I have a 85 gsl with a s4 13b na engine with s4 trans. that i just put the kia 4.78 gears in. Can anyone tell me the math to figure out my speedometer inaccuracies. Remember i also have the 4.1 rear speedometer gear in the s4 transmission. Im horrible at math if anyone can help i would appreciate it.

 

long story short. your speedo will read a little bit faster than you are actually going....which can only be a good thing with regards to the police.

The faster you travel, the bigger the gap between your indicated speed and the actual speed....so around town it will be fairly accurate, on the highways-not so much.

Cam...

 

4.78/3.91=1.22 That means to drive 60 mph actual, the speedo should read 73. To read the speedo and gauge actual mph, multiply speedo by 0.82. This does not factor in any tire differences.

 

tires are stock untill i obtain more funds. thank you very much. thats exactly what i wanted.

 

How did the new gears feel vs stock???

 

You might find this link handy, also:

http://www.catherineandken.co.uk/sti/tyres.html

 

Get on the freeway, and watch for a mile marker. As you pass the mile marker, set the trip odometer to zero. Go at least 10 miles (the farther you go, the more accurate this will be) while watching the markers, and when you hit the ten mile marker then check your odometer. Compare your miles (on the odo) to the actual ten miles you traveled, and you'll have your actual speedo inaccuracy.

Math is great when you have all of the data you need to figure it out, and all that data is accurate. But sometimes seeing the actual real world results is best and/or easiest.



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