GPS Speedo options

[Lewis]

The OE speedo in my 90 is erratic at best, and miles out due to oversized tyres, so I need something a bit more accurate

Presently I'm using a combination of guesswork and wishful thinking to judge speed, or wedge my iPhone in the dash and use a speed app when my route includes speed cameras

I'd quite like a 52mm gauge GPS speedo to mount in the dash either where the voltmeter is or in a separate gauge pod, but all the ones I've found for sale are mega money (£90 or more), which seems ridiculous given that you can get a Chinese satnav for 20quid on eBay

Does anyone have any suggestions?

[CwazyWabbit]

Didn't realise you could get GPS speedos as a package. Am sure you will get a few people suggesting TD5 speedos but by the time you find a used speedo and get the sender as well as some wiring you'll be looking at the best part of 90 quid anyway.

[Ex Member]

Why not do a VDO Vision? They look great and you can program them at any time to be dead on.

http://www.egauges.com/ProductDetails.asp?ProductCode=437-155

That plus a VSS from a Discovery 1 or a TD5 Defender and you have a great gauge that is miles better than stock.

[mmgemini]

Have you tried changing the gear drive on the output shaft of the transfer box ?

I do like the digital speedo from Digital Speedos.

http://www.digital-speedos.co.uk/90mm-speedometer-blue-display-231-p.asp

You'll notice it's out of stock. I keep looking

[Daan]

You can change the gear in the transfer box to suit, but not sure what is what. the wobbly thing you should be able to solv with a new cable. If you want to go racy, I'd fit a terratrip.

[robertspark]

speedo gear choices here if you're interested in just sorting your one out

http://www.land-rover-blog.co.uk/how-to-replace-the-speedo-drive-gear-on-a-land-rover/

seems there are 52mm GPS speedo's (normally for boats??)

http://andytach.com/shop2/index.php/gps-speedometer/atach-gps-speedometer-32.html

http://www.aliexpress.com/premium/GPS-speedometer.html?ltype=wholesale&SearchText=GPS+speedometer&d=y&origin=y&initiative_id=SB_20140425095827&isViewCP=y&catId=0&I18nSearchText=GPS+speedometer

[missingsid]

What is the delay on these? When using my stanav as a speedo there is a delay as I assume it is using averaging to get the speed so not very confident when around cameras!

[GW8IZR]

Is it possible to offset the mileage on these after market (vdo) speedometers?

In other words can I advance a new one to read 102000 miles when its fitted?

I'd rather keep the original miles if possible

[mmgemini]

Is it possible to offset the mileage on these after market (vdo) speedometers?

In other words can I advance a new one to read 102000 miles when its fitted?

I'd rather keep the original miles if possible

I don't know about the VDO ones but the blurb on the Digital Speedos web site say that is done.

[GW8IZR]

They do a LR specific version that reads to 180MPH .. I think I'd have to turn the fuel up a bit for that.

I might drop VDO support a mail and ask if the odometer can be set - I can't see anything in the manuals.

[CwazyWabbit]

If VDO say it is not possible it may be possible to do it in the same way as is possible on the TD5 VDO speedo, although that does require a soldering iron and a chip programmer it is relatively simple.

[Mr Ian]

Hi have you looked at this speedo correction kit? http://www.ashcroft-transmissions.co.uk/speedo-correction-kit-c102.html. Regards Ian Ashcroft

[GW8IZR]

If VDO say it is not possible it may be possible to do it in the same way as is possible on the TD5 VDO speedo, although that does require a soldering iron and a chip programmer it is relatively simple.

That prompted a search which turned up your excellent reverse engineering project - nice one!

[CwazyWabbit]

Was very much a group effort from members of this forum

[GW8IZR]

For sure.. but it was a good project.

Its nice to see good output from cooperation etc.

[Lewis]

Thanks for all the suggestions

None of the other options seem to come close for ease of fitting, and they are all around the same money or more than a gps guage

A GPS speedo only requires 12v, ground and somewhere to route the 10ft of antenna.

Changing to a td5 speedo would need a speedo transducer, speedo head and some loom - plus it would need programming to the correct speed (using a GPS device)

Correct me if I'm wrong but there isn't a speedo drive gear with few enough teeth for 35" tyres? So that option is no good.

So it still looks like I'm down to either the andytach or Kus guages (that robertspark linked to)

Conversely gps speedo heads up displays are a lot cheaper and easier to come by, just not what I'm after

[CwazyWabbit]

I haven't done any research into it but are GPS speedos acceptable t the powers that be as the only speedo in a vehicle?

[muddy]

Would it be possible to 3D print a suitable gear?

[mmgemini]

I haven't done any research into it but are GPS speedos acceptable t the powers that be as the only speedo in a vehicle?

I would doubt it. I don't think anybody would know.

[robertspark]

speedometer legality ..... (GPS or other).

I would suggest (not an expert in these matters) but the SVA (old money Single Vehicle Approval) .... now known as IVA (Individual Vehicle Approval) would be the place to check.

Given the open government policy, all the documents are now available for download and inspection, so the IVA manual is here:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/203591/M1_IVA_inspection_manual.pdf

Pdf page 139, section 17 seems to exclude the use of "GPS" speedometers.... I would have said that the basis for this is the item #3 copied below from the "required standard", which is a GPS speedometer cannot be read at all times day or night given it will have issues reading the speed in a high rise area.... it takes time to obtain a fix ... and it won't work in a long tunnel (I think the technical rule is further than 1 diameter into the tunnel).

Section 17 Required Standard extract below:

1. The vehicle must be fitted with an acceptable type of Speedometer (see note 1)

2. A speedometer must be capable of indicating the vehicle speed in miles per hour (mph) at uniform intervals not exceeding 20mph for all speeds up to the maximum design speed of the vehicle. (see note 2)

3. The speedometer must be capable of being read at all times of the day or night

4. The speedometer must not indicate a speed less than the true speed.

5. The speedometer must not indicate a speed that is in excess of the true speed plus the permitted tolerance in the chart below. (see note 3)

Note 1:

The speedometer must be of a type suitable for M1 vehicle use.

The types manufactured for bicycles, racing only, those that rely on GPS or those that require switching as a separate function to that of operating the vehicle or those that have a separate power source from the vehicle or where they do not operate as an automatic function when the vehicle is driven are not permitted. Where the device is in question the presenter may provide evidence as to the suitability of the device for road use from the manufacturer of the device.

Hope the above helps to guide you, usual disclaimers apply as I'm just a backyard mechanic, do as you see fit, on your head be it.

Speedometers don't come into MOT inspections as far as I can see (manuals here for you to consider):

https://www.gov.uk/government/publications/mot-guides-and-inspection-manuals/mot-guides-and-inspection-manuals

[Lewis]

As I'm not planning to IVA the vehicle I'm not concerned with the DVSA's thoughts concerning GPS speedometers

[miketomcat]

If I were you I would keep the standard one in place and use a GPS Speedo that way if you get pulled up on it your using the GPS for accuracy.

Mike

[Lewis]

Yes, I have no intention to discard the OE speedo, hence my looking for a 52mm additional speedo

[jumping jack]

I might be wrong, but gps speedos don't take account of gradient. So not that usefully on slopes.

[Ex Member]

I really do not understand why not go with a normal VDO speedo. They look much better than stock and work very well. They are very simple to program. The sender can be had for next to nothing at a breakers.

A GPS speedo will be a PITA. Tunnels, tall building, etc.. and it will read wrong. The antenna really needs to be outside to work well. They react slow, especially in bad signal conditions.