Speedometer gears
 

ok so im sick of my speedo being wrong and putting a shit ton of extra miles on the car that im not actually driving so heres the deal .....when i bought the car the speedometer was not working properly so as part of the purchasing deal the previous owner was to fix it he said that he had already orderd the parts anyways...anyways some how the wrong drive gear got installed...i have the factory one that is 15 teeth and the one that is in the car has 17 teeth..the driven gear has 38 teeth but according to the research i have done mine should have 41 teeth on the driven gear but on the site i was ordering the gears from have two seperate housings one for gears with under 39 teeth and one for over 40...now i beleive that it is the original housing but im not 100% sure on that

so does anyone have any experience with this that can figure out exatly what i need?

700R4 trans
3.23 rear
245/50R16 tire which i think is a 24 inch tire? 25 inch??? idk for sure
speedometer revs per mile i think may be 1000? but have also read that it could be 2000???

so yea i have no clue what i really need..if i have to i can take apart my dads car and see what he has cuz it is identical to mine but he would be bull shit at me for messing with his car lol

anyone???? lol

Pretty sure theres diffrent gears for diffrent setups. I have the one out of my trans that was a 3.73 car if you want it.

first off let me give you this site
http://www.transmissioncenter.net/sp...n_______va.htm
then use this calculator for the gears youll need.
http://www.wallaceracing.com/speedo-calculator.php

yea i have been on the first one before thats where i found all the gears and such
but not the second one...the calculator gave me a tire size of 25.65 inches which would make my current driven gear correct...but the tire only measures 24.5 inches? why is that?

depends how your measuring it?

well i read that you can get two different sizes depending how you measure it...if i measure from the outside edge of tire to center and multiply by 2 i get 24inches but if i measure the entire thing i get 24.5 inches....

wrong and wrong. draw a line on your tire and another inline with it on the driveway. i use sidewalk chaulk. drive the car forward one full tire revolution. and draw another line were the mark on the tire meets the driveway. then measure between the 2 of them. you have your Correct diameter.

here is another one
http://www.bgsoflex.com/speedo1.html
remember to measure tire diameter with weight of car on the ground!
or else your speedo will still be off a bit.
what tires do you have on it (brand and part numbers)
also look here
http://www.buicks.net/shop/reference/tires.html

isnt that going to give me the perimeter??? ill go try it im about to pull the car out anyways

PIZZA thats tire circumference not diameter lol.
dont day gots scools in massachewsets?

ok if ya cant figure it out gimme the tire diameter (from top of tire to the ground)
then your rear ratio.
ill tell ya what drive and driven gear set youll need.
btw thats an odd rear ratio?

drive gear is 7
driven is 17.8
round off to 18
youll be off by about 1or 2 mph at 100

sorry i forgot the divide by Pi!! DOUCHE!!!!


A real accurate way to determine your tire diameter is to draw a line on the bottom of your tire, then draw a line on the ground which lines up with the line you just drew on your tire. Then move the car until the car makes one full rotation of the tire and mark the ground where the line on the tire is at the bottom again. Now measure the length between the two lines and divide by pi (3.14) and you'll have your tire diameter to use on the calculator (don't forget to use inches). This is the preffered method to use in determining your actual tire diameter.

ok so pizza with pi i get 24.8 inches which is very close to what i get when i measure it..

DAWG thanks for figuring that out for me that is close to what i came up with as long as those gears would be the equivilent as getting 15 and 38? that is close to a 2.5 ratio....eh i guess not really but the factory drive gear is 15 so thats what i would like to run
and the 3.23 idk if they are un-common i know thirdgen.org doesnt have the code listed but both my car and my dads have them

3.23 is very common for your year car and your motor/tranny setup. only the V6's got higher gears without special option packages.

what size tire are you running? did you double triple check the air pressure before measuring. 10 pounds can take almost a half inch off of the tires hieght with a 50 aspect ratio tire.

um i checked them at the begining of the season like two months ago i will check it again and re-try it