jsb Posted December 8, 2004 Share Posted December 8, 2004 Not long had my Superlight, and the speedo seems to be out by about 20% over runing on standard 13" rims and Avon CR500 175/55 tyres any ideas 🤔should I contact cc. John Yellow superlight 017 Link to comment Share on other sites More sharing options...
rgrigsby Posted December 8, 2004 Share Posted December 8, 2004 This isn't that unusal but I think it's a pain to fix as you need to change the speedo drive gear in the gearbox and I'm not sure you can do this with the gearbox in the car. Is it a new car? if so contact CC if not I suspect they may not be able to do much. Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
blade_runner Posted December 8, 2004 Share Posted December 8, 2004 cheap and easy option is as a lot of people have done... Get a Sigma cycle computor, there only about 15 quid in Halfords, easy to fit.. some glue for the wheel sensor is required, and you have to extend the cable, but they seem accruate and reliable 'Pinky Pics' here Link to comment Share on other sites More sharing options...
old captain slow Posted December 8, 2004 Share Posted December 8, 2004 Or the zero cost option just check true 30/40 60 and 70 and make a mental note. You can even put a small tipex dots on the speedo glass. Works for me - mines got the same problem. It came with HPC wheels that I later changed for 13" running 185/60s and I think that makes accounts for much of the inaccuracy. On the plus side you can impress your passengers with the 0-60 dash as it happens that much quicker 😬 C7 CDW Link to comment Share on other sites More sharing options...
V7 SLR Posted December 8, 2004 Share Posted December 8, 2004 Worth you doing what David suggests because if you ever take the box out, you can speak with Phil Stewart at Road & Race. Tell him exactly how far out it is and he'll put an appropriate speedo drive gear wheel in. He did mine in Sept. If I ever get V7 back on the road again, I'll be able to tell you how accurate it is. It won't be Phil's fault if it's not bang on. I only "suggested" it was about 10% overreading so he put one in that was 10% lower. Link to comment Share on other sites More sharing options...
jackb_ms Posted December 8, 2004 Share Posted December 8, 2004 Do wireless one work well in a seven? Emily, The Very Yellow 21 Link to comment Share on other sites More sharing options...
david nelson Posted December 8, 2004 Share Posted December 8, 2004 My speedo was aout by 17%. If you have the new type speedo you can try ajusting the setings If you go to the back of the speedo you will find some little switchs. Call CC and they will tell you which one should be where.Also look in the arcives hope this helps david Edited by - David Nelson on 8 Dec 2004 20:24:35 Link to comment Share on other sites More sharing options...
jsb Posted December 8, 2004 Author Share Posted December 8, 2004 Cheers for the feedback I will use the white dot option John Yellow superlight 017 Link to comment Share on other sites More sharing options...
stugrip Posted December 8, 2004 Share Posted December 8, 2004 get a tom tom new speedo and free sat nav lol L7 VVC Its blue 150 bhp I like it Link to comment Share on other sites More sharing options...
SPW Posted December 8, 2004 Share Posted December 8, 2004 Maybe a stupid question but short of checking against a GPS system what is the easiest way to check speedo accuracy? Working out theoretical speed using tyre rolling circumference and diff/gear ratios and relating it back to no of revs in a particular gear seems one way but that assumes the rev counter is accurate in the first place. Steve Link to comment Share on other sites More sharing options...
Toe Tags Posted December 9, 2004 Share Posted December 9, 2004 Does this mean recorded mileage will be artificially high? Link to comment Share on other sites More sharing options...
Manxseven Posted December 9, 2004 Share Posted December 9, 2004 Yes L7 BDA Supersprint Joy here 😬 Link to comment Share on other sites More sharing options...
old captain slow Posted December 9, 2004 Share Posted December 9, 2004 And on the downside fuel consuptio will look much better thsn it is. a) because you haven't gone as far as you think and b) because you ain't going as fast as you think either (fuel consumption proportional to power, and power proportional to speed cubed). That's part of the reason why the average tin top always seems to do better than the quoted manufacturer's figures. C7 CDW Link to comment Share on other sites More sharing options...
neil.cavanagh Posted December 9, 2004 Share Posted December 9, 2004 one way to measure speed accurately is on a measured mile on the motorway. There are a few around (one on M4 nr reading). They are posts with a yellow circle on top at the start, with red quarters being added every 1/4 mile until a full red circle at the end. Time yourself over this at a set speed (70mph?) and then work out your real speed when you get home! Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted December 10, 2004 Share Posted December 10, 2004 Changing from a 3.92 to a 3.62 diff sorted my over reading out (not the reson for doing it, but a nice byproduct all the same). Hand held GPS gives a good, accurate speed reading and then you can see how much your Caterham speedo overreads. Link to comment Share on other sites More sharing options...
patneale Posted December 13, 2004 Share Posted December 13, 2004 I had this problem with my new SV last year. I had a word with the instrument makers and all the latest instruments are adjustable. Remove the instrument from dash and reconnect. Remove the rubber plug in the back and you will see a little slot in a potentiometer which you can turn with a tiny screwdriver. Providing you know what the gearing is per 1000 revs in top, then with the back of the car on axle stands and in top gear you can adjust the speedo to match the correct revs. i.e. 19 MPH at 1000 38 at 2000 etc. Check at 1000,2000,3000 and 4000 revs and get the approx reading. The instruments will not be totally accurate at all revs , but not far out. Mine is correct at 1000 and 4000 ,but slightly out by a couple of MPH at 2000 and 3000. Amazingly I found no one at Caterham who admitted to needing to adjust the speedo, but after my discussions with them they have published a "gearing and axle ratio" fact sheet on the website which will show you the gearing with the various gearboxes and wheel and tyre combinations. You will see there is a very wide range of gearing. As delivered my car was showing 4000 revs at 70 MPH when it should have been showing 77 enough error to get nicked !! Link to comment Share on other sites More sharing options...
Michael Scholtz Posted December 13, 2004 Share Posted December 13, 2004 I belive the wireless ones dont work ans they were made for bikes without coils. The electrical Interference gets to them. Birkin S3 Ford Kent 1600 Weber 40's AND just in Maped Ignition. *WOW* Link to comment Share on other sites More sharing options...
DrivRich Posted December 13, 2004 Share Posted December 13, 2004 I read on here a while back....... The best way to remove the gear-box speedo gear is to lift the tunnel carpet (if you have any) and drill a hole in the tunnel wall. Work it out into approx a 2 inch diameter hole using your preferred hand tool and you can then unscrew and replace the speedo gear to your heart content without having to remove the box So simple you could routinely change tyre / wheel sizes and match the speedo gear wheel each time. Once finished, just plug a plastic grommet / cover into the hole to keep out the water. I guess my advice would be to find a suitable gromet first and then make the hole size to match the grommet rather than shopping for a specific size grommet afterwards *idea* Caveat - read it on TechTalk but not tried it Dave Dodge Viper Blue with Metalic Silver nose band and stripe Membership Number 66 😬 😬 Link to comment Share on other sites More sharing options...
DrivRich Posted December 13, 2004 Share Posted December 13, 2004 PS - I think most wireless bike speedo are line-of-sight from sender to head unit. Not sure there is a line-of-sight option on the 7 though On the plus, this has been done to death and there are loads of good threads in the archives - also remember the Low Flying article Dave Dodge Viper Blue with Metalic Silver nose band and stripe Membership Number 66 😬 😬 Link to comment Share on other sites More sharing options...
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