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Old 01-09-2018, 04:34 PM   #1
ElPasoCOunty
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SM 465 Shift Fork Removal

I've currently got an SM 465 torn apart in my man cave but I can't get the shift shafts out of the top cover to remove the forks. I want to replace the springs and detent balls and check for scoring, etc. 1972 K20 350/SM465/NP205.

Roll pins for both 1-2 and 3-4 shift forks are driven out...Reverse is waiting for everything else to clear out of the way. The GM rebuild manual says to drive them out but I've been wacking on them pretty good and they wont budge.

Has anyone had a problem driving them out?

The transmission is out for a number of reasons. I have had major shifting issues after the truck warms up. 10-12 miles out it won't shift out of 2nd up to 3rd, 3rd to 4th, or back down. Doesn't matter if I'm stopped, engine running or off, I cannot shift from 1st, or 2nd into reverse. Clutch and linkage were fine.

The other problem was that its leaking so bad that it won't pass the TUV, which is our annual inspection here in Germany.

Parts can be hard to come by, most of the time I have a 10-21 day lead time.

Any help would be appreciated.

Last edited by ElPasoCOunty; 01-09-2018 at 04:41 PM.
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Old 01-09-2018, 07:31 PM   #2
B. W.
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Re: SM 465 Shift Fork Removal

IIRC, you remove the detent balls & springs, drive the roll pins out of the forks, then shafts are removed out the rear. There are three welch plugs that seal the rear holes.

Are the shafts moving freely in relation to the forks?
Are the shafts stopping at the welch plugs?
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Old 01-10-2018, 12:40 PM   #3
ElPasoCOunty
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Re: SM 465 Shift Fork Removal

The plugs are out.

How do you remove the dent balls and springs prior to removing the shift rails?

Maybe I'm missing something...My top cover exterior is filthy.
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Old 01-10-2018, 04:46 PM   #4
B. W.
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Re: SM 465 Shift Fork Removal

Forgive me, I was going off memory ( the older I get the less I trust it!) I dug out an old cover, the detents are under the rails (or above the rails, depends on how you look at it!) There are 3 holes for assembly:
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Last edited by B. W.; 01-11-2018 at 12:22 AM.
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Old 01-11-2018, 12:21 AM   #5
nonstop
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Re: SM 465 Shift Fork Removal

You also need to start with all the shift rails in neutral. The shift interlock pins might be holding you up.
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Old 01-13-2018, 10:33 AM   #6
ElPasoCOunty
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Re: SM 465 Shift Fork Removal

Thanks everyone.

They're out now but it took more effort than anticipated though. They were in Neutral.

Do you guys know if the interlock pin at the end of the 3-4 shift rail floats and should I be able to move it by hand? Mine doesn't move and it isn't centered..

Thanks again.
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Old 01-13-2018, 02:27 PM   #7
B. W.
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Re: SM 465 Shift Fork Removal

Yeah, the pin & the 4 interlock balls should fall out by themselves or be easy to remove. The pin should slide back & forth. Grease it to hold it in place during re-assembly.
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