What is my speed? Got 3 readings!

webbug · #1 Mon, February 1st, 2010, 08:41 AM

Okay I have F-150 with aftermarket rims/tires, I need to know my correct speed. I havent done any changes to my gryphon and the speeds I get:

35 on grayphon
40 on the gauge
38 on garmin navi

which one should I use to align the rest with?

***88Racing*** · #2 Mon, February 1st, 2010, 09:31 AM

Use your gps reading then adjust your tire size.
What is your tire size and value you are using?
If you post these up we can help you make sure they are right?

***Jackpine*** · #3 Mon, February 1st, 2010, 11:11 AM

Try to get the Gryphon speed to agree with the GPS. That should still leave your dash speedo reading fast, but that 's just the "nature of the beast". Since the Gryphon reads slow right now, you want to increase your TS. However, I'd try to get them aligned at highway speeds, rather than "in town" speeds. I think the results might be more accurate that way.

- Jack

***Longshot270*** · #4 Mon, February 1st, 2010, 06:26 PM

Here is a way to get your speedometer just about perfect. Use the odometer on the GPS and truck. Also to make sure you're making your changes correctly look at what Jack posted just before me on that thread.
http://forum.gopowerhungry.com/gryph...html#post23835

webbug · #5 Tue, February 2nd, 2010, 09:09 PM

Thanks for the info guys, I'm using 33x12.5x20 Toyo Open Country MT's

I guess I cannot adjust the speed and other config until I choose one of the canned program, right?

I'm still running stock, waiting for my customs.

***Longshot270*** · #6 Tue, February 2nd, 2010, 09:25 PM

Quote:

Originally Posted by webbug

Thanks for the info guys, I'm using 33x12.5x20 Toyo Open Country MT's

I guess I cannot adjust the speed and other config until I choose one of the canned program, right?

I'm still running stock, waiting for my customs.

Yeah, pretty much. When you do decide to try a canned tune, try 2661 as your tire size and use the method I mentioned earlier (using the odometer) to get it even closer. Also, dont forget "load previous settings" no matter what your doing, and check the gear value to make sure that is right. You might also be able to get the dealership to recalibrate the speedometer but I dont know if it would be worth the price or trouble. I know a friend of mine got his truck recalibrated at the dealership(because he wanted to get out of a ticket, if the truck really was off then they would waive the fee).