What happens in a transmission rebuild - Part 9

[Mac VP]

LINK TO ORIGINAL POST:
https://www.fordbarn.com/forum/showthread.php?t=278347

Once again, this thread will be set up into several sections. We are beginning to assemble the main gearbox for the transmission. First, we apply some of our wonderful assembly grease to the front thrust surface of the countershaft area. This is where you stick the B-7119 front countershaft washer. Fit the protruding tab into the groove (oil channel) and press it against the grease.

Then we take the loaded cluster gear (with the two caged roller bearings, the inner spacer tube, and the rear thrust washer) and set it down into the case so that it rests against the bottom. If we were using the other type cluster gear with the two prongs on the back end, we would apply the thick washer against the prongs of the gear. Then after dropping the gear into place, we would fit the second thinner rear washer into place (between the thick washer and the rear surface of the gearbox case).

My photos are slightly out of synch here, but at this point we stand the gearbox up vertically on the work bench. I took this photo earlier so you don't see the main drive gear and bearing fitted to the front of the gearbox. We created a spot on the wood bench, with a 2-1/2" diameter opening, in order to be able to stand the transmission up in a vertical setup. The drive gear pokes down thru the opening in the bench. I have placed reinforcing wood below, including a 4x4" post to allow the bench to handle all the weight of a fully assembled transmission in this fashion. You can also stand the gearbox on a couple 4x4 wood blocks to raise it up enough to clear the main drive gear but that also raises the job higher on the worker.

Now we see the cluster gear inside the case, and we are going to install the reverse idler gear next (large shoulder facing to the front). Fit the small idler shaft into the case. This can be a push fit or a much tighter fit in the bore. I like a snug fit and sometimes have to place a drop of oil on the shaft and twist it into place with a drift punch. Locate the gear at the opening as you work the shaft down through the idler gear.

Align the lockpin hole in the idler shaft so that the lockpin can be fitted easily through the pin. Test fit with the lockpin…..if it isn't close to a perfect fit, pull up the idler shaft and try it again until you get the easy fit of the lockpin.

[Mac VP]

Next, I will prep and apply the gasket that fits between the rear of the gearbox case and the overdrive adapter casting. We purchase our transmission gasket sets from BEST GASKET, who make a quality product. Once in awhile, I find that a particular gasket is not stamped out exactly to the contour of the casting. This is the case on this one. I place it over the rear of the case and "trim" it with a ball peen hammer and sharp utility knife blade as needed. I make sure to use a fresh blade in my knife when trimming the inner opening. I have found that their gasket is ever so much smaller in diameter and tends to hang up when the adapter casting is being fitted there.

We use Permatex Gasket Maker, an RTV product, to provide a thin film of sealant against the gearbox rear face. I probably would not need it but I am a stickler for leaks. I also smear it over the idler shaft bore before I place the gasket.

I already have my mainshaft, gear, and adapter assembly ready to go. The next step will be to install that group into the case, and up tight against this gasket. I do this before the gasket sealer firms up. That step will begin in Part 10.

[Tim Ayers]

Thanks, Mac! Loved the series!

[Wayne Schuenke]

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