Ok, so I've started to reassemble a Muncie M20 that will be going in my '31 coupe behind a 364 Buick. Last night I struggled for a couple of hours to get the cluster gear back in the housing. I finally gave up and decided to give it a go again today. I installed all the needle bearings using grease to hold them in, however the problem came in trying to get the cluster back in the housing without it all going to hell in the process. The thrust washers on the housing would move (tabs don't seem to hold them well), or the spacers on the ends of the needle bearings would move/become lodged. There were a couple of times then when I finally got the cluster in, but then one (or more) of the needle bearings would have fallen out of place. Needless to say, my frustration level was maxed out after 10-12 try's at this thing. So with that, there's got to be some trick to get 112 needle bearings, 2 outside spacers and 2 thrust washers to stay in place while putting this cluster back in the housing. I'm running out of grease, ideas and patience! Any advice from those who have been there before me? Thanks in advance.
It's either 1/2 or 3/4 cpvc pipe that's slightly smaller than the countershaft , cut a piece the same length of the countergear , lay in the bearings w/grease & use the platic as a temp. shaft , set the assy in the case & push the plastic out w/ the countershaftt , no lost bearings ... after thinking about it , I'm pretty sure it's 3/4" cpvc
Back when I was doing Muncies. I used heavy fibered wheel bearing grease and had a piece of wood dowel (broom handle) roughly the od of the countershaft, cut to the length of the cluster. Grease up the bearings/spacers as assembled. Insert wood shaft, drop unit into case with thrust washers then push out dowel with countershaft as it goes in from the end. Broke a lot of Muncies. Drag racing in the late sixties/early seventies.
Spacer idea sounds like the trick. Are the thrust washers on the cluster (held by the spacer) or in the case when you install the cluster? I tried both ways last night; both had about the same results. It may go a little smoother now with the spacer holding everything in place inside the cluster. When I was working last night, I tried both installing it horizontally (to keep the needle learnings from falling out the end) as well as vertically. Any recommendations here?
Dummy shaft and old style wheel bearing grease always worked for me; just wish I could still run down to Midway Chev and pick-up parts for cheap.
Make a dummy countershaft.....as close to the diameter of the real shaft as possible. Cut the length to slightly shorter than the actual cluster gear. Pack your needle bearings, spacer tube, and any internal washers into the cluster gear. Use a heavy grease. Keep the whole assembly horizontal. Place to thrust washers into position at the front and back of the gearbox using grease to help hold them in place. Drop the cluster gear into the gearbox bottom. After you've assembled the upper gear assembly, you bring the cluster gear up to align it with the case openings for the countershaft. You can keep the gearbox horizontal and loop a cord under the cluster gear.......or stand the gearbox on its front face. Then it's a matter of wiggling the thrust washers into place so you can tap the real countershaft into the gearbox, forcing the dummy shaft out the other end. Be careful to align the washers at the other end before forcing the shaft through or you'll damage that washer and have to start all over. Not sure on Muncie's but I think the countershaft can only go in from one end. Check the manual to be sure. The dummy shaft can be made from a variety of sources, but it's best to stay close to the actual diameter of the real countershaft. That's why we use old countershafts, cut to the correct length for each job. Chamfer the end of the fresh cut end.
I still have my "lucky" Muncie broom handle countershaft , That and the bearing retainer/slinger wrench are a must have for Muncie's
I did mine with the case vertical and assembly lube holding it all in place. The Paul Cangiolosi book was really helpful to me and had a bunch of really useful pointers. Sent from my iPhone using The H.A.M.B. mobile app
Wooden dowel can be had at the local hardware store. 3/4 or 1 inch depending on the year of your trans. Work the dowel into the cluster as you put your rows of brgs and spacers in and it will hold them in place. I have found it easiest to put the countershaft pin in from the rear of the trans so it is easier to align the pin with the rear brg support. D
SUCCESS!! The tips made all the difference. For future reference if anyone searches, the dummy shaft is out of 3/4" EMT conduit cut to 8 3/8" long. I labeled it for future reference.
Unless you know of a sealer that will adhere to grease , that'd be a waste of time as the countershaft is covered in grease from the bearings ..
If the bore in the case is so loose it leaks , it's time to bore the case & make a bushing...The other downside of a wallowed out cas is , the input gear & front counter gear won't last long
I didn't. I've read where folks put a bit of sealer on the end of the shaft. I'll do that once I get it all back together. Keep the tips coming!
The shaft was pretty tight going in. Took about 10 'whacks' with the dead blow to get it through. I think the case is in good shape.
Aren't you meant to install the input shaft and main shaft before lifting the counter shaft into position or is that just in the later boxes?
You can cheat the main shaft in with the cluster installed. Leave low gear off until you get it installed. Also helps if you slide the 3-4 syncro back into third. D
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