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- - gears (https://www.corvetteforums.com/forum/corvette-c4-forum-14/gears-1702/)

I know ive posted stuff about this before... but does anyone know what size gears the 94s came with? or if they varied, how to find out. i just bought a Hypertech Power Tuning Module and i need to know what size gears i have to tell it my gears are a different size. It is an automatic if that counts for anything. Thanks

yes they did vary

All Manual transmission cars from 85-96 have the D44 rear axle.
All 84s and all automatics have the D36 rear axle.

RPO Codes:
G92: Performance Rear Axle Ratio, means nothing really.
GU2: 2.73 verts option
15 pinion teeth, 41 ring teeth, 7.875" ring gear outside diameter
GM1: 2.59 standard rear for D36 cars
17 pinion teeth, 44 ring teeth, 7.875" ring gear outside diameter
G44: 3.07 standard rear for 4+3s, option on A4s
3.07:1 ratio: 14 pinion teeth, 43 ring teeth, 7.875" ring gear outside diameter
3.07:1 ratio: 14 pinion teeth, 43 ring teeth, 8.5" ring gear outside diameter (manual transmission)
GW4: 3.31 only for 84s with Z51 only
GT7: 3.33 available on Late-89-90 6speeds
GM3: 3.45 standard rear for later 6speeds
GHO: 3.54 available on early-89 6 speeds, and as an option on a few later years.

Check your line sheet for those codes and if the car is original, you can see what ratio you have. [8D]

Raisin, where did you find the line sheet break downs?

thanks mech but hwere do i find my line sheet?

If it is still there, it might be on the wall of your console. [8D]

ok so i found the code sheet... how do i know which code it is?

Read Raisin's post, option codes are usually a letter followed by 2 numbers. He has the option codes for gear ratio's. [8D]

you guys are so smart [8D] thanks for all of your help. now another question... if i went out and bought the Hypertech Programmer III, that would allow me to customize the gears i have in my car and everything working with a STOCK CHIP... i dont have the hypertech chip. I bought the hypertech power tuning module thinking it was the chip but apparently it isnt. So i just need to know if the stock chip is customizable as far as gear ratios and tire sizes and stuff like that go...

If I'm not mistaken, there is no chip in your car. It has a EPROM, which the power tuning module reflashes the stock tuning curve to a more high performance curve. [8D]

ok well if it has no chip, is there a way to tune the EPROM so that i can change the gear ratio and tire size? or even just the gear ratio?

i also just looked at my codes list and i saw that i have the G92 Gear Code and i dont know what the ratio is... can anyone help me out?

sorry for the delay....i found those on a guy's website thats devoted to c4's. its got a bunch of great information on it.

http://temp.corvetteforum.net/c4/vader86/rearaxle.html

Read ALL of Vader's info ESPECIALLY the part about Mods that work and mods that won't he knows what he is talking about!

ok well if it has no chip, is there a way to tune the EPROM so that i can change the gear ratio and tire size? or even just the gear ratio? this is a repost but im really lookin for an answer so if anyone knows, please be sure to let me know... thanks. its a really important question

UNless you know how to burn your own setup, you either have to use the canned setup they offer or you might be able to find someone who can offer a custom tune for it. You can't change gear sizes by reprogramming, only by physically changing the gear set. The the tune is matched to the ratio.

i thought whenever you used the programmer, it game you the codes list or somethin like that and then you could change the gears code to whatever it was. i know its a completely different car, but whenever my friends get gears in their mustangs, they always have to get it programmed to that size gear because it will throw their speedometer off.

i just recently bought the hypertech power programmer. it allowed me to change power and torque curves, cooling temps, shift points, top speed limiter, rev limiter, shift firmness, and can compensate for bigger or smaller tires as well as different gear ratios. i also recomend getting the hypertech powerstat thermostat 160

Both items are pretty useless when it comes to actual tuning. I have the Thermomaster chip and powerstat 160. They are junk. A 160* is not going to make your engine run cooler. At 160* that stat is wide open and will remain wide open until the temp falls below 160* degrees. How often is that car going to run below 160*? At start up. But, as soon as it gets to 160* the stat will open and remain wide open for the duration or until the car is shut off and cools down. If your car is running BELOW 160*, under normal operation, then you have a problem. A car running that cool is going to have some closed/open loop problems and is prematurely and unneccesarily wearing that engine. SBC engines, as most engines do, have been known to have problems with head gasket failure with engines that run as hot as the Generation II LT1 do but with the reverse cooling that the Gen. II LT1 has this greatly reduces the risk or potential risk of this occuring since the heads are cooled first instead of the block. GM got is right this time. Also, by running a car's engine too cool (if you can get it to run in the 160* range under normal operating driving) you are also reducing the oil tempertaure. Since the oil temperature under these conditions is far below the reccomended operating range that oil isn't getting hot enough to boil off the contaminates. You are asking for trouble eventually.

The ptm only makes ignition timing adjustments. If you are wanting to correct for different gear ratio's you need a programmer