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Technical Muncie M20 for dummies

Discussion in 'Traditional Hot Rods' started by Eth727, Oct 15, 2024.

  1. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    Anyone know about this shifter?
     

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  2. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    It's a Hurst , clean , disassemble ,lube it , & run it .
     
    Last edited: Oct 19, 2024
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  3. DDDenny
    Joined: Feb 6, 2015
    Posts: 20,145

    DDDenny
    Member
    from oregon

    OEM GM? GTO? made by Hurst, note no stop adjusters.
     
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  4. MCjim
    Joined: Jun 4, 2006
    Posts: 1,168

    MCjim
    Member
    from soCal

    Yeah, '66 GTO most likely. GTO nerds will pay up for it.
     
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  5. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    But still , a usable shifter , parts is parts..
     
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  6. DDDenny
    Joined: Feb 6, 2015
    Posts: 20,145

    DDDenny
    Member
    from oregon

    In my best Maxwell Smart voice..........missed it by that much!
    My point was only that it is devoid of adjustable stops because GM said "build us a million shifters as cheap as possible" so corners had to be cut to get the contract.
     
  7. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,760

    HEATHEN
    Member
    from SIDNEY, NY

    However, those small pilot holes are in the right spots for the adjustable shifter stops. Drill them out, tap them with a 3/8 tap, get a couple 3/8 bolts and nuts, and you're done...or sell it to someone restoring a GTO and buy another shifter with the proceeds.
     
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  8. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    Dang it. That’s why I bought it because it had the shifter with the linkage attached. The guy said it came from a Pontiac. I’ve got a bench seat ‘63 impala.
     
  9. deucemac
    Joined: Aug 31, 2008
    Posts: 1,560

    deucemac
    Member

    I avoid Muncies with the last three numbers on the case is 325. These are early 63-65 transmissions with a 7/8ths counterpart. They are noticeably weaker and there is a reason GM ZERO went to a 1" shaft in 1966. I had one that was rebuilt 3 times and finally failed completely as I drove over railroad tracks at low speed after making a right turn. I went to a 1" counterpart and never looked back. Previously, I had Muncies in 67-70 cars and never had a problem. It wasn't until I was given a 325 box from a friend who was disposing of his late uncle's stash that I became aquainted with the 325 series trans. I went back to a 550 series and never had a problem. I drove both of them very spirited sometimes. With disastrous results from the 325 and no problems with the 550 series. That's when I had a long talk with a rebuilder and he said that he only recommended the 325 for a concourse restoration. It was an expensive lesson that I never forgot.
     
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  10. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    So use it ....
     
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  11. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

     

    Attached Files:

  12. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    These are the numbers.
     
  13. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    You guys just said it’s a cheap shifter. Isn’t it for a bucket seats also? I wonder if I can weld this style of shifter
     
  14. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

     
  15. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 3,173

    427 sleeper
    ALLIANCE MEMBER

    It's just as good as any other Hurst Comp/Plus shifter, the stop bolts were intentionally left out to satisfy the bean counter's at GM, so Hurst could get the contract from them. The provision's are there if you want to drill and tap the holes for the stop bolts. The stick might even work for you, just gotta try it. As far as the main case goes, you're good there, too. The 010 case's have the 1" countershaft, not the 7/8" shaft of the 325 case. Stop worrying about everything and put it together already, drive it and have some fun. ;):D:cool:
     
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  16. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    Paralysis by analysis!
     
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  17. TRAVLR
    Joined: Jul 18, 2022
    Posts: 152

    TRAVLR
    ALLIANCE MEMBER
    from NC

    Deucemac, your case numbers for the muncie is partially true.
    The 1963 muncie used a case number ending in 704. The only guys wanting these are the matching numbers crowd. They have the smaller input shaft bearing and retainer and the input shaft runs on a bushing instead of a bearing.
    Early 64 cases can have the number 606, it is basically identical to the 325 case that came out in mid 64 and used in 65. The only difference I've noticed between these are some minor casing differences on the case ribs. I'm not sure internally... I've never seen a 606 that hasn't already been gone thru at some point in it's life. There are some 65 cases that used an oddball case number, but they were only used on the 65 m22 rockcrushers used in racing corvettes only. None of these went into a production car. (These use a 1" counter gear shaft like the later muncies... I think that is why the case number is different) I've been told this by several quality rebuilders that the counter gear shaft being 7/8 isn't really the weak point of the early transmissions. (All of the borg warner T10's use 7/8 counter gear shafts) The sliders used in the early muncies used a narrower cone and clusters than the 010,660 and 661 cases. Whenever I have rebuilt an earlier series muncie, I've use the later sliders with the wider clusters and had great results. Of course, if the counter gear case holes are worn, the best thing is to have them bored to 1" and use the correct counter gear setup for that size shaft.
     
    Last edited: Oct 20, 2024
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  18. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 3,173

    427 sleeper
    ALLIANCE MEMBER

    The 65 Rockcrushers had the whole case casting number milled off completely, and the case was bored for the 1" shaft, along with an added drain plug. There were some oddball variations of the 325 casting number that had the 7/8" shaft in wide and close ratios.
     
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  19. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 3,236

    Kerrynzl
    Member

    Cheap as in "a bargain!"

    Hurst make great shifters ,and are totally serviceable.
    I would rather have that old shifter than a modern "out-sourced" shifter

    you can buy shift levers for bench seats
    Here is a 55-57 Chevy Bench seat shift lever for the Hurst shifter [it would probably fit your car]

    [​IMG]
     
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  20. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    It's pretty simple to take a piece of 3/8 SS flat stick & custom make a shift lever that fits what you're doing .
     
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  21. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 3,236

    Kerrynzl
    Member

    I would bend up some round stock [or an old lever from an early truck] and weld a bolt-on stub to it.
    This way you can make it look OEM or vintage
     
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  22. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    Most Hurst shift arms that I recall are flat stock , shift arms made for OEM's were round , but that's my recollection ? And a Hurst shifters gotta be shiney !! :D
     
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  23. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    I had this in mind
     

    Attached Files:

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  24. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    So do I need to remove the linkage to put the cover back on with the shifter forks in position ?
     
  25. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    Looks nice , its just not rigid enough for hard shifting , IMO .
     
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  26. DDDenny
    Joined: Feb 6, 2015
    Posts: 20,145

    DDDenny
    Member
    from oregon

    Nicknamed the "spaghetti" shifter.
     
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  27. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,656

    2OLD2FAST
    Member
    from illinois

    Yes , not that you couldn't do it with them attached I suppose , but I'd never try it .
     
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  28. Eth727
    Joined: Jun 20, 2024
    Posts: 105

    Eth727

    Where do I put the detents on the inspection cover when installing the shifter forks?
     
  29. TRAVLR
    Joined: Jul 18, 2022
    Posts: 152

    TRAVLR
    ALLIANCE MEMBER
    from NC

    ^
    You want to move the slider to engage 2nd gear and set the detent to 2nd gear also. The shifter forks should line up with both sliders and the cover should just drop straight in.
     

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