Sloppy shift selector - TH350 where to start?

[JPTL]

I have a TH350 transplant in my 66 C20. The shift selector has always been vague and sloppy. Since I've had the truck selecting D or R is a matter of hunt and peck vs. a positive "notchy" secretion.
What's the most common cause for this and where should I start troubleshooting?
Thanks in advance!
JP

[pjmoreland]

I'm not familiar with '66 steering columns, but the shifter bowl on the original column in my '68 was severely worn from many years of use. I replaced the entire column with a low mileage one to solve that issue. Here are some videos that show the difference:

Before:
https://youtu.be/5f8jF-DhMsk?si=hkCWFAJSLuN8EMty

After:
https://youtu.be/sZi8EhuJznE?si=MKnnksiyiAQ-85f-

Wear in the column will result in no motion from the shift arm at the base of the column when the shifter lever is slopped back and forth.

There could also be slop and wear in the pivots of the shift linkage running from the column to the transmission. You could have someone slop the shifter lever back and forth while you watch the linkage from under the hood.

[JPTL]

Originally Posted by pjmoreland

I'm not familiar with '66 steering columns, but the shifter bowl on the original column in my '68 was severely worn from many years of use. I replaced the entire column with a low mileage one to solve that issue. Here are some videos that show the difference:

Before:
https://youtu.be/5f8jF-DhMsk?si=hkCWFAJSLuN8EMty

After:
https://youtu.be/sZi8EhuJznE?si=MKnnksiyiAQ-85f-

Wear in the column will result in no motion from the shift arm at the base of the column when the shifter lever is slopped back and forth.

There could also be slop and wear in the pivots of the shift linkage running from the column to the transmission. You could have someone slop the shifter lever back and forth while you watch the linkage from under the hood.

Great advice and info! Thanks for sharing. I'm sure that there's plenty of slop in the shifting arm as in your before video, but at this point, I'm trying to get the slop out of the actual drive selection, and get it back to a positive "notchier" selection.
I'm probably going have to fix both issues.

[HO455]

I recommend doing an inspection of the detents for the shifter. The column in my Burban had worn detents that I welded up and filled down to repair them. (Green arrow in photo) If you're not familiar with how the detent works have someone operate the shift lever through the range and watch the interactions of the parts in the engine compartment.

In addition the bushing at the lower end of the shift selector was bad and I had to fabricate a new one to remove the slop in the selector.

Good luck and keep us posted on what you find.

[LockDoc]

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Spray some PB Blaster, Liquid Wrench, or something similar (not WD-40) into the steering column, where the shift lever goes in. Don't be afraid to give it a good dousing. (put something on the floor if you have good carpet in it). After you spray it pull the shift lever up toward you and push it back down toward the dash. The knob should move up and down a couple of inches. Do this 4 or 5 times. This will help free up any sticking in the shift lever tube. The reason the shift lever moves up and down is because it should be pulled back towards you to shift it into and out of the park position. Also spray the bottom of the column under the hood too.

As HO455 pointed out there is a detent on the lower shifter arm that is supposed to keep the shifter from moving out of park until you pull it back toward you. Your shift tube may be gummed up keeping it from moving up and down.....

Below are a couple of pictures that show the detent. In the second picture (actually both pictures) there is not supposed to be a gap between the two parts, they should be tight together.

Also, Check and see if there is a bushing on the ball end of the shift lever arm. (inside the column)
.

[JPTL]

Very helpful. Your info and images will save me a lot of time by reducing the learning curve!

[LockDoc]

Originally Posted by JPTL

Very helpful. Your info and images will save me a lot of time by reducing the learning curve!

Let us know how it goes.....

[PbFut]

Generally the dentents above are the primary "holders" of the shifter position. My detents are pretty worn from years of use and are less firm in their positions but still reasonably good if everything else is in order. Additionally, I found the linkage in a few areas also suspect and after some attention, the feel was much better. First the rubber bushings were all shot. I found some washers and rubber grommets helped on the shift linkage rod. Next the 2 arms that connects the bottom of linkage rod over to the transmission shifter shaft. It's 2 parts. Both get hogged out over time. An hour with a welder and file will fill and tighten those contact points also improving things quite a bit. Last, and probably first thing you should check, is the nut at the end of the shifter shaft on the transmission. After I did the weld job, I overlooked the lock washer and the nut backed off some. Things got very sloppy until I slid under and saw the nut was loose. Last thing. Don't let things get too sloppy. The neutral safety switch does not have much tolerance for slop. You can be in gear and and the safety switch not locked out. I killed a perfectly good hood and upper grill, along with a work bench from this exact issue. Could have be way worse.