I have a Muncie M-21 with a Hurst shifter and have been having a problem with it popping out of 4th gear. It seems to happen when I am in 4th and off the throttle coasting down the road. Could this be an adjustment problem with the linkage or something internal in the transmission. Any thoughts would be appreciated.

Thanks,
Mark

I had a similar issue with my muncie popping out of 2nd during deceleration and it was an internal problem. The syncros needed rebuilding.

Very common problem. Synchronesizing rings need replacement.

Sometimes using a sidecover 20 lb. detent spring may help on gear hop-out. Hopefully your synchronizer engagement teeth are not worn on your 4th gear.

If a shifter adjustment does not help, most likely it is an internal repair.

When mine did that, it turned out to be that the rollerbearings insied the input shaft wore out and I had to replace the input shaft and syncros.