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 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 05-11-2013, 05:02 AM   #1
74 stepside
Registered User
 
74 stepside's Avatar
 
Join Date: Oct 2009
Location: SoCal
Posts: 815
Gear Ratio Opinions

Ive got 2 different 12 bolt rears. 3.40 and 3.73. Truck has a mild built 350 with 700R4 trans and 295/50/15 rear tires (26" tall). Which gear ratio would be best?
74 stepside is offline   Reply With Quote
Old 05-11-2013, 07:43 AM   #2
b454rat
Senior Member
 
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,469
Re: Gear Ratio Opinions

With that small a tire 3.40s would be good. They are almost 27" tall, have them on my car...
__________________
2000 GMC CCSB 454/4L80 6” lift SAS
1999 Chevy CCSB 454/NV4500 4” SAS
1999 GMC Yukon 350/4L60 6" SAS
b454rat is offline   Reply With Quote
Old 05-11-2013, 02:23 PM   #3
INSIDIOUS '86
Registered User
 
INSIDIOUS '86's Avatar
 
Join Date: Jul 2009
Location: washington
Posts: 4,178
Re: Gear Ratio Opinions

3:73s will make you go fast but use a lil more mpg than the 3:42.
Posted via Mobile Device
__________________
377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac
3''spintech prostreet mufflers xpipe 1 3/4 headers
build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217
Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511
INSIDIOUS '86 is offline   Reply With Quote
Old 05-11-2013, 02:40 PM   #4
tinydb84
Registered User
 
tinydb84's Avatar
 
Join Date: Jul 2009
Location: San Jose Ca
Posts: 2,871
Re: Gear Ratio Opinions

3.40 and even then you will be turning too much rpm on the freeway
__________________
David
Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991
My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985
Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557
Instagram: myfabguy
tinydb84 is offline   Reply With Quote
Old 05-11-2013, 05:42 PM   #5
b454rat
Senior Member
 
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,469
Re: Gear Ratio Opinions

Not with an OD tranny.
__________________
2000 GMC CCSB 454/4L80 6” lift SAS
1999 Chevy CCSB 454/NV4500 4” SAS
1999 GMC Yukon 350/4L60 6" SAS
b454rat is offline   Reply With Quote
Old 05-11-2013, 05:44 PM   #6
tinydb84
Registered User
 
tinydb84's Avatar
 
Join Date: Jul 2009
Location: San Jose Ca
Posts: 2,871
Re: Gear Ratio Opinions

Quote:
Originally Posted by b454rat View Post
Not with an OD tranny.
I missed that. Yeah go with the 3.73s then
__________________
David
Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991
My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985
Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557
Instagram: myfabguy
tinydb84 is offline   Reply With Quote
Old 05-11-2013, 06:47 PM   #7
Keith Seymore
Registered User
 
Keith Seymore's Avatar
 
Join Date: May 2009
Location: Motor City
Posts: 9,226
Re: Gear Ratio Opinions

I vote for 3.73.

That's what I have in my truck with the overdrive and I love it.

K
__________________
Chevrolet Flint Assembly
1979-1986
GM Full Size Truck Engineering
1986 - 2019
Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926
My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524
Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/
Keith Seymore is offline   Reply With Quote
Old 05-11-2013, 06:48 PM   #8
Ziegelsteinfaust
Registered User
 
Join Date: Dec 2012
Location: Temple City
Posts: 3,629
Re: Gear Ratio Opinions

I'd try 3.73's with that wide a tire the extra rpm would not hurt or may help a bit.
Ziegelsteinfaust is offline   Reply With Quote
Old 05-11-2013, 11:37 PM   #9
wraprail
Registered User
 
wraprail's Avatar
 
Join Date: Sep 2010
Location: Lake Havasu City Arizona
Posts: 863
Re: Gear Ratio Opinions

The few times I have come across these trucks at wrecking yard with an OD trans they all had 3.73 rear ratio.
Quote:
Originally Posted by Ziegelsteinfaust View Post
I'd try 3.73's with that wide a tire the extra rpm would not hurt or may help a bit.
What difference does the Width of the tire have to do with gear ratio?
__________________
wraprail is offline   Reply With Quote
Old 05-12-2013, 12:16 AM   #10
74 stepside
Registered User
 
74 stepside's Avatar
 
Join Date: Oct 2009
Location: SoCal
Posts: 815
Re: Gear Ratio Opinions

3.73 it is...thanks guys.
74 stepside is offline   Reply With Quote
Old 05-12-2013, 12:33 AM   #11
Ziegelsteinfaust
Registered User
 
Join Date: Dec 2012
Location: Temple City
Posts: 3,629
Re: Gear Ratio Opinions

Quote:
Originally Posted by wraprail View Post
The few times I have come across these trucks at wrecking yard with an OD trans they all had 3.73 rear ratio.


What difference does the Width of the tire have to do with gear ratio?
The wider or heavier the tire a bit more rpm can help. On a friends C10 switching from 235/70/15 to 275/60/15 made a difference in acceleration, and took a couple mpg off the cruising. Then sometimes it doesn't make a difference, and I have seen it both ways.
Ziegelsteinfaust is offline   Reply With Quote
Old 05-12-2013, 09:37 AM   #12
LONGHAIR
just can't cover up my redneck
 
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
Re: Gear Ratio Opinions

It makes no difference in the gear ratio at all...but it may have some effect on how the truck drives/feels. Wider and heavier tire/wheel combinations can put more load on the entire drivetrain, under-powered vehicles will notice this more.
__________________
You can review the site's rules here.



Quote:
Originally Posted by Longhorn Man View Post
As for reading directions...
The directions are nothing but another man's opinion.
Learn from the mistakes of others, you won't live long enough to make them all yourself...

Bad planning on your part does not necessarily constitute an instant emergency on my part....

The great thing about being a pessimist is that you are either pleasantly surprised or right.
LONGHAIR 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 10:17 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com