Speedo correction.

Submitted: Thursday, May 15, 2014 at 10:19
ThreadID: 107780 Views:3268 Replies:14 FollowUps:14
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Hi. I'm intending to put some oversize tyres on my navara. Is there a gadget available to correct the speedo after doing this. I did a search but couldn't find anything. If there is an article somewhere please point me in the direction. Thanks.
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Reply By: fisho64 - Thursday, May 15, 2014 at 10:36

Thursday, May 15, 2014 at 10:36
that "gadget" could be a couple of stickers at relevant points (50, 60, 110kph).

If you are after something more fancy if would help to provide more detail to ascertain whether it has an electronic or mechanical speedo.
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Follow Up By: Member - Kirk L - Thursday, May 15, 2014 at 16:48

Thursday, May 15, 2014 at 16:48
012 model with electronic.
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Reply By: tonysmc - Thursday, May 15, 2014 at 10:43

Thursday, May 15, 2014 at 10:43
Hi Kirk,
There is gadgets that can be bought to calibrate the speedo, however it is probably easier to buy a scangauge II and have the benefit of water temp and other numerous gauges with it. Also something like a Navman gives you your speed regardless of which tyres you have on and also will tell you what speed zone you are in.
If you calibrate your speedo to a certain size tyre, if you ever change size again the calibration is out.

Cheers, Tony
AnswerID: 532489

Follow Up By: Echucan Bob - Friday, May 16, 2014 at 12:48

Friday, May 16, 2014 at 12:48
Tony

I use Scan Gauge II as my speedo too. The Scan Gauge is mounted on top of the instrument binnacle, and displays speed, % throttle opening, litres per 100 km and RPM. Unfortunately, SG II won't give temperature readouts from the Land Rover ODB2 port. I have a separate coolant temp display and alarm.

You will need a GPS to calibrate the Scan Gauge. My navigational GPS units display speed, but I don't want a GPS display right in my face all the time.

Bob
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Follow Up By: Member - PJR (NSW) - Friday, May 16, 2014 at 16:01

Friday, May 16, 2014 at 16:01
This Scan Gauge, is it able to just show the speed in large etc numbers so it can be seen at a glance.

I change tyres depending on where we go. I have two complete sets of rims and tyres, with one set loaded with ATs and the other with non aggressive mud tyres.

Is the Scan Gauge adjustable from one set to another?

I am not interested in all the other stuff that a Scan Gauge does. I just want the speed. I have it on the GPS but it is smallish and you have to actually "look for it". Just a second or two but it is inconvenient at night. Not just glance.

Thanks

Phil
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Follow Up By: Echucan Bob - Friday, May 16, 2014 at 16:25

Friday, May 16, 2014 at 16:25
Phil

The letters on the display are about 1 cm high and pretty easy to see. They are certainly not as big as some OEM car speedos, but on top of the binnacle you don't need to glance down. You would need to calibrate it against the GPS each time you changed tyres but it is a simple process.

Bob
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Follow Up By: Member - PJR (NSW) - Friday, May 16, 2014 at 18:59

Friday, May 16, 2014 at 18:59
Hi Bob

I think you missed my first question. Can you arrange the Scan Guage to only show the speed and nothing else? ie nothing to search for to find the speed. 2 cm is a little small. The GPS numbers are that big.

I am not keen on things stuck on the top of the dash but we will see what you say. What about a model number or part number which I can use to chase it up on the internet and have a look at?

Phil
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Reply By: Nomadic Navara - Thursday, May 15, 2014 at 10:44

Thursday, May 15, 2014 at 10:44
If your spedo is like the one in My D40 then any oversize tyre will just bring it closer to correct. Mine is also not very linear in its accuracy, its out by a larger percentage at the lower speeds. Suggest you check it with a GPS/navigator to calibrate it before and after the tyre change.

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Follow Up By: Member - Kirk L - Thursday, May 15, 2014 at 16:47

Thursday, May 15, 2014 at 16:47
I normally use my garmin as a speedo. The speedo is out by about 10%. As said above it may correct itself. I know on motor cycles if you change sprockets/ gearing there was bolt on thing which changed speedo to suit.
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Reply By: Matthew G3 - Thursday, May 15, 2014 at 11:13

Thursday, May 15, 2014 at 11:13
Kirk
I Have done it to my 80 series. It was out by 3kmh, not much but when your looking for traks it can be a lot. I took it to a speedo correction place in Shepparton Vic, it was out at the gear box and in the speedo itself. I now have a correction module at the g/b which the speedo cable runs through. It is now spot on with my gps.
Matt
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Reply By: bluefella - Thursday, May 15, 2014 at 12:47

Thursday, May 15, 2014 at 12:47
The Polaris HUD will give accurate speedo reading on your windscreen, just like the flash European cars.
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Reply By: Kumunara (NT) - Thursday, May 15, 2014 at 13:14

Thursday, May 15, 2014 at 13:14
Kirk


Most speedos are out. Check your speedo against a GPS (or time it with a stop watch over 100 m) to ascertain if it is out.

I generally use my GPS rather than the speedo. My speedo 3kms out at 110. In other words if my speedo is showing 110 I am actually doing 107. This also varies through the speed range.

If you speedo is out the oversize tyres may correct it.


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Follow Up By: Member - Terry W4 - Friday, May 16, 2014 at 18:48

Friday, May 16, 2014 at 18:48
Agree. Mine is out by 5kms at 110. Checked it today on a trip back to Canberra from Sydney. Use the GPS all the time. In fact when I queried a few years ago (when I was driving a Honda) the dealer said rely on the GPS it is more accurate.
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Reply By: Steve D1 - Thursday, May 15, 2014 at 13:20

Thursday, May 15, 2014 at 13:20
Nissan used to supply optional speedo drive gears, we used to do it for patrols a lot.
See if they still do it. Was around $50 from memory.

Steve
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Follow Up By: Iza B - Thursday, May 15, 2014 at 13:55

Thursday, May 15, 2014 at 13:55
Ford Couriers too, have a small range of speedo drive gears. Seems a common fix so maybe off to the parts shop?

Iza
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Follow Up By: Member - Kirk L - Thursday, May 15, 2014 at 16:51

Thursday, May 15, 2014 at 16:51
Yeah I had a patrol and you could get different gears for the cable where it was driven in the gearbox.
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Reply By: Member - Dazza - Thursday, May 15, 2014 at 14:25

Thursday, May 15, 2014 at 14:25
Hi Kirk. As has already been said, the standard speedos have an error in them. In my case with a GU Patrol with standard 265/70x16 it was near 5% overreading. I changed to 265/75x16, and now error is less than 1%. If you're making a bigger change than this, get a check of the error by using a GPS then look up the tyre size chart on this site or do a search. The best chart is one with circumference, then a bit of maths and a calculator may find that the error is cancelled out. That could you save you adding unnecessary bits if your change is similar to mine. Monster tyres will probably need corrections.
Maybe if you post the current and proposed size someone may have already done it. I'll try to post a link to the tables when I find them.
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Follow Up By: Member - Dazza - Thursday, May 15, 2014 at 14:55

Thursday, May 15, 2014 at 14:55
Tyre Calculator
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Follow Up By: Member - Kirk L - Thursday, May 15, 2014 at 16:55

Thursday, May 15, 2014 at 16:55
Yes I did find the tyre calculator in my search. I will check it out but thanks for all good replies. Sounds like a not too radical increase may actually self correct the speedo. As I said I do normally use the GPS as a speedo anyway so I will get tyres done and go from there. Cheers.
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Reply By: Member - Craig F (WA) - Thursday, May 15, 2014 at 17:55

Thursday, May 15, 2014 at 17:55
Marks Adaptors do a plug in module that you can use to set your speedo back to the correct reading as it has multiple settings you can get it close to spot on. Will need to see if they have one for your model. I have one on my Patrol works well and can be used for two different tyre sizes.
Other option as stated is swapping out the cog.

Craig
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Reply By: Top End Az - Thursday, May 15, 2014 at 19:19

Thursday, May 15, 2014 at 19:19
So how accurate are GPS units in general? I'm assuming that satnavs in 4WD don't have access to military satellites ( which have much more accurate positioning).
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Follow Up By: Echucan Bob - Friday, May 16, 2014 at 12:37

Friday, May 16, 2014 at 12:37
Top End Az,

Civilian GPS units are deadly accurate. You assumed incorrectly about the satellites. In the past, an error was introduced into the GPS system so that accuracy was limited to about 10 meters for non military users. This was turned off I think during Bill Clinton's presidency. So now we all have access to military grade accuracy.

Bob
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Follow Up By: Nomadic Navara - Friday, May 16, 2014 at 22:26

Friday, May 16, 2014 at 22:26
There is only one set of GPS satellites. The error system for public use was switched off during the Gulf War. They could not get enough military grade units so the errors were switched off to allow commercial ones to be used by the military. It has not been restored.
PeterD
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Reply By: Member - Peter M17 - Thursday, May 15, 2014 at 19:22

Thursday, May 15, 2014 at 19:22
Kirk,

I am with the others on this. I have a D40 Navara STX (Spanish) which came with 255/65x17 tyres and according to my GPS I needed to read 108 kph to be doing a true 100 kph.

I fitted 265/70x17 AT tyres and now it only reads 2 kph slow (a good safety margin).
Note that I needed to fit a 40mm lift kit for clearance on these tyres.

The odometer is also this 2% out

As suggested make sure you sure you know your true speed and you probably will not need any adaptor.

Regards
Peter
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Follow Up By: Member - Kirk L - Thursday, May 15, 2014 at 19:34

Thursday, May 15, 2014 at 19:34
Cheers bud. I already have a 50mm lift so should be good. Sounds like I'll be pretty spot on with the 265's
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Reply By: 2000 Red Rodeo - Thursday, May 15, 2014 at 19:55

Thursday, May 15, 2014 at 19:55
Do a search on ebay for a gps speedo. Will be about $150.

Best thing about it is that it will be accurate regardless of the tyres you put on. Especially if you switch between road tyres and the muddies to save the tread on the muddies

Works a treat.
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Reply By: peteC - Friday, May 16, 2014 at 20:40

Friday, May 16, 2014 at 20:40
Electronic speedo corrector from jaycar, $55
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Reply By: Member - Kirk L - Saturday, May 17, 2014 at 13:28

Saturday, May 17, 2014 at 13:28
Thanks all.
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