RMK

I've had my car for four months now and the speedo is under reading. I have eliminated just about everything and now think that one of the previous owners changed the stock 2.73 gears with something else.

Now, in order to correct the speedo gears I need to know exactly what has been put in there. How do I find out what the new gears are?

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter
I like to think of her as Arnold Schwartzeneger in a dinner suit

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat. K&Ns, AFPR and Air foil.

Future mods:
Cam change
New torque converter
New heads (maybe corvette L98)
Strut brace
Sub frame connectors
Ram Air

Current G-Tech times
0-60mph 6.26 seconds
1/4 14.74@100.2mph

tpsierra

Axle code is stamped on the right front side of the rt axle. If it has been changed, jack up the back of the car, rotate the read wheel and count the revolutions of the drive shaft, the more the more accuracy. ratio= #turns of driveshaft/#turns of wheel.

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1957 3/4 rat
1966 c10 panel
1968 c20 350, 350
1982 camaro 305, THM-200-R4
1984 Monte Carlo, 350, th-350
Everett, WA

five7kid

iTrader: (14)

Jack the car up, but remove the rear cover (which will drain the gear lube). Find the number of teeth stamped on the ring and pinion gears or count the teeth. Divide the larger by the smaller, round off to two decimal places, that's your ratio.

Any other method is an estimation. By doing it this way, you can also determine if it's posi or open, and have an opportunity to get some good gear lube in it.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, TBD heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

RMK

Thanks for the help. I'm upgrading my tranny with the vette shift kit so I'll take the cover off then and count the teeth.

Thanks for the help

Robert