how do u adjust the speedometer ?

[wrong generation]

im going from 215/65/15s in the rear to 275/60/15s in the rear and i figure my speedometer is gona be off atleast 5mph i was wondering what do i have to do in my 86 ta to correct this once i get the new tires ?

[NJSPEEDER]

that would be a mechaincal speedo. the only way to adjust it really is to get new drive gears for the transmission. a local tranny shop may be able to give you info on exactly which gears you are going to need

later
tim

[JerzLT1]

wouldnt it be easier to convert to electric?

[9secfirebird]

no

[HardcoreZ28]

Go onto TGO and ask. Someone should be able to give you the correct color gears you need. I believe they are only like $12 or so from the dealer. Changing them is easy as well. You have to remove the driveshaft and trans tailshaft and then the drive gear is held in the side of the trans with one bolt.

[Fasterthanyou]

It's not THAT easy. For some stupid reason GM decided to use really long bolts to hold the torque arm bushing bracket to the trans tailshaft... lots of pushing pulling and hanging to get enough room to remove the bolts. Then it's easy :) .
http://www.transmissioncenter.net/speedometer_calibration_______va.htm