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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Sun Apr 16, 2017 10:53 pm 
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I Say: Mum, when I grow up, I want to be a pilot! Sorry son, you can't do both!! :D
Vehicle: MY05 XT Luxury AT, white

Posts: 1808
Location: Wynnum West, QLD
Photos of transmission stickers would help?

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Sun Apr 16, 2017 10:58 pm 
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I Say: Car mods are like OddBodz, you got to collect them all! -------------------------------------
Vehicle: MY05 STi swapped sled

Posts: 17168
Location: Spearwood Perth WA
craig747400 wrote:
Photos of transmission stickers would help?

Forget trans codes and numbers and crap. Undo the diff cover and look at the crown wheel... thats the most accurate way to know what ratio your diff is.

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Mon Apr 17, 2017 12:11 am 
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I Say: Car mods are like OddBodz, you got to collect them all! -------------------------------------
Vehicle: MY05 STi swapped sled

Posts: 17168
Location: Spearwood Perth WA
dizzylights wrote:
Grahama wrote:
My speedo reads well over (shows 110 when GPS says 100)


Sorry to hijack, but I would like to know what's going on with this? My car also does this and have often wondered if the previous owner had been running 20's or something

EDIT: Just to add, this would also suggest that the km's travelled on odometer is incorrect?

Check the tyre size fitted to the car. Changes in rolling duameter affect speed and odometer readings to a small degree.

Most OEM speedos will over read the speed vs actual speed to some degree, usually maybe 3-5%. (10% seems a little high). There are a couple of reasons. Firstly it is to take into account that the vehicle will possibly have quite a few different sets of tyres in its life, and there are sometimes variations in tread (rolling diameter) and such between brands and as the tyres wear down. So they over read to cover all possible situations with a little saftey margin. They over read as thats better than under reading and having owners complain of speeding tickets or try and sue for accidents caused by excessive speed. (Ridiculous i know, but this is the world we live in.)

The othwr reason is because guages with moving needles are not always linear. That is at say 50Km/H the gauge will need X number of pulses per minute from the VSS. And at 100km/H, it will require more or less than 2X number of pulses per minute because the gauge itself is not linear in its representation of speed. So again a little safety margin is built into the system.

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Mon Apr 17, 2017 1:45 am 
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I Say: Car mods are like OddBodz, you got to collect them all! -------------------------------------
Vehicle: MY05 STi swapped sled

Posts: 17168
Location: Spearwood Perth WA
The other thing thats wrong with that table that Craig posted up beside the SG XT autos being 4.11. Look at the 2006 WRX manual. It says 3.7:1? Ive never heard that one before. (Maybe a US market only thing?) And the 05/07 Lib gt spec b should be 3.54:1 not 3.45:1. So there is definitely quite a few errors in there.

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Mon Apr 17, 2017 6:53 pm 
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I Say: Mum, when I grow up, I want to be a pilot! Sorry son, you can't do both!! :D
Vehicle: MY05 XT Luxury AT, white

Posts: 1808
Location: Wynnum West, QLD
http://www.subaruforester.org/vbulletin ... ot-113312/

Edit: Subaru is so inconsistent, it truly isn't funny! :roll:

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Wed Apr 19, 2017 8:54 am 
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I Say: I have CDO. It's like OCD except the letters are in alphabetical order, as they should be.
Vehicle: MY05 XTL - Black

Posts: 5063
Location: Tanah Merah - Brisbane
All SG XT are 4.444, there was a split for the GT

**Edit - Correction down further - **

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housemusik wrote:
H-are wrote:
Are you going 6 speed for the strength of it?
I just want to do skids bro :lol: DCCD ftw


Last edited by Tremayne_XT on Wed Apr 19, 2017 10:14 pm, edited 1 time in total.

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Wed Apr 19, 2017 9:12 pm 
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Vehicle: 2007 XT

Posts: 929
Location: South Oz
Tremayne_XT wrote:
All SG XT are 4.444, there was a split for the GT


Are you sure?
Is that for early SG's only?

Late SG XT Autos are 4.111
Late SG XT Manual are 4.444

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Wed Apr 19, 2017 10:13 pm 
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I Say: I have CDO. It's like OCD except the letters are in alphabetical order, as they should be.
Vehicle: MY05 XTL - Black

Posts: 5063
Location: Tanah Merah - Brisbane
99STi wrote:
Tremayne_XT wrote:
All SG XT are 4.444, there was a split for the GT


Are you sure?
Is that for early SG's only?

Late SG XT Autos are 4.111
Late SG XT Manual are 4.444


Checked FSM's and you are correct

Early SG - All are 4.444
Late SG - Man is 4.444
Late SG - Auto is 4.11

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Current Ride - 05 XT Foz
Previous Ride - Your mum ;)

housemusik wrote:
H-are wrote:
Are you going 6 speed for the strength of it?
I just want to do skids bro :lol: DCCD ftw


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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Wed Apr 19, 2017 11:19 pm 
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Vehicle: 2007 XT

Posts: 929
Location: South Oz
Tremayne_XT wrote:
99STi wrote:
Tremayne_XT wrote:
All SG XT are 4.444, there was a split for the GT


Are you sure?
Is that for early SG's only?

Late SG XT Autos are 4.111
Late SG XT Manual are 4.444


Checked FSM's and you are correct

Early SG - All are 4.444
Late SG - Man is 4.444
Late SG - Auto is 4.11


Thanks for clearing that up. :thumbs:

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 Post subject: Re: What's the 07 XT Diff ratio?
PostPosted: Wed Apr 19, 2017 11:54 pm 
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I Say: very little. It always gets me into trouble ...
Vehicle: MY07 X MT

Posts: 425
Location: Perth
dizzylights wrote:
Grahama wrote:
My speedo reads well over (shows 110 when GPS says 100)
Sorry to hijack, but I would like to know what's going on with this? My car also does this and have often wondered if the previous owner had been running 20's or something
On OEM tyres (Geosquealers) the speedo on my MY07X is 8.5% high. Not significantly different on any other of the same 215/60 size, but closer to +3% on 215/65-16's.
Grahama wrote:
EDIT: Just to add, this would also suggest that the km's travelled on odometer is incorrect?
Nope, not to the same extent anyway. (I've seen tinfoil-hat brigade suggestions that it's a Subaru conspiracy to short-change you on service intervals :lol: ).

The Australian spec for speedos is contained in ADR18/03 (https://www.legislation.gov.au/Details/F2006L01392 down at para 5.3 although their symbol set messes it up), and it specifies reading wrt true speed must be between 0% (i.e. can't show as slower than true) and +10% +4kph. So at 100 true/GPS it must lie in the range 100-114.

The TL;DR part: Like most contemporary vehicles, Subaru use an electronic system. The instrument cluster processor uses a lookup table in an EEPROM and drives the speedo needle with a quadrature drive, which is far more linear than old-fashioned analog meters. The key to the accuracy is the lookup table. This allows the manufacturer to make changes to tyre sizes without any other corrections, as well as set the extent of over-reading to suit the market area. For whatever reason, in Oz Subaru seem to target the +8% area or thereabouts. BUT the odometer is also a product of the EEPROM/processor combo and they tend to be closer to 2% high - mine is +1.8% over a measured course.


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