So now what I did was used the components of the tranny to stack up and take the gap between the bearing and the threads. You could use any old spacer if you wanted as well but the actual components work…note I didn’t put on the gears, just the bushings, etc. We don’t want to load up those synchronizers themselves. I simply want to use the large nut to install the bearing.
Now using an old driveshaft to hold the main shaft (covered up to prevent debris from coming down on our nice clean transmission and a crescent wrench…drive it until the bearing is seated. Take your time and use judgment, you don’t want to screw up the threads on that shaft. It should install pretty easy though. You’ll feel when it is seated.
Ok..good thing is the hardest parts are done. Bad thing is that we need to shim this dang countershaft. Here is where I made a fundamental error again. I didn’t catch my error until almost fully assembled and I had to tear back down to address. So I’ll try to talk you thru this.
First thing you want to do is measure the ‘gap’ between the top of the outer face of the rear countershaft bearing and the housing. I used some markings here.
I added the original shim too. I can see that it is undersized and fell into the hole….thus knowing I need a thicker shim. Yours may be the opposite!
I mounted a dial indicator on the end of the shaft.
Now I set a flat block (my polishing stone in this case) over the housing and shim. And measured the slop.
This told me the approximate ‘range’ of shim I need. Basically the measured slop is in addition to the thickness of my old shim…in my case. You want to shoot for 0.000” but not create a binding situation! That’s difficult. But the max slop you can have is 0.002”.
However, here is where I screwed up! Remember we just installed new bearings in our countershaft and I didn’t take account any potential compression by torqueing the nut at the end of the shaft. You need to account for this and it is not easy! What I did was bought four shims in the approximate range I measured. Then I selected the one that was perfectly flat with the top of the flange. I don’t own a depth mic so I had to improvise.
I checked my slop again…it was negligible…thus I went with it.
But again I didn’t take in account any compression during torqueing. When final assembled, I checked my slop again and I was at ~.003” which was out of spec!
To account for this; you can try to assemble the countershaft with the gear components temporarily and deliver the torque and then re-measure. This will be difficult because the tranny cannot be locked into gear yet. What I did was that I knew I was .003” out of spec so I had to select a spacer .003” over what I installed…of which was larger than my largest shim purchased. So I had to order some more…coming from Japan….5 weeks lead-time! Dang! When they came in, I measured them, selected the one closest but not greater than .003 over the last one, tore the hole back end of the tranny back apart, swapped the spacer and reassembled. I guess another avenue would have been to select a shim in the front side of the countershaft that we assembled earlier that was .003” over the one installed….but in either case, it resulted in rework. What I’d do if I were you, is find out what thickness shim you need to achieve zero gap in the un-torqued condition and make sure you buy shims that go up to .003-.005” over. Then assemble the rest of the gear train keeping in mind that you will have to recheck your countershaft slop once the countershaft nut is torqued and that it may result in tearing back down and going with a different shim.
That is long and drawn out, but I hope you get the point. You want close to zero slop but not binding! When it was all said and done, I had ~.0005” slop but it derailed my project for a long time!
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