michaeljclark Posted August 29, 2010 Share Posted August 29, 2010 No I realise that by law a speedo is allowed to OVER read your speed by upto 10% (ie it says you are going faster than you actually are) Owing to the tin tops clutch going yeserday (which will be pricey as it's a Dual Mass Flywheel jobbie on an Diesel) I took the se7en for a road trip and decided to use the TomTom to test the accuacy of the se7ens speedo. On the tin top the speedo is overreading about 2MPH out over the range of normal UK speed limits However the caterhams is something to behold According to the TomTom when the Caterhams speedo is 30 we're actually at 27, at 40 we're really doing 35, at 50 it's really 46, 60 is 56, 70 is 65, infact to hit a TomTom indicated 70, the speedo is hovering at almost 80...... Is this a usual trait? - I'm guessing yes, but it sure explains why, when I've been blatting along at what I thought was 70, other cars have been flying past 😳 Mike 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Link to comment Share on other sites More sharing options...
tbird Posted August 29, 2010 Share Posted August 29, 2010 Not much different from speed indicated against speed on Garmin on my Landy Tim CSR 200 Aztec and Black Link to comment Share on other sites More sharing options...
jeffi Posted August 29, 2010 Share Posted August 29, 2010 My recent IVA results from the speedo check were: Real speed/my speedo reading (mph) 30/31 40/36 50/47 60/55 70/67 So the only speed where mine reads slightly over is 30mph, the rest are under. Jeff Link to comment Share on other sites More sharing options...
Tony Whitley Posted August 29, 2010 Share Posted August 29, 2010 TADTS, apart from the latest cars clearly. Particularly if you fit smaller-than-standard tyres. I rely on a Sigma cycle speedo if I want to know what speed I'm actually doing. Link to comment Share on other sites More sharing options...
TobyCoulson Posted August 29, 2010 Share Posted August 29, 2010 Michael, your readings are very similar to my 150SV which I compared with my Tomtom. Only differences where that for 30,40 and 50 my actual speed was 1 mph higher than yours. A cigarette butt placed beneath a Band-Aid makes a cheap nicotine patch Link to comment Share on other sites More sharing options...
Dickie Normuss Posted August 29, 2010 Share Posted August 29, 2010 Not unusual. With mine a GPS 70 is a speedo 79 VX HPC - Loud and proud here Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere Link to comment Share on other sites More sharing options...
michaeljclark Posted August 29, 2010 Author Share Posted August 29, 2010 Tony - I thought as much Mind you "standard" 10 spoke alloys wheels with Avon ZR3's on, so I guess it is as you say a case of TADTS...... Mike 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Link to comment Share on other sites More sharing options...
John Vine Posted August 29, 2010 Share Posted August 29, 2010 So the only speed where mine reads slightly over is 30mph, the rest are under.Did your car pass, Jeff? JV Link to comment Share on other sites More sharing options...
Myles Posted August 29, 2010 Share Posted August 29, 2010 So the only speed where mine reads slightly over is 30mph, the rest are under. Like a stopped-clock showing the correct time twice a day, you can also sleep-easy safe in the knowledge that your speedo is perfectly accurate at rest... I'll get my coat. 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Ecosse™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Mort Posted August 29, 2010 Share Posted August 29, 2010 Could be that the toothed gear wheel on the speedo drive needs to be changed from 22 tooth to 24 tooth (or is it the other way around) to give a lower reading. How do I know this? Because when I attached my GPS for the first time I noticed that my speedo was over reading by approx 10 mph across the range. As Caterham had to change the drive seal under warranty anyway they kindly changed the gear wheel too, which had been that way since new. Speedo now over reads by approx 2 mph across the range, which is just about perfect. This might account for my previously mentioned excellent fuel consumption too. On the positive side it means that my Seven has actually done fewer miles than indicated on the Odometer. I'm on 13" wheels running 185/70 tyres. Nick It's life Jim, but not as WE know it! Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 29, 2010 Share Posted August 29, 2010 When I set the 3 switches in the back of my speedo according to the website, it over-reads by 4-5 mph below 70, is dead on through 70-85, then under-reads a little above that. Before that it over-read by huge amounts. Link to comment Share on other sites More sharing options...
michaeljclark Posted August 29, 2010 Author Share Posted August 29, 2010 Thanks Nick - most useful Why do I get the feeling that if I had the 24 gear and needed the 22 tooth gear, that it's not going to be an easy job to swap..... SM25T - that too is interesting, I don't suppose you have a link handy? - I've had a google and read the build manual but have drawn a blank! 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Edited by - michaeljclark on 29 Aug 2010 20:44:27 Link to comment Share on other sites More sharing options...
john aston Posted August 30, 2010 Share Posted August 30, 2010 Get a Stack- ine said I was doing 535mph in a 30 limit... Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 30, 2010 Share Posted August 30, 2010 It was on the Caerbont site ...... here is one typical page ...... but it depends on which speedo you have. Mine is from 2002 and only has 4 internal switches. Will search further. Searched .... here is the thread that sorted mine out. If yours is a newer type, you may need to ask Caerbont if the link above doesn't help you. Good luck. Edited by - Stationary M25 Traveller on 30 Aug 2010 07:55:24 Link to comment Share on other sites More sharing options...
jeffi Posted August 30, 2010 Share Posted August 30, 2010 My speedo DIP switches are set to match the tyres, so this is probably the closest I'll get to the correct values. I'll try the sat nav to see how this compares to the IVA readings. John: yes she passed the IVA fine thx. There was a moment when I thought the 31mph would fail as I thought all readings should be over, but there is a margin for error even with the IVA testing kit. Link to comment Share on other sites More sharing options...
Blokko Posted August 30, 2010 Share Posted August 30, 2010 When I was on 70 profile CR322's my speedo was fairly accurate (as compared to TomTom readings). Now switched to A539's on a 60 profile and I get about a 10% over-read. -----Steve - Orange and Black ex Academy - You can either be right or you can be happy. Link to comment Share on other sites More sharing options...
michaeljclark Posted August 30, 2010 Author Share Posted August 30, 2010 Cheers SM25T I'll have a play about later! Mike 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Link to comment Share on other sites More sharing options...
David aka Blue7 Posted August 30, 2010 Share Posted August 30, 2010 Like a stopped-clock showing the correct time twice a day, you can also sleep-easy safe in the knowledge that your speedo is perfectly accurate at rest...sticking out tongue smiley 😬 😬 😬 Mike Have you tried re-programming the speedo using the CC input pulse code appropriate to your tyre size? With the ignition off, hold the button down on the display and turn the ignition to the on position. The display will then start to flash and you can enter the code by pushing the button until the relevant digit appears. Leave for a second and it will move to the next digit. It will be off the rear wheel. The codes according to tyre size are available from CC but if you want me to send them to you send me a pm. Having said that, my speedo died last year and I had to buy a new one and enter the correct code, which I did and it's more accurate than my previous roadsport but is still very optimistic Some guys do tinker around with the code by increasing or decreasing by a couple of numbers until it is correct but personally speaking for perfect accuracy I rely upon the the tone of SWMBO's screams 😬 😬 Blue7 Always remember that you're unique, just like everyone else Blue's pics Blue's vids Link to comment Share on other sites More sharing options...
michaeljclark Posted August 30, 2010 Author Share Posted August 30, 2010 Hi Blue7 I've just sent you a PM The speedo was replaced just before I got the car, so I wonder if perhaps CC South didn't put the right code in?!? The se7en is running Avon ZV3 195/45R15 (at least I think that's what I've just read with a torch) Thanks for your help Regards Mike 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Edited by - michaeljclark on 30 Aug 2010 21:34:20 Link to comment Share on other sites More sharing options...
David aka Blue7 Posted August 31, 2010 Share Posted August 31, 2010 Hi Blue7 I've just sent you a PM The speedo was replaced just before I got the car, so I wonder if perhaps CC South didn't put the right code in?!? The se7en is running Avon ZV3 195/45R15 (at least I think that's what I've just read with a torch) Hi Mike Received your email and have sent the 3 pdf files supplied to me by CC. I don't actually see Avon ZR3 195/45 R15 listed but there are Avon CR500 15" 195/45 x 15 and the input pulse is 039751 If you want to be certain just email James Gibson at CC and he will be able to confirm the impulse code. Good luck Blue7 Always remember that you're unique, just like everyone else Blue's pics Blue's vids Link to comment Share on other sites More sharing options...
David aka Blue7 Posted August 31, 2010 Share Posted August 31, 2010 Avon ZR3 195/45 R15 Oops, that's strange, in the message that arrived in my inbox it referred to Avon ZR3 195/45R15 and yet here on the site it reads "Avon ZV3 195/45R15" 🤔 I assume you edited it and it must be the latter, I see Avon ZV1 195/50 R15 listed and assume that the ZV3 is the 195/45 R15 version? In any case I would have thought that it is the actual tyre size eg 195/45 x 15 that is the governing factor. The two types of Yokohama 185/60 x 13 tyres at the bottom of the list both have the same input pulse but as I said before you may wish to confirm with CC Service Manager James Gibson Blue7 Always remember that you're unique, just like everyone else Blue's pics Blue's vids Link to comment Share on other sites More sharing options...
michaeljclark Posted August 31, 2010 Author Share Posted August 31, 2010 I can't type.... it's deffo the ZV Regards Mike 07 Plated RoadSport SV 150 in Red with Black nose band and stripe Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now