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Discussion Starter #1
Hey Guys,
New to the forum, so this is my first post :)! However its not such a happy one that I hope someone can brighten my day with a solution that isnt brutal:
My old man and I picked up a 66 mustang for cheap because it didnt start and thus didnt run (never got to drive it). Got it home after sale, crossed the terminals on the starter and she flashed right up. Turns out some mice had eaten through the wire to the starter, along with a few other things. Fixed those things, and went to go for our first drive and...
The car goes into gear fine, and drives for about 5 seconds fine, then the transmission lets go altogether and you loose all forward drive. Engine revs, car does nothing, reverse and forward are useless. Turns the car off and put back into gear, nothing... Turn car off and wait 20 mins, put into reverse and she back up for about the same 5 seconds (back into the garage haha) then nothing.
Anyone heard of this or know what it could be? Havnt had any mustangs myself but the Dad has and he has never run into anything like this.
Oh, and we arnt sure how long it sat for with the PO, just knew he couldnt start it so...
Thanks in advance guys, sorry for the long post.
Regards
Krause
 

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Greetings,

You most likely have a clutch or band failure that has generated lots of debris in the bottom of the pan. When you start the unit, the pump starts drawing this through the filter plugging it in short order. Then the vehicle stops. Shut if off and the material starts to settle back down and allows it all to happen again.

Pull it out, disassemble, clean and inspect. Reassemble using parts as required. Install, make proper adjustments, and there you have it.

If you think this will be a long term project, you may try dropping the pan, cleaning it and the filter, and refill. You may get longer periods of movement that will get you through your restoration until it's time to do the transmission properly.

Don.
 

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Discussion Starter #3
Greetings,

You most likely have a clutch or band failure that has generated lots of debris in the bottom of the pan. When you start the unit, the pump starts drawing this through the filter plugging it in short order. Then the vehicle stops. Shut if off and the material starts to settle back down and allows it all to happen again.

Pull it out, disassemble, clean and inspect. Reassemble using parts as required. Install, make proper adjustments, and there you have it.

If you think this will be a long term project, you may try dropping the pan, cleaning it and the filter, and refill. You may get longer periods of movement that will get you through your restoration until it's time to do the transmission properly.

Don.
Thanks Don,
If we pull the pan and the transmission fliud is perfectly clear and free of debris, could it be something else? A sticking valve or loss of vacuum or something?
Regards
Krause
 

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Your tranny is blown. I know C4's, and I can tell you, Don't waste your time. If your fluid is all the way fully, and the car is just reving, Your tranny is a lost cause. Just make sure that it's not a linkage or Vacuum Modulator problem. Always check those issues first. You probably still have reverse though.. If you car drives fine in reverse, and does'nt in the forward gears, Then you've got a blown tranny. Reverse is always the last gear to go, I guess because it's isolated from the other gears.

My suggestion... Use your old tranny as a core and goto AAMCO and get a new rebuilt tranny.. unless you can find a '65/'66 Tranny from a good working 6cyl or V8 car. The trannies are interchangable, You just have to swap bell housings if it is a V8 tranny. Done it many times. A '67-'70 C4 will work too, but You will have to get a '67/'68 Shift indicator bezel for inside the car since the gearing is a little different.

Tony K.
 

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Discussion Starter #5
Your tranny is blown. I know C4's, and I can tell you, Don't waste your time. If your fluid is all the way fully, and the car is just reving, Your tranny is a lost cause. Just make sure that it's not a linkage or Vacuum Modulator problem. Always check those issues first. You probably still have reverse though.. If you car drives fine in reverse, and does'nt in the forward gears, Then you've got a blown tranny. Reverse is always the last gear to go, I guess because it's isolated from the other gears.

My suggestion... Use your old tranny as a core and goto AAMCO and get a new rebuilt tranny.. unless you can find a '65/'66 Tranny from a good working 6cyl or V8 car. The trannies are interchangable, You just have to swap bell housings if it is a V8 tranny. Done it many times. A '67-'70 C4 will work too, but You will have to get a '67/'68 Shift indicator bezel for inside the car since the gearing is a little different.

Tony K.
Tony,
Thanks for the help. It dosnt drive in reverse... It drives in reverse or forward for about 5-7 seconds, then nothing.
What are these vacuum modulator issues and how would i check them? Sorry for the newbie questions guys, not familiar with the C4, have been more of a Diesel/E4OD guy.
Regards
Krause
 

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Hi Krause,
I'm going to give the 1st grade version of how a C-4 works and with the experience you have, you can probably figure it out. The C-4 is a hydraulic machine. Nothing works if the pump ain't making fluid pressure.

The pump is simple and has only 2 cast iron gears that mesh and the teeth make pressure. The pump is driven by the outside of the torque converter which is bolted directly to the engine. Pump turns at engine RPM. The pump is pretty strong and could munch some pretty good size debris before shattering the cast gears.

The spinning/turning parts are almost all steel and look like they could go forever unless subjected to an EXTREME AMOUNT OF HEAT.

The spinning steel parts have several rubber o-rings and some steel seal rings too. Hydraulic pressure that makes everything work needs to get where it needs to be so all these rings need to seal or nothing will work correctly. Slivers of metal or AGE will destroy the rubber o-rings. The steel ones can crack or wear out.

In the rear there's very beefy, steel 1-way sprag clutch that turns in one direction and LOCKS-UP in the other. It is a tank so it would have to be beat with a sledge hammer to hurt it.

Now the most temperamental piece... The valve body. It is cast iron "BOX" that has all the little pistons in it, that change where the fluid pressure is directed, based on engine vacuum adjusted by the modulator canister and the rpm of the output shaft which operates a fluid pressure governor.

That's the best I can do at helping you see the BIG PICTURE so you might be able to detect the problem.
 

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Greetings,

Sorry to burst your bubble here Bryan, but the C4 valve body is not cast iron. You may be thinking of a GM THM 350, or 400. C4 valve body assembly is made up of two aluminum castings, and a steel separator plate.

In the upper casting are numerous spool valves, a rubber shuttle valve ball, and a servo check valve. The lower valve body, also known as the transfer plate does not contain any spool valves, but does contain a high speed kick down shuttle valve ball, a 2-1 reverse cutback TV shuttle valve ball, and a throttle pressure limit valve and spring.

There are several different valve body assy used in the Mustang. 1964 is a unique valve body, 65 and 66 use another style, 67 to 69 along with 70 Falcon use yet another. 70 and 71 another still, and 72 to 81 the latest style.

If I may, I would like to address Ne Faurora's concerns. The symptoms this unit displays are common for a unit that has sat for a period of time. I stand by my diagnosis of why it moves for short periods of time after sitting. Nothing the owner has said would signify a "blown" tranny. "Knowing" these units entails alot more than taking it to AAMCO and trading it in.

As I mentioned before, Mr. Krause, what you do now with this trans depends on your restoration schedule. If you just need the car to move in the short term, drop the pan snap some pictures and let me see. Maybe it is unrepairable, but until you at least do that we won't know.

We're here to help. Let's not scare the new guy

Don
 

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Guess I stand corrected. I had mine in my hands yesterday and it was dark gray so I just assumed it was cast iron. I guess living the last 40 yrs submerged in Type F fluid turns it dark.

Thanks for the Valve Body Anatomy lesson. I just call'em thingys and piston lookin thangs. LOL

My message to Krause, like yours, is that in general, everything that can foul up in the C-4 is easily repairable unless you just about MELT it or run over a boulder and BUST IT!
 

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Discussion Starter #9
Greetings,

Sorry to burst your bubble here Bryan, but the C4 valve body is not cast iron. You may be thinking of a GM THM 350, or 400. C4 valve body assembly is made up of two aluminum castings, and a steel separator plate.

In the upper casting are numerous spool valves, a rubber shuttle valve ball, and a servo check valve. The lower valve body, also known as the transfer plate does not contain any spool valves, but does contain a high speed kick down shuttle valve ball, a 2-1 reverse cutback TV shuttle valve ball, and a throttle pressure limit valve and spring.

There are several different valve body assy used in the Mustang. 1964 is a unique valve body, 65 and 66 use another style, 67 to 69 along with 70 Falcon use yet another. 70 and 71 another still, and 72 to 81 the latest style.

If I may, I would like to address Ne Faurora's concerns. The symptoms this unit displays are common for a unit that has sat for a period of time. I stand by my diagnosis of why it moves for short periods of time after sitting. Nothing the owner has said would signify a "blown" tranny. "Knowing" these units entails alot more than taking it to AAMCO and trading it in.

As I mentioned before, Mr. Krause, what you do now with this trans depends on your restoration schedule. If you just need the car to move in the short term, drop the pan snap some pictures and let me see. Maybe it is unrepairable, but until you at least do that we won't know.

We're here to help. Let's not scare the new guy

Don
Thanks Guys,
Don,
No need to worry, Im a powerstoke/E40D guy, I dont scare too easily...:crybaby:
So if i understand you correctly, your figuring a clutch or band, which need to be replaced with the tranny out, but its not a full rebuild scenario. Just a clean and new part that has failed? Is this best done at a tranny shop? I wouldnt call my tool selection at this particular location amazing, certainly not any tranny specific things, that said it could be wrestled out of the car easily enough. The resto project is at the 'car needs to be drivable' stage, so this is the issue being addressed right now. I could drop the pan, but you figure its a tranny out fix?
Krause
 

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Greetings, Krause.

Not quite what I'm saying, but close. If your intent is to get the vehicle on the road in the immediate future, I would pull the unit, disassemble it, clean and inspect, and rebuild using parts as necessary. If you won't be driving it for a year or so, and only need to move it around, I would only do what is needed to make that happen, then rebuild it near the end of the project.

My first Mustang project was rebuilding a C4 and it turned out beautifully. I procured and read and re-read everything I could find on the units at the time. I made sure exactly what I had to start, and what I wanted when finished. No, I didn't have every special tool, but a little thinking and ingenuity allowed me to work around that. I purchased a couple pairs of quality snap ring pliers at the time, and used a small hydraulic press to aid in servicing the clutch drums. If you've worked on E4OD's, there is nothing a C4 you need worry about. Just arm yourself with as much info as you can, and you'll be fine. I'm pullin' for ya, we're all in this together.

Don
 

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Great thread, and timely for me. Just got my 66 coup out of the garage for the first time following a 3-year restoration of the body and interior. I was hoping to be able to drive it for awhile before the next step, but looks like that's not to be. I can only get it to go into reverse occasionally (maybe 30% of the time), and it gets to pretty high RPM before shifting into 3rd. (I don't have a tach, but it's approaching 45MPH before it shifts.)

So here's the question: My local mechanic says the C4 probably needs a rebuild. He said reverse and 3rd are the same gears, so it makes sense to him that they're both going out. Does that make sense to you guys?

He can rebuild it for $1000-1200, but even though I know nuttin about trannies, I'm kinda interested in taking it on and learning as I go -- just like everything else I've done so far. This thread makes it seem like a dummy like me might be able to figure it out.
 

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Greetings, norski;

Your mechanic is somewhat right. Reverse and third don't use the same gear so to speak, but they do use the same clutch, the reverse/high clutch strangely enough. I'll do a quick run down for you. Drive range first gear requires the forward clutch to be applied and the low roller clutch to hold. For second gear, the forward clutch continues to hold, the intermediate or front band applies, and the low roller over runs. For third gear, the forward clutch continues to hold, the intermediate band releases at the same time as the reverse/high clutch comes on. For reverse, the reverse/high clutch applies, along with the low/reverse or rear band. For manual low, the forward clutch applies along with the low/reverse band. The only function of the low/reverse in low range is to prevent the low roller clutch from over running thus giving you engine braking.

There are plenty of good manuals out there which explain the principles of operation of the C4 clutches and bands, gear train components, and valve body function. Most also cover overhaul. The biggest concern usually involves making certain just exactly which year and calibration of unit you have. Overhaul components are as common as dirt. Transgo still makes a great shift kit that addresses the C4 short comings. Shift kits don't have to mean tire barking shifts, that's just one thing they allow you to have.

If you have any more questions, feel free to contact me.

Don
 

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Go For it

norski66,

If you have enough mechanical ability to assemble a bicycle, you can rebuild your C-4 yourself.

I did it last summer and I have never been into an automatic transmission.
The only special tool I needed was a pair of snap ring pliers and a way to compress the Bellvile spring. ( I used my drill press and a large socket to compress it )

I did order Bad Shoe Productions' DVD for $39 and had the video running on my laptop to make sure I got it back together correctly. That's a lot easier than trying to follow an exploded view in a book.

The (American Made) kit I purchased off Ebay for $69 had all clutches/steels, bands, o-rings, seals, and gaskets, fluid filter, and a new modulator canister. I THINK it included the shift kit but I didn't put it in.

Total cost for rebuild including fluid, LESS THAN $150. I have about 500 miles on it now and it runs and shifts smoothly and doesn't leak anywhere.
I paid very close attention to keeping all potential leak points and gasket surfaces DRY until buttoned up to avoid leaks.
 

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Thanks guys. I'm just looking at the last of the 3 DVDs from Bad Shoe (which are great!), and while there are lots of steps, it doesn't look too difficult. My only other hesitation is that I won't necessarily know when a part is bad and needs to be replaced. Will that be pretty obvious?

Thanks.
 

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One other thing -- my 66 didn't have backup lights on it, but I added those along with the rest of the restore. Is it pretty simple to add the switch on the transmission? I don't know the history of the car, so no idea if it's the original transmission. Are the backup light switches pretty universal on the C4s?
 
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