Transmission Problem

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Oct 28, 2022 | 01:23 PM

79Guy

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4th Gear

Joined: Oct 2022

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Transmission Problem

Last weekend I was going to change the transmission fluid on my 1979 F150 with the 4spd transmission(pretty sure its the np transmission not T-18). I was warming the truck up. Had it in neutral with the clutch pushed in, then I went through the gears with the clutch pressed in. I returned the shifter to neutral and let off the clutch. It made a grinding sound for about 3 seconds and then I pushed the clutch back in and try to move it to 1st but it would not move at all. So now the truck is stuck in neutral and wont go to any gear. Any idea what I did? Hopefully it is an easy fix.

Thanks

Oct 28, 2022 | 03:40 PM

440 sixpack

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It's not anything you did.

When you say stuck in neutral do you mean it won't go into any gear or that the shifter is stuck in place? have you tried it with the engine running and shut off as well ?

Oct 28, 2022 | 03:55 PM

tbear853

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Joined: Feb 2004

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From: The Shenandoah Valley

I've had a couple cases of shifter's loosing index in a shift fork at the notch where the ball on the end of the stick jumped out of the shift fork slot over in front of or behind the other fork. The times I had it happen were old tractors, but I think the NP truck trans is much like them, no external shift rods. Neighbor had one that we kept a wrench and "rod" to unjam it when so "stuck" Involved removing the top of the case with stick, then lining up both forks with the "rod", then setting the case top back in place with that ball on the end indexed there between forks in the notch. Same thing happened on my Wheel Horse. Wear and or fast shifting cane do it.

If it did jump out as you finished rowing gears, instead of neutral, the transmission ciould be in any one of the gears.

Oct 28, 2022 | 04:15 PM

79Guy

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4th Gear

Joined: Oct 2022

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I will check again either today or tomorrow. When this first happened the shifter would not move at all side to side or up and down. However I will test it again and see and report back.

Thanks

Oct 30, 2022 | 09:45 AM

79Guy

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4th Gear

Joined: Oct 2022

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So yesterday I checked again. The shifter will not move at all up or down or side to side. This is both with the clutch pressed in and without the clutch pressed in and engine on and off. Yesterday when I releases the clutch there was a grinding for 1-2 seconds and then the shifter was free and would go into all gears again. However this morning I was messing around with it again and when I took my foot off the clutch it made a smaller grinding noise and now will not move again.

Thanks

Oct 30, 2022 | 07:32 PM

440 sixpack

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If the shifter won't move at all you're going to have to remove it if possible and line the slots up. you might have to pull the top cover anyway since something is messed up.