SM465 gurus...diagnosis wanted

[Prong]

On my 79 K10 when I'm coasting/decelerating in either 3rd or 4th gear, I can kick it into neutral without clutching without much effort. However, it won't pop out on its own. Is this a synchro or shift fork worn/going out? Also, to put it in 1st (low), I have to double clutch it to get it there 99% of the time. Now for reference, the tranny seems to shift fine going through all the gears, both up and down (except for 1st since it's not synchronized). Any thoughts?

[Captkaos]

It shouldn't pop out of gear on its own, if it is, then you have some worn parts.

What is your definition of "double clutching"?

To get a SM465 into L or first gear, you basically have to be stoppped.

[Prong]

to get in 1st, it goes like this at a complete stop: clutch, try to shift and gear grinds a bit, clutch again and in it goes. On the 3rd/4th issue, you shoudn't be able to put it in neutral without clutching, correct? Like I said, it won't do it on its own, but when coasting, you can move the shifter into neutral without clutching at all.

[Captkaos]

pulling it out of gear while coasting with no load is normal for any gear except low.
L isn't synchro'd so it has be be aligned to get in, so this isn't way out of the ordinary.

[JRConnieK10]

I think I know what your talking about thats what I have sometimes the gears aren't lined up to go in L if you bump the clutch you can feel them turn inside and then it will fall in. As far as being able to pull out of 3rd and 4th most manual transmissions can be shifted if the RPM's are matched up as in semi trucks. I know useally the only time you use the clutch is to start and stop at least thats how my dad taught me so I wouldn't wear his clutch out he said.

[Captkaos]

I drove a 4x4 home that a guy was selling that he put the clutch in backwards. 
Got a big discount on the sell price too!  Especially when I told him I wanted to drive it before I bought it (he said it couldn't be driven, and didn't know what was wrong)

[VileZambonie]

If you have to force 1st gear by double clutching even from a stand still try changing the fluid. BTW what are you running for fluid?

[Prong]

Dunno on the fluid. I've had the truck over 18 months and have only put about 300 miles on it. Hopefully, I'll get it all reassembled this weekend at the bodyshop and then I'll service the tranny. The 205 is oozing oil out of the PTO covers, so I was planning on resealing that and service that as well. Novak says to avoid 90W gear oil because of high sulphur that can corrode they synchros. They recommend a 90W mineral oil, but where could you find that at? Or is their view just hookum?

[zieg85]

to get in 1st, it goes like this at a complete stop: clutch, try to shift and gear grinds a bit, clutch again and in it goes. On the 3rd/4th issue, you shoudn't be able to put it in neutral without clutching, correct? Like I said, it won't do it on its own, but when coasting, you can move the shifter into neutral without clutching at all.

I have had a pressure plate with weak springs cause what you are describing.  It is like you can't fully disengage the clutch pedal all the way but the clutch lets out 1/2 way out like it should.

[GoatBeard]

What you are describing on your 1st gear shifting is how all of the 4-speeds with granny-low I've ever owned work.  Push in clutch, try to shift to Low & it will grind a small amount.  To get it in gear you don't need to "double-clutch".  Try letting the clutch out a little while still applying pressure to the shifter -- it should pop in gear without grinding every time.

If that doesn't work, shift into 1st gear before you shift to Low.  As above, let out the clutch if a little while you apply pressure forward towards L.