[Red Snake]

I have a "66 coupe with a V8 and green dot C4 trans. I was told that it can be modified for better reliability and performance. By changing the valve body, installing a "69-70 valve body, along with some other internal mods.
Has anyone tried this and what were the results?
Thanks

 

[Ivy66GT]

I don't know of any reliability problems with the green dot setup. You can swap for a later valve body which gives you different shift options like the later years had but that doesn't have anything to do with reliability.

 

[Charles Reeves]

I swapped the valve body in my '66 C4 years ago with one for a '67. That is the year Ford went to SelectShift, which gives you manual control over first and second. Since you're shifting from second to Drive, the 2-3 shift will be a normal automatic shift. Ditto with Ivy66GT on the reliability issue.

BYW, I sent B&M a letter at the time asking if it was OK to swap the valve bodies. They replied with a full page, single spaced letter tellingl me it would work, but they didn't advise it, with no real reason why. In other words it was a CYA. . .

 

[JeeperJames]

I also installed a 67 valve body in my 66 green dot and years ago in my 65. No problems at all. The big advantage is being able to hold it in 2nd gear. Very useful when on steep hilly roads. With the green dot valve body you can't hold it in 2nd.

 

[btcarmd]

I also installed a 67 valve body in my 66 green dot and years ago in my 65. No problems at all. The big advantage is being able to hold it in 2nd gear. Very useful when on steep hilly roads. With the green dot valve body you can't hold it in 2nd.

On my green dot I was able to hold second, if I start in manual first and after shifting to second I could pull shifter back to low position and it would hold second until I shift back up.

You can modify the green dot trans, there was a good article in Hot Rod magazine some years ago that described all the possible modes. I have built 2 units with many of the modes and both have worked well.

 

[Ivy66GT]

On my green dot I was able to hold second, if I start in manual first and after shifting to second I could pull shifter back to low position and it would hold second until I shift back up.

That works, but beware...if you drop below about 15 MPH it will shift into Low with a very noticeable BANG. It probably doesn't hurt anything but its not exactly a subtle shift.

Holding in 2nd is about the only thing tricky about a green dot. You can force a downshift to 2nd by momentarily pulling the level to Low if you don't want to plant your foot on the floor which will force the same downshift.

 

[btcarmd]

That works, but beware...if you drop below about 15 MPH it will shift into Low with a very noticeable BANG. It probably doesn't hurt anything but its not exactly a subtle shift.

Holding in 2nd is about the only thing tricky about a green dot. You can force a downshift to 2nd by momentarily pulling the level to Low if you don't want to plant your foot on the floor which will force the same downshift.

I have a 67 valve body in mine now

 

[paul289]

While I opted for replacement of the whole transmission to a '72 C4, the green dot can be modified plenty easily. A later valve body, a better intermediate shift servo, and a higher stall converter are popular upgrades. A set of better clutches and bands will also help quicken shifts over stock, and the originals are likely due for replacement anyways.

Some more advanced mods include drilling the governor weights to raise the full-throttle auto shift points, and adding roller thrust bearings from a (gasp!) TH350 to reduce power loss and fuel consumption, but both of those options require machining. If you don't have a mill or a lathe and some good bits or other tooling, you'll have to farm that work out to a machine shop. Not super expensive, but probably time consuming.

This website has some good material for how to rebuild and do some basic upgrades to the C4.

 

[Red Snake]

While I opted for replacement of the whole transmission to a '72 C4, the green dot can be modified plenty easily. A later valve body, a better intermediate shift servo, and a higher stall converter are popular upgrades. A set of better clutches and bands will also help quicken shifts over stock, and the originals are likely due for replacement anyways.

Some more advanced mods include drilling the governor weights to raise the full-throttle auto shift points, and adding roller thrust bearings from a (gasp!) TH350 to reduce power loss and fuel consumption, but both of those options require machining. If you don't have a mill or a lathe and some good bits or other tooling, you'll have to farm that work out to a machine shop. Not super expensive, but probably time consuming.

This website has some good material for how to rebuild and do some basic upgrades to the C4.

Thanks Paul289! This basically what my mechanic and trans guy told me regarding the upgrade.