Now that my speedometer finally works........... its off. I switched the stock 3.90 gears for the optional 3.38 gears.
I purchased the brown gear in the picture with 18 teeth. Hoping it would fit a 1959 3 speed ....... it doesn't ( listed as fits 1960 3 speed). It's a tad wider & wont go in all the way.
The catalog I just got shows a blue gear for 3.38 BUT it's also a 20 tooth .... just like my original .
Thoughts????
Last edited by festerhairball; 01/12/20242:56 AM.
1959 3100, original 235/3 on the tree w/overdrive. Carter YF 2100S carb, 205/75/15 w/front sway bar
The ratio of the number of teeth between the drive gear and the driven gear is what matters. You see how it says the 20 tooth is for both the 3.38 and the 4.11? That is because the driven gear is different between them.
How sure are you that the 20 tooth gear you have is correct for the 3.9? It is possible that you need to replace both gears to have it be right.
Being i'm the 2nd owner of this vehicle, I don't think the previous employees modified it. (it was owned by CA, as a maintenance truck at a state mental hospital) Also the "stock" one is metal & leads me to believe its a oem product.
I didn't think about the "drive gear" inside, but that makes sense. I need to see if those are available for these 3 speeds.
You'd think the parts suppliers would sell them as a pair.
Thanks for the help!
Last edited by festerhairball; 01/12/20244:48 AM.
1959 3100, original 235/3 on the tree w/overdrive. Carter YF 2100S carb, 205/75/15 w/front sway bar
The standard truck 3 speed of that era used the metal gear which corresponds with the drive gear that is pressed on the output shaft. Cars used the same transmission with a plastic gear and corresponding drive gear. I have the car drive gears that I could share. You would have to disassemble the trans to install it. Send me a PM. Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes 1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes 2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans 1947 Willys CJ2A w/F-Head engine
This info may help you figure out what you need. LINK The following page of the link may help you sort it out, although the axle ratio may not be listed. The tire size also factors into it. You may just need to settle for something that's close.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
My truck is a 54 with a 4 speed and it has a 20 tooth driven gear and 7 tooth drive gear probably the same tooth count as it came with the 390 rear that year. It might be easier to put the original back in and go with a adapter that I have read about sounds like they are not that expensive and may be worth a look.Check a few posts back I posted about the Speedo gear on the 4 speed and someone replied with a sheet showing the original Speedo options for 1954
