The Stovebolt Site Forums The Shop Area Driveline The infamous SM-420

Novac kits have both 3 & 4 syncros for the later transmissions that use the same size. As of last summer they did not have the one that is different on the earlier trans. I don't remember which one that is. I lucked out and had enough good syncros to finish the job. I don't remember if the kit contained the 2nd gear syncro. In any case I didn't replace it.

One thing I noticed was that the clutch-gear bearing supplied with the kit has fewer, larger balls than I have seen before on that part number bearing. I have a new bearing of the same size with more balls but no snap-ring groove which is probably why I still have it. Be careful installing the 2nd gear detent springs and shoes. If you don't get them positioned correctly the trans will jump out of 2nd gear. Jumping out of 3rd gear is usually because of worn clutch-gear or rear mainshaft bearing or both. This was the first SM420 I had worked on in about 10 years so my memory for the details is a little fuzzy.