Good Day,

(This is my first post so if I break some rule please just tell me!)

I've had some troubles with A4LD not shifting right, so I'm considering replacing the valve body with a machined block of aluminum that simply receives 7 or 10 solenoid valves.

I would then make a electronic controller that would control all the shifting.

Or maybe I'd just have some switches and use it like a manual

Just to save you from having to inform me that it can't be done, I shall explain that my areas of practice are machining (CNC&manual), electronic design and construction, embedded micro-controller programming, so this project is generally within the scope of my skill.

I did consider just switching to a 4R44E type transmission since they are already electronically shifted, but it seems they still have some valve body complexity, little check *****, and stuff. It seems with the 4R44E series, a single solenoid actuates a servo and a clutch, and I want to get away from the complexity of that due to its difficulty to adjust and troubleshoot as well as it's sensitivity to malfunction.

Sooo my interest in starting this thread is severalfold:

1: Hear of anyone who's tried this, what success/pitfalls they found.

2: Learn more about the specific requirements for valving (i.e. pressure, flow, etc.)

3: Learn more about pressures needed for correct actuation of clutches and servos.

4: Learn more about servos - are they actively driven both ways?

5: Correct oil path

To expand on #2, what would be a good affordable but reasonable quality shift valve? Since I'm machining my own new valve body I can generally make it to fit whatever solenoid valve I want, I don't need to stick to Ford valves particularly.

I looked on ebay, and the cheaper shift valves are mostly plastic. I imagine they don't last too long. The ones with metal valve units are more expensive, but I imagine better.

Most of them appear to be 3 port two-way valves, but some appeared to be two port one-way valves.

To expand on #3, I've seen the youtube videos where the main pressure changes depending on gear and speed, and I've seen references to the pressure regulators, and I know some electronically shifted transmissions have a pressure control solenoid as well.

I'm interested to know if different pressures are sent to different clutches/servos, or if the pressure just changes due to pump speed and how much oil is leaking out due to the wear state of the seals and the number of clutches/servos that are energized at once.

Do different clutches and servos need different pressure, or does it just give it the max pressure it can up to the regulator bypass pressure (125psi or 175 I guess)?

i.e. is it like a gasoline fuel injection system where the pump pumps like mad, and the bypass regulator bleeds off anything over a given PSI, then the electrically controlled valves send fluid to whatever place they want?


To expand on #4, I notice the servos have a release and an apply port. That makes sense, since a piston has two sides. But they also have a return spring.
Does the release port on the servo need to be driven also, or is that just used to regulate actuation rate or whatever?
Will a shift valve pass enough flow to directly actuate the clutches and servos, or do the solenoids have to activate a pilot which controls a higher flow valve?




To expand on 5, correct oil path, what is the flow of oil? My guess is like this:
oil sump -> oil pump ->[ tee off here to supply solenoid valves] -> bypass pressure regulator -> oil cooler -> torque converter (to cool it) -> back into sump.
My reasons for assuming that order is because if the high pressure hydraulic fluid goes directly to the cooler, it might rupture the rubber hoses that mine has.
I'm guessing that the regulator is a bypass regulator because there's oil pressure even in park.
Also, does the oil pressure go up to the regulation pressure when in park if you rev the engine?


Anyway, that's my current thought pattern. If shift solenoids don't have enough flow capacity for directly actuating the servos and clutches then I'll have to use regular hydraulic valves like off man lifts and stuff.


Any constructive input would be most appreciated.


Thank you and have a great day,


Jesse