Technical Muncie Tear Down, What’s Junk, What Can Be Reused?

I’m back. I’ve been gathering Muncie junk (wait, can’t say that again) parts and I’m finally gearing up to put this thing together again.


I got my synchro assemblies assembled and my input bearing on and then took a close look at my mainshaft and found some scratching where second rides. I guess I’ll try dressing it with emery cloth at home today or maybe spin it up on a lathe at work this week. If you can polish a crankshaft, you can polish a mainshaft, right?



Hope it works. I’m tired of buying Muncie parts.

 

If you can polish a crankshaft, you can polish a mainshaft, right?


There’s a joke in there somewhere!

 

I polished my mainshaft for a while this afternoon and got everything nice and smooth. Second gear spins nice and quiet so I think I can get away with it.



I also dressed the midplate with a file and smoothed out some damage.






I then assembled the main shaft components. Unfortunately, my original speedo gear wasn’t looking great. I have to order a new one.
Next up, I’ll clean the case and drill it for a drain plug. Lots of family activities this weekend so I ran out of car time.

 

Much better than what you started with.

 

Does that midplate have a crack in it by the counter shaft hole? If so I would replace it!

 

If you’re looking at this spot, I think it’s just a casting flaw where the aluminum didn’t fully fill. It doesn’t seem to be spreading, maybe…

 

That hole isn't for the counter shaft, anyway. It's for the reverse idler.

 

My mid plate was toast. The countershaft spun and the key acted as a lathe bit, put a nice big spotface in my plate.

 

I wish I could take as good closeup pictures as Lewk!

 

Ok, apparently I’ve been almost deliberately ignoring the damage to the midplate where it prevents the countershaft from spinning. Now I feel blind or stupid or something. I guess I need get a nodular iron midplate. Unfortunately, I just spent my hobby money stash on a 48/49/50 or so Snap On bottom box to match my grandpa’s top box. I guess I’ll get back on the trans in a week or two…

I got the iPhone 14 yo! The camera is killer plus it’s easy to make cheesy photoshops like these:



It’s margarita time. Things are going off the rails.

 

Unless I am missing something the countershaft isn't supposed to spin Lewk, It has a notch at the back to lock it in place.

 

Yes, correct, the shaft should not rotate. I think folks were trying to point out the damage to the midplate where that notch rides, but I was focusing on the casting flaw by the reverse hole. I had seen the damage, but hadn’t considered why it was there. bobss396 describing how his countershaft spun and ate the midplate made me see that mine was headed that way.

 

You won't regret using an iron mid-plate, even if it's only for peace of mind.

 

Yes, the step on the end of the shaft will bore into the mid plate. Mine from day-1 was recessed about 3/16" into the main case. I didn't think it was an issue until it was taken apart. The funny thing is that these shafts are virtually indestructible. My builder had a few drawers of salvaged ones, 7/8" and 1". My case was bored for the 1" shaft.

 

Alright, back on it. The iron mid plate came in and I got it mounted.





I drilled and tapped for a drain hole. (1/2-14 NPT if anyone cares)



The factory magnet basically fell out while I was messing with the drain plug. It would have been exciting to have that latch onto a gear later. I’ll use a magnetic drain plug instead.



I cleaned up my cluster gears. I have two, the one from my trans and one from a helpful gentleman in San Diego. The San Diego gear has some surface rust but much better end bearing surfaces, so I think it’s the winner.






I’ve still got to do the tail shaft bushing and find my driveshafts and choose a yoke to test fit and then hopefully I can do some assembly.

 

Regardless of which mid plate you use , if the counter shaft bore in the front of the main case is loose , the countershaft will eventually spin . most old cases need to be bushed so the case/ bushing/ shaft are a press fit When bushing the case , be sure to maintain the counter shaft thrust bearing surfaces intact, that will help prevent the worn thrust surface as exhibited on your one counter gear .

 

Mine, the rebuilder opted for going to the larger 1" pin. My case must have been egged out with it spinning for so long.

 

Its not so much the spinning that enlarges the case bore , its the input trying to push the cluster gear away , plus when you drop the clutch or speed shift its akin to hammering the shaft sideways in the case . Changing to a 1" shaft requires a different cluster gear . If I had choice between which cluster gear to use , I'd have the better gear ground flat & use extra shim to take up the end play .

 

The countershaft holes are nice and snug. I had to tap the old shaft out and I can’t put the new one in without pressing or tapping it in. I haven’t check endplay yet, but will as a next step. I think the thrust surface on the old cluster gear got trashed by all the debris whirling around in that box. I have a later trans so it’s already a 1”. I thought about facing the thrust surface on a lathe at work but having come up with a good fixturing idea that doesn’t either clamp onto gear teeth or interfere with the surface I’m trying to clean up. Maybe I’m missing an obvious solution.

I found a 27 spline yoke on one of my drive shafts and bead blasted that and the San Diego Cluster Gear. SDCG seems like a winner. Surfaces look pretty good.

 

When putting in the countershaft for the final time use a little red Loc-Tite on it to set the ends of the shaft.

 

Is it done yet?

 

How could that possibly work after passing the counter shaft through all those greasy needle bearing's?

 

Clean off the end, you can only do one end.

 

5 Speed Paul suggests anaerobic sealant in his YouTube videos. All this talk about having that shaft come loose has me thinking I should get an extended countershaft with the screw hole in it to bolt it to my mid plate. I might order one tomorrow.

Sheesh, tough crowd! I know I’m slow but family first, work, and then I try to play cars on the side. I did get the tailshaft housing cleaned, bushed, and sealed.



Paul has a ground down prybar to get the detent ball compressed on his vid, but I found an old church key and it worked fine.
If I order the extended countershaft, I might be out of business for a few days. If not, I’ll keep assembling.

Cluster gear endplay is right around .015, so that’s good.

 

I don’t know about the extended counter shaft. Never had a problem with one wallowing out the case with the red Loc-Tite.

 

Are you putting it on the thicker end closest to the midplate of the shaft?

 

After you push the shaft through the counter gear bearings there'll be enough grease on it to render any loktite useless.
427 sleeper beat me to it

 

The end behind the bell housing if I remember right.

 

I assembled everything last night and my front bearing isn’t seating how I think it should. Everything is too long. I found another thread with a similar problem with an incorrect bearing from the same vendor I got my bearing from.
https://www.jalopyjournal.com/forum/threads/muncie-help-needed.1237877/page-2

I still need to tear it down and compare the new bearing to my original. I ran out of patience last night.

I’ve either got the wrong thick bearing, messed up some sort of basic assembly thing, have a fat early 3/4 hub (that one is used) or my new mid plate is goofy. I’ll tear things apart tonight and see. I also tore a gasket with my repeated assembling last night. Yay.

















I need to spend some time with some bearing websites and try to find the specs for both the new and old.

 

The hub passes the sniff test but the front bearing fails. I guess I’ve got to get a N1307L.




This is the same problem from the other thread and I ordered the part from the same reputable vendor. You’d think this problem would be better known.