Overdrive Over Ride
Thread Starter
Instructor
Joined: Jan 2011
Posts: 165
Likes: 0
From: Eureka Ca
Overdrive Over Ride
My car is an '86 4+3 Z51. Is there a reasonable way, from a cost and difficulty standpoint, of having the overdrive be on demand only? In other words, I want to eliminate the automatic function of it engaging, and have the switch on top of the shifter be an on/off switch? Or installing another switch, as in the '84, to essentially perform the same function?
dws
dws
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The button on the shifter handle acts as an on/off switch but only for the current ignition ON/engine running cycle. The OD can be made to default to OFF but IIRC, it requires making a change in the BIN file on the computer chip. That takes special equipment to do and I believe it requires burning a new chip.This page describes how the OD works in the various years. Note that for 86-88 the OD doesn't work until the coolant temp reaches about 122 degrees. At that point the OD light should come on and at that time (or before it) you can simply depress the clutch pedal and hit the button. The OD will remain off until the next ignition cycle.
Also as shown, throttle position over 60% in 1st will turn the OD off.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Thread Starter
Instructor
Joined: Jan 2011
Posts: 165
Likes: 0
From: Eureka Ca
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Start engine ; hit O/d button.
O/d is now disengaged and under full manual control until you restart car again when it returns to default
No extra wiring needed.
Get settings changed in the program or install switch as above
Can have full manual control or just a switch to over ride automatic operation ;
dependent on how you wire it
O/d is now disengaged and under full manual control until you restart car again when it returns to default
No extra wiring needed.
Can have full manual control or just a switch to over ride automatic operation ;
dependent on how you wire it
Last edited by rodj; Mar 8, 2011 at 06:54 PM.
Race Director
Joined: Apr 2003
Posts: 17,699
Likes: 1,667
From: moraga ca
When my 84 had a 4+3 I did exactly what Rodj suggested. Interrupted the wire going into the tranny controlling the lockup. Rewired my stock switch on the console (now in your shifter). This gave me lockup on demand. I used it as an extra gear on the freeway. The light on the center dash went on too when the overdrive was activated, just like stock.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
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
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
When my 84 had a 4+3 I did exactly what Rodj suggested. Interrupted the wire going into the tranny controlling the lockup. Rewired my stock switch on the console (now in your shifter). This gave me lockup on demand. I used it as an extra gear on the freeway. The light on the center dash went on too when the overdrive was activated, just like stock.