NedK Posted October 31, 2015 Share Posted October 31, 2015 I'm not sure if our speedo is exactly the same as others (we have a different rear axle, and a different ECU...). But I've realised that my speedo is out of whack with GPS speed. 60 on the clock is about 63 on the GPS 70 on the clock is actually 75 on GPS 80 on the clock (on the track, don't worry) was 87 on GPSAre you finding the same? I first noticed it as my MPG via the ECU didn't match what I was finding using the speedo's odometer. There must be a way of reprogramming I guess...(Peter, FYI I use a simple cheap OBD2 transmitter, plugged in by your right knee. It connected immediatetly with my phone, and lets me log GPS and engine sensors - hence my Goodwood video telemetry! )NedPS had my first prang yesterday. I hit a badger on a dark backroad when it ran out from a hedge. The only damage was the front number plate, which flew over my head and into a hedge. The badger (once I'd reversed to get him out from under the nost cone) ran off, presumably with a bad headache! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 31, 2015 Member Share Posted October 31, 2015 There must be a way of reprogramming I guess...I don't think it's been discussed specifically for a 160... what do the speedometer and sender look like?JonathanPS: It's unusual for speedometers on road cars to underread. Link to comment Share on other sites More sharing options...
NedK Posted October 31, 2015 Author Share Posted October 31, 2015 Hi JonathanI agree on the under-read. The speedo looks like a standard Caterham one, though its scale goes up to 160 (geddit?). There are two senders, which plug into each end of the live axle, and are collected up into the very complex loom. Everything presumably is added up by the ECU, so I imagine any calibration would be done there, rathe than in the instrument itself. It was good enough to pass its IVA, but presumably they weren't caning it on the rolling road..Ned Link to comment Share on other sites More sharing options...
DJ. Posted October 31, 2015 Share Posted October 31, 2015 PS: It's unusual for speedometers on road cars to underread.As I understand it, it is illegal to supply a car with a speedo that under reads Link to comment Share on other sites More sharing options...
Leadership Team 700newtons Posted October 31, 2015 Leadership Team Share Posted October 31, 2015 Hello Ned,You might have forgotten (given our lengthy 160 conversations about all the issues we encountered) but my speedo also under read. I noticed it when comparing the drive back from the showroom with a friend.see the discussions in the blog here: http://www.lotus7.club/blogs/collection-simons-160apperently you can ’adjust' the speedo (for example if you change the wheel size).in a nutshell this is what you need to know...'An email from Derek confirmed that my speedo is on the wrong setting. You can press the speedo button in as you turn the ignition and a menu comes up. Apparently the code for the speedo should be 034187. Mine was not and I have since adjusted it'Your badger encounter didn't sound much fun, but probably worse for the badger.all the best...simon Link to comment Share on other sites More sharing options...
NedK Posted October 31, 2015 Author Share Posted October 31, 2015 Of course, Simon, you've reminded me! Thanks very much for the info. I will have a play and put in the new code.You're right about the badger. I was worried it would have smashed the nosecone, or even just knocked the dzus fasteners out of alignment. But luckily not. Tougher than you'd imagine, given the bloody great clonk I felt through the car!All the bestNed Link to comment Share on other sites More sharing options...
John Vine Posted November 1, 2015 Share Posted November 1, 2015 The 6-digit code equals the number of pulses per mile generated by the sensor for a given wheel/tyre combination. You can fine-tune this code to a high level of accuracy by comparing the speed with a GPS device and adjusting accordingly.JV Link to comment Share on other sites More sharing options...
NedK Posted November 4, 2015 Author Share Posted November 4, 2015 All sorted. thanks to Simon's code. Now it has a modest over-read, which is more acceptable. By using GPS data from my phone, combined with the car's ECU data, I can log the two speeds on the same graph, and see the variance. Luckily, I've got better things to do!Thanks to allNed Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 4, 2015 Member Share Posted November 4, 2015 Glad it's sorted, but why not set it spot-on?Jonathan Link to comment Share on other sites More sharing options...
Paul 160 Posted November 4, 2015 Share Posted November 4, 2015 I didn't think a speedo could ever be truly accurate? Given the way tire condition / temp / load etc affects it I always assumed that speedo manufacturers would calibrate to an average of all the factor.Wasn't there something, what 10 or 15 years ago in the news about how a speedo would over read at low speeds and under at high? Link to comment Share on other sites More sharing options...
John Vine Posted November 4, 2015 Share Posted November 4, 2015 Re accuracy, you can tune these electronic jobbies for either speed or trip mileage. These are obviously related, but I've found it more useful to adjust the 6-digit code to produce a highly accurate odometer reading. And when I say highly accurate, I mean less than a 0.1% error. For an accurate speed reading, I use the satnav.JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 4, 2015 Member Share Posted November 4, 2015 Re accuracy, you can tune these electronic jobbies for either speed or trip mileage.I don't understand that. If you can measure elapsed time accurately why is it one or the other? The only factor I can think of is large amounts of spinning or locking the wheels...Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted November 5, 2015 Share Posted November 5, 2015 My thinking was this...Speed display typically over-reads by 5% or so, to avoid legal problems. But the odometer has no such restriction. So, you have two tuning choices: an accurate speed display and an under-reading odo, or an accurate odo and an over-reading speed display. JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 5, 2015 Member Share Posted November 5, 2015 Got it, thanks. But does that legal problem matter for an individual who is calibrating accurately as opposed to a commercial mass supplier?JonathanPS: I have a very low opinion of the ergonomics of most speedometers... but I may have mentioned that before... :-) Link to comment Share on other sites More sharing options...
John Vine Posted November 5, 2015 Share Posted November 5, 2015 Not one jot, I imagine.JV Link to comment Share on other sites More sharing options...
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