Hey guys,

A customer of mine has a 2004 F-150 with a 6" lift and bigger tires. Hes also changed his gearing. He says his speedometer is off by almost half, and asked me what I recommend he do to fix it. I suggested he get a tuner (like a predator) to adjust for the gearing and tires, which I'm pretty sure should correct it. He was also inquiring about the long-term effects this has had on his truck, and if there is a way to correct the miles already accumulated? Will it show up anywhere (by scanning, etc..) that the truck actually has more miles than it shows? Is there a way we can find out the actual mileage since we dont actually know? He wants to keep everything honest and legit in-case he ever sells the truck, by telling them actual mileage. I have no idea about this stuff so I'm asking you guys. Any suggestions?

Thanks!

 

I recommend getting the tuner. It will help him out a lot with performance and adjusting not only the speedometer but the gears too. Im not sure there is anything you can do about the mileage. Just get the tuner as quick as possible. I recommend the Edge Evolution. I have it and it is AWSOME!! I also have a lifted truck 6" with 35s and it is the best money I have ever spent for my truck, except the lift.

 

Yes the computer would correct his problem.

As far as finding out the right mileage I dont know how there would be a way to find out.

 

Personally I wouldn't worry about the extra mileage. What size tires stock and what stock gear ratio? He went to 35's with what gear?

I bet the speedo wasn't/isn't off more than 10%



For instance if I took my stock FX4 with 275/65/18 and 3.73 gears and changed to 35's and 4.10 gears it would be only be slow by 1 mph.

 

You can reprogram the cluster by taking it in to a local dealership from what I understand. You might have to fabricate a story as to the reason, I'm sure they won't do it for the reasons you stated. For instance, I am doing a cluster swap and want my original miles on the new cluster. Not sure if it would fly because usually they have to match the PCM code but it's already correct because you're not actually swapping it out. I don't believe they check your old mileage. If that doesn't work, you can sleep with the service rep.