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boode



Member Since: 11 Apr 2012
Location: Devon
Posts: 430
England 2003 Defender 90 Td5 HT Rutland Red
Speedo changing with bigger tyres
I have fitted larger tyres ( from 205s to 265s ) which has increased the diameter by 9.5%.
The speedo now reads about 10% lower than actual speed - not a problem untill passing speed cameras.
I have lived with it for a couple of years - but now I am doing more traveling, especially on the continent, I think I should correct the speedo.
How can the speedo be altered to fit the new tyre size - or does the ECU need re programming ?
Any advice appreciated.
Post #163687 22nd Aug 2012 11:44am
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Porny
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Member Since: 31 Aug 2009
Location: Sutton Coldfield - West Midlands
Posts: 809
 
What vehicle? Tdi, Td5 or Tdci?

If TDCI then it needs plugging into a dealer spec diagnostic system, and the tyre size reprogramed - which also makes a difference to the way the engine calibration works.

Td5 and Tdi need the gear changed at the end of the speedo drive.


Ian IRB
The home of the first modified Keswick Green 90 - and the first 2.4 Puma through both the 200bhp and 550Nm barriers.

www.IRBdevelopments.com

www.facebook.com/irbdevelopments

www.integrated316.com

www.facebook.com/integrated316
Post #163689 22nd Aug 2012 11:59am
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boode



Member Since: 11 Apr 2012
Location: Devon
Posts: 430
England 2003 Defender 90 Td5 HT Rutland Red
Sorry - its an 03 Td5 - thanks for quick responce.
So is the gear to change easy to get hold of.
Is it at the speedo itself or at the ECU ?
Post #163691 22nd Aug 2012 12:13pm
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Glynparry25



Member Since: 16 Feb 2009
Location: Miserable Midlands
Posts: 3015
Wales 2009 Defender 110 Puma 2.4 XS DCPU Tonga Green
How do you know it is reading wrong?

Reason I ask is because manufacturers normally have the speedo set to 10% over actual speed. So with the initial reading 10% faster and now 9% slower you are probably reading about right.

Check with a decent GPS before worrying about changing gears,

Glyn Dog Sheep
Post #163695 22nd Aug 2012 12:29pm
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boode



Member Since: 11 Apr 2012
Location: Devon
Posts: 430
England 2003 Defender 90 Td5 HT Rutland Red
It is the sat nav and the other traffic that shows me that the speedo is incorrect.
We have a local road that has started handing out tickets if you are doing 65 not 60 - so it will just make it easier to have the speedo showing the correct mph.
Post #163698 22nd Aug 2012 12:45pm
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Glynparry25



Member Since: 16 Feb 2009
Location: Miserable Midlands
Posts: 3015
Wales 2009 Defender 110 Puma 2.4 XS DCPU Tonga Green
Hmmmmm, Not too sure about the Td5s. If it is an electronic speedo it will be a simple change in the ECU..... if it is a cable... maybe Ashcroft transmissions will probably do something

Glyn Dog Sheep
Post #163700 22nd Aug 2012 12:56pm
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Glynparry25



Member Since: 16 Feb 2009
Location: Miserable Midlands
Posts: 3015
Wales 2009 Defender 110 Puma 2.4 XS DCPU Tonga Green
Just did some digging around.......

This is what you will need:

FRC3310 - 20 tooth gear (About £10-15)

-Just double check that the one in yours is green (FRC3311- 21 tooth gear)

Glyn Dog Sheep
Post #163702 22nd Aug 2012 1:07pm
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boode



Member Since: 11 Apr 2012
Location: Devon
Posts: 430
England 2003 Defender 90 Td5 HT Rutland Red
Thanks Glyn

Is the toothed gear in the back of the speedo in the dash ?
Post #163705 22nd Aug 2012 1:32pm
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jwhat



Member Since: 19 Jan 2011
Location: Westmeath
Posts: 134
Ireland 2008 Defender 110 Puma 2.4 DCPU Keswick Green
Thanks for bringing this up, I also have to change mine as it underreads.

Thanks for the part number Glyn

Is it easy to do? Tdci 110 DC
Post #163706 22nd Aug 2012 1:35pm
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Porny
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Member Since: 31 Aug 2009
Location: Sutton Coldfield - West Midlands
Posts: 809
 
boode wrote:
Thanks Glyn

Is the toothed gear in the back of the speedo in the dash ?


No have a look the left hand side of the transfer box, just behind the handbrake drum...

Remove the electronic speed pick up (8mm head bolt) and the cog is behind it. Removing the sleeve that holds the cog in place can be a bit of pain though.


Ian IRB
The home of the first modified Keswick Green 90 - and the first 2.4 Puma through both the 200bhp and 550Nm barriers.

www.IRBdevelopments.com

www.facebook.com/irbdevelopments

www.integrated316.com

www.facebook.com/integrated316
Post #163707 22nd Aug 2012 1:43pm
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jwhat



Member Since: 19 Jan 2011
Location: Westmeath
Posts: 134
Ireland 2008 Defender 110 Puma 2.4 DCPU Keswick Green
Thanks Ian. Tdci 110 DC
Post #163718 22nd Aug 2012 2:39pm
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boode



Member Since: 11 Apr 2012
Location: Devon
Posts: 430
England 2003 Defender 90 Td5 HT Rutland Red
Porny wrote:
boode wrote:
Thanks Glyn

Is the toothed gear in the back of the speedo in the dash ?


No have a look the left hand side of the transfer box, just behind the handbrake drum...

Remove the electronic speed pick up (8mm head bolt) and the cog is behind it. Removing the sleeve that holds the cog in place can be a bit of pain though.


Ian


Ian

Is the pick up the three wires behind the handbrake drum - ie on the front of the transfer box - in a very awkward place,
or the two wires on the side of the transfer box with a nut on top of them, although they are on the right hand side so probably not ?

Gavin
Post #164004 23rd Aug 2012 5:09pm
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diesel_jim



Member Since: 13 Oct 2008
Location: hiding
Posts: 6105
United Kingdom 2006 Defender 110 Td5 SW Epsom Green
The 3 wires behind the handbrake.
Post #164091 24th Aug 2012 6:36am
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Glynparry25



Member Since: 16 Feb 2009
Location: Miserable Midlands
Posts: 3015
Wales 2009 Defender 110 Puma 2.4 XS DCPU Tonga Green
boode wrote:
Is the pick up the three wires behind the handbrake drum - ie on the front of the transfer box - in a very awkward place,
Gavin


Land Rover can't make it too reasy for you Wink

As above, that is the one Thumbs Up a lot of getting your fingers in there and not being able to see anything- bit like a crystal maze challenge

Glyn Dog Sheep
Post #164094 24th Aug 2012 6:45am
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twopoint6khz



Member Since: 18 Aug 2011
Location: North Lakes
Posts: 654
United Kingdom 2005 Defender 110 Td5 CSW Java Black
The alternative way to do it is to take the centre seat/cubby box out and attack in from above. Still doesn't make it any less fiddly, but you can at least see what you're doing properly.

I've never worked out why the non-structural bolt that holds the transducer in has about 50 threads engaged on it - other than to annoy you. You can only turn it about 1/8 of a turn at once Evil or Very Mad
Post #164120 24th Aug 2012 9:19am
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