speed sensor adjustment

[scottnj]

Can someone tell me what I need to buy for my 1991 Blazer with auto tranny so I can set the speedometer correctly.
I have 33 inch tires. Will soon have 35 inch tires, which leads to my second question, what size tires can the stock rims hold? thanks
[email protected]

 

[woody9]

Need to do this job myself on my 91 sub (14FF 3:42 to 4:10, plus 15-> 16" tires). Can get individual piece from GM as I understand it or the SPeedometer Calibration Kit. Kit has a few of the plug-in adjustors that plug into speedo as well as a harness to use to zero out the electronics. Kit was < $40 over the counter. Clip the pins according to what gears/tires u run and it's supposed to bring it back to correct. (Service tech happened to be walking by when I got mine, and said, here, let me clip it for you while I'm here.... also warned about the age of the plastic in the dash and how it's prone to crack vs flex (light switch/heater controls/etc)).
Haven't gotten around to doing it. Can get the box & fetch part #s if you'd like.

 

[dyeager535]

Does the kit include how to set the switches pins, whatever, for X size tires with Y gears, or is it something you have to calculate percentage wise or other?

 

[CCRider]

I need those part #'s!!!!! Is it right from GM? The kit that is! My 91' is about 15mph off @ 55 and shifts kind of funny , tried adjusting the TV cable , but still seems to be lacking something!!!! Thanks CC

 

[dammit32]

yes if someones got the part # for that kit i could use that !!!

 

[jc71355]

Me Too /forums/images/icons/grin.gif

 

[woody9]

PN was 25085515 Calibratin Kit, List $44.18, net $29.16... Thought the instruction/which to clip list was in the box.. but I may have put that in the service manual. Will check that later & see what I did with it! (I miss my memory!)
Seems there was a post on this on one of the suburban
boards?
It's gotten to the point I can just do the math in my head on mine.. (reads 20% fast..... have a static radar station on post/15 zone.. * 20 = +3 = 18.. i do 18.. and it shows 15.. doing indicated 80 * 20 = 16 over....80-16 = 65-ish). So far no problems.. or tickets!