1955 Willys truck F134 engine with automatic transmission.

Whipster

Bigger Hammer
Nov 17, 2017
40
Victoria
First Name
Ed
Willys Model
  1. Wagon
Willys Year:
  1. 1947
Just finished converting this 1955 Willys truck from 4wd manual to 2wd automatic transmission to enable a friend with limited left side mobility (due to a stroke) to continue to drive and enjoy it. For now the front diff will stay in place. Engine is F134 and auto trans is a 3 speed plus overdrive and lock up converter JATCO L4N71B from a GM Holden VL Commodore. Same type was also used in Nissans, Mazdas etc. Obviously not a bolt up conversion.
As the video shows it works a treat so next time the subject of running an automatic transmission behind and F134, L134 or F161 engine comes up the naysayers can be referred to this post.

https://youtu.be/KxHVw2AYMH4

As far as I can tell this is the first modern four speed automatic transmission used behind one of these engines but would welcome seeing photos to prove me wrong. By modern auto trans I mean with built in overdrive gear, lock-up converter etc and not the Warner ASG-5AG three speed auto trans that was used behind the 134 Willys engine in some FJ and DJ Willys/Jeep vehicles.
 

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Very cool. That's super interesting, only share more if you feel like, I'd be curious about the following, but really not going to do this, so enjoy the moment for sure, not trying to take away anything with a million questions. I'm still working on my first auto Trans complete rebuild is why all these come up.

What Trans controller did you have to use?

Do they require a Throttle Valve Cable or Kick Down Cable?

Any special sensors you had to install?

How's the speedometer?

Videos have to get posted to YouTube or other link Vimeo then paste those links in your post.

Sounds like a cool project.
 
No trans controller used in this installation.
All gear changes including shift into overdrive work hydraulically.
Jatco 4N71B has three external solenoids usually controlled by a transmission module/computer in the factory installation.
In this Willys installation the torque converter clutch is activated by flicking a toggle switch mounted on the centre console to energise the TCC solenoid.
By selecting "power" mode on the T bar handle the overdrive solenoid is energised preventing hydraulic engagement of overdrive.
The downshift solenoid is activated by a "kick down' switch added to the 'gas' pedal. This forces a downshift from 4>3>2 otherwise downshift occurs when governor line pressure drops with road speed.

The Jatco 4N71B (and 3 speed 3N71) don't use a Throttle Valve Cable or Kick Down Cable, instead a vacuum modulator is used to control what they call "throttle pressure". The modulator screws in the side of the trans case next to the downshift solenoid and is easily removed to adjust shift points/feel by trimming or extending the length of its rod that pushes against the internal throttle pressure valve.

No special sensors used. Had to reconfigure the wiring outputs of the combined inhibitor and shift position switch on the trans for it to work with a relay, instead of the computer, for the start in only park and neutral function.

Speedometer reads fast but now the truck is driving that will be corrected using a mechanical converter screwed on the end of the cable. Fun fact is that the Willys speedo cable end screws onto the Jatco speedo drive bullet in the trans. Had to convert the Jatco female offset key cable drive to accept the male square ended Willys cable but that was an easy part of the conversion.

Couldn't find and help info on posting videos so appreciate your video posting tip. I'm not a youtube or vimeo user but looks like I'll have to change that.
 
The actual install mechanically looks super clean good job on that.

Thanks for the additional details, TCC switch is pretty cool, we call those "mystery switches",

The Trans I've made a life journey working on is a 1996 Dodge 2500 47RE so its very mechanical as well has a very simple 8 pin set up for a very limited external items. There is very high risk I have turned this into a "let me show you how to take a truck apart and make it never run again".

So its great to read success stories. Thanks for sharing.
 
Moving right along. Good job, awesome truck.
 
Thank you for getting back to me. You may have solved my mystery . Now I just need to tear it back apart and do some machining!
 
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