Doing gears? Don't use DM speedcal, use Ford Racing speed-dial instead

joekd

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If your speedo is off I highly recommend getting the Ford Racing speed-dial speedomter adjuster. My DM speedcal is now in my trash can and here is why.

I recently did 4.10's and of course my speedo as off. I had a DM speedcal which I installed, was a little bit of a pain because you have to repin connectors while lying under the car but did it correctly.

Set the 10 DIP switches as indicated in the install sheet, test drove, speedo still way off. Went to Dallas Mustang website, got a different DIP switch setting, changed, still off.

Called DM, was told to talk to Justin, he gave me another code, still off. Call again, another code, still off. Four more times, still off.

Just to let you know how each was tested I reset my trip odometer, drove EXACTLY 10 miles measured by GPS then wrote down the displayed miles and gave that to Justin. Also I could see with each test my GPS speed compared to my speedo so I knew it was off immediatly.

At this point I was beyond annoyed, went online and bought the Ford Racing speed-dial, as soon as I looked at the instructions I knew it was a better product.

First off no repinning connectors, all you do is splice one wire on the VSS sensor. It does require both a power and ground while the speedcal only needs power, big deal.

Second plus, if you leave all the dials on 0-0-0 (default out of the box setting) as soon as you turn your key on your speedo will go to 45MPH and hold there showing your wiring is correct.

Now for the best part, instead of 10 DIP switches the speed-dial has three rotary switches, you simply dial in the ratio you want. In my case it was 3.27(old)/4.10(new)=.797, they say to round so I went to .80 and set dials at 0-8-0, drove and almost perfect, changed dial to 0-7-9, right on the money. No calling for mystery DIP settings, just simple adjustment and done.

So for right about $130 I highly recommend you go Ford Racing and dont even consider buying a DM speedcal
 

96GT02

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why didnt you just buy a 23 tooth speedo gear? I got one for $10s and my speedo is perfect for 4.10s lol.
 
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joekd

joekd

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I highly doubt your speedo is correct, if you notice the same 23T is recommended for 3.73-4.10 applications which are obviously a lot different ratios

Also with this unit I can make changes "on the fly" if I decide to change tire size and such
 

JerZeyStangz

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Wish I knew this 4yrs ago. I have DM, its not spot-on but its not off either. Maybe I'll upgrade down the road.
 
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joekd

joekd

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Honestly, if it was close I would of said good enough, the closest I could get with the DM using all the settings they gave was 10 actual miles = 8.3 speedo which meant that at 55MPH i would read ~46MPH
 

Twista

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Nice, i have the correct gear for my 3.73's but its still off 5mph most of the time.
 

Ferocious

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Thanks for the info. I'll make sure to go with the FRPP speedcal when i do my gears in a couple of months.
 
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joekd

joekd

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That's weird.. My DM speed cal was dead on after getting for trans swap.

Could be the year of your car and tranny type also, lot of little factors could affect it

For all I know the DM speedcal could of eventually been right, I was just sick of going back and forth calling for new codes, trying them, call for new code, etc so once I saw the Ford piece let you enter the exact ratio you wanted I bought it and uninstalled the speedcal immediatly
 

LilRoush

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I had to use the DM Speedcal II on mine. It's the only thing on the market for getting the speedo to work using a T56. Did the 10 mile drive and called in. Spot on the first time with my tire size and 3.55s. The instructions on the DM site are for the Speedcal I and there are NO instructions out there for the II (not even in the box when you buy it)... you have to drive 10 and call Justin.
 

Venom351R

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There is no correct speedo gear for 4.10's so if you go higher then 3.73 a speed cal is pretty much your only option if you want your MPH and mileage to be correct. I still need to get one for mine.
 
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joekd

joekd

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I had to use the DM Speedcal II on mine. It's the only thing on the market for getting the speedo to work using a T56. Did the 10 mile drive and called in. Spot on the first time with my tire size and 3.55s. The instructions on the DM site are for the Speedcal I and there are NO instructions out there for the II (not even in the box when you buy it)... you have to drive 10 and call Justin.

Yep which is exactly what I did, like I said after calling Justin multiple times for new DIP settings I just gave up and went with the speed-dial. Why keep calling him when I can just make minute adjustments myself?
 

LilRoush

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Good to know it happend. I guess it's odd. I have never heard of an issue with the 10 and call he does. Wonder what happend that it wasn't working out.
 

ProKiller

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i don't like these speed cals. they don't work more often then they do work. and it's not just the DM. i can't tell you how many ford racing ones i've had to deal with that didn't work. its a bandaid, not a fix.

speedo gears are the way to go. our manual trans have an 8 tooth drive gear. since there is no listing for 4.10s w/ 8T, you switch out the drive gear to a 7tooth and then get 23T gear. that simple.

Speedometer Chart
Axle Ratio 6 Tooth Drive Gear 7 Tooth Drive Gear8 Tooth Drive Gear
2.73-1618
3.08-1820
3.27161921
3.55172023
3.731821-
4.102023-
4.3021--
4.5623--



Transmission16T17T18T19T20T21T
ManualWineWhiteYellowPinkBlackRed
AutomaticBlueGreenGrayTanOrangePurple
 

twovalveterror

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so since my gt came with 3.27's I already have the 21 tooth gear and all I would need is the 7 tooth drive gear for my 3.73's? thank you, this is very helpful!

I assume this is all with stock height tires though, correct?
 

ProKiller

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yes. this doesn't factor in tire size, that is the one draw back of this route. but if you look at the difference in tire sizes and how they effect the speed, its pretty moot. although this is from a miata forum, its one of the better online ones out there.
http://www.miata.net/garage/tirecalc.html

for example, i think stock 16s were 245/55s and if you went up to 305/35-18s you're only going .8% faster. which is pretty much 1/2 a mph.
 

96GT02

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Is the 8 tooth drive gear in the actual tranny? how do you go about changing that one? difficult?
 

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