Pure5.0

Why are you guys going back and forth? Everybody know that there is more than one way to get a math problem. Both ways are correct as long as you know how to apply your math. If you don't then good luck in the real world.

.79756 is 21% off from 1 which means that it is the same thing we said. ~25%. You can never give exact numbers because maybe his speedo is not calibrated properly from the factory...it is analog...it does happen. Also his tire size will make a difference too.

So either way you take in math it is both right.

Vader look at the post in the very top of this forum....labeled at "TOP". There is one about the speedo gear you will need to fix your problem

Vader

Vader look at the post in the very top of this forum....labeled at "TOP". There is one about the speedo gear you will need to fix your problem



Got it, Thanks guys for everything.

90GTRagtop

Always think about it like this. The gear ratio for a diffential is defined as the number of revolutions required by the drive shaft for 1 revolution of the wheel. That's why you'll often see them referred to as 4.1:1 3.27:, 3.73:1 etc. So the taller your gear (bigger the number) the more your torque is multiplied and the slower the wheel turns for a given drive shaft speed (that's how gears multiply the torque, it's like a lever but with revolutions instead of linear). So you would divide 3.27 by 4.10 to get the fraction to multiply the speedo by. Oh, and as a by the way, you calculate the gear ratio of a differential by dividing the number of teeth on the ring gear (driven gear) by the number of teeth on the pinion gear (Drive gear). And yes for ball parking the numbers 25% is in the neighborhood, 20% is closer, and 20.244% is nearly spot on.

Where the exact numbers will really help is in selecting the right speedo gear. Remember that you need to make your speedometer cable read slower with the taller gearset and the speedo gear is a driven gear, so it will need to get bigger to slow down. So if you count the number of teeth on your current speedo gear divide by 3.27 and multiply by 4.10 you'll get the number of teeth you need for the new speedo gear. However, just like I said earlier, this is all based on the assumption that the speedo was right with the 3.27 rear end. If it wasn't right to start with, it will still be off by the same amount in the same direction after following this procedure.

95_302_StangMan

i agree even if you figure it out you wont know for sure but anyways it's a good excuse "Sorry officer but my speedometer just started acting up and couldent tell how fast i was going" which he will probley reply "O understand compleatly, After all it was only 60 over" lol

Magiarn71

It certainly is NOT. With that same application of math that is both "right" using a 2.73 and a 5.33, you'll get 1.95, so drop the 1 and it's 95% of what your speed reads? No way. Its 1.95 X your speed at 5.33 to get your 2.73. You divide the other way and get .51 which is what you multiply to go from 2.73 to 5.33. It was chance that they were within 5%, you CANT do it that way.

Pure5.0

Guess you didn't read my thread correctly. Let me clear it up for you. When you do math you have to know which way you are taking and what answer you want. 1.95 is a correct number. Multiply 2.73 by 1.95 or 195% more and you will get 5.33 but if you didn't know which way to take the math in the first place you won't end up with a correct answer. Because you upgraded from 2.73 to 5.33 you will have to take it the other way.

Example you increase 1 to 2 that is a increase by 2. When you go from 2 to 1 that is a 1/2 increase. So in thinking this just take 1.95 and place a 1 over it because you want to get the number that way.

5.33 * (1/1.95) = 2.73

1/1.95 is .51 or 51%.....same number you came up with. See BOTH ways are correct...you just have to know how to apply it.

You can do the same with your speed

MPH * (1/1.95) = New MPH

If you can't seem to figure out the math by going both ways then your knowledge of math is one sided. So why argue?

Magiarn71

Dude, the guy said 25%, not 125%, and you said it was right. It's not. Whether you saw it or not, I dont know, if not, you didnt get all the info and don't deserve to be discredited, my bad. There IS a way to work backwards on everything, you're absolutely correct. He was doing it the WRONG way and getting that "incorrect answer" and you basically said that it was just as right as using the other method. I'm not trying to step on nutz, I just don't want people to think that they can figure out their own individual situations that way, because they won't be anywhere near right.

Pure5.0

Good point towards other people seeing it wrong. We both stand corrected.....

settled4automatic

ok, there were like 10 posts saying the same thing there. i can't believe i read even MOST of that lol. thanks guys!!