'66 Shifter Slips Out of Adjustment

[Joseph S.]

Have an issue with my '66 M21 I have not run into before. I adjust the shifter, (lining up with a home-made gauge) and neutral position and gear engagement is fine. However during a short drive the shifter slips out of neutral position adjustment. I readjust, short drive same result

I have been into the transmission twice. First for bearings and synchros and a second time to renew the main drive gear and idler shaft to eliminate a gear whine. During both transmission teardown, I saw no issue with shifter forks or slides, but I didn't have any specifications on wear limits either. This issue has been with the car since before 9th first transmission teardown.

Before I start tearing things apart again (without a plan) I'd like to know if anyone has run into this issue in the past or has suggestions.

Joe

[David M.]

Re: '66 Shifter Slips Out of Adjustment

How many miles on the shift mechanism?
Might be time to rebuild the shifter.

[Thomas N.]

Re: '66 Shifter Slips Out of Adjustment

Joe
I've had a similar situation happen before. On the shifter body, the housing expands outward due to time and pressure, allowing the shifter plates to move excessively from side to side, and the tang of the shifter hangs up on the shifter plates. I put the shifter body into a vise, and squeeze until the plates and shims fit tight in the shifter (with a little clearance). I don't know if this is your situation, but something to look for. It is hard to diagnose without seeing things.

[Joseph S.]

Re: '66 Shifter Slips Out of Adjustment

Sorry for the late response out of the country- Thanks for the input Tom. I'll give it a try
Joe

[Joseph S.]

Re: '66 Shifter Slips Out of Adjustment

Shifter loosing neutral adjustment- '66 Muncie

For those that are interested - I had a conversation with Larry at D & L Transmission in NY. Larry advised me to look again at my 1-2 and 3-4 shift levers on the transmission. Any free play (other than a near press fit)at all between the rectangular post on the fork lever and the shift lever will effect the ability to keep neutral on the shifter. In addition Larry noted that the current supplier replacements are typically no better than a worn OEM lever.
Well Larry was correct- I purchased new shift levers; 1-2 lever fit as a tight almost press fit - however the new 3-4 lever was no better than the original worn lever I had.
I shimmed the original 3-4 lever to tighten the fit and as of now all is good - shifter retains its neutral adjustment.

Big shout out to Larry of D & L Transmission. In addition be advised aftermarket supplier replacements may be of poor quality and leave you with the same situation I had.

Joe

[Mark E.]

Re: '66 Shifter Slips Out of Adjustment

Good to know about a near press fit needed with the levers.

Clarifying the symptom... "the shifter slips out of neutral position adjustment."

Do you mean it slips out of gear into neutral?

[Joseph S.]

Re: '66 Shifter Slips Out of Adjustment

Mark-
In my terminology, the shifter would loose it's "East/West" adjustment between the 1-2, the 3-4 gate and reverse gates. I would adjust for a smooth movement between gates and after a bit of driving and shifting I no longer had smooth movement between gates. Just slight movement between the transmission fork stud and shifter lever created the issue.
Hope that helps
Joe