What speedometer gears do I have? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 04-09-2007, 06:19 AM
1969 Camaro owner
Join Date: Sep 2001
Location: manitoba
Posts: 69
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
What speedometer gears do I have?

I am going to need to correct my gears. What I need to know is what drive gears did GM put into 1974 Novas with th350's? I've determined through novaresource.com and my own experience that the original car had a 2.73 differential. (I've got a 3.08 in my camaro and the speedo is 1000rpm/mile and the speedo is going too fast AND I'm going even higher to 3.73's, meaning the original had 2.73 in that nova, the only possible gear lower than 3.08 available for novas that year) BUT using the calculators, I'm somewhat guessing at tire diameter, I put in a 26" which is the standard size the nova would have come with.

Aftermarket companies sell 7,8,9 and 10 tooth drive gears but others seem to suggest GM only put 8 and 10 tooth drive gears in, or only black and purple. Did GM put 7 or 9 tooth in them? What color would these be?

I'll have to change out the drive gear if its anything other than a 7 or 8. I've never done that before, is this the basic procedure?:
-drop out driveshaft
-drain fluid
-remove speedo driven housing/gear
-remove 4 tailshaft bolts
-remove/replace drive gear
more or less?

thanks for any help.

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 04-09-2007, 09:28 AM
F&J F&J is offline
Registered User

Last journal entry: 32 Ford cabriolet conversion/windshield
Last photo:
Join Date: Mar 2007
Location: Connecticut
Age: 63
Posts: 1,571
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
The older GM parts books have a big section on which gears for a certain trans, axle ratios & tire by size. I've seen them in the 73-78 book and a newer book, they were truck books but showed your trans, so info is correct.

Easy way is to get the car out on a highway with mile markers, and go 5-10 miles to figure out what percent it is off. Then go to ebay under "speedometer adapter" to find one of those GM factory corrector gearboxes to dial it right in. They list them by how many percent underdrive or overdrive. Some of the buy-it-now are pricey but in regular auction format, you can do better. 2 minutes to install.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-09-2007, 02:15 PM
Deuce's Avatar
Hotrodders.com Moderator
Last wiki edit: Choosing a trailer
Last journal entry: Jan 13 2013
Last photo:
Join Date: Aug 2002
Location: Deuceland USA
Age: 67
Posts: 5,657
Wiki Edits: 6

Thanks: 0
Thanked 10 Times in 9 Posts
IF ... you are going to a 3.73 gear ...

just change the driver and driven to the gears you need ...

No big deal ( this is NOT a Turbo 350 but the principal is the same ... )
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-11-2007, 10:19 PM
Last photo:
Join Date: May 2003
Location: Shreveport LA
Age: 66
Posts: 5,106
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos
Gear in this thread - Powered by O'Reilly Auto Parts

Quick Reply

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may 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

Similar Threads
Thread Thread Starter Forum Replies Last Post
speedometer gears k1500_3 Transmission - Rearend 1 12-16-2006 08:59 AM
Help Speedometer Not Working (at all) phebbler Transmission - Rearend 7 08-01-2006 02:13 PM
Tranny gears or rear gears? strummin67 Transmission - Rearend 4 06-12-2006 11:17 AM
7 hours, 33 phone calls, &30 pages of Threads later... Rearend? Tranny? Need Guidance 68ChevelleFromHell Suspension - Brakes - Steering 19 01-13-2006 02:01 PM
Speedometer Information. M&M CUSTOM Transmission - Rearend 0 04-03-2005 09:47 AM

All times are GMT -6. The time now is 12:27 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.