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Well, we found a used 1958 235 with a 3 speed standard from another truck, and we installed it in our 1956 3200 (which had the same combination originally). The "new" engine fired right up and ran well. We adjusted the linkages so that it shifts smoothly through the column shifter's "H" pattern, and we adjusted the clutch pedal to the factory specs (3/4" to 1" of freeplay). Here's whats happening now. With the clutch pedal depressed fully, if we try moving the shifter through the gears, we immediately get a really loud grinding sound (we were testing it without the driveshaft at this point). We shut it off and I crawled underneath to conduct further tests. When the shifter is in the neutral position, I can easily spin the rear splines by hand and it sounds very smooth. The same goes when my son fully depresses the clutch pedal (with the shifter still in the neutral position). If he keeps the clutch pedal fully depressed and puts it into any of the gears, I cannot budge the rear splines. Am I doing something basically wrong here? As long as the pedal is fully depressed, should'nt it turn easily regardless of where the shifter is set? (I'm not a mechanic, and this is our first project of this type, so any advice on what to try next would be appreciated!)

Thanks!
Stephan

It sounds like the clutch disc is stuck to the flywheel/pressure plate.
Someone will come along shortly with a good remedy for you.

being in two gears at the same time will lock-up a trans. but when you adjusted the linkage, did you check the shift gates' alignment in their housing on the column?

chapter 7
http://chevy.oldcarmanualproject.com/shop/1948_51truck/index.htm

I would suspect the clutch. If clutch discs are in dampness a long time, rust under the facing bulges the friction material. It may be the wrong clutch, a warped pressure plate or a warped flywheel. Can you turn the output shaft at all with the clutch depressed. If the frictional material is just dragging a little, it may wear itself in with a little use.

The shift gates were checked during the alignment of the 2 linkage rods and are good. The engine/transmission was purchased as a unit that was still bolted together (and had not been unbolted in a long time, judging by the layer of crud on them), and both were working fine when pulled from the other truck last year. It was well covered, but was still stored outside for about a year. The output shaft turns easily by hand when the clutch pedal is depressed, and also turns easily if the shifter is in the neutral position with the clutch pedal not depressed. I'm not quite sure what to try next!

I think you have eliminated it down to something dragging in the clutch. I would try giving the pedal a little less free travel just to try to find the trouble. You shouldn't drive it with no free play, but it will tell you if you are looking in the right direction. Did you remove the transmission from the engine and reinstall it? If so, possibly the pilot bearing got messed up on reinstalling it. Having too much play at the tip of the input shaft will allow the disc to move around.

I'm thinking that without the drive shaft installed the input shaft is turning enough to cause the grinding. So put the drive shaft in and see what happens.

Sucess! The clutch disk appears to have been stuck against the pressure plate (likely due to being stored outside). A quick application of the starter with the clutch depressed and the tranny in 1st gear popped it free. Well, perhaps it wasn't all that quick. I spent the entire day battling the driveshaft/Ubolts/linkages etc, but by this evening the truck made it to the end of our driveway and back under its own power. My kid was thrilled! Thanks for the tips!

Stephan

Just a quick comment...I had a similar issue on a rebuild....turned out to be that hooking up the driveshaft put just enough drag on the transmission gear train to stop the gears from freewheeling, even when the box was in neutral. Figured there must have been some drag from the pilot bushing that fed back and kept things inside the box moving just enough to make her "talk." Had no more noise once we bolted on the driveshaft. Whodathunk!!

Dave