A 904 Rebuild Project I took on.

Hello,
This transmission is backyard built and ready! I took on this rebuild project for a friend and I took lots of pictures along the way of the disassembly process. This was my first time rebuilding a 904 transmission and I thought that this would be a good place to post the pics for reference if anybody needs it. The transmission I rebuilt was a 904 transmission with the heavy duty rear band and lock up converter.

I used a rebuild kit from Summit Racing. Performance Automatic, kit number PAKT12701, with shift kit and band included. I installed the shift kit using the street settings.

I had to order the rear band separately. I also had to order additional clutch and friction plate for one of the clutch packs in order to get the correct clutch clearance.

The transmission had been going forward in every gear and after disassembly, we figured out why. The clutch pack was welded together.







Old torque converter.


New band that was ordered off Ebay.


After removing the pan.


The filter did it's job of keeping the foreign material from going through the transmission.




Removing the front pump.






One of the screws on the snap ring cover for the extension housing was a huge PAIN. I ended up using an hand held, hit with the hammer, impact driver to get it off.






Snap ring to remove the extension housing.




Snap ring to remove this bearing.


Snap ring to remove governor.

This shaft has to be removed to get the governor off.






Pump finally separated from the case.




Removing the band so I can pull the rest of the guts out.






One way clutch rollers and springs.


I used a big C clamp to slightly compress the servo so I could take the snap ring out.






The rear clutch pask inside of here was welded solid!!!! It was a task to get these separated. I ended up clamping the smooth part of the input shaft in a vice and using a big punch and hammer to tap it, rotating after every tap intil it started sliding out. All of the friction clutches were worn completely out. The steel clutches, and both pressure plates had too much heat damage to re-use. I was able to get two new pressure plates from a local transmission shop.


After separation!!


Valve body. Cleaning all of these parts up really good and getting them back together took the longest out of the rebuild. I completely put the valve body and transmission back together. After that, I then followed the instructions that came with the shift kit to install it.

Checkballs!!




More checkballs in here.




After running everything through the parts washer, then rinsing off with water and drying.




New torque converter.


New Clutches! If I remember right, the clearance I had here was 0.102


Pre-soaked them for a hour in atf, after checking clearances, before final installation.


Shift Kit.


I had to open the valve body back up for the shift kit install. Did some drilling on the plate, drilled using the template on the cast iron body, and removed a two check balls, per the kit instructions.


Everything buttoned up and ready to go.


In this picture and the next, I got the test port and cooling line plugs mixed up. Caught the mistake before we got the transmission back under the car. I was in Ford mode for a second and placed the cooling lines on the passenger side by accident!




Here is the car on final installation day. In order to get the transmission under the car while on the jack, we had to lift one side up a little higher. Once it was pushed to the tunnel area, we squared everything back up even and level all the way around for the install.


The test drive was great!! Transmission shifts perfect with the shift kit and the car idles alot smoother now than it did before the old transmission had its major malfunction.

Great write up man!!

Great work !

Excellent write up! Ive got mine torn apart right now and just trying to be really patient and not rush anything.

Jake

dadodgekid said:

Great write up man!!

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Thanks. I should have taken more detailed pictures, but transmission fluid and cameras don't get along that well!

Turbo poly said:

Great work !

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Thanks.

xLURKxDOGx said:

Excellent write up! Ive got mine torn apart right now and just trying to be really patient and not rush anything.

Jake

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Yep. This was my first time building one of these. Now that i've done it, I could do another one in less than half the time.

Nice job man! They're quite easy aren't they! I did my first on in high school auto shop in 1981. Been hooked on doing them ever since.