New gears and 35s... Speedo and Odometer way off!!!! - Ranger-Forums - The Ultimate Ford Ranger Resource


Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

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Old 09-13-2009
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New gears and 35s... Speedo and Odometer way off!!!!

Ok so my speedo and odometer are way off. My truck is a 95 with the 4.0 and i have 4.88s with 35x12.5/15. I'm trying to figure out my MPGs and want to keep track of my oil changes and other maintenance. I looked on TRS and counldnt find a calculator. Maybe a tuner of some sort will correct it? Is there a formula for figuring out my correct MPH and miles?

Thanks!
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Old 09-13-2009
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What is your stock tire size and stock ratio? I can do the math for you to figure out how far off your speedo is.

Mine was 30.5 and 4.10, currently 34.8 and 4.88.....my truck thinks it's going 104% faster than it really is going.
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Old 09-13-2009
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Buy an SCT tuner and it will tune your ride and recalibrate your speedo and a whole lot more.
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Old 09-13-2009
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On a 95 it probably has a mechanical speedo cable, not positive though. If it does have one you need to change the gear on the end of the cable that goes into the transmission tail housing. There is an equation on TRS to help you calculate the proper amount of gear teeth.
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Old 09-13-2009
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Quote:
Originally Posted by Fx4wannabe01 View Post
What is your stock tire size and stock ratio? I can do the math for you to figure out how far off your speedo is.

Mine was 30.5 and 4.10, currently 34.8 and 4.88.....my truck thinks it's going 104% faster than it really is going.
I think the tires are 225/70/14 so that's about 26" and 3.08s
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Old 09-13-2009
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Quote:
Originally Posted by My91Ranger View Post
On a 95 it probably has a mechanical speedo cable, not positive though. If it does have one you need to change the gear on the end of the cable that goes into the transmission tail housing. There is an equation on TRS to help you calculate the proper amount of gear teeth.
Nah, already checked there is no speedo cable.
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Old 09-13-2009
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dangit! Can't find my formulas!
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Old 09-13-2009
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i forget the formula, its been so long since i've used it. its like origional tire diameter/new tire diameter.. then multiply that against the calculation of the fuel mileage? i dont remember.

Quote:
Originally Posted by Fx4wannabe01 View Post
What is your stock tire size and stock ratio? I can do the math for you to figure out how far off your speedo is.

Mine was 30.5 and 4.10, currently 34.8 and 4.88.....my truck thinks it's going 104% faster than it really is going.
i still don't get your truck.. EVERY lifted truck i've rode in says its going slower than it is.
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Old 09-13-2009
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I can't find my darn July 08 issue of Off Road Adventures!



My truck is geared 4% lower than stock combined with the tires....thus giving me a higher speed reading than I'm actually going.
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Old 09-13-2009
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I can't find my darn July 08 issue of Off Road Adventures!
If you find it let me know. The odometer moving this fast is driving me crazy. Thanks for the help!

Anyone know if a 95 is OBD1?
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Old 09-13-2009
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I believe '95 was the first year for OBDII for the ranger....but idk if it has everything to fully function as OBDII. If you figure out your revolutions per mile, the dealer can reflash the PCM to show the speed and odometer correctly.
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Old 09-13-2009
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your truck is VSS and can be changed with an NGS unit.... too bad you arent in MI
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Old 09-13-2009
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Originally Posted by Toreador4x4 View Post
your truck is VSS and can be changed with an NGS unit.... too bad you arent in MI
Could you explain this a little bit more? Maybe something i could do instead of taking it to a dealership?

Im looking for the cheapest way to try and fix this im pretty broke right now.
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Old 09-13-2009
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Originally Posted by MugenCRX04 View Post
Could you explain this a little bit more? Maybe something i could do instead of taking it to a dealership?

Im looking for the cheapest way to try and fix this im pretty broke right now.
Get a Dakota Digital SGI-5 unit. It's one of the cheapest solutions you will find around. And it can always be re-calibrated. Very easy to hook up as well.

Universal Speedometer Signal Interface

I would recommend that you read the Superlifts' Truspeed instructions for the install, very similar, and you will find what wires to tap into easier. The SGI-5 is universal so it will take some toying around with it to get it right. But it works very well.
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Old 09-14-2009
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an NGS is a ford scantool and it has the capabilities of going in to the GEM module to change axle ratios and tire size
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Old 09-14-2009
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Quote:
Originally Posted by Toreador4x4 View Post
your truck is VSS and can be changed with an NGS unit.... too bad you arent in MI
The NGS cannot be used to correct 95-97 Rangers because they use interchangeble gears (like a cable speedo) to drive a signal generator for the electric speedometer.
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Old 09-14-2009
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owned by bob...i was under the impression that the 95-97 rangers had the same speedo set up as a 98-00...thats what i get for assuming!
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Old 09-14-2009
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This was changed several times and can be very confusing. Here's a listing of the different speedo systems as I understand them:

94 and earlier:
Traditional cable-driven speedometer/odometer
Adjustment Method: interchangeable gears at transmission or transfer case
Adjusts for: axle ratio and tire diameter.

95~97
Electric speedometer geared to odometer
VSS source: gear driven pulse generator on the trans or t-case
VSS wire to speedometer: Gray/Black
Adjustment Method: interchangeable gears at transmission or transfer case
Adjusts for: axle ratio and tire diameter.

98~2000
Electric speedometer geared to odometer
Raw VSS source: the ABS sensor on the rear diff housing reads the tone ring.
Corrected VSS Wire to speedometer: Gray/Black
Adjustment Method: (RABS trucks): flash adjustment in the Generic Electronic Module (GEM) using a dealer tool such as NGS+. WDS, IDS may also work.
ADJ Method: (4WABS trucks): flash adjustment in the 4WABS Module using a dealer tool such as NGS+. WDS, IDS may also work.
Adjusts for: tire diameter only.

2001~2003
Electric speedometer geared to odometer
Raw VSS source: Output Shaft Speed sensor fits into a window in the transmission extension housing where it reads a toothwheel machined on the output shaft.
Corrected VSS Wire: Gray/Black
Adjustment Method: flash adjustment in the Powertrain Control Module (PCM) using an aftermarket flash tool. Dealer tools such as NGS+, WDS, IDS may also work BUT the adjustment range is probably factory limited by VIDBLOCK.
Adjusts for: axle ratio and tire diameter.

2004~2006
Cluster microprocessor controls speedometer and digital odometer
Raw VSS source: Output Shaft Speed sensor fits into a window in the transmission extension housing where it reads a toothwheel machined on the output shaft.
Corrected VSS Wire to cluster: Gray/Black
Adjustment Method: flash adjustment in the Powertrain Control Module (PCM) using an aftermarket flash tool. Dealer tools such as NGS+, WDS, IDS may also work BUT the adjustment range is probably factory limited by VIDBLOCK.
Adjusts for: axle ratio and tire diameter.

2007~2009 (Unconfirmed)
Cluster microprocessor controls speedometer and digital odometer
Raw VSS source: Output Shaft Speed sensor fits into a window in the transmission extension housing where it reads a toothwheel machined on the output shaft.
Corrected VSS to cluster: Transmitted from PCM over Module Communications Network
Adjustment Method: flash adjustment in the Powertrain Control Module (PCM) using an aftermarket flash tool. Dealer tools such as NGS+, WDS, IDS may also work BUT the adjustment range is probably factory limited by VIDBLOCK.
Adjusts for: axle ratio and tire diameter.
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Old 09-14-2009
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Quote:
Originally Posted by rwenzing View Post
This was changed several times and can be very confusing. Here's a listing of the different speedo systems as I understand them:

95~97
Electric speedometer geared to odometer
VSS source: gear driven pulse generator on the trans or t-case
VSS wire to speedometer: Gray/Black
Adjustment Method: interchangeable gears at transmission or transfer case
Adjusts for: axle ratio and tire diameter.
Where can i find a interchangeable gear for the tranny?
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Old 09-14-2009
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Quote:
Originally Posted by MugenCRX04 View Post
Where can i find a interchangeable gear for the tranny?
Ford dealer, maybe elsewhere. First, you need to calculate the change in overall ratio from the old and new tire diameter and the old and new axle ratio. Then you need to find out what size gear is in there now. Together, that info will tell you which color gear to buy. There's a chart with part numbers in the TRS tech library.

Last edited by V8 Level II; 09-14-2009 at 09:17 PM.
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  #21  
Old 09-14-2009
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damn.. I wish I would have went with 4.88's instead of 4.56's
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Old 09-14-2009
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^^^^
LOL, i wish i went with 4.56s instead of 4.88s. I do alot of highway driving and it sucks.
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Old 09-14-2009
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Quote:
Originally Posted by MugenCRX04 View Post
Anyone know if a 95 is OBD1?
my 95 is OBD II, but earlier 95's could have OBDI.




did you see this page on TRS?
Ford Ranger/BroncoII speedometer gear change/calibration
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Old 09-14-2009
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all this is making my head spin! just an SCT tuner and be done with it...
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Old 09-14-2009
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Quote:
Originally Posted by 08XLT4x4 View Post
all this is making my head spin! just an SCT tuner and be done with it...
Will not work on Rangers before 2001.
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