my manual showed a completley different valve body :mad: )

    Now my problem, it certainly works better (no overheating now), BUT, the damn thing still want's to slip or not engage drive when it's first started in the morning (it's been quite cold lately) Once it's in motion it will be fine for the rest of the day. What did I miss or fail to do? Is the valve body at fault or is there still a problem with the forward clutches?

    Really can't afford a pro shop to do it, that's why I "attempted" a repair myself...maybe not my wisest decision but did learn a little more about autos.

    Ideas? :shrug:

  2. Sounds like it could be a front pump issue. If the front pump isn't moving the proper amount of fluid, you won't get proper engagement. It sounds to me like the pump took a dump, then the clutches overheated from not enough fluid pressure to lock them completely, and wiped out the trans. Now you've got all new stuff in there, so it's engaging "better", but most likely still has the same pump issue and will head down the same path. Just my 2 cents, I've gone a lot of trans work in the past.
  3. Thanks, So do you happen to know what kind of pressures to expect in a normally operating C4?. I do have a MAC transmission pressure gauge kicking around, just never used it. :doh:

    Is it hooked into the output (forward) cooling line? and at what rpm/gear should I be taking readings?

    Looks like I'll be yanking it back out real soon :(

    Thanks for any advice

  4. the c4 has a port for testing transmission pressure... I think it's in front of the shift linkage. I had a guy with something like you were describing... his fluid was low, check that, and then make sure the bands are adjusted correctly, if those are fine, and they probably are, you could have pump issues, or maybe even valvebody issues
  5. I think Sal might have something with the pump. I bought a pump from a local shop, 45$ US for a rebuilt unit. I doubt you'll find a guy like I have to deal with but... I talked to him a explaned my lack of cash and told him I was doing it myself. He said, "Cool, a C4 is an easy trans to work on and if I had any questions stop around." That and he GAVE me a thin snap ring to allow the use of 5 clutchs in the front drum. Super nice guy! But youmight want to look into the pump. Did you get all of the seals replaced in the forward clutch? Removing the apply piston, and did you clean out and verify the operation of the apply piston with air? Just asking questions.....

  6. Thanks all,

    Parthos: Thanks, I'm going to find that tester and give it a chec this weekend. Correct pressures anyone? :shrug:

    Tim: I am fearing the piston may be the problem now, being in a major rush (could only use the borrowed, heated garage for one day) I did not have time to get the right tool to compress the spring and replace the seals on the piston. May be my big mistake, my flawed? logic was if the car remained mobile even with the clutches worn to the point of just metal to metal contact (they were toast!) that the piston was still supplying enough pressure. Stupidly I also skipped the operational test since the heated garage had no air (my -20 garage of course does :p )

    The pump appeared ok, but the pressure check will verify.

    Looks like doing things in a rush that I've never done before will bite me in the a$$. I'll have to take it easy on the car for a few weeks untill I can borrow the space again, pull it, and do it right this time. At least this time around it should go faster :)

  7. Francis,
    When I get home I'll check the manual and get you the pressures. Most likely it is the seals have gotten hard over time and when they are cold they will bleed off and not seal for $hit. Your thinking might be a bit flawed, if the clutches were toastred they weren't getting enough apply pressure to keep them from slipping that is prolly why they got fried.
    You don't REALLY need and special tools I just used teo "C" clamps very CAREFULLY to compress the spring and get the locking ring off. If you need me to scan a couple of pages of my Haynes Ford auto trans tech manual and get them to you I will. Let me know. But I bet you will need to change out those piston seals before you get a solution.

  8. I had the bottem of the pan get bent up and blocked the pickup.
  9. C4 oil pressure test, all with engine idling, and breaks applied

    Neutral 50 to 90; Drive 60 to 90; 2nd or 1st 90 to 110; reverse 150 to 180 psi.

  10. Thanks! :nice:

    Exactly the same specs Tim emailed me last night. :)

    Found the tester hanging in my Dad's garden shed today (exactly where I left it 19 years ago! :p ) Hopefully get a chance to check out the car within the next day or two.


    BTW, should I stick with the deeper pickup (MII specific?) or is it ok or preferable to use the generic one? I checked with my parts store and the deeper MII one was not in stock and I would have to wait several weeks (I just gave the old one a good solvent cleaning and re-used it last time) :shrug:
  11. Does the tranny have the deeper pan on it? If it does I would say you want to put the II filter in it. That would make sure you keep sucking straight from the bottom. It probably wont matter though really.