The GMC CCKW

Short of draining and replacing, how do I tell if there is enough fluid in the differential?

When I go to Autozone, what do I ask for to refill the differential?
How much do I need to do all 3 axles?
Is there a gasket I need to replace?

Neil

Have you got your manuals yet?
The tranny and transfer have drain plugs ,about half up there is a fill plug, the oil level should be to the fill plug
Banjo axles have 2 fill plugs the lower one is the correct one ( the other is when the cover is mounted 180 degrees as is the case on a front axle.
You will have to remove the cover to drain it
Get some Gasket material sheet stock similar to what was originally used ( save a piece you removed ) NAPA has it
Timken axles have a drain as well as a fill plug
Don't forget the PILLOW block
Use 80-90 wt Gear Oil
Synthetic fluids are avail. but I don't use them.

I buy my GO by the 5 gallon pail ( approx $80 - $90 )and I use a $40.00 ( Local NAPA prices )pump to fill the cases ( because a funnel and qt containers won't fit all the time.) and it is the best way to keep them top off with oil.

I printed out the TM 9-801 Manual and put it in a binder. It is a LOT of reading!

I have the Banjo axles. I will get the gear oil and gasket material.

Neil

SpookyDad wrote:I printed out the TM 9-801 Manual and put it in a binder. It is a LOT of reading!

Neil

Yes but EVERYTHING you need for maintainence is printed in there

Besides...it ain't bad bedtime reading

John

And VERY important to prevent the dreaded and expensive "GMC clutch", adjust the clutch and keep it adjusted so that it just completely disengages 1" above the floor. The free play at the top does not matter unless there is none in which case you need a new clutch disc. As the clutch wears, the free play will become less and less until there is no more. If you adjust the clutch so that it diengages more than 1" above the floor, you are over stressing the diaphram spring in the pressure plate and it will eventually (soon) fail.

*The manual says:clutch free pedal travel =2 1/2".

DISREGARD THE FREEPLAY

With a new clutch adjusted properly, you will have a lot of freeplay. As the clutch disc wears, the freeplay will disappear until there is no more.

As the disc wears, it gets thinner. The pressure plate (moveable part) gets closer to the flywheel. The fingers stick out more. They get closer to the throwout bearing. The throwout bearing (and pedal) must be adjusted to be farther away to not touch the fingers (freeplay). That will decrease the freeplay you observe inside the cab. This is the process of freeplay.

You want the clutch to just completely disengage about 1" off of the floor. That is what counts. Freeplay, as I explained above is a function of the thickness of the clutch disc. If you adjust for freeplay, you will overstress the pressureplate diaphram and it will twist and will then fail to disengage.

If you want to experience a "GMC Clutch", adjust it for freeplay... There is only one maintenance manual that is correct. The other 4-5 are wrong.

BEEN THERE TWICE

And oh by the way, only one manual tells you how to rebuild the pressureplate. DON'T just send it out. It will come back JUNK! Been there too Again, only one manual is correct. You have to add shims behind the pivot points.

http://br.youtube.com/watch?v=MBmLJCeGu7o&NR=1 Thanks for your help Dr.Deuce.