62 Speedo drive gear. Tell me what I have here. PICS

69ttop502 · 02-01-2013, 11:51 AM

I am taking my 62's original T-10 in for a freshen up. I pulled my driven gear since with the 3.36 Posi I added my speedo (recalibrated head) is way off. It also had a ratio box on it when I bought it. The driven gear appears to be the small diameter with 20 teeth but it is definitely metal and not plastic.

I saw a post by JohnZ in reference to C2 rears that the 4.56 cars had a special metal drive gear and metal 20 tooth driven gear. Is this the same for C1's and is this what I have? If my car originally had a 4.56 rear, that means my T-10 is close ratio. Would you stay close ratio with a 3.36 rear, or rebuild to wide ratio? Thanks for the input. Here are the pics.

63Corvette · 02-01-2013, 12:09 PM

I can't answer your metal drive gear question, However if I were to run a 3.36 rear (all things equal) I would want to run it with the WIDE ratio gearbox for better acceleration in the lower gears.

rick charles · 02-01-2013, 12:39 PM

Wide ratio for sure..................

JohnZ · 02-01-2013, 01:51 PM

The 20-tooth driven gear for a 3.36 axle is in the "small" family (0.8" O.D.), and is blue nylon; it's used with the "large" 8-tooth DRIVE gear (1.85" O.D., .610" thick) and mates with the 18-22-tooth nylon gears that cover 3.08 to 3.70 axles.

The 20-tooth STEEL driven gear is in the "large"(0.87" O.D.) family, and was only used with a special "small" (1.77" O.D.) 6-tooth DRIVE gear; this combination was ONLY used with the 4.56 axle.

Visually, both of the standard 8-tooth DRIVE gears show six full teeth across the gear face, and the special 6-tooth for the 4.56 axle shows four full teeth across the gear face.

With a 3.36 axle, I'd build it as a wide-ratio.

69ttop502 · 02-01-2013, 09:06 PM

Thanks guys and great info as always JohnZ. Explains why my speedo was so far off.

I am going to wait and see what the transmission needs before I decide what to do with the change from close to wide. As long as I have the larger drive gear in there, I can put a 3.70 ring and pinion in and just swap in a driven gear later on. I only went with the 3.36 because I finally found a case that was date correct for my early car. It just happened to have a 3.36 in it. Was going to go through the rear end at some point anyway.

Bill