Been driving my pickup and the current M22 has bad synchros, so I'm going to swap it out. I have another one that is fresh rebuilt (about 8 years ago) and never used. I've been holding onto it but lost track of it in storage the last couple of years. I went to install it this weekend and the shaft doesn't turn freely by hand. A little pissed, I opened up the side plate (where the forks attach) and found a little surprise. The backside of the plate has some steel and the forks and fork clutch sleeves (is that what you call them?) are rusty. Not horribly, but surface rust. I can clean the forks by hand, but the clutch sleeves (which I cannot remove with disassembling the transmission) also have surface rust. I have NO intentions of disassembling this trans. Anyway, I'm trying to figure out how to clean out / flush the rust scale and get rid if the oil that has turned to sludge. Should I fill it with kerosene, gas, mystery oil, etc..? spray with brake cleaner, and then drain it? Which of these would do the least damage, or would any of them be ok? Which would remove the most scale? Will I have to reinstall new seals? Any help would be great. BTW: the gears and synchros and the inside of the case all look really good...there is minimal rust, but I need to get rid of it before installing this gearbox. Thanks guys...
If the rust comes off that easily, I wouldn't be worried about the gears. Not turning by hand makes me question the bearings though. New or not, if there's rust on the bearings they're junk.
Know this isn't for everyone but if it were mine I'd disassemble it, properly derust all of the internal parts and reassemble with new gaskets/seals. During the course of my drag racing days I have rebuilt 200+ of these transmissions and the whole job wouldn't take me more than an hour to an hour and a half to do the job. I made a fair share of my racing budget doing manual transmission repair. When you get to being able to do it with your eyes closed it's kinda boring. Frank
I would fill it with fresh clean ATF on the bench and gently turn back and forth by hand to free it. Spend some time, it will save you money. If it gets to turn free in all gears, drain and flush, fill with 90 wt and go.
I think one way or another that Trans will be coming apart weather you like it or not. You can do it now or after you burn it up. Read SBCwelders post a few times, you'll talk yourself right into taking it apart. Rust never sleeps.
I've never taken one of them apart, so it seems daunting to me. If I disassemble it and don't change anything at all, can I reassemble it without having to check tolerances or adjusting anything. The part that concerns me is getting the tolerances and specs correct.
This might help to let you know what you'd be in for, Buzznut. Looks like it's pretty detailed. Have fun. http://www.powerblocktv.com/two-minute-tech/2min-74/rebuild-a-muncie-4-speed-transmission-part-1
X2. If it wont roll over, its gotta come apart. How stupid are you going to feel when the trans packs it in a couple weeks after you put it in the truck because the bearings are fragged?
If you decide to disassemble it, look for a copy of Pertersons "Basic Clutches and Transmissions". Back in the late 1960's to late 1970's Peterson's Publishing, (Hot Rod Mag.), printed a series of basic "How To" books, all on auto related subjects. They are all well written and illustrated. "Basic Clutches and Transmissions" has a section on rebuilding Muncie 4 speeds, with LOTS of photos. There are alot of good tips in these books, too. Since they are long out of print, I found my copy on Ebay. There were many other titles such as "Basic Carburation, And Fuel Systems", "Basic Chassis, Suspension And Brakes", etc.
Look on these guy's YouTube channels for more comprehensive rebuild videos. I think there are others as well. http://www.youtube.com/user/greenSN95gt?feature=watch https://youtube.com/user/robinsonsauto?feature=hovercard http://www.youtube.com/user/WeberAuto?feature=watch http://www.youtube.com/user/JonesysAutoClub
Maybe I'm posting the obvious but if they are in 2 gears at once they will lock up and it does sound like you're not entirely familiar with how they work. Make sure all the levers are in neutral and report back. Maybe stick an old clutch disc on the input shaft to give you more leverage to try to turn it as well.
I am very familiar with how they work...I shift one every day. It is not stuck in a gear...it was turning freely just 4 months ago or so. I rebuilt one about 18 years ago in class I took, and this one was rebuilt (by a professional) about 8 to 10 years ago. The videos have jarred my memory, I just need to crack it open and do it. M22 are somewhat the holy grail of early GM transmissions. I have the one in my truck and the one I'm talking about here and two M21's that I's like to rebuild or have rebuilt as well.
Good luck to ya. I think pulling it apart to check it out is the right choice. You should be happier in the long run.
i use an older motors manual,one thru early 70's should have all the info you need to do one. there's a motors manual on e bay right now in those years i think the starting bid is 12.00 with 7.00 shipping can't go wrong with it. hope this helps hot rusthttp://www.ebay.com/itm/141232344700?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
I've never been into a trany till I did my 3 speed (since the trabs shop didnt know how) anyways figured it won't hurt to try myself got a book on how to rebuild it and didn't even touch it really manual tranys are very easy if you are still ify take lots of pics it helps your first time good luck
If you able to reuse the parts and carefully seperated gaskets, all your clearances and endplay should stay as they are. The only difficult areas that I remember are getting the reverse arm back on the reverse gear whe n reassembling trans. Non caged roller bearings can be held in place using wheel bearing grease or vaseline. There are 4 rows on the cluster gear and 1 row at main drive gear and mainshaft. The synchro hubs are sometimes pretty tight on the mainshaft, which you may not need to take apart if it all spins freely once away from the cluster gear. if you need to get the synchro hubs off the mainshaft a press helps or you can just bang the the end of the mainshaft on a block of wood several times, using the inertia to separate each hub.Snap rings can be squeezed back to keep them tight. Lay your parts out in order and try to keep them in order.
I know this is months later, but I did get the transmission completely apart and found that the bottom of the 3rd and 4th gear had been sitting in a rusty soup (partially submerged) which left some slight pitting. It turns out that this second unit is a wide ratio and not an M22. I completely disassembled and cleaned it and put it in my truck. It whines a bit in 3rd and 4th, likely from the irregular surface on a few gear teeth. I'm going to rebuild the M22 I took out and put it back in and keep the one I'm currently using as my backup. One thing I do plan on doing is converting the M22 from a close ratio to a wide ratio, as the deeper first gear helps a ton during take-off. I'll be replacing the entire countershaft / gear assembly and the input / 1st gear cluster in order to convert it to a wide ratio. I'm also going to install new collar, hub and synchro assemblies, new bearings and a new redesigned steel center plate. In total parts will run me around $600 and the M22 should be bullet proof behind my 400hp mill.
If you convert to wide ratio on the M22 I would be interested in the close ratio gears for my gasser project.
Tell ya' what....I like 'em both. You are in good hands with the M22 for sure....always....but that other.....M21???......is bad ass too. My 71 442 had a stump twisting 455 and 80,000 miles on it with nothing ever done to it. Wish I still had that one. M21 took all the abuse a stupid 19 year old could throw at it, in those days. This 42 year would definitely treat it better today. Thumbs up for Muncies in Texas !!