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Muncie 4spd. Inherent problems, weaknesses?

Discussion in 'The Hokey Ass Message Board' started by gasser, Feb 21, 2006.

  1. gasser
    Joined: Mar 3, 2001
    Posts: 150

    gasser
    Member

    Just wondering if there are any common problems with them?
    The trans I put in my coupe was bought "rebuilt" and has covered only 7000 miles. Selecting reverse and it seems mushy plus I am getting a rattle / rumbling in low and a creaking? type noise when pulling off
    Just trying to do a little homework before I pull it..
    Are they an easy fix at home?
    Any input welcome.
     
  2. 53sled
    Joined: Jul 5, 2005
    Posts: 5,817

    53sled
    Member
    from KCMO

    which muncie? Never had that problem, could be a worn shaft. I have had m21,22s apart. pretty simple, bearings and forks. take a picture of it at each stage and use a zip-tie to keep the synchros in order.
     
  3. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,562

    HEATHEN
    Member
    from SIDNEY, NY

    I see the quotation marks around "rebuilt"--kinda like all of those "rebuilt" engines everyone's always trying to sell? That may be your problem. I've beat the hell out of several Muncies over the years, and never had a problem with one until repeated abuse gave it an excuse to misbehave. I don't know how handy you are with four speeds, but they're not that difficult to fix if you have some guidence from a knowledgable Muncie man the first time around. Funny, 90 per cent of the Muncies I've gone to look at over the years were alleged to have "just been gone through". One tool that is very handy is a dummy shaft that slides in as the countershaft slides out to keep the 4,594 needle bearings from falling out.
     
  4. Russco
    Joined: Nov 27, 2005
    Posts: 4,327

    Russco
    Member
    from Central IL

    They are fairly easy to rebuild at home you will need a press, the weak link in them is case deflection but they will handle a decent amount of power
    check all your shift linkage out first it may be in the shifter/ linkages
     

  5. Arizona Geezer
    Joined: Oct 18, 2005
    Posts: 499

    Arizona Geezer
    Member

    I agree, at least about the mushy part, that could easily be in shifter linkage. Check that out before you bother to pull the tranny
     
  6. Smokin Joe
    Joined: Mar 19, 2002
    Posts: 3,770

    Smokin Joe
    Member

    Muncies seem to all have a problem with the reversers because of people grinding them into reverse. Especially in snow country where people rock the cars to get unstuck. When they get rebuilt, most don't bother to replace the well worn reverse gears. They just swap out the synchros, stops and all those 100+ little needle bearings and call it good.
     
  7. Smokin Joe
    Joined: Mar 19, 2002
    Posts: 3,770

    Smokin Joe
    Member

    A few things to remember.

    1:All used cars..."Ran fine when we parked it there" Yup, that's why they let it sit for 15 years...
    2:All Muncie trannys..."Just been gone thru" Means they pulled the side cover, dumped out the filings & synchro stop chunks and replaced the oil with ATF to make them shift. Rebuilt means they had to replace the synchro stops and needle bearings to make it shift. They may or may not have a few extra needles when they got it done.
    3:All bare SBC blocks are out of a 64 corvette. No heads or crank, but they usually have have a Muncie that's "Just been gone thru..." to go with that "Corvette engine"...
    4: Rebuilt, only 7000 miles. Answer A: 1/4 mile at a time... Or 25 laps at a time down south...
    Answer B: Cheapest engine rebuild kit the parts store had, put in by the local high school autoshop class without useing a torque wrench or micrometers.
     
  8. 30roadster
    Joined: Aug 19, 2003
    Posts: 1,793

    30roadster
    Member

    Where would you go for a rebuild kit?
    I've seen an ebay kit for an m22 conversion/ rebuild?
    Whats the advice there?
     
  9. Russco
    Joined: Nov 27, 2005
    Posts: 4,327

    Russco
    Member
    from Central IL

    Parts should be readily available its been a few years since I did my m22
    I got my stuff form these guys they were very helpful http://www.5speeds.com/newm22.html they have a video I think they sell that goes step by step on rebuilding them if in doubt get it.
     
  10. brandon11130
    Joined: Sep 20, 2006
    Posts: 50

    brandon11130
    Member

    hey, i realize this is an old thread I didnt want to waste space by starting a new one,


    I have a muncie 4speed swapped in behind a buick v6. anyway i bought it supposidly in "drivable condition" it goes into reverse, 1st and 2nd smoothly but it grinds real bad going into 3rd and a little bit going into 4th. It goes all the way into gear and will drive it just grinds horribly going in.

    since its in my jeep it has a dana20 transfer case behind it so it has some sort of custom linkage, it looks like a hurst shifter but with the rods shortened. do you think that the linkage is off causing it to grind? or do you think its the synchros? would your average transmission shop be able to do this? how much do you think they would charge if i brought them the tranny?

    sorry for all the dumb questions

    oh yea and what exactly is my tranny? an m21 or an m22?

    [​IMG]
     
  11. Retrorod
    Joined: Jan 25, 2006
    Posts: 2,034

    Retrorod
    Member

    You can make a dummy shaft for the cluster needle bearings if you have an old shaft lying around....just cut it off the proper amount so the cluster & shaft will clear the case when you take it apart. They are really a bitch to put together without that special shaft.
     
  12. that looks to be a saginaw.
     
  13. Retrorod
    Joined: Jan 25, 2006
    Posts: 2,034

    Retrorod
    Member

    MUNCIE TRANS INDENTIFICATION<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    Case casting numbers, relating production years and ratios available

    Casting: 3831704 Years: 1963 Only Ratios: M20 2.56 1st , M21 2.20 1st </PRE>
    Casting: 3851325 Years: 1964 - 1965 Ratios: M20 2.56 1st , M21 2.20 1st </PRE>
    Casting: 3885010 Years: 1965 - 1967 Ratios: M20 2.52 1st , M21 2.20 1st, M22 2.20 1st</PRE>
    Casting: 3925660 Years: 1968 - 1970 Ratios: M20 2.52 1st , M21 2.20 1st, M22 2.20 1st</PRE>
    Casting: 3925661 Years: 1970 - 1974 Ratios: M20 2.52 1st , M21 2.20 1st, M22 2.20 1st</PRE>
    Ratios of the M20 , M21 , M22

    Year 1963-1965 Type: M20 Rings: None Ratio: 2.56 / 1.91 / 1.48 / 1.00 / 3.16</PRE>
    Year 1966-1974 Type: M20 Rings: Two Ratio: 2.52 / 1.88 / 1.46 / 1.00 / 3.11</PRE>
    Year 1963-1974 Type: M21 Rings: One Ratio: 2.20 / 1.64 / 1.28 / 1.00 / 2.27</PRE>
    Year 1967-1974 Type: M22 Rings: None Ratio: 2.20 / 1.64 / 1.28 / 1.00 / 2.27</PRE>
    Input Shaft Tooth and Spline Count Related to Year

    Year 1963-1965 Type: M20 Rings: None Spline: 10 Tooth Count: 24</PRE>
    Year 1966-1970 Type: M20 Rings: Two Spline: 10 Tooth Count: 21</PRE>
    Year 1970-1974 Type: M20 Rings: Two Spline: 26 Tooth Count: 21</PRE>
    Year 1963-1970 Type: M21 Rings: One Spline: 10 Tooth Count: 26</PRE>
    Year 1970-1974 Type: M21 Rings: One Spline: 26 Tooth Count: 26</PRE>
    Year 1967-1970 Type: M22 Rings: None Spline: 10 Tooth Count: 26</PRE>
    Year 1969-1974 Type: M22 Rings: None Spline: 26 Tooth Count: 26</PRE>Please note that there are 7 different Muncie input shafts. All 26 spline inputs came with 32 spline output shafts and all 10 spline inputs came with 27 spline output shafts. A common mistake is thinking that all "fine spline" 26 spline input shafts are M22 heavy duty types. This is not true. An M22 gearbox has a 20 degree helix angle on the gearset as opposed to a 45 degree angle. Also M22 gear sets were of a higher nickel alloy. The straighter angle was designed to produce less end loading of the gear train and less heat but created more noise, thus the nickname "rockcrusher". The higher nickel alloy allowed for more impact of the gears. Another misconception is if you have a drain plug you have an M22. Again this was only true when the first M22 boxes were created. But all 3925661 castings had drain plugs.
    Reading Serial and VIN Numbers
    Serial numbers for Muncie 4 speeds always begin with the letter "P". P stands for Muncie. Why.... I have no idea. The serial number is a date code the transmission was built for a particular year. Serial numbers from 1963 to 1966 included only the month and day. P0101 would indicate January 1st. From 1967 to 1968 the serial number got a year designator and a letter designator for the month such as P8A01, meaning January 1st 1968. One important point is that if you have a Muncie dated with a December build date it was actually built the prior year. An example would be the date code P8T13. This is for a 1968 production car. The T stands for December and 13 is the day. To confirm this simply look at the VIN number. It will usually begin with a 18S101350 or a 28N12950. This means the Muncie was assembled December 13, 1967 for the 1968 model year. The VIN number will usually be a low number. 1969 to 1974 Muncies got a ratio designator at the end of the serial number. An example would be P4D23B. This equates to April 23, 1974, M21 ratio.
    Month Code Chart

    January Letter: A May Letter: E September Letter: P</PRE>
    February Letter: B June Letter: H October Letter: R</PRE>
    March Letter: C July Letter: K November Letter: S</PRE>
    April Letter: D August Letter: M December Letter: T </PRE>
    Ratio Code Chart

    Letter: A M20 Ratio</PRE>
    Letter: B M21 Ratio</PRE>
    Letter: C M22 Ratio</PRE> <o:p></o:p>

    <!-- text below generated by server. PLEASE REMOVE --></OBJECT></LAYER>
    </SPAN></STYLE></NOSCRIPT></TABLE></SCRIPT></APPLET><SCRIPT language=JavaScript src="muncie_files/mc.js"></SCRIPT><SCRIPT language=JavaScript src="muncie_files/geov2.js"></SCRIPT><SCRIPT language=javascript>geovisit();</SCRIPT><NOSCRIPT></NOSCRIPT>[​IMG] <!-- w9.geo.scd.yahoo.com compressed/chunked Thu Jul 10 19:33:47 PDT 2003 -->
     
  14. Bill.S
    Joined: May 5, 2004
    Posts: 449

    Bill.S
    Member
    from NW OH

    That looks like an M20 Saginaw, 7 bolts and reverse lever on sidecover.
    Muncie dosen't have reverse lever on sidecover.
     
  15. Duration
    Joined: Oct 2, 2006
    Posts: 543

    Duration
    Member
    from Wayne, MI

    likemost muncie trnas, synchros go first. if you rebuild the trans before the gears get tore up you can fix them cheap. they are tough enough to handle most potent small blocks and mild or stock big blocks to.
     
  16. brandon11130
    Joined: Sep 20, 2006
    Posts: 50

    brandon11130
    Member

    im not familiar with these side shift 4 speeds, that wasnt a picture of mine, just one that look likes the one i have, ill go under my jeep and snap some pics for you guys, thanks a ton for helping me out, none of the guys on the jeep forums know anything about these trannys.

    assuming it is the synchros, how hard is it to change them? is it somthing a 17 year old can do in his garage? i dont have a press or anything. and i dont have a ton of money either, so if i could replace as little as possible to get this tranny functioning properly that would be awesome.

    ill pull the side cover and see if the gears are in ok shape. lol i wish i would of done this before a put the body back on:rolleyes:
     
  17. brandon11130
    Joined: Sep 20, 2006
    Posts: 50

    brandon11130
    Member

    ok heres mine, sorry the pics are about the best i could do without pulling the body. hopfully you can tell what it is by the side

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  18. oldspert
    Joined: Sep 10, 2006
    Posts: 1,263

    oldspert
    Member
    from Texas

    I'd still call that a Saginaw transmission.
     
  19. BriggsBodied28
    Joined: May 13, 2006
    Posts: 88

    BriggsBodied28
    Member

    Nah, just use some grease to hold the bearings in place as you put them in...they'll stay in place just fine. Just keep count.

    I can't recommend the help from Paul at http://www.5speeds.com/muncie.htm enough. Awesome quality parts, great rebuild video, and extremely helpful on the phone and/or on the forum. Their rebuild kits and gears were of outstanding quality! Sign on to the forum and do some searches before posting a question that has likely been answered dozens of times.

    Also, http://www.autogear.net/pdfs/munciecat.pdf has a schematic of the Muncie that some of you may want to pull down for future reference.
     
  20. Moonglow2
    Joined: Feb 4, 2007
    Posts: 660

    Moonglow2
    Member

    Muncie shifters were pretty sloppy new and yes - the first things to go were the brass synchronizer rings. To add to the dummy shaft info given I always used axle grease to keep the needle bearings from crossing up or falling out as I slid in the shaft pushing out the dummy. Mine was just an aluminum pipe I had laying around that was just a hair smaller in diameter than the shaft itself. Muncies replaced T10s in 64 I think and could handle a tad more torque. By late 60s the rock crusher M22 with straight cut gears came out as horsepower kept increasing. Remember the "Two Lane Blacktop" movie? You could tell there was an M22 behind that big block from the whine it made.
     
  21. tomslik
    Joined: Mar 3, 2001
    Posts: 2,161

    tomslik
    Member

    that IS a saginaw....
    ALL car 4 speed muncies were aluminum
    m20's had a 7/8" cluster gear shaft
    m21+22's had 1" shafts
    m22's had a drain plug...
     

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