im doing a 2.73 to 3.42 gear swap in my camaro and i had a question. I know a mechanical speedo uses drive and driven gears but does the VSS also use them? If thats true, i already know the part #'s for the drive/driven combo i need. Are the gears how the VSS gets its reading?

 

yes

 

Does your transmission have the RPO code MD8?

 

yes, both of my cars do... Im taking the 3.42 rear out of the berlinetta... could i use the speedo gears from it?

 

I'm sure I will get some feed back on this. But yes I don't see why you can't use the speedo gear & VSS from the berlinetta in your 91 RS. The reason I asked about the RPO codes is because the information that I have on the MD8 transmission using the 3.42 rear-end is that the tires used are smaller than what is on your 91RS. Here are the tires that are listed for use.

P195/75R14

P205/70R14

P215/65R15

Also remember that you have a VSS buffer box in your car, whether this will have any bearing on it I don't know.

 

yeah, mine had the smaller 14's on it... why would i have to use the VSS from the berlinetta in the RS? I thought just the gears needed changing?

 

When you change to a different ratio rear end, you also have to change the speedo driven gear and the drive gear in the transmission to calibrate the speedometer so that it will accurately display your speed. You wouldn't want to have your speedometer reading 55 and a cop pull you over and say you are doing 75 now would you?i

 

so the VSS gets its reading off of the drive/driven gears? This is my question... i understand PERFECTLY well that changing gears or tire size screws up the speedo reading. My car uses an electronic speedometer and i was under the assumption that it got its reading from the VSS... I am confused as to how drive/driven gears play a role in changing the reading of an electronic sensor... the VSS.