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Technical So, just how hard is it to rebuild an automatic transmission?

Discussion in 'The Hokey Ass Message Board' started by BamaMav, Mar 20, 2020.

  1. Black_Sheep
    Joined: May 22, 2010
    Posts: 1,172


    Mopar 727’s are pretty simple, I’ve built a few. The most important thing is to have a good manual or step by step video to follow. You’ll probably need some bushing drivers, good lock ring pliers, feeler gauge and a compressor for clutch springs. I made my own compressor out of stuff that was sitting around the shop. The basic rebuild kit is usually frictions and seals, you will likely need some bushings as well.

    To familiarize myself with the process, I disassembled and reassembled the trans a few times using the original parts. Once I figured it out, I disassembled and cleaned everything up again before assembling it using new parts.
    lothiandon1940 and Desoto291Hemi like this.
  2. Bamamav ,

    I understand how you feel,,,,several years ago I felt the same way .
    I had done many 4 speeds,,,,never any automatic .
    The economy was bad then,,,,and I just couldn’t afford the price .
    Like some say,,,,,it was like black magic,,,,woooooo,,,,,,( oh my goodness,,,I can’t possibly do this ) ,,,LoL.
    Well,,,,I didn’t have the money,,but it had to be done,,,,,so it fell on me .

    Long story short,,,, it wasn’t that bad at all,,,,,and I learned that I was better than I thought.
    I have done several since then,,,,,,no,,,,,it is not black magic !

    The clutch packs need attention,,,,,,mic the old fibers,,,,mic the old steels,,,,,,mic the new ones as well .
    There is a certain amount of clearance in the clutch pack and the drum it fits in,,,,,go by the manual .
    Can you remove old seals and install new ones without damage ?
    Clean and inspect all metal parts ,drums ,shafts,,,,,take note of snap rings.
    There are tons of videos and diagrams on the internet,,,,study them .
    And besides,,,you even have a spare to experiment on .

    Now ,,,,ask yourself,,,,,,do you feel you can do it ?
    It all goes back to your mechanical ability,,,,only you know your limitations !

    Like Dirty Harry said .

    lothiandon1940 and pitman like this.
  3. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,399


    I inquired about having a trans shop near where I worked rebuild a C-4 and he told me the C-4 was too old for him and would rather do a AOD.
  4. patterg2003
    Joined: Sep 21, 2014
    Posts: 590


    The $900 seems reasonable. It includes the cost of the converter, then back out the cost of the OEM parts, specialty tools etc and that leaves about 1/3 for labour. The shop likely gets a discount on parts and may be sharing that with you. Having a transmission shop do the work saves buying specialty tools and reduces the risk of an error. So for about $300 - $400 cost for the professional labour to rebuild the transmission is a good deal and the comfort that it will be long lived.
    arkiehotrods likes this.
  5. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 2,877

    Flathead Dave
    from So. Cal.

    I paid $600 to have my C4 rebuilt plus converter by Luke's Transmissions in Riverside. Great investment. Great service and great people.
    I don't know that I would attempt a rebuild any more.
    Last edited: Mar 21, 2020
  6. One time i blew up 6 "rebuilt" aod's in 9 months....last one let go on the way home from picking it up at the transmission shop...

    All covered under warranty. But still...

    Sent from my SM-G965U using The H.A.M.B. mobile app
    lothiandon1940 likes this.
  7. DDDenny
    Joined: Feb 6, 2015
    Posts: 13,440

    from oregon

    I have forgotten 99% of what I learned about automatic transmissions from tech school in the early 70's, the part that I do remember the instructors emphasizing was DO NOT use red cloth shop rags to wipe ANY parts down with them, this includes the inside of cases, extension housings, etc. as this can clog the filter.
    Sounds trivial I know!
  8. two couped up
    Joined: Feb 22, 2006
    Posts: 61

    two couped up
    from pa.

    I plan on doing a C4 after I get the 9" that I just took apart yesterday back together. I have rebuilt standard transmissions with overdrives and banjo rears with Columbia's but this will be my first 9" and automatic. Looks easy enough in the video! I have a complete set, all 5 volumes of Ford shop manuals for 1975 and they cover everything, special tools and lots of pictures. I like to do my own work except for machine work, that way I know what was done.
    lothiandon1940 likes this.
  9. jazz1
    Joined: Apr 30, 2011
    Posts: 1,479


    I would pay the $900 if you are not someone who pays attention to detail... I was supposed to use a 9x13 pan for my Rice Crispie squares, details are important

    Attached Files:

  10. derbydad276
    Joined: May 29, 2011
    Posts: 1,310


    did you ever notice... their sign says Transmission Shop Only...
    you don't see brakes,shocks,tune ups on their Sign...
    that right there should be a hint...They Do Not Need to Do Anything else...
    Automatic Transmissions are Evil !
  11. I don't know how mechanically inclined you are.
    I watched a couple vhs tapes, then rebuilt a th 350 and th400.
    They all worked in my daily drivers.
    Worked out great.
    So I bought a couple more..
    727, 708, and a few 700r4.
    So far so good. my last one, a 700r4 is still going 15 yrs later.
    All I can say is that you have to decide whether you are mechanically inclined enough to make sense of a shop manual or if you have had previous "misadventures" with other types of projects.
    Only you can decide whether you are likely to be up to the task.
    study a bit on your own, and you can probably tell whether it is in your abilities.
    What is your success rate on other new talents?
    consider those to be clues :)

  12. woodbutcher
    Joined: Apr 25, 2012
    Posts: 3,205


    :D I rebuilt the C6 that was in my other OT truck.Was to me pretty easy.But it only lasted about 120k miles:rolleyes::p.
    Good luck.Have fun.Be safe.
    lothiandon1940 likes this.
  13. I'm assuming that your car is the one in the picture - 46-48 Chevy? If it still has the original gearbox mount cross-member, it is riveted in, not welded. I have been looking at one of these, and am going to drill out the rivets (easier said than done), and replace the cross member with a bolt- in job, for a T700 conversion. This should make replacement easier, without pulling the mill/trans together.
  14. jaracer
    Joined: Oct 4, 2008
    Posts: 326


    $900 sounds like a good price since it includes a converter. I taught auto trans rebuild for a few years back in the 70's. My students progressed from Powerglide to 904/727, to C4/C6/FMX to 350/400/200. I did have one 425 from a Toronado, but it wouldn't mount on the dyno. I'm sure you will need some special tools, even the stuff I worked on required at least a few special tools. The problem a first timer has is knowing what to look for. If it failed there is a reason; you need to find before it goes back together.
    lothiandon1940 likes this.
  15. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,161

    from Berry, AL

    UH, right game, wrong ballpark:rolleyes:

    1947 Lincoln Zephyr, same suspension layout as pre 49 Ford, wishbone suspension. Lincoln frames are welded together, and the body is welded to the frame. Believe me, if there were an easy way to cut it out and make it a bolt in, I would have done it. It's a main crossmember, the wishbone mount for the front axle is on the bottom, the trans mounts on the top. It did have a SBC with a Turbo 350 in it before I put the 302 AOD, and it had to come out the top side, too.
    lothiandon1940 likes this.
  16. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,161

    from Berry, AL

    Weighing all options, it looks like going to the rebuilder is going to be the easiest. He does the work and I get his warranty, while if I do it myself I can't blame anybody but myself. If it wasn't so hard to take out, I think I'd give it a try.

    Now if all this China virus shutdown crap will get out of the way! I'm still working, but even though I've got the money stuck back, I'm going to hang on to it a few more days. Or weeks. They could shut us down any day, so I'm thinking ahead....
  17. oldolds
    Joined: Oct 18, 2010
    Posts: 2,970


    I recently had one of those rebuilt. That was the price. To me the warranty that my guy offers makes it worth the price. One year, he pulls it out if it needs to come out again.
    lothiandon1940 likes this.
  18. glrbird
    Joined: Dec 20, 2010
    Posts: 474


    Ask your rebuilder how to set the TV cable. You can smoke an AOD in a few miles if it is wrong.
  19. winduptoy
    Joined: Feb 19, 2013
    Posts: 1,961


    Kind of sounds like you have made up your mind but...
    You got the advice to take photos for reference. If you do tackle it yourself, do what a transmission rebuilding buddy taught me...take it apart on a wire, you keep things in proper order that way...
    good luck
    Desoto291Hemi likes this.
  20. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,161

    from Berry, AL

    I'm using stock Ford cable, mount and linkage on the trans end, Home made bracket on the carb linkage with dimensions taken from a Ford bracket. Cable bracket is the exact distance from carb shaft as the throttle cable is, and pulls the exact same travel distance, so it's supposed to mirror the factory install.
  21. rjordan
    Joined: Jun 8, 2017
    Posts: 5


    I have owned a shop 40 years and have been building transmissions 50 years. Pay the man and save your self some real time.
    patterg2003, jazz1 and lothiandon1940 like this.
  22. Budget36
    Joined: Nov 29, 2014
    Posts: 3,464


    I know clean, clean, clean. But, after you pull the trans pan on a 20k unit and see the stuff in the bottom of the pan, how did it live?

    Who builds an engine or transmission in a hermetically sealed environment?
  23. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,263

    from Phoenix,AZ

    The best AOD's are from 1989 to 1993 those have the upgraded valve body and lubrication upgrades if yours is an earlier one use it for a core exchange. ;) Badshoe is the best for Ford transmission videos
    saltflats likes this.
  24. southcross2631
    Joined: Jan 20, 2013
    Posts: 3,754


    I worked at a Ford dealer when the AOD came out. About 2 months later we got a car in with a leak turned to be a cracked case so the shop foreman gave it to me because I had been doing most of the automatics.
    I was leery ,but I was up for the challenge . I laid out a long piece of cardboard on my bench and labeled the parts and set them as I took them apart. Of course we had all the factory tools.
    Even though we had a factory shop manual. Setting up the clearances is critical and now they are not so scary. I also recommend a B&M shift kit and I like a B&M 2200 stall convertor in street rods.
    The shift kit gives you more control over the transmission if you want to get frisky. It also lowers the trans temps because it cuts down on the slippage designed to make them smooth.
    The convertor wakes up the car without making it slip too much as a higher stall would do.
  25. scofflaw
    Joined: Jul 26, 2006
    Posts: 103

    from Ohio

    I had a AOD that sat in a junkyard for a while, same problem. Turned out a couple of the valves had some slight surface rust/ corrosion that you could barely see. I pulled the valve body, with the transmission still in the car and cleaned and lubricated the valves. The transmission worked great after that!

    Sent from my iPhone using The H.A.M.B. mobile app
    Desoto291Hemi likes this.
  26. I promise to stay 6 feet away, but could I please have a big piece of your Rice Crispie Treats?

    Sent from my iPhone using The H.A.M.B. mobile app
    lothiandon1940 likes this.
  27. I just R&Red a Ford 4R75E in an O/T daily driver. Took me 18 hrs total. Consider getting a new cooler or if you have to a cooler/new radiator don't want to flush a bunch of Metal and friction material bits through your brand new rebuilt unit. Other thought is: can you find a good used one out there, maybe low miles or rebuilt? Mine was $400 had 44k on it, pan was clean. Shifts great. Got it with the converter included. Rebuilding my old one would have been $205 for the master kit and $200 for the billet front pump (mine cracked is why the transmission wouldn't move in forward gears). Plus I would have had to reuse my old T/C.
    Last edited: Mar 22, 2020
    lothiandon1940 likes this.
  28. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,830



    Buy this book, read it, then decide. It got me through a C4 rebuild.
    lothiandon1940 likes this.
  29. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,161

    from Berry, AL

    Sounds like info from a man who knows...

    I have thought about that since there was water in the pan. I can't remember if I can get to the pan bolts or not, they are real close to the crossmember in the back. Well worth trying! Most it would cost me is another filter kit and three more gallons of fluid.

    I'm just a little scared to buy a used one, that is unless I could drive it first. So many scumbags out there that will tell you anything is good just to make the sale. I'm using an aftermarket cooler, so it should be easy to flush. I don't think there will be any metal in it since it only ran a few minutes after I had changed the filter.
  30. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,830


    When they say "surgically clean" they mean it. When I rebuilt my C4, I installed a Transgo shift kit but I never completely disassembled the valve body to clean the other half. When I test drove it, it wouldn't upshift from 2nd to 3rd because the 2-3 valve was sticking. Removed and disassembled valve body and soaked it in cleaning fluid. I put the cleaning fluid through a coffee filter and found particles from the bands/clutches that you could barely see. The tolerances are so tight that a splinter will jam them.
    lothiandon1940, Gammz and Old wolf like this.

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