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rebuilding auto trans

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  • rebuilding auto trans

    I have a 82' ford E250 with a C6 transmission.
    The tranny is starting to slip and fall out of gear. Fluid is burnt.

    What is involved exactly in rebuilding?
    The extent of my involvement with transmissions is breaking the pump gear on this one when I installed the engine about 8 years ago.
    I dropped it and took it to a rebuilder who fixed it for me, then I reinstalled it.
    Also fluid changes.

    What special tools are need?

    I have an adapter for the floor jack I made for the last time I dropped the tranny. Worked well. Its also great for removing/ installing fuel tanks.

    Where can I buy a rebuild kit?

    Any specific advice about the ford C6?


  • #2
    Back when I was younger, messing around with cars and drag racing, I rebuilt a few Turbo 400's. I then rebuilt a 727 for one of my trucks.

    I'm sure you can find a manual for rebuilding, I think back then I bought one from JC Whitney. Rebuild kits can be purchased on line.

    You just have to be methodical in the disassembly. I made up a BIG, LONG bench, and took it apart and layed each piece in order of how it came apart, so I would know how to get it back together, in the right order. Clean everything well. The clutch-packs can be tricky, and make sure there is clearance in them once the steels and clutches are in place. If you have to you can get steels of different thicknesses.

    It's already broken, so you can't mess it up but so bad!

    It's a great project, I had fun doing them, but you don't want to be in a rush. Unfortunately, I never worked on a Ford trans, just GM and the Dodge. Have fun.


    • #3
      My bro runs a ton of C-6's in his old work trucks,,, I cant really tell you all whats involved in a rebuild but i do know this, if your just starting to experience slipping and it hasnt gone on for to long change your fluid and add a can of BG auto trans reconditioner, the stuff is amazing and it removes burnt varnish from the clutch plates and has additives to help old valve body seals -------- Personally iv have seen BG's other products work amazingly well, like there MOA and fuel injection/intake valve/combustion chamber cleaner, i think they are a heck of a company and its helped my bro get more service out aprox. half of these trannies when it would have been a tear down for sure.....
      Last edited by A.K. Boomer; 08-23-2006, 08:51 AM.


      • #4
        Anyone from Summit racing to Napa Auto Parts and even autozone should have rebuild kits - look for a good rebuild manual. Haynes has several that aren't very useful for troubleshooting but they are great for the actual rebuild if your positive thats what you need to do. They will have a list of all the special tools you need and where you can order them and various substitutes if you don't want to buy specialty tools. At least thats the way it was for the TH-400. You need lots of space like RWS said!


        • #5
          I'm surprised that with regular, or even infrequent fluid changes that your c-6 is slipping. It's a tough transmission. I suspect that if it is falling out of gear you have a mechanical linkage problem or the valve body is screwed up.

          Try it in manual 1, 2, and 3 and see if it holds. If so you may still have enough friction material left on the discs to avoid a rebuild and only have to go through the valve body.

          If it slips everywhere, its rebuild time - and it's not tough, just messy. Usually no special tools needed, but follow a step-by-step book for the C-6 and not a general book that has several different types covered.

          B & M sells good rebuild kits and are a little more complete than some of the basic kits, but as has been said, almost any auto parts store has one for sale or order. They (B&M) also exchange trannys but specialize in kicked up hot rod models.

          Also, you might look around for a transmission rebuilder that will exchange your old one for a ready to install unit if you don't want, or can't have, the down time.


          • #6
            A good place to start would be the ATSG (Automatic Transmission Service Group) web site. They sell repair manuals for most transmissions at a reasonable price. These are the manuals that most transmission shops have.

            The manual for your transmission can be downloaded right from their web site,

            The manual will give you some basic diagnostic procedures, list the special tools that are needed and give disassembly / reassembly steps. A good source for the rebuild parts is Transtar,
            Transtar has about the best price on overhaul kits. These kits have all of the parts needed to rebuild your transmission less any hard parts needed or torque converter. If you rebuild the transmission I would recommend replacing the torque converter with a rebuilt one. They can also be purchased from Transtar and are fairly inexpensive. To give you an idea of the prices at Transtar, a deluxe kit, which is the most comprehensive kit they sell, is about $90.00. A master kit is about $67.00 and the rebuilt torque converter is $64.00. The web site lists what each kit has. I probably shouldn't tell you guys the prices because now you know just how much profit those transmission shops make on that $2000.00-$3000.00 overhaul.

            If your transmission is just slipping it might be the clutch piston seals are failing. This is a common thing and would be covered with the deluxe kit mentioned. The ATSG manual has a troubleshoot chart that can help you narrow down the problem, so if you rebuild the transmission you will know what component to look for in the trans.

            Another inspection that should be made is removing the oil pan and see how much debris is in the fluid. There will always be some but you shouldn't see a lot of glitter. If you do you could have hard parts damage or bushing failure.

            The actual overhaul is not impossible for a guy at home, with the right manual and tools. One tool that is needed for almost every trans overhaul is a way to compress the clutch packs. This tool is very easy to make. A simple piece of all thread rod and some bent steel will work. Or a couple hours of time can make a really nice tool. If you would like a picture of mine I could send it. A transmission pressure gage is needed to help diagnose the problem. Another item that is needed is a way to clean the parts. One of the most important parts of rebuilding an automatic transmission is thorough cleaning. All of the small passage ways need to be cleaned, parts need to be cleaned for inspection and particles need to be removed from all the parts. A pressure washer will work to clean the outside of the trans before disassembly, a tub of solvent will clean the hard parts and aerosol cans of brake clean will work for final cleaning of parts. One other thing about cleaning parts, do not use cloth rags, use lint free paper towels especially around the valve body. The valve body is probably the hardest part of the rebuild. In your case I would just split the valve body and clean it with brake clean and not remove any valves. The valves can usually be inspected well enough if you split it. If you split the valve body you just need to be careful with the check ball location. The manual will have check ball location charts. If the problem is in the valve body and you put it back together it is not hard to remove the valve body with the trans in the vehicle, at which point you could try to rebuild it or buy a rebuilt one from Transtar.

            Just a few reminders if you decide to try the rebuild,

            Follow the diagnostic steps in the manual to narrow the problem down.

            When you disassemble the trans it’s going to be very messy, there’s a lot of fluid in one of those things even if you drain the pan and converter. It helps to have a way to tear it down and catch the fluid.

            Clean everything almost surgical clean.

            Inspect all parts for wear especially where there’s metal to metal contact and where a shaft rides in a bushing, bushing wear is a very common pressure loss area and bushing kits are available from Transtar.

            Check all clearances such as clutch pack clearance, oil pump gear side clearance, transmission endplay and any others given in the manual. These clearances are usually easy to check but can cause problems if out of spec.

            When replacing all the friction components such as clutch discs and bands make sure you soak them in trans fluid for an hour or so, these components are all included in the deluxe kits.

            When assembling components use Vaseline, trans assembly lube or ATF only. Vaseline and trans assembly lube also work well for holding thrust washers and bearings in place when trying to assemble components.

            Try to keep components organized. If you are not sure where a thrust washer or bearing goes the ATSG manual has a thrust washer location chart but some times they are not easy to read.

            When installing the torque converter make sure it’s all the way in. Most of us saw what happened with Jesse James in Iraq when the kid didn't install the converter all the way in. There are three shafts that need to engage for it to be all the way in, oil pump drive, stator and turbine. A good way to know for sure is measure from the converter to the bell housing before removing the converter. After unbolting the converter from the flex plate push it all the way back in the trans and measure, make a note of the measurement and it should be the same when installing it.

            There’s probably a ton more stuff that I'm forgetting, it’s been about 2 years since I worked in a transmission rebuilding shop. I was an auto technician for 24 years many of those years was rebuilding transmission but since I have turned to my hobby of machining to make a living I am trying to forget everything I know about working on cars (LOL).

            If you have any other questions feel free to contact me,

            Mark Hockett
            Island Tech Enterprises
            Clinton, WA 98236

            More chip less lip
            Last edited by Mark Hockett; 08-23-2006, 02:11 PM.
            Mark Hockett


            • #7
              My advice is take it back to the rebuilder that fixed your broken pump gears for you. Ask him if he'd do a bench job for you which will save you some money in the R+R (Removal and Replacement) by removing it and re-installing it yourself. Just remember to make sure your converter is in all the way this time. It's not a job for the novice. It may cost you more $$ in the long run if you attempt a rebuild yourself, put it back together and she doesn't work? Also, you'll probably need more specialty tools to do-it-yourself than money saved by doing it yourself, for example: Pump Puller, Bushing Driver Set, just to name a few. I've rebuilt many (back in the late 70's early 80's) and had more than a few guys come in with their trans in a box after realizing they bit off more than they could chew. Remember, the longer you drive it in its current condition, the more likely you'll need more than a basic overhaul. You may tear up some hard parts: Pumps, bands, clutch drums, planetaries, etc,. HTH, Paul.

              Edited to add: I agree with everything Mark has written and admire his generous offer to help.
              Last edited by ProGunOne; 08-23-2006, 02:28 PM.
              "The men the American people admire most extravagantly are the greatest liars; the men they detest most violently are those who try to tell them the truth." H. L. Mencken

              "All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."

              "When fear rules, reason and logic are ruled out."


              • #8
                1: Get a rebuild manual. The clearances and such are critical. You will need this as a referance.

                2: Always check clutch free play dry, but you MUST pre-soak all of the friction plates in fluid prior to final assembly.

                3: TransGel is your friend! Use it almost everywhere there is metal on metal contact. Also works great for holding check balls in place during assembly.

                4: Cleanliness is Godliness.

                5: Be sure to check the valvebody for stuck or worn valves.

                6: Isolate the cause of the failure. Sounds mostly like you just have normal wear and the trans has exceded it's lifespan. But if it was caused by another system failing, crack in a housing, bad O-ring or teflon ring or similar failure, it will fail again almost immediately.

                7: Backflush the transmission cooler in the radiator. Connect the return line to some source to force trans fluid backwards through the cooler. Circulate a few quarts in there to remove debris and potentail blockages.

                8: Replace the torque converter. They're only about $100 on the rebuild market, and a bad or contaminated converter can toast a new trans by the end of the driveway.

                Don't be too intimidated though, it's not rocket science and that should be a pretty simple unit to rebuild. I've never done a C6 but I have done quite a few 4L60E (computer controlled 700R4's), a much more complicated unit and even those were not extremely difficult. Attention to detail is key.

                Don't be afraid to replace other components while you're in there too, like the vacuum modulator. Carefully check the sun and planet gears for wear, also the sprags. They are generally very inexpensive.


                • #9
                  On a C6 you dont need specialty tools pump puller use allthread and angle iron too pull the pump,C clamps on the clutch packs.go get a book a read before you do anything.


                  • #10
                    Thank you for your replies.

                    A.K. Boomer

                    Thanks for that tip. I never heard of BG auto trans reconditioner.
                    I tried some other brands, but I can't say I feel any improvement.
                    I will try to find it locally.


                    It does shift pretty well manually, when warm it drives OK.
                    It sometimes doesn't down shift when stopped. Several seconds after a complete stop it will suddenly shift and try to lunge forward. It may do that more than once sometimes.

                    Mark Hockett

                    Thank you for your generous offer of your time and experience. If I do actually tear it down myself I may need some advice. I plan on trying BG auto trans reconditioner as recommended by AK Boomer, first. I always take the path of least resistance first :-)


                    The guy who fixed the pump for me 8 years ago is no longer around.

                    I already inquired and there is no discount if its off the vehicle. (at least at the shop that I would use, rec. by a friend who knows)

                    Part of the reason I want to do it myself, is to learn how to do it.

                    8 years ago I swapped engines in this van with no previous experience.
                    I bought a junkyard engine for $200. built an engine stand, tore it down, found very little wear, decarbonised the head, replaced all the gaskets, borrowed an engine hoist and swapped engines.
                    When I busted the trans. pump, I made an adapter for the floor jack, dropped the trans. and took it to repair, then reinstalled.
                    I had never done any of these jobs before.
                    Now that I have done it, I wouldn't be so apprehensive to do it again.
                    I just never took apart an automatic transmission yet.

                    One problem I have is lack of space.
                    Or a suitable place to do the job.
                    I did the engine swap in a friends driveway.
                    I'll probably have to do the tranny there too.

                    Thank you all, for your advice.


                    • #11
                      Almost forgot about this thread. So how did it turn out after all the pretty darn good advice?
                      "The men the American people admire most extravagantly are the greatest liars; the men they detest most violently are those who try to tell them the truth." H. L. Mencken

                      "All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident."

                      "When fear rules, reason and logic are ruled out."


                      • #12
                        More c6

                        One thing that gets missed alot and is so crucial is the cooling tank in the radiator.
                        This tank is a depository for all the crap that comes apart in your trans. Many shops don't deal with it and end up with come-backs. The same crap that came out of your trans ends up contaminating your new one. just blowing it out with air doesn't help much, they need to be flushed properly.
                        When I was still wrenching for a living, my last wrenching job was at a trans/driveline shop. we had a cool rolling unit that had a pump and filter unit to flow solvent through the cooing lines and tanks. When we did a bench job we sold the customer several cans of a compressed solvent that had the aproppriate fitting on a flex hose. real easy to use, was pretty effective at flushing out the lines and tank. Use 2 or 3 cans.
                        On a van, I would recommend an additional cooler mounted on the outside of your radiator, B&M makes a nice basic one that you can run in series with your existing sysytem. Take a close look at your valve body, Ford use some non-metal check balls and they actual dissintegrate after a long time. Sounds like there is an issue or two in the valve body. CLEAN,CLEAN<CLEAN. Have fun, the C-6 is an awesome trans, and pretty simple.
                        grumpy old fart