Vintage GPS Speedometer question

[BB767]

Trying to clean up some loose ends on the build. There is insufficient information in the literature for the Vintage gauge set so I am looking for someone who knows more than I at this point. I know how GPS works, so I do not understand what there is to "calibrate" on it. Is this requirement in the instructions left over from older, non-GPS versions? Or is there some mechanism in the gauge that needs to be synced with the antenna?

I have about 40 miles on the speedometer go-karting up and down my street.

The directions are adamant that the speedometer will not work without calibrating it but it seems pretty darn accurate as is both in speed and mileage.

Question is, once I get it legal, out on the street, and can maintain a constant speed, (as per the instruction manual) do I really need to do a calibration on it or not?

[Papa]

Brien,

There isn't any calibration needed that I've found. If there were a separate pulse signal coming into the gauge, yes, but purely GPS, no.

Dave

[BB767]

I agree with you. So why does the instruction sheet have in BIG BOLD LETTERS that is MUST be calibrated? I am concerned there is something else to it that we do not know about.

[Papa]

I agree with you. So why does the instruction sheet have in BIG BOLD LETTERS that is MUST be calibrated? I am concerned there is something else to it that we do not know about.

I don't know what there could possibly be to calibrate? GPS is purely a time-based system for user equipment like the speedo. It's simply measuring the time delay of the PRN for four or more satellites to calculate pseudo-range from the receiver to the satellite. It takes three for location and one for time to calculate your location. I don't recall seeing that in the instructions, but honestly I didn't look that closely. If in doubt, a call to Speedhut should clear it up. By the way, I actually work on the GPS program. I'm integrating the ground control segment's new architecture called OCX.

Dave

[Papa]

Brien,

I just went and pulled my gauge instructions out of the shop and I can't see any reference to calibration except for the fuel gauge. My instructions are labeled 14650 Revision B July 2007. Is it possible that you have a sheet for a mechanical gauge?

Dave

[BB767]

I have the exact same version. Pages are numbered 1, 2, 3, 4, blank, 7, 8, 9, 10.
The page after 4 with no number on it has the "Speedometer Operation and Calibration Instructions".
Page 4 is labeled "Speedometer Instructions".
Weird.

[Papa]

My page numbering is jacked up, too. I have 1, 2, 3 and the rest have no page numbers. What would be page 4 is "GPS Speedometer Instructions" - no mention of calibration anywhere. Do you want me to scan mine into a PDF and send them to you?

Dave

[BB767]

If it is not to much bother. Obviously I do not have that page.

Looks like you finally got those headers squared away. How's the rest of the build coming?

My chassis goes back to the paint shop next week. Four or five weeks later I should have a car that is pretty close to being done! Now if I can just get it registered here in the peoples republic of California...........

Thanks

[Papa]

If it is not to much bother. Obviously I do not have that page.

Looks like you finally got those headers squared away. How's the rest of the build coming?

My chassis goes back to the paint shop next week. Four or five weeks later I should have a car that is pretty close to being done! Now if I can just get it registered here in the peoples republic of California...........

Thanks

I'll be working on body adjustments this weekend. The car is definitely coming together. I want to get some drive cycles on the PCM to see how it reacts to having the O2 sensor finally in the loop. PM me with your e-mail and I'll send you the PDF for the gauges. It sounds like you got a completely different set of instructions.

Dave

[edwardb]

Speedhut has all their gauge instructions on the web. Obviously sounds like you received the wrong ones with your gauge set. Should have received instructions like this: https://www.speedhut.com/instruction...structions.pdf

No calibration required for the GPS version. Just power it up and go. The GPS gauge has some features that aren't on the others, plus there's a specific "Hot Start" wire you should include in your wiring.

[BB767]

Nice.

Thank you both, it's great getting instant satisfaction! That is exactly what I wanted to see.

Won't need the PDF now Dave, thanks for the offer.

[Papa]

Nice.

Thank you both, it's great getting instant satisfaction! That is exactly what I wanted to see.

Won't need the PDF now Dave, thanks for the offer.

You bet! I still think I owe you a few more of these to make up for the EFI help you gave me. The instructions in the link Paul provided are exactly the same as what are in the package I have.

Dave

[BB767]

You bet! I still think I owe you a few more of these to make up for the EFI help you gave me. The instructions in the link Paul provided are exactly the same as what are in the package I have.

Dave

Naw, I will collect with a nice drive in the mountains and refreshments after.

Glad you could make the FAST system work. I got so frustrated with it I returned it and got the Holly Sniper. Had MUCH better luck with that so far.