Speedo conversion MPH to KPH

dickdasr1234

Hi, is anybody aware of a speedo conversion specialist in Dublin?

cnoc

https://www.boards.ie/discussion/2058336326/speedo-conversion-mph-to-kph

Divide the Miles by 5 and multiply by 8

dickdasr1234

Really?

Hannaho

Logic automotive, Rathcoole Dunlin. Did mine from.kph to mph. They were excellent. Gave me the paperwork for the change of speedometer for import into UK. I think the cost was 229 euros.

advisemerite

https://www.boards.ie/discussion/comment/121772713#Comment_121772713

Do you need a new clock fitted or how does it work if you don't mind me asking. Thanks.

dickdasr1234

https://www.boards.ie/discussion/comment/121772713#Comment_121772713

Brilliant - thanks!

kirving

It depends on the car. Swapping the plastic is easy, but some cars require more coding or component replacement.

dickdasr1234

It's a BMW 118d. All that it requires is a simple clip-in plastic insert but that is not available anywhere online. The dealership says it requires a new unit at a cost of €1400 which is quite ridiculous.

They insist that the speedo unit is a sealed with a tamperproof sticker and cannot be opened without voiding the warranty, in effect saying that their mechanics are not qualified to work on the car's speedometer.

GSBellew

https://www.boards.ie/discussion/comment/121773763#Comment_121773763

They would be correct in that opening it will void the warranty on the speedometer unit, the parts themselves would not be available to purchase from BMW either, it would be the entire unit.

On many cars in the past I have bought a secondhand set of clocks and swapped the speedometer foil from one to the other (once the speedo scales match), then either changed it to km in the cars clock menu or via coding on a computer depending on the car.

Whatwicklow

A long time ago this issue was routinely remedied with a sticker (specific to the car) to go under the the needle and over the mph or kph range.

User1998

If the clocks are in miles does it not show your speed as kilometres as a digital readout?

kaahooters

mph kph

20 -- 32

30 -- 50

40 -- 62

50 -- 80

60 --102

70 --115

80 -- 130

roughly quick conversion, if your under teh mph, say 38mph, youll be under the kph limits

Esel

Quick rule of thumb to use:

MPH + 50% = Km/h

When you allow for speedometer usually showing more than real speed, it is reasonably accurate, and easy to calculate.

e.g. Speedo shows 80 mph, so 120 km/h (which is actually = 75 mph).

User1998

https://www.boards.ie/discussion/comment/121775363#Comment_121775363

The speedometer shows more than your actual speed, not less. It usually shows around 5% more. So if your speedo says 120, your actual only doing about 112 or so

Esel

https://www.boards.ie/discussion/comment/121775437#Comment_121775437

My mistake, edited.

Rule of thumb works though! 😃

kirving

https://www.boards.ie/discussion/comment/121775437#Comment_121775437

https://www.boards.ie/discussion/comment/121773763#Comment_121773763

The speedometer doesn't necessarily over read, I've had a car that was bang on perfect, and others which over-read by varying amounts at 120km/h.

Depending on the year th 118d is, BMW are correct. My UK import 330e was the same. You can code the car so that it will show your speed in km/h in the digital display - for some stupid reason it's not enabled from factory.

Secondly, apparenly there is no way to change the speedometer configuration from mph to km/h. At least not that I found. My understanding is that they have linked the base software/hardware of the circuitry, with the plastic speedometer panel.

I can only think the reason they didn't give the option was that it was a ham fisted solution to help prevent clocking cars.

dickdasr1234

https://www.boards.ie/discussion/comment/121776505#Comment_121776505

The plastic panel is not in any way linked to the electronic circuitry.

Clocking cannot be done as the mileage is held centrally.

The speedo is apparently sealed to prevent the insertion of electronic gadgetry.

It is bewildering that BMW cannot entrust speedometer work to their own qualified staff.

Surely it is not very difficult to provide a method of re-sealing the unit?

So much for the era of recycle/reuse!

kirving

https://www.boards.ie/discussion/comment/121777280#Comment_121777280

It is linked, in the sense that the electronics of KPH/MPH units are "different" to one another in some way (hardware/firmware) and you cannot buy a unit with MPH on the plastic dial, and easily code it to display the odometer or cruise control speed in KPH on the digital display.

I'm not sure what you expect a mechanic to actually do? As far as I've managed to find out, this is very low level hardware changes, and firmware programming and is in the realm of an electronics engineer. BMW don't even make any electronics themselves, the instrument clusters are made by a thier party who do most of the design work and programming.

I agree that it should just be a very simple change on a menu, but for some reason BMW or their supplier chose this way, and it's now very difficult to do.

I just remembered that 50km/h is 30mph, 80km/h is 50mph, and 120km/h is 75mph and didn't bother going to big effort to change it.

Esel

A new one to remember for you so 😀

30 km/h 'equals' 20 mph

dickdasr1234

https://www.boards.ie/discussion/comment/121777340#Comment_121777340

You seem to be misunderstanding. It is an analogue speedometer. The needles are mechanical. All that is required is a different scale as a backdrop.

(Read GS BELLEW post above)

The odometer KPH/MPH reading is readily changeable via the iDrive.

beachhead

https://www.boards.ie/discussion/comment/121775437#Comment_121775437

Always thought it was less.

kirving

https://www.boards.ie/discussion/comment/121779820#Comment_121779820

Ah ok, I assumed the issue was similar to an F30 3 Serier, where the Cruise Control speed on the instrument cluster could not be changed to kph, even though it could easily be done for anything which was displayed on the iDrive menu.