clutch problem

[bigred1]

when engine is running cannot get into any gear. when engine is off can move shifter into gear. 1963 gmc 1500 305ci 4 speed manual

[FetchMeAPepsi]

Do you have fluid in your reservoir?

[bigred1]

yes, had been hearing rattling noise in first and reverse gears

[FetchMeAPepsi]

Might be a worn first gear. First and reverse are the same if I remember right. It's VERY easy to drop the transmission on these and it's not overly heavy. You might hit up one of the parts guys in the marketplace for a new first gear then start pulling the tranny. I've got a full writeup, bolt by bolt, in my build thread here (https://6066gmcclub.com/showthread.php?p=50025&highlight=sleeves#post50025).
Even if you don't need that gear, it's good to have extras on hand for later. If you do need it, it should be there by the time you're ready for it.

[bigred1]

thanks

[Jim A]

Your clutch is not releasing fully. Check fluid, then have someone watch the linkage from below as you cycle the clutch (NOT running).
There is an adjustment for proper clearance (not too much, not too little) that may solve your problem.
I doubt that the problem is in the tranny.
I also wonder what technique Fetch uses to make tranny r&r easy.
I have done mine twice over fifty years and would say it is hard to get to and VERY heavy.

[FetchMeAPepsi]

I also wonder what technique Fetch uses to make tranny r&r easy.
I have done mine twice over fifty years and would say it is hard to get to and VERY heavy.

Haha, my technique is drop the fluid, unhook the shifters, unbolt the driveshaft, unbolt the tranny and pull it backward. Tada! It's really not too heavy. It's not a sack of flour, but it's probably a big sack of dog food, just easier to get ahold of.

Mine's a SM318 though, yours might be different.

[lizziemeister'sV6]

Haha, my technique is drop the fluid, unhook the shifters, unbolt the driveshaft, unbolt the tranny and pull it backward. Tada! It's really not too heavy. It's not a sack of flour, but it's probably a big sack of dog food, just easier to get ahold of.

Mine's a SM318 though, yours might be different.
Believe his is 4 speed - a little more "heft" would be needed. Be like a big sack of dog food with a Saint Bernard attached!

[Ed Snyder]

Believe his is 4 speed - a little more "heft" would be needed. Be like a big sack of dog food with a Saint Bernard attached!

If you can believe the info on the internet, the three speed SM318 weighs about 65 pounds, and the four speed SM420 weighs about 135 pounds.

[FetchMeAPepsi]

Well there's your trouble! Your transmission is 70 lbs too heavy!
:teehee::teehee:

[Prowbar]

Well there's your trouble! Your transmission is 70 lbs too heavy!
:teehee::teehee:

Feel free to crawl under my truck and bench press that SM420 a few times!

[bigred1]

thanks Jim a, I'll try that

[Jim A]

It is important to make sure you have the full stroke range at both the master and slave cylinders.
There needs to be a little slack at the throwout bearing to protect it, but also enough travel of the slave rod to fully release the clutch disc.
I fought this situation for years and the fix. after waiting too long, was very difficult.

[TRybas]

When you say you can’t get it into gear with the engine running I assume you mean the gears grind when you try to engage? I believe ‘63 was the same as my ‘60. Is it a sm420 with a hydraulic clutch?

Sounds to me like the flywheel is not disengaging which is throwing the synchro off. Try cycling through all the gears with the engine off. Ending in 4th. Than start it up and see if you can put it back into 4th. Also try pumping up the clutch a few times before shifting. May or may not work but could give you a better idea of what is going on.

There is an adjustment nut where the slave cylinder meets the fork. Try setting it out further. Or master/slave cylinders could be on there last leg. Get eyes on the slave cylinder when someone pumps the clutch and see how much travel you get.

[bigred1]

thanks for the info