GPS Speedometer Build

[kb0nly]

I hinted at another project i had in the works in my 81 ATC200 build post.... Well here it is! I have all the initial parts together, parts designed, prototypes made, and its come together enough for a sneak preview!

My 200ES has a speedometer which is nice because we city ride them here, but we are required to stay under the posted speed limit. The speedometer has gotten me out of a few arguments already when someone accused me of "tearing across town" and i showed the cops the speedometer which they didn't expect me to have. So for my 81 ATC200 i wanted to do the same thing but finding an affordable Hondaline Speedo is not an easy task these days. So i went searching for other possibilities. I did look at cable drive options, ones that used inductive sensors, you name it i looked into it. Then someone told me about a GPS speedo they have on their boat, although that one is calibrated in knots instead of MPH. However these GPS units are available in MPH also!

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Cost was $53 shipped to my door, thats pretty cheap honestly. The body is plastic, the face is a metal ring and polycarbonate lens, not glass unfortunately but for the cost i wasn't really expecting glass. It has the most basic of connections, Ground, 9-32v DC for the Speedo, and 9-32v DC for the backlight, so just three wires. The GPS antenna is a separate unit that connects with small coax and SMA connector. I tried to find a speedo unit with a built in antenna but the choices were rather limited, and i suppose that makes sense as generally its going to be in a dash not in the open like it will be mounted on my 200 so a remote antenna is required.

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I started by taking the original Honda speedo bracket and drawing it up in Fusion360 and then laser cut a wood prototype to compare to my OEM bracket, then i modified the dimensions to fit the GPS unit. It was actually not that far off on the hole spacing, the GPS unit is 70mm center to center on the mounting studs, the OEM Honda is narrower. So i just moved out the outward hole a bit, added another hole for the SMA connector to peek through the bracket, and then cut another prototype.

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The end result was a perfect fit! Now as for the bushings, i did find bushings available from McMaster that would work for the GPS speedo and the stock bracket hole size of 1/2", but i didn't want to order 50 of them to get a couple. So i designed and 3d printed the bushings in TPU, TPU is a thermoplastic polyurethane, which is the material bushings and bumpers are made out of. I have had good luck with this material making grommets and bushings for other projects, headlight bushings, plugs, etc. So i made up a set for this. I did make them as two pieces though so they were easier to print and install in the bracket. Then i took some 6061 aluminum rod to the lathe and turned it down to 1/4" OD and drilled a through hole of 4mm to pass through the studs from the GPS speedo, the end result is an OEM style isolated mount.

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I just got done designing a cup that will go around the speedometer, as well as cover and hide the wires exiting the back of the unit. Its currently printing, so once thats done hopefully later today or tomorrow i can get that all put together and get some more pictures of the design. The cup is going to be sanded and painted black to look like the normal metal can of a speedometer. It will all make more sense when its done and i get some pictures!

The mounting bracket design has been sent off for cutting in metal, i should have that next week i hope. I went with 6061 1/8" thick aluminum. I know the originals were steel, but this speedo is very light... Like less then a pound light, and even with the cup i am making to go around it the weight will not be such that the bracket will be stressed in any way, plus there won't be a speedo cable hanging down to the front wheel, etc. There just wasn't any reason to go super heavy on the bracket. The cost vs steel wasn't much different, but my plan was by going aluminum that i can anodize it black if i want, no painting, no rust, etc.

Anyway, that's where this project is for now, more updates as they become available. I also have a small rectifier/regulator that i am testing with the ATC200's AC output to give me the power i need for the speedo. The speedo is very forgiving, rated for 9-32v input, i tested it on my bench supply it gets a GPS lock in seconds after its first initial cold start, and works great across the entire voltage range. So that info will be shown when i get that done as well. The GPS antenna is going to go up in the headlight bucket, it will just get bundled with the DC wiring and get stashed in there. The plastic bucket won't cause an issue with the GPS signal. But the coax is long enough you could put it anywhere on the ATC front to back no problem. Just needs a clear view of the sky.

[kb0nly]

Next piece made... The outer shell/cup to go around the Speedo is made. I made a little hood that goes over the wiring, the wiring will get loomed later and a TPU boot on the end of the wire looming will push into the wire hole on the little hood, should be a nice finished look. The cup has a small weep hole in the bottom, so if any moisture does get in-between it can just drain out. The Speedo is rated for direct weather exposure, IP67 rated, so it shouldn't be an issue. There is an o-ring around the back lip of the front black trim ring, the cup i made has a slightly rounded edge around the interior of the top edge to seat against that o-ring, once its installed into the bracket and the nuts tightened down on the studs it tightens the cup up against that o-ring and against the back of the front black ring. Looks like a pretty good seal, but again doesn't need to be submarine tight. The hole for the SMA connector will get a TPU boot on the connector from the antenna, just haven't made it yet, not so much waterproofing as just giving a neat finished appearance.

Other then making those two TPU wiring/connector boots i am now just waiting on the water jet cut aluminum mounting bracket, and i have to take this back apart and lightly sand and paint the cup a nice semi gloss black.

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I will of course keep you updated as progress is made!

[coolpool]

I'll say you have some mad skills my friend! That will be a nice factory level addition to your ride while keeping the po po off your back.

BTW, did you get the CDI's I sent your way yet?

[BarnBoy]

Very cool KB. Whats your day job? At work we use Fusion360 for a lot of design and machining work. Im trying to learn 2D CAD, and eventually 3D like Fusion when I can.

I like your concept, I think it will be a very cool setup. One question I have is, how reliable is the GPS signal? I know you mostly street ride but I could see being on a trail through the bush or down in the hills where signal wouldnt be very reliable. I could be wrong though, curious if you've seen others do this on offroad equipment before?

[kb0nly]

I'll say you have some mad skills my friend! That will be a nice factory level addition to your ride while keeping the po po off your back.

BTW, did you get the CDI's I sent your way yet?

Got em! Just got on here and sent you a private message then noticed the posts on here.

[kb0nly]

Very cool KB. Whats your day job? At work we use Fusion360 for a lot of design and machining work. Im trying to learn 2D CAD, and eventually 3D like Fusion when I can.

I like your concept, I think it will be a very cool setup. One question I have is, how reliable is the GPS signal? I know you mostly street ride but I could see being on a trail through the bush or down in the hills where signal wouldnt be very reliable. I could be wrong though, curious if you've seen others do this on offroad equipment before?

Very reliable... It gets a lock in my basement workshop, if it can do it there i can't see how it wouldn't amongst trees, this is a brick house and only a couple basement windows, so its getting signal through who knows where but it did maintain a lock. I also checked it in the garage, just thinking what it would do if i was to start there and it couldn't get a lock would it attempt to again after driving out of the garage, the garage is also a brick structure, so it was getting signal through the roof and the attic floor, because the only opening would be the garage door and that was closed at the time, and its a steel door which would be quite effective at blocking the signal.

I've seen a lot of guys with hunting GPS units on their quads, if their GPS will work in a grove of trees in the bottom of a valley i would assume this would. It doesn't need a super accurate positional lock either, its just calculating the moving speed, so if its positional accuracy is like 20-30 meters it won't matter anyway because i am not mapping my location.

Time will tell how it does, i'm waiting on the aluminum mounting bracket and a few other bits to finish making my wiring harness and converting the AC lighting system on the ATC200 its going on to DC. Its getting a conversion with a rectifier/regulator module, a small battery, and LED lighting as well. I do plan on taking this speedo and just using some cable ties to fasten it to my 200ES and give it a good test run though. I have been meaning to but last week was busy, this weekend got even busier and today it was raining and thunderstorms, so i just didn't get that far. However it did work just moving around the yard but i want to get out on the street and up to speed limit and compare it to the speedo on my 200ES which i know is accurate from testing it after i rebuilt it.

[kb0nly]

Forgot to mention... My day job is product design and prototyping, i do design work for numerous companies, and i also do some custom design and fabrication work that i sell myself. Fusion is not hard to learn if you take it in steps, i started in the 2D world as well, doing AutoCAD drawings for sheet metal parts with a previous employer. With Fusion your just starting from a 2d sketch and then your extruding into a 3d object from there, its actually pretty easy to get going on, i've been using Fusion for 6 years now as my only design software and i love it.

I have a room full of 3d printers, both FDM and MSLA, i have a mill, a lathe, and i make a lot of stuff in various materials. Currently my day job is self employed business owner!

[kb0nly]

I did settle on one minor design change. Originally i was going to put the antenna for the GPS up in the headlight bucket, mostly out of convenience to get it out of the way and deal with cable management, but then after testing and see how well it locked onto satellites i decided instead to test it with the antenna mounted under the bracket for the Speedo. The Speedo itself is mostly plastic, and even though the finished bracket will be aluminum i don't think its going to be an issue as the antenna seems more then capable and will be mostly exposed with its backside to the bracket, if i have to change it when i get the aluminum bracket so be it, but if it can get a lock in a basement i think it will work fine. So i moved the antenna to the bracket, it will be a drilled and tapped hole for a cap screw. I took the antenna apart, shortened the RG-174 coax on it which was easy enough by desoldering it and cutting it to length and soldering it back on. And now its a more compact all in one piece that will just have a few wires coming off it.

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[kb0nly]

Aluminum brackets are here! So thats the next step down. Currently waiting on some connectors and bits and pieces to finish the DC conversion then i can get going on the work to install it!

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I got the battery box made as well, its just some scrap 3/4" steel angle that i had to make the bottom frame, a piece of poly sheet for a bottom for the battery to sit on, the battery clamp is just a couple 1/4" bolts going into some standoffs welded on the sides that i drilled and tapped and a scrap of flat bar. I also made a plastic battery cap that i designed and 3d printed to go over the battery and under the clamp, the reason is the battery is going in the trunk at the far front of the trunk, so it will be tucked up to the front and out of the way and not take much space but i need to add some insulation to the terminals to protect it from stuff getting put in the trunk. The battery will be a YTX4L AGM 3Ah, yes i know thats not a lot of battery but its only going to be acting as a filter for the rectifier/regulator to knock down the AC on the output as well as giving some reserve so the lights and speedo will work without the engine running. I don't need hours of reserve to run the lights, so this small battery is a nice compromise and a perfect fit for the front of the trunk space.

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[BarnBoy]

Very reliable... It gets a lock in my basement workshop, if it can do it there i can't see how it wouldn't amongst trees, this is a brick house and only a couple basement windows, so its getting signal through who knows where but it did maintain a lock. I also checked it in the garage, just thinking what it would do if i was to start there and it couldn't get a lock would it attempt to again after driving out of the garage, the garage is also a brick structure, so it was getting signal through the roof and the attic floor, because the only opening would be the garage door and that was closed at the time, and its a steel door which would be quite effective at blocking the signal.

I've seen a lot of guys with hunting GPS units on their quads, if their GPS will work in a grove of trees in the bottom of a valley i would assume this would. It doesn't need a super accurate positional lock either, its just calculating the moving speed, so if its positional accuracy is like 20-30 meters it won't matter anyway because i am not mapping my location.

Time will tell how it does, i'm waiting on the aluminum mounting bracket and a few other bits to finish making my wiring harness and converting the AC lighting system on the ATC200 its going on to DC. Its getting a conversion with a rectifier/regulator module, a small battery, and LED lighting as well. I do plan on taking this speedo and just using some cable ties to fasten it to my 200ES and give it a good test run though. I have been meaning to but last week was busy, this weekend got even busier and today it was raining and thunderstorms, so i just didn't get that far. However it did work just moving around the yard but i want to get out on the street and up to speed limit and compare it to the speedo on my 200ES which i know is accurate from testing it after i rebuilt it.

Wow, ok if it gets a lock down there I dont see why it wouldn't on all the but the most remote trails. But even then satellite access shouldn't be too bad.

I'm starting with QCAD, drawing parts I can cut on the plasma table at work. Would love to branch into 3d once I figure this all out. Sounds like a neat job, and you get to make a lot of neat things.

Looking really good so far!

[big specht]

Keep us updated this is a interesting project

[Baba Yaga]

There are GPS speedo units that have the antenna built-in. Might be easier. :)

[kb0nly]

I will keep you guys updated! The ones with the antenna built in are a bit easier, but not a whole lot of trouble for the antenna, and it gives me the look i want. I wanted it to look like a regular old mechanical speedo, not a digital readout or an LCD display, i picked this one more on looks then features. If there is a mechanical GPS one with a built in antenna i haven't found it, these are generally made to be mounted in a dash panel so the antenna is an external part with a long cable.

I have seen the ones with the antenna built in though, that could be an option for someone that doesn't want the old school looking speedo.

Just waiting on parts now. Next week i should have the rest of the connectors i need to make the harness for adding the rectifier/regulator and the battery to convert to a DC electrical system. Then it should be pretty fast moving from there to finish this off.

[kb0nly]

Some minor progress, this project has been slowed down waiting for parts and the USPS being slower then slow these days. I did however get the 200E dash installed, ignition switch popped in just not wired up yet, and started making the harness to install the rectifier/regulator. Really just waiting on the rectifier/regulator i ordered for this project to get here now, also have a choke cable coming to install, going to switch it over from the detent style choke lever on the carb to a cable actuated choke up on the dash. The main reason for adding the ignition switch is because i wanted to switch the DC off and on to the speedo and lights through it like the other models are wired up. I do plan on eventually putting a left control on with a headlight and kill switch and removing the universal kill switch from the right side and the headlight switch from the headlight bucket, basically so its more like a 200E but no electric start. I just haven't had time to dig around for a left control switch yet.

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Today i got sidetracked playing in the snow.. Just over 4 inches of snow fell today, so of course i had to go out and play.

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Once i get some more parts i will get back on this. Its nearly complete though, just waiting for the final bits and then i put it all together. In the end i know it will be a hodge podge of years and parts, but it's what i want and i think it all goes together nicely.

[kb0nly]

A little progress today, i got caught up doing a rear axle seal replacement on my 200ES today, along with some other pre-winter projects. However the Rectifier/Regulator finally showed up so i got the harness made to T this into the harness, using the 82 optional DC kit wiring diagram as my inspiration for adding this. Hopefully this weekend i can get to work on installing all the parts. I also found a lefthand control for the kill switch and headlight, so i got to take that apart and clean it and refurbish its internals, then i should have all the bits i need to install and convert it to DC, then i can bolt on the GPS Speedo as well. Future project will be converting the headlight to LED like i did on my 200ES, but for now the lights are fine and will be better on a regulated DC system anyway, but at least i will have the option for LED now.

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Starting to feel like doing this project is like that old song.... One Piece at a Time... Waiting for the mailman every day gets old!

[kb0nly]

Its basically done now! Got all the wiring done, speedo installed, really impressed with how fast it gets a GPS lock and how reliable it is, even in my brick garage it had a lock in seconds. First lock after being off a while, aka a cold boot, takes about 30-40 seconds, but then a warm boot after a ride and shutting it off for a while and back on its pretty quick, seconds. Takes about 20-30 minutes it seems like before its doing a cold boot again after being shut off for that long.

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The speedo backlight turns on with the headlight switch, i forgot to turn it on for this quick snapshot. I am making a TPU plug to fill in where the original headlight switch was on the headlight bucket, i changed that out to a headlight/kill switch on the left handlebar from an 83. The ignition switch acts like it does on all of them that have a battery, turns on power to the headlight switch and GPS.

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The rectifier/regulator is mounted to a small piece of flat bar that i drilled and tapped and welded to the frame, i normally don't like welding stuff on a frame but this ended up to be the cleanest and easiest option to mount it.

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The battery is in a hold down bracket that i made and pictured earlier, its mounted in the trunk with a couple small machine screws going through the floor of the trunk and the heatshield on the bottom, makes for a plenty sturdy mount for a small battery that don't weigh much.

I will get some better pictures when i finish up the headlight and can get it out in the daylight, it was getting dark by the time i finished tonight and i couldn't get much light for pictures.

[jasong_10]

Nice work, it looks OE

[kb0nly]

Thanks! That's what i was going for, i don't care if its not 100% accurate... I just wanted something that looked the part, mechanical speedo, mounted in a similar fashion. The backlight on it is super nice, i will try and get a picture of it when i close everything up tonight, i gotta go finish cleaning up my mess of tools... LOL

The odometer display on it is pretty neat, it shows your direction in degrees, and changes between that and miles, it alternates on its own, i think when there is a heading change it goes back to the degrees shows that change in heading for a bit, then goes back to odometer. I know some other ones have a button on the bottom that you can press to change modes on the display, and some even have RGB lighting in them so you can select your backlight color. This one is a pretty basic unit, but it works great.

[kb0nly]

Picture in the dark... Was surprised, went out and turned on the key and it had a lock in like 20 seconds again. So perhaps the 30-40 second cold boot i was seeing was because of the garage, in the shed its normally parked there is far less obstructions, no brick or metal, to the sky.

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Overall i am quite pleased how it turned out. Once i get a plug in the headlight hole where the switch was this project is done. That was really satisfying being able to turn on the key and have lights on it without running. I have been spoiled by my 200ES all these years. LOL