I have a 1989 Camaro RS with a 3.23 Limited Slip rear end, i just swapped over to a 145 speedometer gauge (85 before), stock 15" rs wheels, don't know the tire size, 700r4 tranny, don't know if theres anything else I should add. But i'm looking for my speedometer to read accurate and from what i know of theres 2 things that need to be changed, 1) tranny speedo gears which the teeth of the gear turns the cable 2) vss? the yellow box that is screwed to the back of the gauge cluster, it has 3 or 4 resistors which each decode to the tires, rear end, wheels.. IIRC

What I'm asking is if anyone knows of how to tune a speedo to rear everything properly? Wish this was all computerized, just go and get it tuned, lol.. IF no one can help I'm deciding on going to a GM dealer and let them do it... -shivers- but I'll get the details so i could at least post something and hopefully get it stickied for future reference for others.

 

An 89 would have a cable-driven speedo (the VSS on your car is the yellow box on the rear of the cluster). If the car is stock--rear, trans, tire size--the speedo should read correctly as is. Check the following link for possibilities:

https://www.thirdgen.org/forums/inte...eedo-woes.html

EDIT: If you've swapped rears, as it appears you may have, you'll need to swap the drive and/or driven gears in the trans.

JamesC

 

I've swapped speedo & rear end, plus i have different tire size than stock.

went from a 85mph speedo to 145, and the rear end was a 2.73 open diff to a 3.23 limited slip

 

Only the rear and tires will make a difference in the speedo reading. A call to the following site will no doubt get you the correct trans gearing:

http://www.transmissioncenter.net/sp...n_______va.htm

JamesC

 

I don't have to mess with the resistors in the vss?
so a:
blue 7 tooth drive gear w/ a 18 tooth (p/n 3987918) Brown drive gear?

 

No.

The gears you mention are for a T-5; the autos are different.

JamesC

 

what do i use for auto then? i'm running a 700r4

 

As I suggested (and forgot to paste in), call the site above. People there should able to provide the proper gear(s) for your OE application and/or tire size.

EDIT: I found the following on PATC:

With 18 Tooth Drive Gear
Axle Ratio Tire Height Driven Gear Teeth
3.23 26 45
3.23 26 1/2 44
3.23 27 43
3.23 28 42

JamesC

 

Thank you!!