AX-15 Manual to TF999 Automatic Transmission Swap in a 1990 Wrangler

PARTS LIST:

  TF-999 Three speed factory automatic transmission
  Torque Converter
  Automatic Transmission Fluid (ATF)
  3-speed floor shifter, I used a Winter's
  Flex Plate for 1990 Jeep
  Dipstick & holder
  Automatic Input gear for transfer case
  4x4 Shifter linkage / brackets for automatic Jeep
  New Automatic floor board cover with boot
  Throttle Valve linkage

GETTING A TRANSMISSION:
Now that I knew what I wanted, I needed to find the transmission. Surprisingly the very first phone call I made I found the tranny I was looking for. For my application I wanted to just use the factory equipped automatic transmission that would have been in the Jeep from the factory. I found mine at a local wrecking yard, (same place I got my 8.8 rearend). Being local yard this was even better. Now the real question, "How much, I asked". He said the computer shows $300 for the trans. including the torque converter and linkage. That also includes a 60 day warranty. I thought heck that's not bad. So one day on my lunch break from work I went down there and picked it up. I brought the transmission home and started by cleaning it and giving it a clean new paint coating.

INSTALLING TF-999 (automatic):
This was going to be my first automatic transmission installation so all this was new to me. I started by buying all the necessary components that an Automatic transmission Jeep would have. Such as a Flexplate instead of a Flywheel which I picked up at local parts store for about $55.00. It only took the parts store two days to have one for me. The brand I used is a Pioneer part no.# FRA-410 (as shown in the picture below.) Also when mounting the flexplate I later realized I was going to need shorter flywheel bolts. The 5-speed (old) flywheel was much thicker and used a 1" long bolt. For the automatic application I used 1/2" long bolts. (grade-8 of course, using lock-tite as well). These bolts were snugged up with the required 55lbs. of pressure. The dust cover that my AX-15 used was going to work just fine, although it has a couple differences nothing that required changes except cutting a hole in the cover to access the torque converter mounting bolts. This leads us to the torque converter. I used a factory style torque converter. For mounting the torque converter, I used (4) 5/8" by 1/2" long grade-8 bolts with locktite. These bolts were tightened down to the spec's.

CUSTOM THROTTLE LINKAGE:
From the factory this transmission was controlled on the steering column. I choose to get a floor shifter. There are many different floor shifters available manufactured by company's like B&M, Hurst, Art Carr, and Winters. For my application I chose a Winters Shifter. These are almost exactly the same an Art Carr but a little less price. See pictures below. Also, Im going to be writing an article on my Winters Shifter so look forward to this upcoming article. 

TRANSFERCASE MOD's:
I'm sure your wondering if the transfer cases are the same on the automatic's as the AX-15 (5-speeds). I wondered this myself and upon research I never got a straight answer. Some places I called said it would work fine and others said there was a different input gear in the Auto than in the 5-speed. To answer your question from someone thats done this conversion the answer is No your 5-speed t-case has a different input gear than the auto does. The auto one is longer. I opted to just go buy an automatic input gear for my Np-231 T-case but later decided to just go ahead and purchase a Tera Low 4:1 conversion for a Jeep with an automatic. The Tera Low kit comes with a new Input gear. This would solve my t-case problem and give me some extra low gearing while in 4lo.