Our VDO Speedo has been failing for a couple of years so when I saw a GPS speedometer online, I checked it out, compared them and bought the one I have linked to. They come in all styles but I wanted one that would match the OEM Speedo. The model pictured has both odometer and speedometer with two settings for the ODO. The first resets each time the key is turned off and the second stores the trip mileage until you reach the back of the speedo and reset it. Make sure it has a black rim so it will match the rest of the VDO instruments. Some are chrome.
Warning: the GPS receiver must be plugged in before applying power to the speedo or it may never operate correctly.
I installed it a vehicle using a 12V hot strip with lighter plug. The GPS speedo takes a minute or so to first locate itself. After that, it's ready to go quickly. The hand is smooth and only lags by a second or so when accelerating and is not noticeable. The GPS receiver is on a 12 foot cable so can be mounted anywhere but best out of the sun. The new speedo is dead accurate at all the speeds that I tested it against the SUV speedo.
Here is the link for it. 85mm GPS Speedometer 120km/h Odometer 0-80MPH 8 Colors LCD Trip Gauge... (https://www.ebay.com/itm/224260594107)
If you have an electronic engine and your speedo has not worked for a while, you can take a reader and multiply the MPG times the gallons used since new to to get an accurate miles since new for the coach.
The factory hole in the instrument panel is a very tight fit for the original speedo and it took about five minutes to remove the old one. I used a stone on a die grinder to take off the high spots so the new plastic speedo would install without forcing it.
The only negative is the face is convex so reflects more than a flat face would. The speedo is sealed so no dust or moisture can get in. If it goes bad, it can't be repaired. You have to buy a new one. The wiring plug locks in place so it also cannot be removed.
COG means Course Over Ground in magnetic degrees. This is for boats so the Trip should be selected. Knots, Kilometers can also be selected. Default is miles/mph. Lots of color choices. Easy to change them.
I used a felt marker to mark the Set and Select buttons. When installed, the select/mode button will be toward the curb/passenger.
Remember to screw in the GPS receiver before applying power. I used the old 12V speedo power wire that is hot when the key is turned on. I just cut and used the old wire for the light bulb from the old speedo. Ground is easy with several green wires with connectors already installed. The LEDs for night lighting don't dim well to match the rest of the instruments but it's not too bright.
80 mph will be a good match for the new M rated tires.
Pierce
Where did you mount the gps?
I just ran it over to the ps windshield base.
So it can't be under dash?
Probably could be under the dash top. Just have to see if it works as well there. Coil the excess cable and tie wrap it. The biggest thing is to keep it out of the sun. I've had trouble with remote GPS receivers that had the sun on them. Garmin GLO bluetooth receivers are dead accurate but quit if they get warm at all.
Pierce
GPS Speedo review after a trip:
Took our first trip after the GPS speedo installation. Works great, nice and smooth. I was going to set the trip ODO to record mileage without resetting but decided to try the reset every time the key is turned off. Decided that I like it that way. Cold start for the speedo's GPS takes about 10 seconds before it's ready to drive.
Pros: Easy installation, perhaps 2/10
Nice and smooth plus very accurate
Sealed so waterproof, no dust possible inside
Lighting in several colors
Inexpensive
Will work in any vehicle, boat, jet ski with Knots, Km also direction you are going
Cons: Convex face so it picks up reflections from a fairly large area in the daytime
Numbers are OK but not as subtle as the VDO tachometer as seen in previous post
Wish it had an external connection so you could easily change colors, miles to knots, trip ODO, etc.
You have to open the dash top and push button on the back.
Overall, very pleased with it.
Pierce