Help - 1966 with muncie shift problems

[Fred R.]

today, I had to have the car towed to the shop for the 2nd time in 3 days. At first the muncie close ratio 4-speed was getting more and more sticky on the 3-2 downshift. this is a mostly stock 1966 with the 327/365 hp motor. the transmission was rebuilt two years ago along with a new clutch. I did not think the linkage was perfectly adjusted ever since I got it back from the shop, however, it did work pretty good.

What happens is when I am going slow and downsifting from 3rd to 2nd or 3rd to 1st (pulling in the driveway), the transmission will completely "lock" up and not shift - my mechanic said it was stuck inbetween two gears.

Today, the same thing happened again after he adjusted the linkage this am. Any ideas on what is causing this and why it keeps recurring?

[Ray G.]

Re: Help - 1966 with muncie shift problems

Hello;
Reading your description indicates the shifter has excess play allowing the bottom end of the shift lever to move out of the shift gate for 1st & 2nd or 3rd & 4th before reaching neutral.
Replacement/repair of the shifter appears to be in order.
Adjustment and lubrication of the mechanism is crucial.
Looking at the back of the shifter you can see an alignment slot for a round guide. I use a drill bit (don't remember the size at the moment, but it is pretty much self evident with shifter removed) Or there is an alignment tool (as wide as the slot) in which the bottom end of the shift handle moves sideways.
Service manuals and Assembly Instruction Manuals also help understanding through pictures.
Hope that helps.
Ray

[Mike B.]

Re: Help - 1966 with muncie shift problems

Fred,

There is no question that the complete lockup is from more than one gear being engaged at the same time. That can be caused by incorrect linkage adjustment for sure, but you also want to confirm that the detents are working. These are usually spring-loaded balls mounted in the transmission or on the cover (I can't remember) that engage a flat spot on the shifter shafts. They are what provide the "snick" when shifting and give the positive feel when stirring the gears. But without them the shift forks and respective gears can migrate out of position. It is possible that during a rebuild one or more of the detent balls went missing, or the springs might have collapsed or got stuck in the bores (not likely).

To test it the car should be put on a lift, block the wheels and put it in neutral. Then disconnect the linkage rods from the arms on the transmission. You should be able to move each linkage arm forward and back (only do one at a time) and you should feel it more or less snap into position, especially while in the neutral position. Try that exercise for each of the three arms making sure that the other two are in neutral. (Note that you may have to rock the drive shaft a bit when trying to move the linkage arms, but there should always be that confirmed feeling of clicking into place in the center neutral position.)

Providing they all pass the detent test, it is then the perfect time to properly adjust the linkage rods. As mentioned by Ray, depending on the shifter, there is usually a drilled bore or slot wherein when lined up a drill bit or piece of bar stock can be put in place to hold the shifter plates aligned - that is the neutral position on the shifter. Then it is simply a matter of threading the linkage rods in or out so that they easily slip back together on the respective transmission arms that are also placed in the center neutral position.

If after all of that you still have problems, then there is something amiss inside of the transmisison. It could be worn synchros (that symptom is usually popping out of gear on deceleration) or something as simple as missing snap ring that allows an internal gear to migrate to someplace that it shouldn't be. But keep your fingers crossed that just simple shifter rod adjustment is needed.

Good luck.
Mike

[Jim T.]

Re: Help - 1966 with muncie shift problems

Fred it has been many years since I have had to do it, however with the situation you described your car did not have to be towed in my opinion by experience. With the wheels chocked or a good emergency brake applied, from underneath the car, just move both arms on the 4-speed to the neutral position and drive home.
Some of your shifter could be missing, parts for these old shifters are available or you can buy a new shifter.
I would take it out and clean it up and regrease it if all the parts are there and adjust it using the service manual procedure.