This is kind of a 2 part question. Currently I have a 2.73 open rear end that I want to install am SLP take-off posi diff and 3.42 gears. I know it will work as I know I have 28-spline axles. My questions pertain to how to get the speedo to be calibrated correctly.

I know at some certain year GM switched from cable operated speedos to electronic speedos, and I'm pretty sure my '92 RS has the electronic speedo. If this is the case, can I just swap out the speedo drive gears in the tranny tailshaft or do I need to get that Cyberdyne box? I would think that I would just need to swap out the speedo gears, but maybe I'm not understanding this correctly. So what's the story on this?

Also, if I just need to swap out the speedo gears, does anyone know which ones I'll need and what part numbers they are? I am running with 245/50R16 tires and going from a 2.73 open rear to a posi 3.42 rear. I have an automatic transmission.

Thanks!



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Dana M. Brandt
1992 Camaro RS
25th Anniversary Heritage package

"Shop smart... shop S Mart."

 

I have done the same swap into my 90 RS camaro. In my case it was swapping in a 3.45 9-bolt for my 10-bolt 2.73. Your car and all 90+ Camaros has a Vehicle Speed Sensor (VSS) which will need to be replaced along with the new driven gear. Your existing VSS has a red driven gear. Unfortunately, the 3.42 gears were never available with an automatic. The closest you can get is gears and VSS for a 3.27 gear ratio. The new driven gear you need is gray and has 44 teeth. The new VSS is p/n 10456089. There isn't a closer gear and VSS available for your tranny. You have to replace the VSS because of the new larger diameter driven gear. I have some speedo error, (it reads higher than actual) I suspect about 5 mph @ 65 mph. You don't need the Cyberdine box. It is used if you were putting a newer tranny (such as a T56) into an older car with a mechanically driven speedo. I don't have a solution for correcting the speedo error yet. There may be a way to run it through some sort of buffer to correct the signal, but that is buyond my expertise. My swap is only temporary until I can swap in my WC T5 tranny. Good luck, Lon.

 

For 3.42s, you will need a
15 tooth gray drive gear p/n 8642620
41 tooth yellow driven gear p/n 25513048

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-Justin-
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