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 > General Truck Forums > All 4x4 Tech & Off Roading

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-12-2013, 09:55 AM   #1
Shorthair_Hunter
Registered User
 
Join Date: Jan 2012
Location: Yakima WA
Posts: 31
Swap Ring and Pinion or New Rear End?

When I traded my 71 GMC C20 for an 85 Chevy K20 last year, the guy told me that the PO had swapped the rear end and the gears no longer matched up with the front differential. Other than that, the truck was great and it was an awesome deal, so I made the trade.

The spid in the glovebox says 4.10 gears so I assume that is what is in the front. I'm also guessing that the rear is something like a 3.73. When I was driving in 4wd recently, my dad was following me and said he could see my rear wheels kick up on occasion which tells me they are moving a bit faster than the front. It also felt lurchy around corners, straightaway not so much. At most I went 20 mph.

So - would it be best to get a new 4.10 ring and pinion to put in or go junking and find a complete axle that already has the right gears? I have heard the pros and cons from a few people I know but wanted to hear from the wizards on here before I made my decision. My current axle is a GM Corporate 14 bolt, 8 lug.
Shorthair_Hunter is offline   Reply With Quote
Old 07-12-2013, 10:22 AM   #2
Bigdav160
Registered User
 
Bigdav160's Avatar
 
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
Re: Swap Ring and Pinion or New Rear End?

With that mismatch of gear ratios, I'd be very surprised if the vehicle would move at all.

Best thing would be to pull the covers and verify what you have.
__________________
My Classics:
'72 K20 Suburban + '65 Dodge Town Wagon
'72 Corvette Roadster +'67 Corvette Roadster
'73 Z-28 Camaro
'63 Ford SWB Uni Pickup
'50 Ford Coupe
Bigdav160 is offline   Reply With Quote
Old 07-12-2013, 11:19 AM   #3
Ol Blue K20
Proprietor of Dale's Corner
 
Ol Blue K20's Avatar
 
Join Date: Nov 2012
Location: Vacaville , CA
Posts: 15,829
Re: Swap Ring and Pinion or New Rear End?

Quote:
Originally Posted by Bigdav160 View Post
With that mismatch of gear ratios, I'd be very surprised if the vehicle would move at all.

Best thing would be to pull the covers and verify what you have.
X2
__________________
"Some Days Chickens And Some Days Feathers"

Dale
XNGH ECV Sam Brannan 1004

R.I.P. 67ChevyRedneck
R.I.P. Grumpy Old Man
Ol Blue K20 is online now   Reply With Quote
Old 07-12-2013, 09:28 PM   #4
LONGHAIR
just can't cover up my redneck
 
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
Re: Swap Ring and Pinion or New Rear End?

If they really are different, DO NOT drive it locked in. You WILL damage "something".

As the others have stated, verify the current gearing and go from there.
"Lurchy" around corners could mean that the previous owner installed some kind of traction device. Detroit Locker maybe? Yet another reason to pull the covers.....
__________________
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 12:36 PM.


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