Terry Field Posted April 8, 2013 Share Posted April 8, 2013 I have the old style (1996) Caterham speedo which is under reading by something like 10 - 15 mph. In other words, with a speedo reading of 60 mph, the true speed is well over 70mph. Is it possible to have the speedo calibrated? I have used Speedy Cables for repairs previously. Thanks Terry Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted April 8, 2013 Share Posted April 8, 2013 Is that vintage a mechanical cable driven beast ? Link to comment Share on other sites More sharing options...
Mankee Posted April 8, 2013 Share Posted April 8, 2013 You could try checking and/or changing the speedo drive gear in the tail end of the gearbox. I think Caterhams only used 24-tooth drives, so someone may have had a fiddle in the past if it's underreading by that amount. Apparently the drive is swappable without removing the engine and gearbox, but space is very tight. Have you changed wheels and tyres or diff ratio from standard? This may cause the speedo to be out as well. I've used JDO in the past to repair a dodgy tacho and he might be able to recalibrate your speedo. Alternatively, if you can catch me between trackdays, I can send you my speedo to try out on your car. It's the same vintage as yours. I'll be getting rid of the speedo eventually when I redo the dash, but it's quite useful at the moment... Link to comment Share on other sites More sharing options...
Big Bad Baz Posted April 9, 2013 Share Posted April 9, 2013 That's weird. I guess I've got a similar vintage speedo, but mine over-reads by about the same amount. 80mph on the speedo is actually a Sat-Nav checked 70mph. Link to comment Share on other sites More sharing options...
Terry Field Posted April 9, 2013 Author Share Posted April 9, 2013 Yep it is the mechanical drive version. I haven't changed anything for at least 10 years except the angle drive which goes into the side of the gearbox. The replacement came from Redline, so I have no reason to think that it is anything but the original spec. It is always possible that it has always under read, but that no one has commented on it to date. (It has recently been picked up by both a fellow blatter and my wife who were following me). Mankee, thanks for the kind offer, but I'll pass for now and perhaps give JDO a call. Alternatively I might just invest in a satnav! Terry Link to comment Share on other sites More sharing options...
Andy Lef Posted April 12, 2013 Share Posted April 12, 2013 Mine has always read approx 7 MPH faster than actual speed; I currently run a sigma 1600 bike speedo in tandem - works a treat once you've set it up to the tyres you're running. Link to comment Share on other sites More sharing options...
shn7 Posted April 12, 2013 Share Posted April 12, 2013 Pretty sure I have 1 maybe 2 angle drive gears at home. Not sure of spec but can check tonight if it helps. Link to comment Share on other sites More sharing options...
charlie_pank Posted April 12, 2013 Share Posted April 12, 2013 Do you have the same rolling circumference as the original spec? Link to comment Share on other sites More sharing options...
Terry Field Posted April 12, 2013 Author Share Posted April 12, 2013 Charlie, I changed from Michelin Pile Ups to Yoko 21's about 12 years but nothing else. Steve, Thanks for the offer; having moved house just 3 weeks ago I won't have much time for a while to do anything, but I will give you a shout if I feel the urge to get down and get dirty! It is beginning to look like a case of TADTS, so maybe I will live with it, watch the cameras and buy a satnav. I guess it is tempting fate to say that so far, I haven't fallen foul of any speed traps Terry Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted April 12, 2013 Share Posted April 12, 2013 That's the KOD for your licence then !! Link to comment Share on other sites More sharing options...
charlie_pank Posted April 12, 2013 Share Posted April 12, 2013 Do you have the same rolling circumference as the original spec? Actually it doesn't matter anyway, give Venhill cables a call and they'll get you sorted. Link to comment Share on other sites More sharing options...
Brian Soper Posted April 12, 2013 Share Posted April 12, 2013 I run a 3.6 diff with a speedo calibrated for a 4.5 diff helps with the 3000 mile limit but who is looking at the speedo better looking for the cameras!!! Brian Lotus 7 series 2 and never raced Edited by - Brian Soper on 12 Apr 2013 20:33:34 Link to comment Share on other sites More sharing options...
shn7 Posted April 17, 2013 Share Posted April 17, 2013 Terry, Did you get my BM? Link to comment Share on other sites More sharing options...
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