86 A4LD swap to 93 A4LD or Fix the 86?? | Ford Explorer Forums - Serious Explorations

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86 A4LD swap to 93 A4LD or Fix the 86??

October 24, 2012
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City, State
Fort Wayne, Indiana
Year, Model & Trim Level
1986 Ford Bronco II
I have a 1986 Bronco II with an A4LD Transmission. It has a smooth 1-2 shift and the shift from 2-3 is a very high rpm (4500 roughly). After the 2-3 shift, it will not shift to 4th at all. I did not have my 2-3 shift and then I replaced the shift modulator and got that back. I have two routes I am contemplating going:

Route 1.

Clean the governor in hope of getting a better 2-3 shift and then cleaning the valve body in hope of getting my 3-4 shift back. My fear is having a first gen A4LD that even if that does fix it that something else will go wrong in the near future from what I read from other users posts everywhere.

Route 2.

I found a guy that has a 93 A4LD from a 93 Explorer 4x4 (used the engine in his Ranger). Had 105,000 when pulled 3 months ago. Says he never had any problems with it at all and guaranteed to work for $75. IF I do this the issue becomes I have a transmission with no 3-4 shift solenoid and the newer transmission does. I have heard you can convert the wiring to accommodate this. Has anyone done it, know how to do it, or know of a post that talks about this? This seems like the best solution to get the newer transmission in the truck but I am worried about compatibility.

What are the expert opinions here? Thank you in advance for your help.

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I have heard you can convert the wiring to accommodate this. Has anyone done it, know how to do it, or know of a post that talks about this?
I haven't actually done it, but I can see what would be needed. A lot depends on how "automatice" you would want the 3-4 shift:

1) To get it OEM quality (controlled by the main PCM), you will need a PCM from a newer BII/Ranger with a 2.9. That will likely create other incompatibilities (such as the presence/absence of the EGR system). It certainly can be done, but it is going to require enough research to identify the differences between the engine management systems and make sure all the wiring will work out.

2) If you will tolerate manual control of the 3-4 shift, the wiring is quite simple. The 3-4 shift solenoid is a fairly simple, ground side switched DC circuit. Follow the wiring diagram for the 3-4 shift solenoid in the donor vehicle, putting your own toggle switch where the PCM would be in the circuit.

3) If you don't want to replace the PCM, but still want the shift to be somewhat automatic, I've heard of people using an appropriate pressure/vacuum switch attached to engine vacuum. Properly adjusted, this switch will then be closed when engine vacuum is above a certain level, telling it to shift into 4th gear.

Mr Shorty:

Thank you for the reply. I never thought about the pcm until you mentioned it honestly. I am leaning more towards trying to repair the original. My Dad, mechanic for 35 years, says it shifts way to good 1-2 and 2-3 to have internal problems such as clutch or broken bands and thinks cleaning the governor and possible the valve body would do it. What are your thoughts? Experience there?

if you have a smooth/good 1-2 shift, your governor is working ok.
your OD servo may be not working properly, OD band may not adjusted, or the OD clutches may be worn.
also, the valve body may be clogged/stuck.
have you changed the fluid & filter ? was any debris in the pan ? have you checked the fluid pressure ?
there are stickies at the top of this section that explain things better than I could "guestimate"
J...happy wrenching !

would the governor affect the 2-3? I have to get to 4700 rpms to get the shift. the guy i bought it off of changed the fluid and filter and claims nothing was in the pan. have not checked fluid pressure. May try that this weekend. i have adjusted the bands but everyone says different turns on the bands. also, would the 93 valve body go into the 86 a4ld and still shift like the 86 or would that require some mods and everything?

The shift solenoids are in the valve body, so, even if the newer valve body fits into the older transmission, you would still be trying to figure out how to control the 3-4 shift.

Mr Shorty:

Here is my game plan. I have the 93 tranny with the newer valve body. I am have my 86 valve body out (Found pins and metal on it so I have bad gear or something in the 86 tranny). All valves and everything work perfect on the 86 valve body. I am going to put the 86 valve body in the 93 transmission. This way I won't have to do any wiring or rigging of any kind. Hopefully you followed and can give me insight on any problems I might encounter. From what I know and have read this will work. Can you confirm or deny this? Your assistance is MUCH appreciated. Have a great day.

Unfortunately, I can neither confirm or deny that it will work, as I've never tried it either. It is probably going to be the easiest approach, though, if it does work.

I am going to open the 93 transmission one night this week and hope find a clean valve body and no issues and then put my valve body in.