When I changed from 2.73 to 3.42...I also changed my speedo gears with the 15/41 gears......what would cause my speedo to be off by about 5miles....its ok down low from 0 to about 55-60...but gets off once I go higher....


whats wrong? what do I need to do to fix it?

 

3rd gen speedos get progressively less accurate as speeds increase. 5mph off seems normal past 60 or 70.

 

well damn!..thats not cool...thats gonna get me pulled one of these days!....LOL

So there no way to fix it?

 

Not really. I have stock gears and merely went to a taller tire and my speedo is off by 6mph or so. Jut do some math to figure out what rpm's you need to run to stay at common speed limits. However, take that with a grain of salt since our tachs are also off.

 

speedo off by a percent = ratio error. (ie dead on at 5mph, lil off at 35, off at 60, way off at 120)

speedo always off by a given number = needle is out of position on gauge (ie 0mph shows 5, 35 shows 40, 60 shows 65)

 

5 MPH is nill, police give you 5 over 90% of the time unless they have to make quota for the day. If you want to fix the problem I'd suggest getting a driven gear with 1 less tooth, that will give you a happy medium of not too fast and not too slow.

 

did I not get the correct gears to begin with? I got the 41 driven and the 15 drive.


Should I have gotten the 40 driven and the 15 drive?

 

bowtieoverdrives.com calculates that I should have a 17/45 set.

How can I have gotten off that bad. I went by what I have read on some of the threads about speedo gears when changing from one ratio to another.