Numbers on Quick Change Gears

What do these #'s mean and how can I tell what QC they fit ? Thanks

 

Should mean gear teeth number and set number....old gears not sure what brand. Quartermaster, clincher, Chester bros, ....there are so many manufactures. Maybe somebody can identify them......you have to run the matched set...

 

If I'm not mistaken they are "set numbers", which tell you what ratios they will produce when matched to the number table that they supplied. Most of the Speedway racing catalogs have the number table reproduced in them. You look them up by set number, ring and pinion number and it'll give you your final ratios flipped either way.

 

Google Change Gear Charts, and you will get gear set charts for 10 and 6 spline gears. It should help determine if you have sets or just random gears. I believe the fitment is strictly by spline count in the quickchange...but I've been wrong before.

Charlie

 

Those are 10 spline gears. I think for somebody's Champ rear. I seem to remember V-8 and Midget have 6 spline gear sets.

 

cool thanks

 

Older quick changes used the 10 spline straight cut gears. Could be frankland, halibrand or winters and maybe a few others. the numbers will tell you the gear ratio when used as a set. example...
20 / 30 would be either 7.29's or if flipped over they'd be 3.24's when used with a 4.86 differential
If used with a 4.11 diff, then you'd have 2.74 or 6.16's
Clear as mud ehhh

 

What you have, is set numbers 20 and 21 for a 3/4 ton rear.

Set 20 - ratio 1.300:1 or .769:1 w/4.86 R&P results in 3.74 or 6.27 final drive
w/4.11 R&P results in 3.16 or 5.47

Set 21 - ratio 1.526:1 or .665:1 w/4.86 R&P results in 3.18 or 7.41
w/4.11 R&P results in 2.73 or 6.27


I think the 1 and 8 on the #21 is the date of manufacture (Jan of '58, '68 etc.)

Interestingly, these numbers were assigned in order of development, with no regard to ratio. Frankland tried to change their numbering system to reflect the change ratio, but it never caught on.

Oval track racers frequently borrow and lend change gears. They sometimes refer to set numbers but more frequently they ask for the final drive ratio desired. I've seen mistakes made when the borrower and lender have had different ring and pinion ratios. This results in a real dog off the corners or over revving at the end of the straight. And everyone has put the gears in 'upside down' at least once.

To get the 'Big Number' the Big Gear goes on top!

 

"I like my gears like I like my women...big on top, little on the bottom!!" Was told that a long time ago and never have put a set in upside down.

 

some sets consist of 3 gears too so you can get 2 ratios