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Technical Muncie input shaft no good?

Discussion in 'Traditional Hot Rods' started by model A hooligan, Mar 14, 2018.

  1. Picked up this m20 that was supposedly working when it was removed (yes I know the bearing retainer is short) I have a new one one the way,the guy seized the throw out bearing and cut it off.

    Anyways,doesn't the pilot look super short??? It doesnt look cut ( no irregular grinding or evidence of someone messing with it. but every one I have seen is much longer it seems. Can I use this? maybe this ones splines start sooner than the others I've seen?
     

    Attached Files:

    Last edited: Mar 14, 2018
  2. coilover
    Joined: Apr 19, 2007
    Posts: 696

    coilover
    Member
    from Texas

    A careful measurement from the mounting face of the trans to end of input and another from the bell housing trans mounting face to the pilot bushing will let you know exactly how far the the pilot will enter the bushing. The bushings job is to keep the shaft aligned but really no lateral or longitudinal pressure on the pilot so even 1/2" into the bushing should do the job. There is space between clutch center and the bushing so one could turn bushing on a lathe to have a shoulder that reached to the start of the splines with just a little gap. CAREFUL measuring needed all the way around. The first thing I'd do is smear some grease on the pilot and stab the trans just to check where it's at as is.
     
    wheeldog57, LOU WELLS and lowrd like this.
  3. This is a common problem on Ford toploaders. The pilot shaft for a FE is shorter than other applications, so using one behind other Ford motors can result in inadequate depth into the pilot bushing. The solution is a steel sealed bearing with the right ID and OD. The bronze bushing can hog out, the steel won't....

    This is assuming you can find one for your application. Try your local bearing supplier.
     
  4. C69A
    Joined: Jun 6, 2008
    Posts: 90

    C69A
    Member

    Just measured one I have, end of input to mounting face is 6.5625"
     
    model A hooligan likes this.

  5. It may look a little short, does the end still have the center they use for grinding? If the center is there it is probably okay. That is a '67 and up input shaft.
     
    Truckdoctor Andy likes this.
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 55,935

    squirrel
    Member

    looks like it's ready to be replaced. The pilot is supposed to be longer.
     
    Johnny Gee likes this.
  7. Mine is 5 1/2 from the tip to the flat part of the bearing retainer.

    Why in the hell would anyone cut it? Maybe for a automatic crank?
     
    Last edited: Mar 14, 2018
  8. That's a good point. I was thinking about that also.its supposed to have a cone ground inside right? Cause mine does not
     

  9. That's impossible considering I'm piecing this together. The car has a automatic in it now.
     
  10. Looked at one online... yours is definitely not right. Maybe it was dropped and the bad part ground off.
     
  11. I'm guessing it was behind a automatic crank like a olds? No idea. Supposedly it came out just how it sits. I'll have to hunt a used input shaft I guess. Need a rebuild kit for the I.t.m stock shifter I picked up. Not sure if that's even worth screwing with though
     
  12. looked in my applications manual from gm and there are several input shafts listed for the Muncie depending on the year and the number of teeth ranging from 21 to 26. count the teeth and I may be able to get you the gm product number.
     
  13. Fordors
    Joined: Sep 22, 2016
    Posts: 5,372

    Fordors
    Member

    To ID a Muncie is easy if you look at the rings, or lack of them that are cut into the input shaft. The two grooves show that particular trans is an M-20 4spd. with a first gear ratio of 2.52, the input has 21 teeth and the 10 splines tell us it was built from 1966-1970. The 1970 and later M-20’s used a fine spline input.
     
  14. Yep. You are correct on everything you said.
     

  15. I briefly skimmed through the listings a few nights ago. I noticed that I could get one for around 55-60 on the cheap side. Still need a shifter since mine is junk. But I'll look for that part number cause I wasn't 100% sure on the number. So the consensus is it for sure needs to be replaced,I need a gasket for the bearing retainer don't I? I've got a new retainer on order as we speak.

    I need a Drive line yoke.,mine only leaves about a inch of engagement. I've seen those for I think 89$? Unless anyone knows of a better option? I have the 5 3/4 yoke
     
  16. Can I change the input shaft but just removing the bearing retainer and that nut on the input shaft? Or do I have to do a bunch of other work?
     
  17. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,216

    2OLD2FAST
    Member
    from illinois

    You have to disassemble the trans to change the input , time consuming...
     
  18. Plan on a small parts kit, synchro brass, bearing or two...... Good luck with the rebuild.


    Sent from my iPhone using The H.A.M.B. mobile app
     
  19. Great. Just great. I really don't want to rebuild or have the money.

    T5's you can change the input shaft without taking the whole thing apart
     
  20. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member


    You can machine up an extended pilot bushing that will protrude from the crankshaft [It is quite common when adaptors are used in transmission swaps]
    Do some careful measuring with a straight edge across the bellhousing and across the flywheel etc
    or
    Unbolt the flywheel and clutch off your engine. Then bolt your trans to the Bellhousing and dummy assemble it.
    With a torch look inside the Throw-out fork hole and see if the snout is inside the back of the crank enough.

    Here is an example [but it uses a bearing extender]
    1 pilot%20bushing%202%20s.jpg

    here is another extended bushing

    1 Adapterkit006.jpg
     
  21. [QUOTE="With a torch look inside the Throw-out fork hole and see if the snout is inside the back of the crank enough.

    torch....aka flashlight! Don't want you burning your eyelashes off with a torch as us Americaners know it Mr. Hooligan
    :):):)
     
  22. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member

    We speak English mate! The last thing you need is a flashing light :p
    check this out
    https://www.google.co.nz/search?q=t...zk5fHZAhVHgbwKHaf8BZ0QsAQINA&biw=1366&bih=673
     
    Last edited: Mar 16, 2018
  23. DDDenny
    Joined: Feb 6, 2015
    Posts: 19,138

    DDDenny
    Member
    from oregon

    Don't forget to use GL- 4 gear oil.
    Sta-Lube from NAPA.
     

  24. I've got two questions. Wouldn't that brass wallow out sticking out like not not being supported? And would that interfere with the clutch?
     
  25. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member

    It would only interfere with the clutch plate if the clutch plate slid off the spline.
    You don't want it sticking out so much that the gearbox won't slide all the way home. And you don't want it to be larger diameter than the input spline
    If the brass pilot is long enough inside the crankshaft, it would have enough support

    The pilot bushing is doing the most work when the car is in gear but not moving [clutch pedal to the floor] and the pilot is spinning and the input is stationary.

    As I said earlier , Measure everything. Chances are the M20 will slide in enough not to require any added support.
     

  26. Yeah I'm going to start ripping out all the automatic stuff to get this ready to test fit.im going to run this input shaft,if it needs a special pilot bearing made so be it. It's cheaper and easier

    I took the side cover off to look inside,synchros look pretty good so I'm going to run it. Took the bearing retainer off,notice the front bearing as a sheet metal cage and it's broken allowing one bearing to move. So my question is,how do I get that skinny nut Off and then I can change the bearing by prying it out I think
     
    Last edited: Mar 17, 2018
  27. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member

    Some people use a pipe wrench to remove the "slinger/nut" but I made a special wrench 1/8" steel.
    put the gearbox into gear, and also put it into reverse to lock it up ,the undo the nut. The nut is usually "staked" with a centre punch so it wont come undone.
    Muncie gearboxes can be put into 2 gears at once [if one is reverse] or the side cover is removed

    To pull the front bearing hold 2 screwdrivers under the snap ring on the front bearing , then hit the input with a brass hammer [this is easier with 2 people]
    Repeat this again and again as the bearing slowly comes out. I sometimes use 3 nuts under the snap ring [going larger as the bearing comes out more]

    Don't replace the bearing with a M22 bearing which has more rollers designed for higher radial loads.[many fools believe it is a heavy duty bearing and a good upgrade]
    M20-M21 front bearings have less rollers and deeper grooves for the rollers. This is needed for higher Thrust loads due to the 45deg helix on the gears of a M20-M21 trans

    And remember to "stake" the retainer nut with a centre punch
     
    pitman likes this.
  28. Fordors
    Joined: Sep 22, 2016
    Posts: 5,372

    Fordors
    Member

    I’m not clear on what you are referring to with the mention of the thin plate slinger. Is it something on the bearing itself that is damaged or is it immediately in front of the thin nut? There is a flange on the front of the thin nut and it helps keep the lube in a Muncie.
    To remove that nut you will need to remove the side cover and manually place the trans in two gears at once so the main drive gear won’t just free wheel. You most likely will need to fabricate a thin wrench to remove the nut, as you can see there is not much depth to the hex.
    I have never tried to pry out the front bearing but really I’m not so sure it could be changed that way. The fit of the input shaft to the bearing will likely require tapping it out of the bearing.
    Regardless, whether you put a small parts kit and new bearings in or not when you are going to reinstall the front bearing retainer slip it on the input without the gasket. It will seat against the flange on the thin nut that I mentioned before and you will have a gap between the retainer and trans case. If your gasket easily slips in between the retainer and case it is too thin and you will distort and maybe even crack the retainer when you tighten it down. In a quality gasket set you will get two gaskets, thick and thin. As said above, use the thick one if the thin will slip in place.
     
  29. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member

    The front bearing nut is the actual slinger, that is why you need a special 1/8" wide wrench [or the hack job cold chisel/pipe wrench method]
    With the bearing retainer unbolted there is a bit of end play in the input ,so you pull it out as far as possible.
    Then put a couple of screwdrivers [or nuts] behind the snap ring to hold the bearing out, and tap the input back in [the bearing will slowly slide off the shaft]
    I've used this method successfully before.

    You don't need to pull the side cover off a Muncie to select 2 gears at once, because there is no safety detent on reverse gear. But the OP did mention he pulled the side cover to inspect inside it.

    Here's some pics of my homemade "Muncie Wrench" [monkey wrench]

    Muncie Wrench...jpg Muncie Wrench..jpg Muncie Wrench.jpg
     

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