72 4x4 automatic farm truck

MSS3020 · Feb 3, 2015

Before I tear into it thought Id ask before to save me some time.. 72 chevy automatic 4x4 3/4 shifter wont go into park.. will shift in all others but not into park..Where should I go first..Ive read something about a shift collar??? no such thing by that name listed on parts book.. any help appreciated.. by the way this thing sits mostly in the shed until I haul hay or wood..thanks

cole in mo. · Feb 3, 2015

Might be in the linkage, and it might make a difference if its a 350 or 400 trans.

BANDITFARMER · Feb 3, 2015

Without looking at it hears what I think is going on. Ether the drivers side front cab mount is rusted or the rubber cab mount has gone bad and the cab has dropped down some. So you will need to adjust the linkage. Pretty simple loosen the bolt on the clamp and pull the linkage up a little (you should hear a click from the trans when its right) tighten it and check it. If its not repeat till it dose. That's the great thing about these old trucks, There pretty easy to figure out. By the way I have a 1968 Chevy 1/2 ton 4x4, BTDT Bandit

Bob · Feb 3, 2015

Do you mean the shifter won't physically go into park, or it shifts into park but there's no holding effect of the park mechanism?

If it is failing to hold, the park pawl may be broken, or the linkage that operates it may be bent, broken, or damaged.

The link below shows the mechanism in a THM-400 tranny, is yours is a THM-350, the mechanism is VERY similar.

<img src = "http://67-72chevytrucks.com/vboard/attachment.php?attachmentid=805980&stc=1&d=1317049016">

Key # 713 is the pawl.
Linkage that operates the park pawl

BANDITFARMER · Feb 3, 2015

Should have said " Pretty simple Loosen the bolt on the clamp on the steering colum ( under the brake master cylinder) and pull the linkage up a little. Opps Bandit

crawlerjohn · Feb 3, 2015

The shift collar is the thing the shift lever pins into on the top of the steering column. I would disconnect the shift linkage from the transmission and see if it will lock into Park manually. If it does then the problem is in the column. Sometimes the cab mounts sag down and the linkage will not move far enough to compensate for the sag.

old · Feb 3, 2015

As said I would take the linkage loose at the transmission that way you can find if it is in the transmission or the shifter it self. Maybe a simple linkage adjustment

MSS3020 · Feb 3, 2015

thanks alll.. You have given me what I needed..

armand tatro · Feb 3, 2015

Firs thing to do is drop the pan and drain the transmission than look at the spring and tapered sleeve on the end of the actuator assembly, parking lock rod Ref # 708. possibly broken spring or sleeve. I had a '77 chevy K 20(K =4X4). that would not shift out park. When I pulled pan had my son move the shift lever on the colom and I could see that the small end of the tapered sleeve was broken. A new sleeve cost about $20 at the time. Because you truck will not shift into park I think you could have a broken spring or the big end of the tapered sleeved is broken. At that time I only had to buy the tapered sleeve. If those parts are NLA I would think your local machine shop could make them. If you have any questions start a new thread and ask for me name. My e-mail is not working. Armand

72 4x4 automatic farm truck

MSS3020

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cole in mo.

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BANDITFARMER

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Bob

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BANDITFARMER

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crawlerjohn

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old

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MSS3020

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armand tatro

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