Transmission rebuilt
Got the transmission back today from Harold’s Automotive in El Cajon. Like the rest of the car, it needed just about everything new – new second and third gears, new synchros, shift forks, and seals.
Made some marks at the input and output shafts to verify gear ratios-
As I suspected from the drive home (now over 1 year ago!) first gear is the tall 2.2, making this an M21 transmission, the standard unit in the ’67 Z28. Apparently the M20 wide-ratio was available as an option. Might seek one out if ProSolo launches with this tall first gear don’t work well.
The other thing it could be is the fabled “rock crusher” M22 Muncie. The M22 had a much shallower gear helix angle which made the gears stronger, but the transmission was very loud.
M20 and 21’s have an average helix angle of 35 degrees, M22’s have an average angle of 21 degrees. This one’s definitely an M21:
[…] as I went to install the Hurst Competition Plus shifter on the freshly rebuilt trans, I realized there was no freakin' way it was going to fit, without re-creating a monster hole. […]