79 12 bolt question (gear ratio) - Off-Road Forums & Discussion Groups
GM Standard IFS Trucks & SUV's All discussion of full sized IFS Trucks, SUV's to include Suburban

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 08-06-2001, 02:08 PM Thread Starter
 
Join Date: Mar 2000
Posts: 534
Thanks: 0
Thanked 0 Times in 0 Posts
 
79 12 bolt question (gear ratio)

got some axles off a 79 blazer. my friend and i tried to figure out what the gear ratio was last night by turning the axle and counting the number of times the yoke rotated - 1.5 times... this doesn't sound right - the truck had a 350/350/203. both the front and rear were 1.5... anyone care to enlighten me on this... i did it on my 89 s-10 and it was a 3.73... we tried to figure out if the 203 had a reduction in it, but it doesn't... thanks all

Craig

'89 S-10 P/U 4.3L 31" Yoko M/Ts
'99 S-10 2.2L 2WD 5 Speed Stepside Totally Stock [img]/wwwthreads_images/icons/frown.gif[/img]
Fishyoo7 is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 08-06-2001, 02:20 PM
Blazer1970
Guest
 
Posts: n/a
Re: 79 12 bolt question (gear ratio)

If you have one wheel in the air, and one on the ground, you have to turn the tire two revolutions to read the gear ratio directly from the driveshaft. I would guess that you have 3.07 gears (1.5 X 2). That was pretty much the standard ratio for trucks with a 350 in the '70s.

'70 CST Blazer, 350, SM465, NP205.
'87 Suburban 4X4, 350, 700R4
'01 GMC 2500HD, Duramax/Allison
post #3 of (permalink) Old 08-26-2001, 03:43 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: 79 12 bolt question (gear ratio)

3.08 is most likely what it has. My 79 had the same drivline set up and that is what it had stock. The most accurate way of checking is to locate the stamp in the axle tube. Write down the letter/number combo and call you local chev dealer. They will be able to look it up and let you know what the ratio in that axle was.

79 Blazer,4x4, modified 350cid, 33", 4.10 gears
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 08-26-2001, 09:27 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: 79 12 bolt question (gear ratio)

the most postive way to tell what ratios you have is to pull the covers off and see what is stamped on the ring gear it will have numbers on it like 11 and 41 divide it this is a 3.73 or so on it will also have a date on them also while you have the cover off look for damage and put new gear oil back in

4x4k20
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome