If you want to do the most affordable over-haul and replace the minimum amount of parts then measure each part very carefully for wear. It’s pretty easy, even I’ve done it!
Only replace what you absolutely have to. Look for uneven wear and I would serious consider replacing both the countershaft and the idler shaft if there is any wear. This would require either replacing the cluster gear (expensive, not sure what current pricing is but it was about $100 when I did it the last time…Richard Grace of Georgia, if still in business, …doesn’t advertise much had the best prices anywhere) or at least the bushings contained in the cluster glear and reverse idler. Well I was going to go on but I cover this in my book and Richard Grace and Jim Gilmore say it better…
From Page 6 of Trouble Shooting And Rebuilding The T-84J:
Richard Grace. “The minimum parts replacement would have to be the small parts kit whic includes the main driver gear rolls, thrust washers, synchronizer dogs and springs. One other almost necessity is mainline bearings.”
Jim Gilmore. Suggests “replace the pilot bushing (in the flywheel). It is critical as replacing the main bearings. Failure to do so can set up your main drive gear to wobble–resulting in rapid wear to your bearing.”
I would add to this a new clutch disk and throwout bearing. Working on the transmission is very easy as there are only about 57 parts. All you have to do is follow the steps (and pictures) and you will have done a better job then many “experts” who just crank this so called “rebuilt” transmissions out. This is not to disparage all T-84J transmission overhaulers but some don’t carefully measure the old parts to see if they need to be replaced.
This is way the T-84J is often accused of being noisey. If you are over 50 years old (60 plus for a jeep) you would creak too if you have worn parts that don’t get replaced!
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