mx5cartalk.com

Hi,
Looking to install a HUD speedo (as current speedo not accurate enough). Don't have OBD so it has to be GPS.
Any experience with visibility of the digits in the sun, especially in a convertible?
Any recommended models (quite a few on fleabay for around $100). I'm after quality and longetivity.
I've used my phone with an app, but it is impractical putting it in and out.
Ta

Why is current speedo inaccurate? Mine (in a NA6) was spot on, are you running the right wheel size and speedo sensor?

Anyway http://www.jaycar.com.au/Automotive-%26-Mobile-Security/Car-Safety-Products/Other-Car-Safety-Products/Heads-Up-Display-%28HUD%29-GPS-Speedometer/p/LA9023

Be aware that GPS is NOT the most accurate and will not work when there is no clear sky above it, for example in a tunnel.

If you are after quality and life span you can install an aftermarket speedo and sensor like this http://www.bsmsport.com.au/ecommerce/index.php?productID=52. This sensor will allow the signal to go to an aftermarket ECU as well as any other display that can use it.

You can purchase speedo correctors for electronic speedos, they basically alter the pulses so you can take up the inaccuracy.
Won't work on a cable dríven speedo though.


from memory though, you've got an SR20 in your car havent you? so i'm assuming very little Mazda left in regards to gearbox/diff/speedo cluster.

If you just want a temporary solution you can download HUD speedo applications for your phone, from my experience they work fine. However in direct sunlight they get a bit hard to see.



The jaycar unit looks like the best value permanent solution though.
I'm even tempted by one...

I run the DigiHUD app on an old android phone with a not very bright screen and a Qstarz GPS bluetooth receiver. Even then the fluoro yellow numbers on black background are good enough in daylight.

edit: sorry, just re-read your first post and realised you don't want a phone app. The info may help someone though.

Thanks for all the advice.
Yup, not much MX left in my car. I've got a converter box but can't get it accurate enough (too many speed cameras here so every kay counts).
Plus HUD would be easier to see, as my steering wheel blocks part of the speedo.

Just curious, how far off are you?

And is it off by say a %, or by a set figure? (if it’s 10kph off at 100kph, is it 5kph off at 50kph?)


If it’s off by a percent, then it may just be that the speedo adapter thing doesn’t have enough adjustment (I assume it’s set to maximum adjustment and still not the right speed?)

You could either look into a different adjuster, that allows a far greater adjustment range (I think most are assuming the speedo is maybe 5% off max, if you’ve got completely different diff/wheels/gearbox it could be far beyond that)
The other option may be to talk to someone who knows about electronics, they may be able to design and make a circuit that allows as much adjustment as needed (from memory it’s just taking a pulse of X per second, and having the circuit either speed it up or slow it down before sending it to the gauge)


If it’s off by a set amount at all speeds (10kph at 50, 10kph at 100, etc) then it may be as simple as the speedo needle being put on in the wrong position. I know some speedos need the needle set at a certain point to read correctly. This is as simple as removing the needle, drive the car at whatever speed (check with a phone GPS or something) and then lightly pushing the needle on to point at the speed the GPS says. Then when you’re stopped you can test it at a few other speeds, and if it’s ok push it on properly.

I just can't seem to adjust my converter to be accurate. It is not linear, so it drives me up the wall.

bruce wrote:I just can't seem to adjust my converter to be accurate. It is not linear, so it drives me up the wall.

ahh, fair enough.

I know the basic way they work on paper, but i've never actually used one so can't really help sorry.



If you know the diff ratio, and the size of the rear tyres/wheels I can do some calculations and let you know how many rotations the tailshaft does for every km travelled compared to a stock MX5, which can help give you a baseline of what the main differences are speedo wise.

You might then be able to set the speed corrector thing better, or maybe even just see if an electornics guru can make somehting that takes those figures into account (you dont want me to try that..... I can make electrical fires, but not much more... the maths bit i'm fine with)

Hey,

I have the Polaris GPS HUD which I was using in my last car. I really liked it, but haven't tried it in the MX5 because it is too easy to reach in and steal (or worse, slash the top and steal).... same reason I haven't moved my dash cam over.

I bought mine from: https://www.ja-gps.com.au/Polaris/gps-speedometer-hud/ and was happy with the service.

Depending on the day it can take a minute or two to connect to the GPS signals. Generally if you start the car outdoors its connected within 15-20 seconds or so.

I tested it and it was accurate with the speeds. Whenever you pass under a bridge or something it glitches out for a second, and obviously doesn't work in tunnels or the like. One thing I did find a little annoying was the 2-3 second lag between speed updates, if you take off hard you can easily hit 70+ before it gets to 60.

I didn't use the tint film they supplied. I found it generally bright enough (a bit dull in glarey sunlight), but sometimes a bit too bright at night on a dark street.... I found an easy solution was just using the tilt on the unit to push it away from the glass when it was too bright and pull it up close when it is too dull.

The speed readout is nice and big, and in a classy white colour, which turned me off a lot of other options.

joshuam wrote:I bought mine from: https://www.ja-gps.com.au/Polaris/gps-speedometer-hud/ and was happy with the service.

I've taken their advice at the St Kilda store on a few GPS things in the past and they've been very good. Might be worth a visit and open discussion.

Got a Polaris green. Roof down in sunshine you can't see it. Will have to try the tint film.

Works well. Tint film compulsory when roof down in the sun.