Speedometer off 5 mph

Does anyone know if there is a way to adjust your speedometer? Mine is about 5 mph fast. I have big tires and an aftermarket gear ratio installed.

 

Don’t think anything can be done to adjust the speedometer directly since this would “manipulate” the odometer

 

I believe you can can use some sort of scan tool to adjust this... hyper gauge or ultra gauge something along those lines. Not 100% sure though.

EDIT: http://www.hypertech-inc.com/default.aspx

These guys appear to have something if you enter your truck info and scroll down to speedo calibration tool

 

About average. Even on the third gen...five Mph give or take. Easiest way would probably be changing tire size

 

Dealership can do it,BUT they wont.

 

Techstream?

 

Dakota Digital is what I used. I bought it 10 years ago, so not sure if they are still around. You can also just get a Scangauge and calibrate it, or use the speed indicated on a GPS navigator.

 

Amazon

 

Dang that thing looks complicated. Why won't someone make a rear wheel speed sensor to re-calibrate for tire size, shouldn't matter gear ratio.

 

Not worth it. Around 3 mph is as accurate as they can get them anyway even with factory tires. Wait a year, it'll be closer to accurate.

Still won't matter, your tire size is changing constantly anyway. If the speedometer is 100% accurate when the truck leaves the factory the tires will be one size smaller by the time you replace them and the speedometer will be showing 3-5 mph faster than you're actually going. Odometer will be off by ~5% as well. If the speedometer is showing you 3-5 mph slower than you're actually going when new, it will probably be accurate when the tires wear down.

It's always been this way, drivers just never noticed until they got a GPS. Changing to a different tire size does complicate things, but as long as you're within one size it isn't enough to matter. If I were going from 30" tires to 35" tires then I might want to change things. But for most people at speeds at speeds of 70-75 mph you might be off by 3-5 mph which isn't hard to compensate for. At slower speeds not enough to matter.

 

This is what I have and once I put it in and speed matched to gps it’s exactly on point....

 

The hyper tech piggyback is stupid easy to install. All you need to do is plug it into your computer, select tire size and gear ratio, unplug it and take your dash apart, maybe 10 min to do so, plug it into your current speedo and hook the speedo wires into the hyper tech piggyback unit, shove it into the dash and put the dash back together and boom donezo..

 

Can it be reprogrammed, say after a gear swap or tire diameter change?

 

If you do decide to go with the Hypertech, do yourself a solid and get a 6ft USB data cable and plug it into the unit when its behind your dash then secure the loose cable somewhere under the dash. That way, you don't have to take the dash apart to make any changes down the road if you decide to go with a different tire/gear setup. It's not like its difficult to take the dash apart like others have said but every time you take it apart you run the risk of breaking the snap clips that hold the dash surround (ask me how I know ).

Yes, you are not committed to just one program. When I used it, the GUI was fairly simple. Prior to installing it in your vehicle, you hook the black box up to your computer via USB and there's a drop down that will allow you to choose year, make, model. Then you input the stock tire/gear ratio via drop down/text entry and the new tire/gear ratio much the same. Hit save/update and disconnect, then install it in your vehicle.

-J

 

I know my speedo is off but here is my theory.. In VA you can get out a speeding ticket with defective equipment ticket (no points).

 

What kind of hassle is it though? Fix-it ticket, or a ride-along for proof. I can see you getting away with a '9 you're fine, 10 you're mine', but doing 25 over? Thats asking for a bit much. With the Hypertech, at 75 mph, my speedo is off by 5 mph. Everything below that is negligible, that's the margin of error for tire wear/tread diameter.

-J

 

Come on is it really that hard? I know my speedometer is off by 5 mph it has been since the bigger tires went on, so when the speed-o is at 50 mph I know I'm doing 55. Is it really that hard to figure out while driving? I've been dealing with this for years and never had an issue.

 

Not all towns in hold to the 9 your fine rule.. After getting a ticket, find a company that does speedo recalibration ($100), present the results to the court and the ticket will be reduced due to equipment..
Be careful in VA there are alot of small towns that have speed traps to fund the town. For example google Emporia VA.. Speed trap capital.lol

 

I've found Brunswick county (next county west along 58) to be far worse than Emporia when it comes to speed traps.

 

Not really, especially since you drive it all the time. You'd get to a point where it becomes second nature to you as the daily driver, now lets say you forget to tell someone you lend the vehicle to that the speedo is off and they get blasted doing 20 over. It's one of those piece of mind things. Second, I personally wouldn't want to be doing fuzzy math while driving especially when driving through those speed trap zones @cjsqueeky brought up, I'd rather be focused on driving and know that when I quickly glance down at the speedo that it's about dead on the money. That's just me though.

These are the reason that I'd like my speedo to be as close to dead on as possible. IIRC radar guns have a margin of error and I believe 'most' LEO would be lenient because of tire wear and the +/- margin which is why they are lenient about doing 5 mph over. True that some LEO follow the 9/10, not all do and you run the risk of a ticket.

-J