C4 leaking from inspection plate. Repair or replace?

[Augie]

The C4 in my 71 Grande is leaking from the inspection plate. I believe that it is the front seal. I have never driven the car and it is not in driving condition at the moment so I have no idea what the condition of the transmission is as far as drivability. I have been quoted by two shops with prices at a minimum being $500 to $600 just to replace the seal. That does not include parts. My questions are

1. Is this a repair that someone with a decent amount of wrenching in their history could do? I have never been in a transmission before so I have no idea what it'd be like.

2. Should I just have a shop do it. And also while they are doing that repair have them completely tear the transmission down and search for anything needing replaced. A shop said it could cost as much as a grand if everything needs replaced. If that is the case I would rather just get a manual transmission and do a conversion if I am going to be spending that much money.

Thoughts, opinions, anything is appreciated.

 

[Don C]

Replacing the front seal shouldn't be a problem for you. However, I have found that most times the reason the seal has failed is because the bearing behind the seal is bad.

Replacing the C4 with an AOD is easier than converting to a manual. A built AOD with wide-ratio gear set may be cost competitive compared to a manual, plus you would have overdrive.

 

[Augie]

Do you know of any threads of a C4 to AOD swap? I can't find any. Seems like there are many of the FMX to AOD swaps though.

 

[Don C]

The conversions for an FMX and C4 should be very similar.

You might also check the AODE and 4R70W threads. They will be close to the same as for an AOD, the major differences are the throttle kickdown rod for the AOD and the electronic controller for the AODE/4R70W.

 

[mjlan]

Replacing the front seal is straightforward. If you can do it in a engine front cover or rear axle, you'll be fine. The biggest hurdle is getting the trans out and the convertor off whithout making a huge mess.

I've heard that transmissions that sit do tend to leak, particularly when they're old. This is due to air getting in and letting fluid drain out of the convertor. Since it holds a shitload of fluid, when it drains back into the trans from sitting, it sometimes seeps past a worn seal at the front pump....

The front seal is probably less than $5, why would you pull the trans out and go through the trouble of converting to an OD or rebuilding it without even knowing if it's worn out or not? When you have it out to change the seal (check the convertor snout for wear, you can get sleeves I think if it's worn), replace the pan gasket and filter and see what the inside looks like. If the fluid is dirty, discolored and smells, decide what to do at that point. If there's just normal dust and clean fluid, slap it back together and beat on it!

Just my $0.02.

Personally, I would rather have a manual, so instead of rebuilding or upgrading I'd swap to a toploader or TKO...

 

[Augie]

Replacing the front seal is straightforward. If you can do it in a engine front cover or rear axle, you'll be fine. The biggest hurdle is getting the trans out and the convertor off whithout making a huge mess.

I've heard that transmissions that sit do tend to leak, particularly when they're old. This is due to air getting in and letting fluid drain out of the convertor. Since it holds a shitload of fluid, when it drains back into the trans from sitting, it sometimes seeps past a worn seal at the front pump....

The front seal is probably less than $5, why would you pull the trans out and go through the trouble of converting to an OD or rebuilding it without even knowing if it's worn out or not? When you have it out to change the seal (check the convertor snout for wear, you can get sleeves I think if it's worn), replace the pan gasket and filter and see what the inside looks like. If the fluid is dirty, discolored and smells, decide what to do at that point. If there's just normal dust and clean fluid, slap it back together and beat on it!

Just my $0.02.

Personally, I would rather have a manual, so instead of rebuilding or upgrading I'd swap to a toploader or TKO...

I will take your advice and do it myself. The converter is brand new btw.

 

[Augie]

Has anyone on here every taken a manual 5 speed from a fox body mustang and put it into a 71-73?

 

[72MustangSprint]

Has anyone on here every taken a manual 5 speed from a fox body mustang and put it into a 71-73?

yes, Droptop73 has. I would search to see if he has written up his conversion.

 

[mjlan]

Kind of...

I had a 72 that I bought without a motor that was a 3-speed car.

If you have a 302, it is pretty easy as you can use 5.0L stuff, just pay attention to the engine balance as early small blocks are different than the 5.0's. I used Modern Driveline's cable conversion and crossmember with a Ford OEM 5.0L bellhousing and fork.

If you are converting from an auto, I think your speedo cable might be different, and I'm not sure about the driveshaft. My 72's driveshaft was the right length for the T5 I think...

There's probably more that I'm forgetting. A flywheel with the early imbalance and the 5.0L diaphragm clutch pattern might be tough to find, I think Ford Racing has one...

 

[judge]

For about thirty years I have worked for companies that had fleets, I seen my share of fluid leaks. Some fluid were not always top priorty. I tried Lucus power steering leak stop in my Toyota pick up. The leak stopped and hasn't needed fluid for years. I've recommended the Lucus transmission leakstop to a few friends and they had similiar experience with the leaks stopping. Now it's pretty pricey, but I know its worth every dollar.

 

[Justin71]

I had my C4 completely rebuilt for $550. I had it out of the car, took it to a reputable shop and they did everything to it. all seals etc. It shouldn't cost $500 just to look at it - especially if front seal is as easy as folks are saying here.

 

[72MustangSprint]

I had my C4 completely rebuilt for $550. I had it out of the car, took it to a reputable shop and they did everything to it. all seals etc. It shouldn't cost $500 just to look at it - especially if front seal is as easy as folks are saying here.

I agree, i'm having my trans rebuilt for $600. Its out of the car. The guy who does my trans work is a Ford guru.

 

[judge]

Y'all remain fortunate. Prices here for rebuilding automatic transmissions. Went from $375 in 1995, to $650 in 2003 then to the current price of $1,400. You now can save $100 by taking it out yourself.

 

[turtle5353]

I have a local guy thats a retired ford master tech. He builds all my auto trans for me. He does all my c-4's for around 400-500 bucks and that includes the rebuild kit. But if you need hard parts, like pump or valve body, then its more. The rebuild was the cheap part of my c4. My valve body was built by broader, and I have a B&M 3000 stall converter. That stuff cost way more than the trans LOL!!