Odometer error is pretty big

[regularman]

I took a trip of 57 miles and the odometer said that I only went 35. I got to figure that out. 38% if my math is right. I need to do the mile post thing on the interstate to make sure. No wonder I am getting such bad mpg from what I had figured.

 

[zimmy]

wow, guess thats good if ur selling it later..... :wink: ...z

 

[regularman]

wow, guess thats good if ur selling it later..... :wink: ...z

yeah, right :lol: I just want to know how far off the trip meter and odometer are so I can set it and know how far I can go before empty, just in case I don't trust the fuel gauge. Its good to know so I can do the numbers in my head.

 

[dklawson]

Well... it sounds like the wrong speedo is fitted. Didn't you just reset the needle to give you good speed indication?

There is something else you may want to do (temporarily or permanently). You can fit a Sigma BC-1600 bicycle computer and quickly calibrate it to work with your tire size. That will free you up to investigate the mechanical speedometer situation in detail and still enjoy driving your car (at the legal speed!)

 

[regularman]

Well... it sounds like the wrong speedo is fitted. Didn't you just reset the needle to give you good speed indication?

There is something else you may want to do (temporarily or permanently). You can fit a Sigma BC-1600 bicycle computer and quickly calibrate it to work with your tire size. That will free you up to investigate the mechanical speedometer situation in detail and still enjoy driving your car (at the legal speed!)

There probably is not correct speedo for the rear gear that I have and the 5 speed. I have to make it work for the speedo and remember my % error for the odometer.

 

[bugimike]

Well... it sounds like the wrong speedo is fitted. Didn't you just reset the needle to give you good speed indication?

There is something else you may want to do (temporarily or permanently). You can fit a Sigma BC-1600 bicycle computer and quickly calibrate it to work with your tire size. That will free you up to investigate the mechanical speedometer situation in detail and still enjoy driving your car (at the legal speed!)

There probably is not correct speedo for the rear gear that I have and the 5 speed. I have to make it work for the speedo and remember my % error for the odometer.

Then the bicycle speedo sounds like a good alternative, Kim!!! :wink:

 

[dklawson]

Kim, I didn't realize that you had changed your gearing to something that wouldn't be standard. You've already put a lot of effort and money into this so I'm hesitant to suggest more but there is a fix for your problem.

When my wife and I put her GT6 back on the road 15 years ago we discovered that my father-in-law (the previous owner) had put a different rear end in the car and that there was no "proper" speedo for the drivetrain. I had Nichols Speedometer in Greensboro clean and service the speedometer AND I had them make me a ratio box. The ratio box goes inline between the transmission and the speedometer head. It takes the turns/mile from the gearbox and converts it (up or down) to match what your speedometer needs. You need to supply them a new speedo cable and work with them to determine the ratio you'll need. The ratio box will allow you to have a working and accurate speedometer and odometer.

There are lots of other places that can do this but since you're in NC and I used these people many years ago I suggest you contact them. Their "contact info" web page is:
https://nsifleet.com/contact_nsi.html

Fitting the Sigma bike computer to a Spridget will be a little more complicated than on a Mini but I remember someone on this board has done it. I've very pleased with the Sigma as a backup speedometer/odometer on the Mini. The only thing it lacks is built in 12v backlighting.

 

[Trevor Jessie]

Not sure if this has been discussed.

For $$$ rivergate can supply you with a angle drive that corrects the ratio. You provide them with your specs (rolling radius of tire, diff ratio, speedo turns per mile) and they send you the correct gearing. I bought one about a year after installing my 5-speed and was glad that I did.

 

[regularman]

Well, I have the speedo adjusted where the needle is fairly accurate in the 40-70mph range with 60 being about spot on. I did this by simply moving the needle on the shaft. This is good enough for me. I just want to find out the error of my odometer and remember it. I did this on my kia sportage when I put bigger tires on it. I corrected the speedo at 60 and then just remembered that I had to add 9% to my odometer and trip meter mileage to be correct. I always like to do this and have a good idea how many miles I should be getting to a tank full. Once you know that, then its a good way to spot problems if that mileage changes. I am not going to spend a lot of money on this. I talked to rivergate about this once and they wanted a lot for a ratio box. Long as the speedo needle is ok then that is good enough for me.

 

[Jim_Gruber]

For $21.95 or less you can always add a Sigma 1200 wired Bicycle Computer that will be spot on for mileage as well as Odometer reading. Mount on dash from mirror bracket, fun project. Got details if you want. A whole lot less than getting speedo recalibrated.

 

[Trevor Jessie]

I understand not wanting to spend the money on the angle adapter. I drove mine for a year based on the tach (I never hooked up the speedo). Then one day I was "clocked" doing 35 in a 25 (school zone)while in third gear. I was let off with a warning, but I had to get the faulty equipment fixed and inspected. So suddenly it became "economical" to buy the adapter. If that incident hadn't occurred I might still be driving based on the tach. But, it is nice to have the speedo working now (esp when my wife drives it).

 

[regularman]

For $21.95 or less you can always add a Sigma 1200 wired Bicycle Computer that will be spot on for mileage as well as Odometer reading. Mount on dash from mirror bracket, fun project. Got details if you want. A whole lot less than getting speedo recalibrated.

Is there a web page for that? Does it use a magnetic pickup mounted on a wheel or something?

 

[dklawson]

Kim... I mentioned the Sigma BC-1600 in my previous posts. There's nothing wrong with the BC-1200, but the 1600 has an eeprom that stores the data (odometer and scale factors) when the coin cell battery goes dead or is removed for replacement. The 1600 is a bit more expensive but I think it's worth it.

As for web pages, Jim will have to fill you in on where and how he mounted the magnet. (It's different and easier on a Mini). I believe both Jim and I eventually replaced the supplied magnetic reed switch to an industrial one that is more stable.

If you Google the topic you'll find lots of motorcycle threads that discuss the Sigma bicycle computers. The BC-800 was the one of choice until it went out or production a couple of years ago. I'll be happy to send pictures of what I did, I'm sure Jim has more applicable photos of how this is done on a Spridget.

EDIT: I have no idea how much Rivergate charges and it's been a long time since I bought a ratio box. At the time (15+ years ago) I paid $80 for the inline box we mounted on the GT6. Factor in some inflation and I'm assuming that would be at least $160 now.

 

[Trevor Jessie]

$125 according to their website. Paul A. (Morriservice)price is probably similar.

 

[RickB]

Tell me more, how do you hook these up to your car?

BTW I found BC-800 units online for about $10 and BC-1200 units for $15.

BC-1200 here

BC-800 here

 

[dklawson]

Repeating what I was saying earlier, while there's nothing wrong with the Sigma BC-800 (which I thought was NLA) or -1200, the -1600 has an eeprom (memory chip) that retains all the settings if and when the battery goes dead. It's nice not having to worry about loosing the odometer setting or having to reprogram the wheel size variable. However, it comes at a price. The Bike Nashbar site above sells the BC-1600L for $32.

Rick, Jim has done this on a Spridget, I've done it on a Mini. Succinctly, you mount the magnet on a component that rotates at wheel speed. A magnetic reed switch is mounted on a fixed component that the magnet can pass close by. You cut and extend the pickup wires and run them into the car. You attach the mounting bracket for the display somewhere that's in plain sight.

I think Jim bonded his magnet onto a brake drum. On the Mini each wheel has a driveshaft so I was able to mount the magnet on a half-shaft U-Joint. If you Google for threads on the Sigma with additional keywords like "car" you'll find a few that discuss how various people mounted the magnets.

 

[regularman]

Its got to be similar to the magnetic pickup used on the old cruise controls that I installed in the past.

 

[dklawson]

For the bicycle computer it's a magnet that normally attaches to a spoke. The pickup is a reed switch with wires that go to the bracket to mount the display head. That's all there is to it. It probably is similar to the old aftermarket cruise controls... only smaller and less robust looking.

 

[RickB]

Thanks!
Sounds like fun, I ordered two!

 

[Pythias]

how far away has from the transmitter has anyone set their receiver on a wireless sigma set up.. the instructions say 90 cm max.. that's further than the dash is from the rear end...


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