axle ratio count, two full wheel turns? - Third Generation F-Body Message Boards

Randy82WS7 · 09-26-2009, 11:29 AM

ok now i have owned billions and bilions different cars and trucks over the years somewhere around or over 200 since 1994. and ive taken apart and put many rear together and i normally always pull the diff cover to check ratios or at least run the stamping code to determine what they should have in them. however with this 82 t/a it has been very difficult and i have never been sure of whats in the damn thing. i know its either 2.73 or 3.23 that came in these. it is factory LG4 and 200C.

now. i just read on a page where you can turn the wheel with the other one on the ground exactly two turns and however much the driveshaft rotates that is your ratio ?

right?

i have always done it by going ten tire turns and counting the driveshaft revs and doing the math

however this is not working at all on this car for some odd reason.. i have no idea why not...

i just turned the wheel exactly two turns and got a hair more than 3 turns of the pinion yoke exactly

this would HAVE to be 3.23 right?
or am i just wasting my time still ?

was there a factory 3.23 drum 10 bolt 7.5" in 1982?

or was it only a disc rear thing ?
please straighten me out on this one.

normally i dont need it.. but in this case i DO

i would just pull the damn cover but i am not ready still to change out fluid in the rear and all that i am going to wait til i get exhaust on it and some other little things and then drive to the shop and put it on the lift so i can clean up and paint/seal underneath, and replace any bushings/brakes, etc that need it.. in which will be very minimal and really will just be brake rotors calipers and pads and hoses

thanks!!

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big gear head · 09-26-2009, 11:55 AM

Just past 3 turns should be a 3.08.

AlkyIROC · 09-26-2009, 02:06 PM

The 82 TransAm with an LG4 only had one gear ratio option. Both the M4 and A3 transmissions got a 2.73 gear ratio. There were other ratio options available that year including the 3.08 but for different model and engines packages.

Assuming the diff oil has never been changed, now would be a good time to replace the oil. While you're at it with the cover off, you can count the teeth to confirm the gear ratio.

Atilla the Fun · 09-28-2009, 05:25 PM

my info agrees that the 2.73s were standard, but 3.23s were an option. To determine, just check your rpm against your mph. gear times 336 times mph divided by dia. equals rpm. like 2.73 times 336 (=918.4) times 65(=59696) divided by 26 (like a 215/65R15) is 2296, or 2300 rpm. With a 3.23:1, this would be 2714, or 2700 rpm.

Randy82WS7 · 10-06-2009, 01:43 PM

hmm well its not legally driveable yet since there is only open manifolds so i cant go do that

its bene killing me for 9 years now not knowing what is in the thing and normall amny other vehicle i can figure it out pretty quickly but not on this oen for some reason hmm

but then 3.23 isnt too great either

i also tried to get the stamping code off the axle tube but can only read one of the letters... so thats fail also..

so i guess its not a big deal regardless

either way its still got a crappy axle under it. so..

hmm..

since 3.08 wasnt even an option in these 82's its not gonna be that..
and i got over 3 turns of the yoke

so its gotta be 3.23 then..

i wish they would have RPO stickered these things in 82..

they RPO stickered the trucks since 1967

but couldnt do it on the cars til 84

dumb..

i dont understand why..

i bet a million dollars that 84 Z with 305 and 700r4 my buddy is junking has a 3.73 under it.. as most this year and model and drivetrain did... in which i have owned several of and were dirt common..

too bad i cant get that rear...

hmm..

thanks