What color speedometer gear for 4.10 gears and 32’s?

[bosshoff]

I have 32.0” tires and 4.10 gears. What color speedometer gear do I need to correct the speed displayed on my gauge?

 

[Timmy390]

I'm 98% sure I run the "black" and it's dead on per the little radar signs with my 33's.

Tim

 

[Broncobowsher]

Depends on how many teeth are on the driving gear on the output shaft.
Viperwolf has a really nice spreadsheet that has been posted over and over again on this site. Just follow that.

 

[Viperwolf1]

Best practice is to measure actual speed with gps and compare it to indicated speed on the speedo. Get a % of error and use that and the current gear to determine which direction and how far you need to go. A one tooth change is about 5%.

You have either a 6 or 7 tooth drive gear and it's difficult to determine which.

 

[gr8scott]

Here's a really good GPS speedometer app for Android.

DigiHUD Speedometer - Apps on Google Play

GPS digital speedometer with head-up display (HUD) for phone or tablet.

play.google.com

 

[bosshoff]

Depends on how many teeth are on the driving gear on the output shaft.? How do I determine this? Driving gear on output shaft? This is not something I understand.
FYI, I pulled the speedo gear from the cable, and the gold/yellow plastic gear has 17 individual teeth. What/where do I need to be looking at to determine how many teeth are on the output shaft?

 

[Broncobowsher]

One way is to know the error you had with the 17 tooth gear. What % error. Calculate off of that.
Or count the teeth on the gear in the transfer case. It can be done through the speedometer cable hole. Little neck twisting with a small light or maybe an inspection camera. Mark a tooth with a sharpie, spin the output shaft (guess you need a jack and jackstands or unbolt the driveshaft). Spin and count.

 

[Viperwolf1]

Some of the speedo drive gears are colored plastic. If you can get a good picture of yours I can tell you if it's 6 or 7 tooth. If it's a steel gear it can be either one.

 

[bosshoff]

Tom’s offroad has this chart. Used it as a guide, and bought an 18 tooth gear. Might not be 100% accurate. I will give the 18 a try and report back.

 

[DirtDonk]

Are your tires “32’s” or they actually measured at 32 inches?
And instead of measuring top to bottom, it’s more accurate to measure center of hub to bottom. Called rolling radius.
There’s not always a huge amount of compression on tires with the weight of the bronco on them, but that depends on the tire and the air pressure.

 

[FordBronc]

Maybe...

 

[bosshoff]

Ok, the 18 tooth did not work. My glass gauge is still off by 10%. When driving 60 MPH (verified with GPS App), the dash gauge needle was displaying 66 MPH. Should I go with a 19 tooth or 20 tooth?

 

[Viperwolf1]

20 will get you closer.