1966 Mustang 289, automatic transmission trouble. When cold, it does not transmit. A few months ago, in occasions, it began slipping and did not transmit power. I added ATF and worked OK. Now it is slipping and not transmitting power always when cold and in first gear. When hot, it works OK.
Adding ATF didn’t resolve the problem.
What next steps should I give?

 

Still with my C4 Transmission problems, that it won't transmit when cold.
I took it to a specialist that drove the car and found it worked OK, so he told me not to open it. He didn't see it working when cold.
He suggested to use a additive for ATF.
He told me he had seen some other mechanics that added a few cc of brake fluid to soften the rubbers in the C4, but he would not recommend it.
Can you suggest me an additive for C4?
Any experience adding brake fluids to a C4?
Thank you.

 

The translation to "won't transit" seems to mean that when cold neither 1st or reverse engage when the transmission is cold - like it is in neutral. If it is a "green dot" transmission, when cold will it engage in 2nd gear if you put the shifter at "2"? Also, I have experienced this, but it has always been low transmission fluid level, which you have already addressed. I think adding brake fluid is a terrible idea.

 

Thank you Mostang66.
You are right. I didn't make it clear enough.
When cold, reverse works OK, but none of the forward gears will move the car. Putting the shifter is in Low or 2nd gear won't transmit power to the wheels. It feels like there is no engagement of gears. After long minutes with the engine running to heat it up, and then putting the shifter in 1 (low) or 2 and lifting revs up, you can feel it engages and begins transmitting some power to the wheels. If it is not hot enough, it begins slipping and not transmitting power.
I hadn't heard of the "green dot" transmission.
It looks that mine is a C, or a C4, for what I have heard.
Thank you for your comments. It feels good to know someone is on the other end of the line.

 

"Green dot" is an unofficial name (here in the states anyway) of the earlier transmissions where the shift sequence on the shifter is 1, big green dot, 2, N, R, P. Starting in '67 Ford changed the pattern to 1, 2, D, N, R, P. It is interesting that it will go in reverse, but will not go into either 1st or 2nd, which in the green dot transmission is a partially separate group of valving and clutch. Looking through some older posts, a couple suggestions come up. Make sure you are checking fluid level when the transmission is at operating temperature, the engine is running, and the car is relatively level. Inspect the vacuum line from the carb/manifold to the transmission for tightness at each end and for holes. There are seals on the forward clutch pistons that can become hard over time and start to leak.

 

Thank you Mostang 66. Mine is a "Green dot", then.
The fluid level is has been checked as you say. I also verified that the vacuum line is working OK.
It seems that the problem is on the rubber seals of the pistons.
But before doing a mayor work on the transmission I decided to put a new fluid and filter, because 2 months ago y added an additive that was not meant to be used in an F type fluid.
Perhaps that can help.
Again, thank you Mostang66.