The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1960 - 1966 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 08-16-2014, 05:52 PM   #1
GMCNUT
Senior Member
 
GMCNUT's Avatar
 
Join Date: Jun 2007
Location: Arab Alabama
Posts: 1,591
decoding the 64-66 1/2 ton Rear end gear ratio

Hey guys - I have a "known to be good" spare 1/2 ton rear end I saved for a rainy day and I am building a 66 short fleet, so I decided to pull the inspection plate and see if I could count the teeth or something to determine the ratio....I could not tell if I was counting the teeth right, so I snapped a picture of the stampings on the ring gear and decided to sling this info at you guys and see what you can tell me? not even sure these markings tell us anything, but willing to try! See pictures below.

Hopefully you can see these markings clearly, but in case you cannot, starting from left to right, is the GM pt # 3817778 followed by an 11 then a 41GM then a 3 then what looks like a date of 64 1 27. on the opposite side of the ring gear it says 2-18.

If this info does not tell us the gear ratio, please feel free to suggest something. My next idea was to wipe a little white paint on one of the teeth and turn the ring gear and try to get an accurate count that way. As for counting the pinion gear teeth, I have no idea how to do that since it sits deep behind the carrier and everything - may have to remove it to tell. Thoughts? Thanks, Steve
Attached Images
  
__________________
My Projects and Toys - All 100% Stock
1972 CST "Highlander" Blazer - #'s matching 350 auto, PS, PB, A/C, Tilt, Tach, AM/FM & Positraction + Hickey Tire carrier and Sidewinder winch
1966 Chevy SWB Fleetside BBW Custom Cab, #'s matching 327 V8 & Powerglide, factory PS, PB & A/C, Tinted Glass, sway bar
1963 GMC SWB Fleetside BBW Custom Cab, #'s matching 305V6 & 3 spd - Factory solid Black 53K orig miles "barn find"
1961 Chevy SWB Fleetside BBW Custom Cab #'s matching 283 V8 & Powerglide w/ uber-rare Cool-Pack A/C, factory PB, Clock, Tach
1960 GMC SWB Fleetside BBW Custom Cab #'s matching 305A V6 & Hydramatic, factory PB, Clock, Tach, Compass, Hood Jet
1959 Chevy SWB Fleetside BBW Custom Cab w/ rare stainless bed trim, #'s matching 283 V8 & Hydramatic, Deluxe Heat, radio
1958 Chevy Cameo #'s matching 283 V8 & Hydramatic, radio, window washers, Factory PS & PB
1958 GMC BBW SWB Fleetside Custom Cab, #'s matching 336 V8 Hydramatic, Factory PS, PB, Clock, RSD, Deluxe Heat & Hood Jet
1957 GMC Suburban Pickup (GMC's Cameo) #'s matching 347 V8 Hydramatic, uber-rare vacuum ashtray, Factory PS, PB, Clock, RSD, Hood Jet
GMCNUT is offline   Reply With Quote
Old 08-16-2014, 06:33 PM   #2
66Submarine
Registered User
 
66Submarine's Avatar
 
Join Date: Sep 2012
Location: Dallas, GA
Posts: 1,498
Re: decoding the 64-66 1/2 ton Rear end gear ratio

11 - 41 = 41/11=3.73
__________________
1965 C30 pickup 350/SM420/4.10's (daily driver) thread
1968 Impala 4 door sedan (future driver project) thread
66Submarine is offline   Reply With Quote
Old 08-16-2014, 09:26 PM   #3
jayoldschool
Registered User
 
Join Date: Dec 2012
Location: ON, Canada
Posts: 1,663
Re: decoding the 64-66 1/2 ton Rear end gear ratio

Yes, factory gears are easy to do the math on.
jayoldschool is offline   Reply With Quote
Old 08-17-2014, 09:02 AM   #4
GMCNUT
Senior Member
 
GMCNUT's Avatar
 
Join Date: Jun 2007
Location: Arab Alabama
Posts: 1,591
Re: decoding the 64-66 1/2 ton Rear end gear ratio

Quote:
Originally Posted by 66Submarine View Post
11 - 41 = 41/11=3.73

Awesome - thank you. Never had a reason to know that was how you did it....thanks for the info!
__________________
My Projects and Toys - All 100% Stock
1972 CST "Highlander" Blazer - #'s matching 350 auto, PS, PB, A/C, Tilt, Tach, AM/FM & Positraction + Hickey Tire carrier and Sidewinder winch
1966 Chevy SWB Fleetside BBW Custom Cab, #'s matching 327 V8 & Powerglide, factory PS, PB & A/C, Tinted Glass, sway bar
1963 GMC SWB Fleetside BBW Custom Cab, #'s matching 305V6 & 3 spd - Factory solid Black 53K orig miles "barn find"
1961 Chevy SWB Fleetside BBW Custom Cab #'s matching 283 V8 & Powerglide w/ uber-rare Cool-Pack A/C, factory PB, Clock, Tach
1960 GMC SWB Fleetside BBW Custom Cab #'s matching 305A V6 & Hydramatic, factory PB, Clock, Tach, Compass, Hood Jet
1959 Chevy SWB Fleetside BBW Custom Cab w/ rare stainless bed trim, #'s matching 283 V8 & Hydramatic, Deluxe Heat, radio
1958 Chevy Cameo #'s matching 283 V8 & Hydramatic, radio, window washers, Factory PS & PB
1958 GMC BBW SWB Fleetside Custom Cab, #'s matching 336 V8 Hydramatic, Factory PS, PB, Clock, RSD, Deluxe Heat & Hood Jet
1957 GMC Suburban Pickup (GMC's Cameo) #'s matching 347 V8 Hydramatic, uber-rare vacuum ashtray, Factory PS, PB, Clock, RSD, Hood Jet
GMCNUT is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:54 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com