It finally happened. My original Ford Worldwide T4 transmission in my CJ7 finally failed on a normal trip around town. The T4 is a very light duty transmission and I knew I was on borrowed time with the upgraded V8 engine. I did get around 10 years of use out of it so it was not a complete waste of time keeping it.
I removed the transmission and opened it up. I found some gear failure shown below.
3rd gear completely failed and left metal parts all over the inside. This is repairable and I have another spare transmission but I have decided to scrap this unit out and go with something else. I wanted a stronger transmission so I have decided to go with the Muncie SM465 transmission using in the GM Pickup trucks. Its a popular CJ7 adaption and its wildly supported and documented.
The best documentation I found was on the NOVAK Conversion website. They have everything you need if you want to buy a kit and they have all the detail if you want to make your own adapters.
My plan is two steps. First is to adapt the AMC V8 to the SM465 which I will make all my own adapters and second is to adapt the SM465 to my Dana 300 transfer case using the Novak Adapter kit.
Step 1 : AMC V8 to SM465
Novak has some great instructions on how to adapt the AMC V8 to the SM465. I suggest you read up on that as it is the process I followed. There are 3 main modifications that need to done to adapt the SM465 to the AMC V8.
The bell housing needs to have the main opening that accepts the bearing retainer opened up to fit the SM465 bearing retainer. I opened mine to 5.005″. This was pretty easy using a old Bridgeport mill and an adjustable boring bar. I spent most of the time centering the original hole to the boring bar and was able to get it within 0.001″. The actual boring out the hole only took about 20 minutes.
The next step is to remove the bearing retainer from the SM465 and turn it down to 5.000″ in a lathe. I turned mine down to 5.000″ which is a slip fit into the bell housing which is 5.005″. Again, I spent more time indicating it in to be centered than to make the cut. The actual cutting took about 10 minutes.
This next part took me a long time. The bearing adapter needs to have a sleeve made to make it longer and larger in diameter. This requires the manufacture of a thin sleeve that needs to be lightly pressed onto the bearing adapter. Novak gives the dimensions but you need to custom fit it to the wear on the adapter by measuring.
I made a drawing for this sleeve. Novak notes a “light” press which means 0.0005″ – 0.001″ interference fit. This sleeve is very thin so too much press will crack it. I used non-heat treated D2 I had laying around and targeted 0.0005″ interference fit. It took me many hours to make this sleeve but it worked perfect.
More to come. Next is to drill the mounting holes in the bell housing to accept the SM465.
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