As some of you know i got a used white faced cluster to replace my black faced one. ONly problem is, the mileage was wrong on the new one, so i ended up swapping parts which involved removing the speedo needle and screwing up the reading. Well an idea came to me today while driving, right now it reads 10mph to slow, so i figure if i have it tore apart enough to get the needle off while driving slowly at lets say 20mph(using gps) i can pull the needle off and then put it on facing 20mph therfor making it right. I also figured this would work for people like me with bigger tires or different gearing! best part its free! I will let y'all know if my idea works, but it should...?

 

Bigger tires introduce a percentage of error. So, the faster you go, the wronger it will be.

On the older trucks, you can change the speedometer driven gear to account for a tire size change, and then do your needle dance to get it accurate at ALL speeds.

 

So I adjusted my speedometer in the way i posted and it worked perfect! I also snapped a pic of the cluster

 

The odometer is not going to be accurate.

 

Why wont it? Its the original one from my old cluster?

 

If the speedo does not read correctly without doing your mod, how do you think the odometer is going to without any kind of mod?

 

What size tires do you have on your truck?

 

I have 33-1250-15s on my truck with 3.92 gears. The speedo was only off because i messed up putting the needle on when i swapped odo's. So i readjusted it to be correct. Originally it was off about 5mph for the tires and now thats corrected, so the odo shouldn't be to far off?

 

The speedo and the odo get readings from the same source. Moving the needle might fix the speedo, but the odmeter is not going to be effected and will still be wrong.

 

Assuming your stock tires were 245/75R16's, and the 3.92s are also stock, you have an induced speedometer error (and, odometer as well) of about 7.8 percent. So, when your speedometer reads 65mph, you are actually doing about 70. If you swapped out the gears, from the 3.55s, the error is going to be even larger.