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Registered:
December 2004
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Speedo Re-Calibration
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Thu, 16 December 2004 08:41
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Hi All,
I have an 04 Liberty and am upgrading the stock tyres 215/45R17 to a decent set of 235/40R18. I know this is going to throw out my speedo and odometer.
How do I go about re-calibrating everything or can anyone recommend where I get this done..I'm in Sydney..
Cheers Everyone
Tomski
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 08:44
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Why not get 235/35/R18's?
Or 215/40/R18's?
Then you speedo would be perfect.
Thats the logical and normal thing to do.
Are you not normal?
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Location:
sydney
Registered:
March 2003
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 09:26
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if your speedo is electronic
i can seel you a speedo ratio box and its fully adjustable
to make your speedo faster or slower
jaycar have a kit out but it is always delayed its release day
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Registered:
December 2004
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 10:08
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Unfortunately the Maths of it isn't that easy.
Try These sites to see what I mean
http://www.1010tires.com/TireSizeCalculator.asp?ac tion=submit\
OR
http://secret-secret.com/turbo/DIY/tirecalc/turbot ire.html
The rolling diameter changes with width and profile of the tyre.
If I had a mechanical speedo, then I have no problems as I just send it to a mechanic and he can calibrate it. But electronic speedo's are more funny. I've spoken to 3 Auto Electricians and they alll said that they don't have the equipment. Subaru doesn't want to touch it either.
Cheers
T
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Location:
Campbelltown
Registered:
November 2003
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 10:17
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not really 235x.4x2+18x25.4=645.2
215x.45x2+17x25.4=625.3
The speedo would be reading under by 3%
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Location:
sydney
Registered:
March 2003
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 12:02
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it is piss easy to do
i have devices that adjust the signal comin in to what goes out to the speedo
all u need to do is get a car with accurate speedo to drive beside you and you adjust yours till its similar
mind you its not 100% accurate but if u put the car on the dyno then u can adjust it to be accurate
i have fitted many of them and its no problem
i dont know what theyre talkin about
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Location:
Sydney/Wollongong
Registered:
October 2003
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 13:55
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| Tomski wrote on Thu, 16 December 2004 18:08 |
Unfortunately the Maths of it isn't that easy.
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Actually, those tyre sizes I listed will make your speedo accurate within less than 1% (0.6% actually).
As opposed to the tyre you suggested which is 3% out.
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Location:
Perth
Registered:
August 2004
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Re: Speedo Re-Calibration
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Thu, 16 December 2004 14:05
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Jaycar sells a kit which modifies the pulse signal from the gearbox to the speedo.. There $70 from memory...
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: Speedo Re-Calibration
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Fri, 17 December 2004 00:49
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Good thread this, as mine is currently out as well. It was supposed to be running stock 215/70R16's all round, but it's now running 255/50R17's all round (beefy bastards) and not only that, the gearbox is from an ST205, so it's calibrated to turn the speedo at the ST205's factory rim and tyre spec's and rolling diameters.  It's been thrown WAY out now, running approx. 5km/h slower (on the speedo) than actual speeds at around 50km/h. I really need one of these calibration units... 
How hard are they to install on an electronic sender (gearbox -->> speedo)?
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I Supported Toymods
Location:
Perth
Registered:
May 2004
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Re: Speedo Re-Calibration
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Fri, 17 December 2004 01:10
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while u guys are calculating stuff, help me out with this, i had a standard diff in my sprinter before 4.1 i think, my new lsd one is 4.3, whats the differance in speed?
I think when im going 70 speedo says 77 so yeah
Thanx
Adam
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: Speedo Re-Calibration
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Fri, 17 December 2004 01:13
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| Bobski wrote on Fri, 17 December 2004 09:10 |
while u guys are calculating stuff, help me out with this, i had a standard diff in my sprinter before 4.1 i think, my new lsd one is 4.3, whats the differance in speed?
I think when im going 70 speedo says 77 so yeah
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Think about it dude, you're revs have increased but 4.3/4.1 ~ 5%
Therefore for any given speed, you speedo will now read higher.
So 70 on the speedo, is 73.5 in real life.
But, if you tyres are out, or your gbox has been changed, then you can't even go by that.
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