3.73 Gears & An Electric Speedo... HELP!!

[Mark B]

Hey guys,
I hate to ask this question, because I am sure its been asked before. But I have been searching the forums for 30 minutes and cant find an answer to my question.

I have a 91 RS 305TBI/700R4. I recently swapped 3.73 gears into it to replace the stock 2.73's. I need to fix my speedo. I have a electric speedo w/ a VSS. The guy at the GM dealer cant help me because now my car isnt stock. (If a computer cant tell them... They give up) Are the speed sensors driven by a gear? If so, do I need to get a new speed sensor, or a new drive gear? Part #'s would be helpful if you have them, but I would love to at least know what I should be looking for.

Thanks,

Mark B

[Benm109]

Yep, you have to change a couple of gears, a gear on the VSS and a gear on the rear of the trans. somewhere. I found a chart somewhere on Thirdgen.org, let me see if I can find it for you.

[azkkn]

when i did mine in my 1994, i needed to change the reluctor ring only in the rear end, the one that presses on with the ring gear on the carrier, and i also got the speedo calibration unit from SLP.

[bru333]

The new issue of Chevy High Performance has an article about swapping out speedo gears. Has charts of speedo gears and axle ratios.