how do i know my diff ratio?
Thread Starter
Advanced
Joined: Aug 2008
Posts: 72
Likes: 0
From: Springfield Gardens & Jeddah none
how do i know my diff ratio?
I just wanted to know where do i find my diff ratio i looked all around but could find it or maybe i couldn’t recognize it.
i know the most autotrans vettes come with 2.73 and some came with the 3.15 just wanted to make sure whice one is mine .
and would changing the number with my Diablo predator to a higher number damage something.
i know the most autotrans vettes come with 2.73 and some came with the 3.15 just wanted to make sure whice one is mine .
and would changing the number with my Diablo predator to a higher number damage something.
Melting Slicks
Joined: Mar 2005
Posts: 2,891
Likes: 4
From: North Port Fl
You can not change the gear ratio with a Diablo predator. To change the gear ratio you must physically change the ring and pinion gears or the differential itself.
The Diablo predator might be able to correct the speedometer after a gear ratio change or a tire size change, and it might be able to change the shift points after a gear ratio change or tire size change. I don't know you'd have to read the book that came with it.
Instructor
Joined: Aug 2008
Posts: 204
Likes: 0
From: Lake Placid Florida
Gear ratio...
My thought would be email the Corvette Museum your VIN# and a hundred bucks and they'll tell you more things about your car then you can imagine. See their website, and join or not, they will tell you what the VIN means, they will send you a real copy of your original window sticker and build sheet and a book with all the codes for all vettes, and real unopened dealer brochure for almost any year vette. Good deal, good organization to join. I found out that my '98 coupe has the 3.15 rear with the A4, in fact most vettes that year had that ratio, but, also all the options it came with from the factory. Try it, you'l like it. 
Racer
Joined: Aug 2007
Posts: 401
Likes: 1
From: Ashburn, VA
I just wanted to know where do i find my diff ratio i looked all around but could find it or maybe i couldn’t recognize it.
i know the most autotrans vettes come with 2.73 and some came with the 3.15 just wanted to make sure whice one is mine .
and would changing the number with my Diablo predator to a higher number damage something.
i know the most autotrans vettes come with 2.73 and some came with the 3.15 just wanted to make sure whice one is mine .
and would changing the number with my Diablo predator to a higher number damage something.
2730rpm = 2.73 gears
3150rpm = 3.15 gears
Racer
Joined: Nov 2008
Posts: 279
Likes: 2
From: Cabot Arkansas
The predator axle ratio change only affects the rpm that the transmission shifts at (assuming an a4). The speedometer is not affected because it reads rpm at the output shaft after the gears. Tire size settings affect the speedometer and the wheel sensors and if set incorrect can negatively affect the active handling and traction control so don't mess with this unless you physically change tire and or wheel sizes. If you physically change the ratio in the diff enough the engine will hit the rev limiter if the shift rpms are set incorrectly. Do not change this unless you actually change the gears.
Le Mans Master
Joined: Feb 2002
Posts: 6,937
Likes: 21
From: Waldorf MD
To expand a little:
Put your tranny in the gear that has a 1:1 ratio (3rd for autos, 4th for 6 speeds). Accelerate to 75 mph, then check your tach.
2,730rpm = 2.73 gears
3,150rpm = 3.15 gears
3,420rpm = 3.42 gears
Put your tranny in the gear that has a 1:1 ratio (3rd for autos, 4th for 6 speeds). Accelerate to 75 mph, then check your tach.
2,730rpm = 2.73 gears
3,150rpm = 3.15 gears
3,420rpm = 3.42 gears
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
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Racer
Joined: Nov 2008
Posts: 279
Likes: 2
From: Cabot Arkansas
Just to be a little technical the RPM's listed above will be approximate. Tires diameters will alter the actual reading. If you don't have stock tire diameters they will be off quite a bit but even worn and different brand tires will affect them some.
Le Mans Master
Joined: May 2007
Posts: 5,393
Likes: 17
From: Belleville Mich.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Drifting
Joined: Jun 2008
Posts: 1,333
Likes: 32
From: cruising between USA and Canada... SAVE THE WAVE!
