M-37 trans gears grind

[Cliff]

This is a problem that only recently began and has gotten worse over the last couple of times driving the truck. When I first start the truck up and move it out of the garage the trans goes into gear just fine with no grinding . However by the time I have driven a couple miles if I have to stop at an intersection when I try to put the truck into either first or second gear it won’t go into gear. It just grinds severely as though I were trying to put it into gear without depressing the clutch. If I put it in either fourth or even reverse first and then try again to put it in either first or second it will go right in with no grinding at all. Another tidbit of information is that if when I first stop at the stop sign I immediately put it in either first or second it will go right in without grinding at all but if I sit at the intersection for a while and then try to put it in gear I then can’t get it into gear without first putting it in either fourth or reverse. Does anyone have any ideas of what is wrong ? It has never done this when the ambient temperature is cold. It also doesn’t do this when I first start it up as though when the engine and transmission warm up after driving for a while has something to do with it. Any suggestions and opinions would be appreciated.

[vit16]

Seems that the clutch is not releasing completely. I would split it looking for seized input shaft bushing.
1st and 2nd gear are not synchronized so they will grind if inputshaft still turning. Same thing with reverse gear.
Maybe in 1st gear low the truck will creep.
When it gets hot input shaft bushing inside the flywheel will start dragging the input shaft. this will only occurs at idle in neutral because it is the only situation in which it spins. that explains it won't happen on cold and also explains that it is in that condition that it will take a while until bushing warms up and start dragging input shaft.
You can try clutch pedal adjustment but I suspect lack of lubrication or seized bushing.
Hope you understood my english

[Cliff]

Thank you very much for your information and explanation of the problem. That makes sense to me and I will check that out. Your English is great! Have a great day.

[vit16]

was thinking that too light oil can do the same. also warped clutch disk.
by adjusting clutch fork free play you may isolate it before splitting it.

[Cliff]

The clutch peddle has 3 inches of free play. My understanding is that it should be closer to an inch. I was wondering if it is possible that because of all this free play that the clutch is not fully releasing but not by enough that when it is cold it makes a difference. But when everything warms up and expands maybe then the clutch is still engaged enough that it is as though I am not fully depressing the clutch peddle but in fact I really am but the clutch is still engaged enough that I can’t shift into first or second. It would be nice if a “simple” clutch adjustment would solve my problem. It is unfortunate that I am not more mechanically talented. I have ordered some TM manuals hoping they will contain instructions on how to adjust the clutch. We’ll see. I may have to take the truck to a shop to have this fixed.

[NAM VET]

Aways good to have a full set of TM's but if you look under at your pedals, you will see a bolt that adjusts the clutch engagement. It is "double-nutted", so you loosen both, turn the bolt in a few threads, and see if that is enough to fully release your clutch. It moves the clutch foot pedal engage/disengage higher or lower on the pedal., Let me see if can go out an take a pic of what I mean. Hal

[NAM VET]

here is a pic of the adjustment of the clutch pedal. Loosen and thread the bolt in or out to move the pedal engagement point. Hal
[url=https://postimg.cc/rDx2jf9D][img]h ... .jpg[/img][/url]

[Cliff]

Thanks for the help and especially the picture. I am a picture guy. I looked under my truck and I see what you are talking about. Excuse my ignorance but when I adjust those bolts is that only changing how high the clutch pedal is in the cab of the truck or is it changing the point of resistance first felt when depressing the clutch pedal? If I am not fully releasing the clutch even though my clutch pedal is depressed clear to the floor it seems to me what I need is to be able to move the point of resistance first felt higher (thereby reducing the clutch pedal free play) consequently increasing the distance of travel from the point of resistance first felt when depressing the clutch pedal to the point the pedal hits the floor. If I am able to do that wouldn’t that be going in the right direction to fully releasing the clutch so my gears don’t grind? I apologize for being so ignorant on this stuff. I really appreciate your guidance.

[Cliff]

I took a picture of the adjustment point on my truck and the first thing I notice is the difference between how my truck is currently adjusted vs how your truck is adjusted. What I mean is the two bolts (upper and lower) on your truck are adjusted evenly whereas as you can see by my picture of my truck the adjustment is way to the lower side. I don’t know if that is relevant but it seems to me it should be.[img][img][/img][/img]

[NAM VET]

per my pic, to increase your pedal travel, to completely disengage the clutch disc, loosen the lock nuts, screw the bottom bolt in a few threads, after loosening and backing the upper bolt out a few threads,, then see if that fixes your disengagement problem, if not turn in a few threads more, and once it works ok, tighten the two lock nuts. Try to have no "play" or looseness in the bolts/nuts/pedal "thingy." I may have this adjustment scheme completely backwards, but this how you moved the pedal and where it disengages the clutch disk. Put some grease or oil there, too. Hal

[NAM VET]

turning your pic to compare to mine, it seems to me that your lower bolt is not screwed in far enough, , and the upper bolt is way too long. Shorten the upper bolt, screw the lower bolt in more. See if that helps. That should move your disengagement up oof the floor. Hal

[NAM VET]

oh, wire brush those threads first, then put some Kroil or other thread loosening oil on the threads. Hal

[Cliff]

I will do as you suggest and I will let you know the results. Thanks.

[Cliff]

I did as you suggested and it did not work for me. It moved the free play from 3 inches to 5 1/2 inches. That means the clutch was releasing less than before so I adjusted the upper and lower bolts back to the same position As when I started. I also moved the truck in and out of the garage and it shifted just fine after I reset things back to the position In my picture. But keep in mind I have not driven it enough for everything to warm up to see if it still grinds in 1st and 2nd after sitting at a stop light in neutral as it was doing before. My guess is it will still grind. I will drive it tomorrow to see how it does. I will let you know. Cliff

[Cliff]

I forgot to mention I would have adjusted the other direction but as can be seen by my photo there is virtually no space to go the other way. Is there another place in the linkage to make adjustments or am I looking at a clutch replacement?