I hate when this happens.

[BuiltPoly318]

I bought a speedometer gear and housing for my car and put them in the trans. I was sure it was green, either 31 or 34 teeth. My speedometer is off a little, when the speedometer reads 31 I'm doing about 35.

So I went and bought a 30 tooth gear and when I took the other one out it was also a 30 tooth gear (both are yellow). Dammit!


According to the charts, some say 29/30, others say 31 based on my input. Since it's not accurate with a 30 tooth I don't know which direction to go... up one tooth or down?

I'm a 3.23 rear and a 275/60R15 tire... also, does anyone want to trade a 30 tooth for a __________ (whichever one I will need)? Or have one to sell me?

Thanks...

 

[1badstroker]

It looks like a green gea Overall Tire Diameter

Axle Ratio
24" 26" 28" 30"
2.76 2538930(Yellow) 2538928(White) 2538926(Red) 2538924(White)
2.94 2538932(Black) 2538930(Yellow) 2538928(White) 2538926(Red)
3.21 2538935(Orange) 2538933(Yellow) 2838931(Green) 2838929(Black)
3.55 2538939(Green) 2538936(Red) 2538933(Yellow) 2538931(Green)
3.91 2538943(Blue) 2538940(Orange) 2538937(White) 2538935(Orange)
4.10 2538945(Yellow) 2538942(White) 2538939(Green) 2538936(Red)
4.30 2538944(Black) 2538941(Red) 2538938(Blue)
4.56 2538945(Yellow) 2538943(Blue) 2538940(Orange)
r is closer to your gear and tire size.

 

[BuiltPoly318]

Thanks, I've seen a lot of charts, and a lot of formulas, but none of them tell me whether I need to go up or down a tooth if I'm reading incorrectly.

One chart says 29/30, another says 31. I'm at 30 now, since I have two answers depending on the various charts I'm trying to find out which direction is correct. I don't want to buy a 31 tooth and then find out that I should have gotten a 29. My tire size is in between what's on the charts, too.

Besides... those charts drive me crazy. Does Mopar have a 3.21 Gear Ratio? I'm pretty sure mine is 3.23, but none of the charts have that!

 

[brandon64]

well if you think about it mathematically. less teeth would speed the speedo up and more teeth would slow it down. so if your speedo reads slow then get the 29 tooth.

 

[BuiltPoly318]

lol... I tried doing the math but got discombobulated and brain farted.

I found one chart where you enter your gear ratio and tire size... it comes up with 31 teeth, and I think that's where I got confused about it.

thanks..

 

[msbaugh]

Hey i know this is an older post but I'm looking for a speedo gear housing. Do yall know where I can get one? I have the right gear, I just need the housing