Is your speedometer off?

[VXorado]

That's great to know an option exists to match the speedo, I figured it wasn't available for Isuzu.

My speedo was 12% off for years and even though I got used to it, I always wanted it to match at highway speeds. Last year, I adjusted the speedo by adjusting the span manually on the gauge. I was able to adjust the speedo to be perfect at 65 MPH, but it would start deviating accuracy from that speed.

The speed accuracy looked similar to this:
75 MPH =77 MPH
65 MPH = 65 MPH
55 MPH = 56 MPH
45 MPH = 47 MPH
35 MPH = 38-39 MPH
0 MPH = 7 MPH

Before adjustment:
55 MPH = 61 MPH
65 MPH = 72 MPH
75 MPH = 83 MPH

Overall it was an improvement but there's still some error. Essentially, I just put most of the error at the low speeds.

Only problem with adjusting the speedo (either way), is that any tire size or gear change will throw the speedo off again... and some of us can't make up ours minds regarding tire/gear choices.

[raider]

I would like the information. Thanks!

[ohiovx]

He built this box for my exact percentage it was off. So I'm sure you can get the correct gears to put in the box if you change tires again. He just had me go 40 on the gps & give him the indicated speed on the speedo, then the same at 50, & 60. Mine came out to a 1.25 increase. They offer other ratios that are more common for a little less money, but since mine wasn't a stocking item it cost a little more to build custom.
I'm very happy!!!

[ohiovx]

http://www.transmissioncenter.net/sp...n_______va.htm

about 1/4 of the way down the page it says GM/Dodge/Ford adapter.

the email contact for the guy that did it is. jim@700raptor.com