Allows for a corect speedometer on both manual & automatic transmission Mustang without the need to purchase an expensive tuner!
Corrects for rear gear & tire size changes
Fits 1994-2010 Mustang
What's in the Box
(1) FRPP Speed-Dial Speedometer Recalibrator
The Ford Racing (FRPP) M-4209ADAPT-AC Speed-Dial Speeometer Adjuster/Recalibrator for 1994-2010 Mustang is used to correct your Mustangs speedometer because of tire size or rear gear ratio changes. No longer is it required to purchase a tuner to get your speedo working again!
This speedometer calibrator scales a frequency based on the vehicle speed signal up or down to maintain accurate vehicle speed indication to the instrument cluster and PCM.
1994-2004 Mustang with manual or automatic transmission
2005-2010 Mustang manual transmission
2005-2010 Mustang automatic, but is limited to equivalent of one step higher or lower gear change ratio (+/- 10% change). For example, if your 05 automatic has 3.31 rear gears stock, you can step up to a 3.55 & keep your speedo correct using this adjuster.
NOTE: To maintain cruise control function on 2005-2010 Mustang automatic and manual transmissions, gear change is limited to equivalent of 5% higher or lower ratio (<+/-5% change). For example, a gear change from 3.55 to 3.73 results in a gear ratio reduction of 4.8% so cruise control will continue to operate normally. A gear ratio change from 3.55 to 4.11 results in a gear ratio reduction of 13.6% so cruise control operation is lost.
Needed a way to recalibrate the speedometer on my 1996 Cobra when changing to 4.10 gears. Looked at other boxes on the market and they already had plugs to intercept the VSS negative wire down by the transmission. I liked the idea of being flexible with the mounting location.
The box came with limited directions that pointed you to Fordracingparts.com website to get the latest and full instructions. After pulling down the full PDF, the install sheet talked about alternate location under the hood, tapping in to the transmission harness. I did just that, easily locating the VSS negative wire and key on power in the transmission harness. Once I soldered the wires together (with heat shrink tubing) and retaped the harness, all I needed to do was find a good ground and the box was installed.
As you can see in the attached picture, I mounted the box to the firewall of the Cobra. Two stainless screws hold the box on and are easy to back out to be able to open the box up and change the settings.
Another reason for purchasing this box is the switch settings represent a % change from stock. There are 3 dial switches, each labeled 0-9. If you have stock tires and stock gears, the box would be set to 1-0-0 an interpretation of 1.00 change (no change in this case) of the gear ratio from stock, since you leave the stock speedometer gears in the transmission.
In my case, I put 4.10 gears in the rear, with stock sized tires and wheels. In my case I simply divided the stock ratio 3.27 by the new ratio 4.10 to get a 0.80 difference in ratios. Plugged 0-8-0 into the box and all is set. If you change wheels/tires and gears, a bit more math is required, but it is still a ratio change from stock that gets plugged into the box.
It has a test circuit that when all the dials are placed at 0-0-0 it will indicate a pre-determined MPH on your speedometer at rest. In the case of my 1996, it would indicate 45 MPH, which means the box is working correctly.
Overall a couple bucks more than other recal boxes, but I highly recommend for the ease of install options and settings.
Thank you for the very thorough review!
Yes, I would recommend this item to a friend!
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Caleb T. on
I bought this part to correct my speedometer and it did exactly that! It was pretty simple to install and not hard to figure out how to adjust it.
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