Mike Molloy Posted December 11, 2002 Share Posted December 11, 2002 Does anybody have information about the latest "Caerbont Automotive" electronic speedos (as fitted to 2002 Roadsport, 1.6K, Ford 5-speed, 3.92 diff)? It is fitted with 4 dip switches and what appears to be a twiddle pot. According to Caterham, they only use two switch combinations for the entire range of vehicle fitments. Switch combo 1 = 8614 pulses per mile, combo 2 = 8260 pulses per mile. How many pulses per rev does the speed sensor on the gearbox output? Link to comment Share on other sites More sharing options...
Klaus Loske Posted December 13, 2002 Share Posted December 13, 2002 Mike, I have retrofitted a VDO electronic speedo. Unfortunately I failed to source a gearbox speed pick-up sensor which plugs straight into the ford 5-speed box. So right now I am using a hall sensor which is driven by the speedo cable. Do your know if there is a sensor now available which plugs into the gearbox? Thanks Klaus 1700+ X-flow Combustion is not a secret Link to comment Share on other sites More sharing options...
Ben C Posted December 14, 2002 Share Posted December 14, 2002 Your local lorry tachograph fitting agent may be able to count the number of pulses coming out of the generator It may also be possible for them to supply pulse generators to fit on gearboxs. Lucas or LSUK are often agents Link to comment Share on other sites More sharing options...
MartinWoodham Posted May 17, 2005 Share Posted May 17, 2005 Mike, did you ever get an answer to this one? Having gone from Cr322S TO Cr500s I'd like to be able to recalibrate as well... thx Martin Roadsports B If everything's under control you're going too slow (Emmerson Fittipaldi) Link to comment Share on other sites More sharing options...
Mike Molloy Posted May 17, 2005 Author Share Posted May 17, 2005 IIRC there are 4 dip switches. The furthest left is the speedo cal. 0 = LOW (8216 pulses per mile) 1 = HIGH (8614 ppm) The other 3 are ODO cal. 100 = LOW (8380 ppm) 011 = HIGH (8790 ppm) The gearbox speed sensor on my 2002MY 1.6K gave 2.333 pulses per prop rev. Hence speed cal affected by rear tyre size and diff ratio. Still have the exel spreadsheet which gives indicated speed at an actual 60mph: On "LOW" setting, CR322 = indicated 58mph, CR500 = 65mph On "HIGH" setting, CR322 = 55mph, CR500 = 62mph. I actually cal'd mine on the bench using a signal generator to get it spot on with the GPS check (bit anal, but there you go... ). N.B. This assumes a 3.92 diff and 175/55-13 CR500s (526mm dia.) Hope this helps. Edited by - Mike Molloy on 17 May 2005 16:22:59 Edited by - Mike Molloy on 17 May 2005 16:27:19 Link to comment Share on other sites More sharing options...
MartinWoodham Posted May 17, 2005 Share Posted May 17, 2005 Mike, many thanks. Blatchat knows all! I'm trying to get my head around this - surely for a given number of pulses, a CR500 will do less distance than a CR322..so ought to record a lower speed, not a higher one? I could believe that at a true 60mph a CR500 indicates 65.... but not sure the other way round? Martin Roadsports B If everything's under control you're going too slow (Emmerson Fittipaldi) Link to comment Share on other sites More sharing options...
Mike Molloy Posted May 17, 2005 Author Share Posted May 17, 2005 😳 Quite right. Edited (twice!) to correct the order of "indicated" and "actual"... Ahem. Link to comment Share on other sites More sharing options...
MartinWoodham Posted May 17, 2005 Share Posted May 17, 2005 All is clear! thanks Mike! Martin Roadsports B If everything's under control you're going too slow (Emmerson Fittipaldi) Link to comment Share on other sites More sharing options...
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