4+3 Tranny
Thread Starter
4th Gear
Joined: Jan 2002
Posts: 4
Likes: 0
4+3 Tranny
I'm new to corvettes, but definately have the bug. I don't completely understand the 4+3 tranny in many descriptions. Can you help me define?
My husband has a '71 Nova that we just bought a Scott Shafiroff motor that will take us into the 9's in the 1/4 mile. So keeping in the Chevy family, I am trying to learn quick. :yesnod:
My husband has a '71 Nova that we just bought a Scott Shafiroff motor that will take us into the 9's in the 1/4 mile. So keeping in the Chevy family, I am trying to learn quick. :yesnod:
Burning Brakes
Joined: Sep 2000
Posts: 1,199
Likes: 1
From: NewCastle IN. USA
Re: 4+3 Tranny (vettelady)
the 4+3 is (basic description)
a regular doug nash 4spd, with a small 2spd automatic (overdrive) added on to it.
it only uses the OD in 2nd 3rd and 4th gears (hence the +3).
you have a button for manual use of the OD but the computer will control it the rest of the time.
it was cutting edge tech in its day..
if you get one make sure to do regular fluid changes in the OD ( it doesn't hold much fluid and can turn expensive if it goes out)
a regular doug nash 4spd, with a small 2spd automatic (overdrive) added on to it.
it only uses the OD in 2nd 3rd and 4th gears (hence the +3).
you have a button for manual use of the OD but the computer will control it the rest of the time.
it was cutting edge tech in its day..
if you get one make sure to do regular fluid changes in the OD ( it doesn't hold much fluid and can turn expensive if it goes out)
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Re: 4+3 Tranny (ol,RJ)
It's based on the old Borg-Warner Super T-10; many of the internal parts interchange.
The ECM control of the overdrive is a PITA. Luckily, the guys here have outlined (many times!) how to bypass the ECM and make the OD demand-only.
There's a filter in the OD sump; change that as well as the fluid (uses ordinary ATF fluid in the OD; 90w gear oil in the trans section).
If yours is a convertible, then the X-braces have to come off to service the OD.
...And they all leak... :rolleyes:
The ECM control of the overdrive is a PITA. Luckily, the guys here have outlined (many times!) how to bypass the ECM and make the OD demand-only.
There's a filter in the OD sump; change that as well as the fluid (uses ordinary ATF fluid in the OD; 90w gear oil in the trans section).
If yours is a convertible, then the X-braces have to come off to service the OD.
...And they all leak... :rolleyes:
Melting Slicks
Joined: Nov 2000
Posts: 3,388
Likes: 1
From: X
Re: 4+3 Tranny (vettelady)
If you would like to look at one E bay has one for sale
http://cgi.ebay.com/ebaymotors/aw-cg...587150&r=0&t=0
http://cgi.ebay.com/ebaymotors/aw-cg...587150&r=0&t=0
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Re: 4+3 Tranny (vettelady)
...when I buy mine.
Be advised that this transmission hasn't been made in...what, 10 - 12 years??? Parts are scarce; mechanics who *know* how to work on them are even scarcer (this I know; I have to pull mine to correct a New Jersey mechanics mistake); and they are a pain to pull the first time...
After that, it gets pretty easy...
Note to all above on oil leaks: howdjadoit??? :D
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
