# slipping out of 4th gear



## ronayers1965 (Feb 14, 2019)

My Muncie M-20 is slipping out of 4th gear occasionally. It doesn't "pop" out, just seems to slip out. It up-shifts smoothly and no problem in re-engaging it in to gear when it slips out. I think and hope it's just in need of a shifter adjustment. Has anyone else experienced this and if so, what was your solution?


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## BLK69JUDGE (Jun 10, 2010)

64-66 are notorious for the linkage slipping out of adjustment,,,
is your linkage original 64-66 ?


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## ronayers1965 (Feb 14, 2019)

No, It's an early welded Hurst Competition plus, but not the original round handle. I will trying doing a linkage adjustment today. I used the metal, not plastic bushings in the linkage.
Thanks!


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## PontiacJim (Dec 29, 2012)

Well, this would be my poor man's fix if I was 22 again. Add a throttle spring to apply a little pressure on the linkage to keep it in gear. Used to own an old 1975 Peterbilt Cabover tractor that the trans shifter would pop out of 13th gear on big bumps. Rubber bungee hooked to it for a little pull worked well.


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## ronayers1965 (Feb 14, 2019)

I adjusted the length slightly on the 3-4 lever to give it more throw in 4th and that seemed to correct the problem.


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## ronayers1965 (Feb 14, 2019)

I discovered yesterday that my lever adjustment didn't fix the problem after all. It is still slipping out of fourth gear, usually when at cruising speed and not under acceleration. Since it shifts great, I am reasonably sure it's not the syncro's. I've rebuilt a couple of Muncie trans, but it's been years since doing so,and can't figure out what would be causing this. I am not sure if it's a transmission problem or a worn-out shifter. While my car is a 65, the Muncie M-20 is from a 70 model. Has anyone experienced this and if so, was it a transmission or shifter problem and if a transmission issue, what was the fix?


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## BLK69JUDGE (Jun 10, 2010)

if
there is no vibration = bearings or noise 
and
being a 70 -74 you mention is the oil clean ... they do have magnets in the bottom of the case too
and
the HURST linkage adjustments ... any stoppers ? is it a 3138 housing with the 4555 HURST stick
with 7/16 linkage and bolts not nuts holding the levers on ?



Im not a tranny builder as I have a good friend that is ....
butt
I have had that issue b4 and .....
we replaced the sliders with new ones..





__





Muncie Zero-Rok Slider and Hub


Buy new Muncie zero rock synchronizer hub and slider for your Muncie 4 speed M20, M21, or M22 transmission.




www.5speeds.com


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## ronayers1965 (Feb 14, 2019)

Yeah I've been watching some you tube videos and a company called 5speeds.com seems to have it figured out. I am going to first remove the side plate and check the shifter forks for wear and that the springs are in good condition. If that's good, I will need to pull out the tranny and replace the sliders. It's just opening a Pandora's box that I would rather not open. The guy from 5speeds pointed out that the available replacement parts are usually made in Taiwan or Italy and are not fully compatible with the original GM gears which are apparently no longer available. Sadly, you can't just go to the local Chevy dealer and buy original Muncie parts like we did in the day, but instead now have to try mixing and matching parts to find the best fit and hope they don't introduce new problems such as gear noise from the mis-match of the old gear pitch mating with the repo gear pitch. Or pay a fortune for a professional rebuilder, which my friends have had mixed results from.


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## ronayers1965 (Feb 14, 2019)

I replaced my worn shifter forks and that seems to have fixed the problem!


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