[Alex van de Wetering]

Some years ago I bought a spare civvy 4 speed Chev transmission from the web, but never looked at the internals of the box. So, now was the time. Both transmissions boxes were disassembled and after cleaning everything I started comparing the parts from the two. At first everything seemed the same, but than I found out the sliding gear of the spare box had one more tooth than the one from the original box....and I found out the main shaft of the spare box was slightly shorter than the one from my C8.

The bearings in both the original box as well as the spare proved to be in good condition, but sadly I found out the mainshaft front bearing (the cage one with the long needles) in the original box was gone....I only found a bunch of the needles....and, after close examination, one end of the bearing cage. Sadly the lack of a proper bearing, meant the inside of the main drive gear was very beaten up, as was the end of the main shaft.

After checking the parts manual I found out all CMP 4 speeds use the same main shaft....even though the u-joint setup of the C8 differs from it's bigger sisters. Tracing the partnumber in a master parts list, I read that it was supposed to be 10,5” long.....a 11” main shaft is also listed, but not used on CMP's. To cut a long story short, it seems the main shaft of my C8 box was replaced at some stage for an 11” replacement. The spare box had a 10,5” shaft....and above all the end of the bearing surface on the end of the shaft was in good condition, so I used that one....combined with the spare main drive gear ......and selected the best parts of the two boxes to rebuild the gearbox.

Alex