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 06-17-2010, 12:05 AM   #1
64c10stepside
Registered User
 
Join Date: Oct 2009
Location: Mesa, AZ
Posts: 17
Low rearend gearing with a granny gear trans

Has anyone ever looked into running a real low gear ratio in the rear end so the the granny gear functions as a real 1st gear and the top gear would be an overdrive??
Is this possible?
64c10stepside is offline   Reply With Quote
Old 06-17-2010, 12:45 AM   #2
apachedaddy
Registered User
 
apachedaddy's Avatar
 
Join Date: Feb 2008
Location: pooler, GA
Posts: 213
Re: Low rearend gearing with a granny gear trans

It would work but you would have to run a real high 2:?? or low 3:?? to get there. That also means changing out your carrier to take that high of gear.
__________________
66 short wide fleet sbw = Gave to my best friend
66 short wide fleet bbw
apachedaddy is offline   Reply With Quote
Old 06-17-2010, 01:32 AM   #3
Captainfab
60-66 Nut

 
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,246
Re: Low rearend gearing with a granny gear trans

The one problem with that is I don't believe there is a synchro on 2nd gear, so it will grind everytime you shift from 1st to 2nd. I could be wrong though....

Quote:
Originally Posted by 64c10stepside View Post
Has anyone ever looked into running a real low gear ratio in the rear end so the the granny gear functions as a real 1st gear and the top gear would be an overdrive??
Is this possible?
__________________
Power Steering Box Adapter Plates For Sale HERE
Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE
Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE
Hydroboost Mounting Plates HERE
Captainfab is offline   Reply With Quote
Old 06-17-2010, 04:48 AM   #4
raycow
Registered User
 
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
Re: Low rearend gearing with a granny gear trans

Second gear is synchro on the SM420, so no problem shifting on the fly. Actually, you won't be using first gear very much anyway, even with the taller rear gearing. Second on the SM420 is lower than first on the 3 speed.

Ray
raycow is offline   Reply With Quote
Old 06-17-2010, 10:48 PM   #5
Captainfab
60-66 Nut

 
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,246
Re: Low rearend gearing with a granny gear trans

What about in the SM465?

Quote:
Originally Posted by raycow View Post
Second gear is synchro on the SM420, so no problem shifting on the fly. Actually, you won't be using first gear very much anyway, even with the taller rear gearing. Second on the SM420 is lower than first on the 3 speed.

Ray
__________________
Power Steering Box Adapter Plates For Sale HERE
Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE
Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE
Hydroboost Mounting Plates HERE
Captainfab is offline   Reply With Quote
Old 06-17-2010, 11:07 PM   #6
raycow
Registered User
 
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
Re: Low rearend gearing with a granny gear trans

Second and third are roughly the same on the 420 and 465 (about 3.5 and 1.7 respectively). First is slightly taller on the 465 (about 6.5 vs 7.0). I have a page bookmarked somewhere with the actual ratios and if I can find it I will post it.

Ray

Last edited by raycow; 06-17-2010 at 11:07 PM.
raycow is offline   Reply With Quote
Old 06-17-2010, 11:31 PM   #7
raycow
Registered User
 
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
Re: Low rearend gearing with a granny gear trans

Ok, found it.

http://members.cox.net/jeepinrandy/r.../transinfo.htm

Ray
raycow is offline   Reply With Quote
Old 06-17-2010, 11:36 PM   #8
Captainfab
60-66 Nut

 
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,246
Re: Low rearend gearing with a granny gear trans

Is 2nd gear on the SM465 synchro'd the same as the SM420?
__________________
Power Steering Box Adapter Plates For Sale HERE
Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE
Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE
Hydroboost Mounting Plates HERE
Captainfab is offline   Reply With Quote
Old 06-18-2010, 12:05 AM   #9
raycow
Registered User
 
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
Re: Low rearend gearing with a granny gear trans

Yes, the 465 has synchro on 2nd. Sorry, I didn't realize that was what you were asking about the first time.

Ray

Last edited by raycow; 06-18-2010 at 12:09 AM.
raycow is offline   Reply With Quote
Reply

Bookmarks


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 09:15 PM.


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