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'15 OB Limited 2.5L; '97 Wrangler 2.0L
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46 Posts
Discussion Starter · #1 ·
I've searched around the site and haven't seen this posted anywhere yet. Does anyone know how to calibrate the speedometer? Tossing the 215 winter tires on instead of the 225 all seasons shows my speed is 8mph faster than I am actually going. Hopefully there is a way I can take care of this myself without bringing it in.

(I know there are a few people who will say, why let it bother you. But I toss on enough miles I want the odometer to be somewhat accurate).
 

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2008 OB Limited 2.5i, Portland OR USA
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7,796 Posts
Your options:

1. Correct tire sizes, as noted.
2. Memorize the offsets at a few specific speeds.
3. Memorize the tachometer position in highest gear (essentially the same as #2)
4. Mark key positions with tape on either speedo or tach.
5. Design and install a custom overlay dial for the speedo (essentially the same as #4)
6. Live with the error.

That's about it.
 

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85BRAT97SVX03Baja5mtHonda's
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2,170 Posts
These are MY pictures and cannot be reshared or posted anywhere without my permission

You can open the right side of the front diff retainer cap, and pull out the Speedo Driven gear.
You can then pull out the driven speedo gear, then you can swap with others.
All this can be done via a VERY good mechanic, all you have to do is pull the axle and the rest, is work Not easy. Can be done. You have to find the prelash and assemble same.









all the "goods"are found once the bearing is out……DON"T drop the tiny cir-clip. You will need to be patient on that part, and a magnet for the times you drop the circlip of the driven gear.
I have changed this on a "few" of the older ones where the gears strip out….you can get specific speedo drive gears and specific driven gear from subaru, based on your year maek and model, but then you can find the one you need for your tires. ….good luck


In my best honest opinion, this job is not for the amateur. You will be in over your head(s)
But yes, this is doable, and the trans doesn't have to come out……you need a way to pull the bearing, you need lots of love of your car ……most are not in that category. I was and still am there. NOBODY else will be.

there you have it…nobody else above knows this stuff.
love.
 

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Premium Member
2016 Outback Premium 2.5 CVT w/EyeSight+SRVD
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7,584 Posts
You can open the right side of the front diff retainer cap, and pull out the Speedo Driven gear.
You can then pull out the driven speedo gear, then you can swap with others.
As far as I can determine, the CVT-equipped Subarus no longer have a mechanical speedometer drive like you describe. The G1 CVT mated to the H6 engine has only a "front wheel speed sensor" which consists of a Hall-effect sensor mounted at the transfer driven gear. In the Factory Service Manual there is no reference to a speedometer drive gear (or gears) in either the G1 (TR690) or G2 (TR580) CVT.

I don't know where the vehicle speed value originates in the G5 Outbacks. The speedometer display module picks the road speed value off the CAN-bus. I suspect, but can't confirm, that the road speed value originates in either the transmission control module or (more likely) in the VDC controller. The VDC controller, in turn, could generate a road speed value from any combination of the transmission output shaft speed sensor and/or individual wheel speed sensors.

Bottom line: None of these speed sensors appear to be accessible for field modification.


Edit: Subaru training materials (Module 602) indicate that the vehicle road speed value originates in the VDC controller, calculated from individual wheel speed inputs. The road speed value then passes through the Body Integrated Unit (BIU) on its way to the Combination Meter (a.k.a the instrument cluster) for display.
 

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'15 OB Limited 2.5L; '97 Wrangler 2.0L
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46 Posts
Discussion Starter · #6 ·
Darn, I was hoping with more and more of vehicles becoming electronic instead of physical (like the gears mentioned above) there might have been a way to make an adjustment through the data port. Similar to how tpis can be updated. Guess I am just going to have to live with it this year and hope the tires are finished come spring time
 

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2015 Subaru Outback 2.5i Limited
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172 Posts
I know this is a gravedig, but does anyone know why there's a 1-2 mph difference between the digital display and the analog one (The analog one slower)? Yes I'm running the right tires etc.
 

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2016 Outback Premium 2.5 CVT w/EyeSight+SRVD
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7,584 Posts
I know this is a gravedig, but does anyone know why there's a 1-2 mph difference between the digital display and the analog one (The analog one slower)? Yes I'm running the right tires etc.
For starters, there is a +/- 1 least significant digit uncertainty inherent in all digital displays. Next, the accuracy of analog displays is usually stated as +/- some percent of full scale.
 
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2011 OB 2.5i Prem CVT HK/AWP, Ruby Red Pearl
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For 1-2mph, there's also parallax error introduced on a needle gauge (unless you're normally at ~80mph).
 

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2007 EDM H6
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These are MY pictures and cannot be reshared or posted anywhere without my permission

You can open the right side of the front diff retainer cap, and pull out the Speedo Driven gear.
You can then pull out the driven speedo gear, then you can swap with others.
All this can be done via a VERY good mechanic, all you have to do is pull the axle and the rest, is work Not easy. Can be done. You have to find the prelash and assemble same.









all the "goods"are found once the bearing is out……DON"T drop the tiny cir-clip. You will need to be patient on that part, and a magnet for the times you drop the circlip of the driven gear.
I have changed this on a "few" of the older ones where the gears strip out….you can get specific speedo drive gears and specific driven gear from subaru, based on your year maek and model, but then you can find the one you need for your tires. ….good luck


In my best honest opinion, this job is not for the amateur. You will be in over your head(s)
But yes, this is doable, and the trans doesn't have to come out……you need a way to pull the bearing, you need lots of love of your car ……most are not in that category. I was and still am there. NOBODY else will be.

there you have it…nobody else above knows this stuff.
love.
I hate shitty image posting sites like photobucket beyond imagination

Such a gem post, yet it's likely lost forever, unless bheinen74 is still around to re-share the photos
 

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2014 2.5i PZEV Tungsten Outback Limited W/Moonroof, Accessory Value Package A.
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114 Posts
Isn't tampering with the speedo illegal? Yes its a felony, so trying to adjust the speed would have the same effect on miles.
 

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2018 Dark Blue Outback 3.6R Touring arrived 8/31/2017
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343 Posts
Isn't tampering with the speedo illegal? Yes its a felony, so trying to adjust the speed would have the same effect on miles.
Speedometers need to be accurate within limits to be legal, and there are multiple factors involved, including how worn tires are. If it's not sufficiently accurate, that violates the law most anywhere.

Other than that, the odometer must also be kept accurate and not be tampered with to roll back mileage, because that would also be illegal.

I did a bit of web searching (not exhaustive) but didn't find any support for it being a felony to modify a speedometer/odometer, as long as you don't violate accuracy requirements.

Of course, what's legal will vary depending on jurisdictions.

Consider: there are shops that specialize in working on speedometers. Who do you think makes changes to them when they go awry, and have no problem doing it? What's the logic of think that only they can legally do it, if someone else can also do it, so long as they're accurate enough?
 
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