I need new gears to match my 323 rear and the guy at the gm dealership told me he needed the color of the gears. So if anyone can help me out I would be thankfull for it.
Brad

 

Crap i should have posted this in the tranny/drivetrain board. I must still be hung over, sorry about that.

 

Auto or manual, and what size tires?

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1989 IROC-Z 5.7L
NOS 5151 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

It is an automatic, and the tires are 245/50/16.

 

15T Gray Drive (8642620)
39T Brown Driven (25513046)

------------------
1989 IROC-Z 5.7L
NOS 5151 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

Thanks alot.

 

wouldn't the correct speedo gears for that tire and 3.23's be 17/43?

 

You could use a 15/39, 16/42, or a 17/44.

 

Actually, if it's 91, shouldn't it be a electronic speedo? Which would mean no speedo gears to change, just have to get a calibration box...

 

$15 for a gear, or $300 for a box.....

Hmmmm..... I'm having trouble deciding this.... can I consult my financial adviser?

 

Good point RB83L69. I just didn't know that the gears could be changed on the electronic speedo's. Thanks for the info.

 

What would the gear be if i had 3.42 and a 25.7 inch tire.

 

the 91 is not mechanical so how would you calibrate with a new posi 3.27 rear? calibration box is the only answer?

 

With a differenr gear. Same as you'd use for an old 3.27 posi. The same thing you'd have to do if you put a good stock gear in it, like 3.73s for example.

Something drives the VSS you know. It's a gear. It fits on the shaft that sticks out the end of the VSS.

The Speedometer Magic Universal Constant is 1000 rotations of the cable (or VSS) per mile. Work it out for your tire size and gears. You'll come up with a ratio, somewhere near 1:3; depending on what trans you have, auto or stick, you'll be limited to certain combinations of drive and driven gears. About 7 in a T-5 or 15-19 in a 700 for the drive gear, and about 18-22 in a T-5 and 39-48 in an auto for the driven. Life is easier if you go look at the drive gear you've already got, and figure out how teeth would need to be on the driven gear to work with it, and see if GM makes such a thing. Sometimes you get lucky. Not always, especially if you started out with something really terrible, like even worse than 3.23 or 3.27; but it's worth a look.

 

yea... where are this gears located (sorry for the newbie questions)

 

On the VSS.... at the back of the transmission.