Okay remember awhile back I was telling you all about swapping the Chevy engine that came in my truck for the 289 that my husband pulled out of his 65 Mustang. Well the 289 once installed jumped back to life with no hiccups, even after it had been stored in our shop for 10+ years. Now you can imagine our excitement to try this baby out, Right! Wrong!
That C4 tranny apparently did not do as well as the engine during its dormat life, it would go in reverse, then start out pretty smooth in 1st, but to 2nd it was rough, then 3rd was pretty much non existing. By the time we got back to the house (which wasn't but a block or so) the fluid literally boiled out of the pan. So on with some research, we found that when one re-installs a tran that was bone dry, you should add the fluid with the engine running. ( Yes we put fluid in the converter) So we made sure all the first fluid was drained and started adding fresh fluid with the truck running (and on jack stands) now we are to the point where all gears are working pretty smoothly. So we take another test run, shifts out of first great, second again smooth, going along in 3rd no problems. Back to the house we go, and think well I be damn that was the ticket.
Next day, start up the truck back out of the shop no problem, shift into drive, and the same scenario as our first attempt. What the ****
Now I'm to the point of putting this trucks out of it MISERY... Needless to say we just went to the house! A few weeks later we find a old workmate has a 1981 Fairmont and it just so happens to have a C4 tran. but we will have to swap out the smaller bellhousing for the larger one on the other tran. When we test drove the Fairmont it ran smooth as silk, we have yet to put that tran in due to the Alabama wishy washy weather of 70 one day and 30 the next. So if any of you Automatic Trans guys who know more than we do, by all means give me your tips.
Sorry I ddn't keep you posted with the progress, but I just get to involved with problems at hand. Oh and here is another note, when the fluid boiled out of the pan it looked like used engine oil, so we pretty much decided this trans is worthless, besides the Fairmont was a better deal than rebuilding. Thanks for letting me take it out on ya"ll

 

Yeah!, I'm familiar with the story..+Ran fine 10 years ago, doesn't do squat now...
Always best to swap while it's still "warm"....
Still...it's alot of work .

 

Hey Kathy, when you change the bellhousing on that C4 make sure you change the input shaft from the trans. C4's have 3 different ones that I know of, I bought this lesson the hard way. DONT ASK! Just remember to change it. The input shaft comes out real easy all you have to do is pull it out and put it in the new one.


Hope this helps

 

Thanks Terry, your always there when needed!

 

you an buy a new one from jegs for like 500 bucks

 

I had quite a scare running my C4 without fluid..Shifting into drive, lurching, and then...nothing..Vroom vroom, no movement.

Pulled the stick out, bone dry.

Throwing some Type F fixed it right up. It's a testament to these old beauties.

 

it'll be alright ! mine is almost always giving me some sort of new hiccup . i just use a few choice words , walk away , then go attempt to fix it if i have time . when i go for a drive again the bad memories just seem to go away .

 

You're very welcome Kathy!! As I said I learned that one the hard way. I forgot to tell you, and someone else already did to use Type F fluid. Also, you may want to replace the modulator valve on the C4 you're goin to put in. They're bad about goin bad from just sitting. A bad modulator valve will cause a trans to NOT shift at all, or shift real wierd. Be careful and dont loose the pin or plunger whatever you want to call it that goes in behind the modulator valve. It's what pushes on the modulator valve. Also do you have a good solid manifold vacuum source connected to the modulator valve? If you dont have enough vacuum, or it's throttle vacuum, it will shift wierd. I was half asleep last night when I posted to you, so since then I remembered a few more things to tell you.

GOD bless

 

Just wanted to let you all know I appreciate that I can rely on you to always give some solid info.

Terry to answer your info, yes we have a solid vacume line, and when we test drove the Fairmont the tran in it shifted smooth. But here is another question, at some point in time Fords changed fluid type for the C4 from Type F to mercron. According to the dipstick on the Fairmont, it says to use CJ fluid, I have read somewhere about CJ fluid but just what is it? Ok quite laughing I know it is a Transmission fluid, but is it considerd mercron or what?

Anyways I will get a new modulator and change out the input shaft, and check and double check everything else before this one gets a test drive.

Thanks again guys your wonderfull people!!!

 

Mercon: 1977 and later C6's / 1980 and later on everything else.

C4AZ-7A377-B .. Modulator Valve (Motorcraft TM-2) ~ 1965/71 C4

 

Welcome to the world of hot rodding! Now what's the problem?


This is just part of the deal when working on these things. I had my '53 all done, (or so I thought), took it out on it's maiden voyage, all 18 miles of it, and the "rebuilt" C6 blew up. I had to wait 9 months to get the funds together and have one built...and I mean it was built. Extra clutches, manual/automatic valve body, stage-2 shift kit, and an 1800 rpm torque converter. The 410 can throw whatever it want's at it now, it's all good

 

In the words of Tim Allen: ARRRRRRRRRRRRRR ARRRRRRRRRRRRRRRRR!!

 

Hey Number Dummy thanks!! I forgot what year the change over was?? I'm very glad you straightened us all out! I remembered that there was a type F for a while, and then they went to Mercon.

 

NumberDummy, I gotch ya on the Mercon for the 1981 tran that I'm about to put into my Truck, Thanks for clearing that up for me.

Thanks to all you guys for sharing you trans stories, Fatfndr I would have had a come apart if the first tran blew up!!!

I'm hoping that Sunday we can get this other one in, I will certainly let ya"l know how everything goes??????????????????

Kathy

 

Inside the modulator valve is the "throttle control rod."

Be careful when you remove the old modulator...the rod will fall out. Without that rod, the modulator is worthless...the trans won't shift without it.
Just in case...

C4AZ-7A380-A .. Throttle Control Rod ~ 1 11/16" long / 1/8" in diameter.

Used on all C4's, 1964 thru 1972 with the threaded type mod valve (C4AZ-7A377-B).

Some 1972 and later mod valves are the push in type.