Rear Gears
Thread Starter
Melting Slicks
Joined: Nov 2001
Posts: 2,622
Likes: 0
From: Vancouver BC
Rear Gears
just wondering about my cars gears i have no idea what the mods are really just was wondering about my gas mileage again.. its kinda high in my opinion compared to a buddies vette which is much more power ful than mine but burns less fuel....... either way i heard on the forum that it might be my o2 sensor or even my rear gears...... ok well someone told me on the forum that i should drive my car up to about 65mph and get the reading on the tach..... well ok you techies! i was running 65mph in OD at about 17-19 RPM..... do i got stock rear gears? oh and this is the 1988 Coupe.
thanks
davin
thanks
davin
Melting Slicks
Joined: Aug 2000
Posts: 2,069
Likes: 25
From: Orlando FL
Re: Rear Gears (dmalhi1)
i was running 65mph in OD at about 17-19 RPM
Interesting... you're running about the same RPM as my GS coupe at 70mph but it has 4.10 gears (and a six speed, of course). ;)
Thread Starter
Melting Slicks
Joined: Nov 2001
Posts: 2,622
Likes: 0
From: Vancouver BC
Re: Rear Gears (Z06VERT)
i was running 65mph in OD at about 17-19 RPM
Yep, those should be the 3.07's, not 2.59's. Check your RPO codes to see if your car came with the 3.07 performance axle ratio, option G92.
Interesting... you're running about the same RPM as my GS coupe at 70mph but it has 4.10 gears (and a six speed, of course). ;)
Yep, those should be the 3.07's, not 2.59's. Check your RPO codes to see if your car came with the 3.07 performance axle ratio, option G92.
Interesting... you're running about the same RPM as my GS coupe at 70mph but it has 4.10 gears (and a six speed, of course). ;)
but is this the reason i might be using up so much fuel aswell ? and wheres the build codes?? under the lid of the console right? ok i'll check later on tomorrow.
thanks guys...... i still dunno what 3.07 rear gears mean though.... whats it do compared to this 2.59 that is stock for the 88 ?? hope i'm not bugging ya in getting you to inform me.
any replies are highly appreciated.
thanks again
davin
Burning Brakes
Joined: Jun 2000
Posts: 865
Likes: 6
From: Auburn Michigan
Re: Rear Gears (dmalhi1)
For the moment, I have 2.73's in my 85 auto, and at 70mph the tach reads 1900rpm, so it does sound like you've got 3.07's. I hope to have 3.73's in mine in the spring..... I drive my Cavalier Z-24 5-speed for the mileage, the Vette for smiles, and my wife's Dodge Stratus R/T 5-speed for a little of both. (I hate to admit it here on the forum, but her Dodge is a blast to drive on a nice tight road.)
Later,
Carl
[Modified by cohocarl, 7:59 PM 12/15/2001]
Later,
Carl
[Modified by cohocarl, 7:59 PM 12/15/2001]
Safety Car
Joined: Oct 2001
Posts: 4,763
Likes: 2
From: Connectivette
Re: Rear Gears (cohocarl)
My '88 came with 2.73 stock and I am at 1900 rpm's at 70 mph. I am however picking up a new rear this weekend with 3.07. I not planning on any higher gear ratio with my stock cam.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
Re: Rear Gears (chucks88)
dmalhi1 - To be as simple as possible, the rear gears act as a torque multiplier for your engine. The trade off is loss of high end speed. We can all thank CARB for not having the option to select our own gear choice at the dealership. Why do I need 2.59 gears??? Who can go 172mph in this country?? Would rather have had 3.45 or 3.73 as an option. :crazy:
Team Owner
Joined: Sep 2001
Posts: 62,180
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Rear Gears (Goody)
lower gear ratio, higher number, means youre quicker off the line but you lose the top speed as he said. Gas mileage should not be a major problem, i get an average of 19mpg with mine and have the 3.07's. I still get better mileage than every SUV on the road.
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Rear Gears (Goody)
Torque multiplier? yes! And a speed reducer. Lower (ratio) gears have higher numbers than high gears, which are lower numerically. Among other things, your rear axle gears reduce the drive shaft speed, by the amount of the ratio, to the output to the wheels. The torque is multiplied by that same ratio. Four to one is a lower gear than a three to one. With 4:1 gears, the wheels turn at 1/4 (25%) driveshaft speed. And the input to the rear end torque is multiplied by 4. Three to one gears only drop the wheel speed to 30 percent of driveline speed, and multipy the torque by 3. Higher gears equal reduced engine rpm at a given driving speed. Lower gears provide greater torque muiltplication for quicker acceleration. There is a lot more to this, but these are the basics.
Thread Starter
Melting Slicks
Joined: Nov 2001
Posts: 2,622
Likes: 0
From: Vancouver BC
Re: Rear Gears (Z06VERT)
ok my cars lil console sticker doesn't say G92 but says G44.... now at the same time i am confused cuz i ran my vin (yes i finally found it) that i found on the console lid with the RPO codes and well carfax says my cars got 4 reports i gotta see and that its not an 88....... its an 89..... now.... my car is a rebuild they say..... so maybe that center console box isn't the one thats supposed to be there or something? maybe its from an 89 and the sticker is to another car? i dunno i'm confused either way lemme know if G44 is a RPO Code for 3.07 gears aswell.
Team Owner
Joined: Sep 2001
Posts: 62,180
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Rear Gears (dmalhi1)
G44 is the 3.07's. Its that way on mine as well, i dont have G92 performance ratio but still have the G44 3.07's. I dont trust Carfax reports anymore either, since it was wrong in my cars case.
