Hi im a bit confused with what axle ratio my car has..

Its an 86 Z51 Auto - it`s got the G44 on the rpo code which i think i`ve read is 3.07 - but it does not have the G92 which is listed as performance axle - are these two different things and what code would it be for the 2.59 ratio

Also for my year (with 255-50 16" tyres) what should be the MPH at 2000 RPM in OD (with tcc locked) with 3.07 and 2.59 ratios respectively.

Tnx in advance guys,

Dom

 

Could it be that the performance axle is part of the Z51 package, so GM thought it would be redundant to also note it as G92? Just a guess. As for RPMs at 60 mph in OD, I downloaded the gear.exe program at the link below, plugged in your variables and came up with 1498 rpms for 2.59 gears and 1663 rpms for 3.07s...

http://home.att.net/~jroal/slist.htm

 

G92 designates the "performance ratio" for THAT particular car. It can vary based on year, engine, trans, and in some cases body. Mostly, it is meaningless. G44 IS the ratio, regardless if it happens to be the "G92" for your car or not.

My '84 with a 3.07 gear and the same tire size cruises at 70 mph at 2000 rpms. With 2.59s the rpms would be substantially lower.

RACE ON!!!

 

I was also wondering to know what my gear ratio is, I've checked for the rpo codes but they are missing from my car.

How fast should I be going? and should it be in D or OD when I take note of the RPM ?

 

In 86, with Z51, you have the 3.07 standard like I do. All 86 Z51s got this as standard.

70mph in OD, you should be running 2000rpm.

 

GM1 = 2.59
G44 = 3.07

 

Any speed you want and any gear you want. Then just do the math. OR, you could jack the car up and count the drive shaft revolutions for one turn of the (both) rear wheels. Haven't we been through this before?

RACE ON!!!

 

Thanks to u all for the info - it all makes sense now

One last thing though - is the speedo pretty accurate on these - it just feels as if i am goin so slow compared to the speed it shows.

There again, my last car was a fiero - I guess 60 MPH in a fiero feels a bit faster than 60 MPH in a vette - I`ll have to get someone to tail me and check my speed.

Cya,

Dom