Richard Hammond Posted August 7, 2001 Share Posted August 7, 2001 Just a thought...Can you trust the mileage stated on the speedo of a Se7en ? I would hope that they are sealed in some way to stop people tampering with them. I know that you can match the reading with the service record and MOT but this is hardly conclusive... L17 KAR Link to comment Share on other sites More sharing options...
kenny. Posted August 7, 2001 Share Posted August 7, 2001 Ray, It's like most cars with mechanically driven speedo's, they are a doddle for people to take off...especially when most people have built cars themselves. I tend to believe though that most 7 owners I know don't engage in this practice due to the relatively small mileage thy knock up, and I believe that most low mileages are true.I got mine on the road in'96 and it's still done less than 4000. The only thing is that even a genuine mileage can be wrong.......i.e. if car has 16" wheels as standard and 13" are retro-fitted, the nylon speedo drive wheel needs to be changed to allow for this...and vica versa.....or mileage will vary up and down. I also had a spate of the big washer on the speedo drive body failing(untill they changed its design).....it was such a prat to get the circlip back in, in situ that I always put job off for a couple of weeks.......someone else may have knocked up a couple of thousand miles in that time.(I didn't though). On the whole I'm trusting enough to believe that most of the low mileages you see are in fact genuine. Kenny HPC Link to comment Share on other sites More sharing options...
aideen Posted August 7, 2001 Share Posted August 7, 2001 You've got to be joking, yeah? biggrin.gif The speedo's very easy to disconnect and isn't very accurate anyway. A bunch of receipts for servicing and parts with dates is probably the best thing to check. How well a car has been looked after is more important that how many miles it's done. Aideen Link to comment Share on other sites More sharing options...
ashaughnessy Posted August 7, 2001 Share Posted August 7, 2001 When I bought my car second hand from Caterham, the clock showed only about two hundred miles but Caterham told me it had done about 21,000. A full record of receipts and MOT certificates is the safest way to tell, IMHO. Anthony Link to comment Share on other sites More sharing options...
Richard Hammond Posted August 7, 2001 Author Share Posted August 7, 2001 In the past I had an MGB with a mechanically driven speedo and was hoping that the Se7en was set up more securely. Kenny, hadn't considered that the wheel size would have a significant effect... There appears to be a general feeling that the speedo is inaccurate. Why do Caterham continue to fit this model speedo if it is inaccurate ? What are the tolerances ? I've seen some threads about cycle computers being fitted. Can something that cheap really be more accurate I've now got Gatso panic ! L17 KAR Link to comment Share on other sites More sharing options...
Mike Bees Posted August 7, 2001 Share Posted August 7, 2001 The standard speedo is driven from a cable which is in turn driven by a speedo gear drive in the gearbox. There is plenty of scope for inaccuracy due in no small part to the wide combination of diff ratios & wheel/tyre combinations that people run. The bike speedos are dead accurate as long as they're accurately calibrated - they need to be told the rolling circumference of the wheel on which you've put the sensor. They see one pulse per turn of the wheel and they know the circumference, so it's just like putting some numbers into a calculator and wondering how accurate the answer will be. Mike Link to comment Share on other sites More sharing options...
aideen Posted August 7, 2001 Share Posted August 7, 2001 Alternatively you can send your speedo off to Speedy Cables in London and they'll recalibrate it for about 40 quid. A bike speedo would seem the cheaper way. Aideen Link to comment Share on other sites More sharing options...
kenny. Posted August 7, 2001 Share Posted August 7, 2001 Mike, Good idea with regards to the bike speedo, would the sensor just be fitted similar to the launch control sensor, which I've set up in close proximity to the 4 hub bolts? Kenny HPC Link to comment Share on other sites More sharing options...
Mike Bees Posted August 7, 2001 Share Posted August 7, 2001 The one I bought (Sigma 700 IIRC) needs a magnet to trigger the sensor, so I don't think the disc bolts would do it. I araldited a small magnet to a wheel rim, removed a similarly-sized balance weight, and cable-tied the sensor to the (cycle) wing stay. Mike Link to comment Share on other sites More sharing options...
philwaters Posted August 7, 2001 Share Posted August 7, 2001 Hi Ray, I run a bike speedo, a Topeak Panoram. You have to make up a small bracket to hold the sensor and fix the magnet to the wheel (a dab of Araldite works well) and then find somewhere to locate the display in a good position to view it. This is the hardest part I have found. The Topeak is pretty large, it has 3 displays for speed, distance and times so finding somewhere to put it takes a while and I am currently moving mine. In use they are great. much better than the Caterham speedo, and I was amazed how far out mine was from changing from 70 to 60 profile tires. These too can easily be tampered with, however. Becasue the battery will run down in time most manufacturers allow you to re-imput your total distances and total times, etc, so it would be very easy to knock off a few thousand miles if you wanted to. I have left my standard speedo connected from day one so this is the one I quote to the insurance company, even though I know it over reads by a lot... in effect I am loosing out on my limited milage policy, but its not worth the grief of getting the mot center to use the bike speedo's milage etc.... I agree with Aideen, how the car has been looked after is far more important than the milage. Phil Waters Q181 ABL - 1600 X/F smile.gif Link to comment Share on other sites More sharing options...
allen Posted August 7, 2001 Share Posted August 7, 2001 IMHO Mileage is not the be all & end all, check the condition of the car generally. Fitting larger whells & tyres or a taller dif may give fewer miles on the speedo, and possibly less wear on the rear bearings, but probably makes no difference to engine and gearbox wear (may do the oposite as more gear changing may be required). a car with 10,000 on the speedo might have been thrashed for most of them, track days etc., whilst one with 20,000 may have been much more carefully driven and maintained. You can tell the diference without reference to the speedo, and I know which of the two I'd have. Regards allen Edited by - allen on 7 Aug 2001 15:44:52 Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted August 7, 2001 Leadership Team Share Posted August 7, 2001 I fitted a Sigma cycle speedo because of the inacuracy of the OE item - the Sigma's accurate to 0.1 mph when checked using a handheld sat-nav system. The HPC wheels read approx 8% higher speed on the OE speedo than the sigma - my 13" wheels are even worse! Doddle to fit - super accurate! Stu. Link to comment Share on other sites More sharing options...
stevefoster Posted August 7, 2001 Share Posted August 7, 2001 concur on the Sigma. They are very good. 0.2% out when I calibrated it on a measured mile. We did 10 runs and averaged. The VDO / Caterham unit is secure but it's easy to disconnect... Link to comment Share on other sites More sharing options...
Paul McKenzie Posted August 7, 2001 Share Posted August 7, 2001 Stu/Steve, Which Sigma model do you use ? - I believe there is more than one Thanks, Paul Link to comment Share on other sites More sharing options...
Richard Hammond Posted August 8, 2001 Author Share Posted August 8, 2001 The Sigma sounds good - where can you buy them and what is the cost ? Exactly where do you fit the sensors ? L17 KAR Link to comment Share on other sites More sharing options...
Allan Haighton Posted August 8, 2001 Share Posted August 8, 2001 I echo the previous comments about speedo inaccuracy and changes in wheel size and diff ratio. To keep me on the safe side of Gatsos, I've replaced the mechanical speedo with a VDO electronic speedo. (If the speedo is right for 70 profiles, then 60 profiles will over-read by about 10% and vice versa). I can recalibrate the new speedo at the touch of a buttom (well, several tocuhes actually) to compensate for the above. So no, my mileage reading definitely isn't accurate. But I can always show the accumulated mileage on the speedo I've removed, if need be. Link to comment Share on other sites More sharing options...
murph7355 Posted August 8, 2001 Share Posted August 8, 2001 How do you do less than 1k miles a year? Mine's at an average of between 7-8k and I was out of the country for about a year (probably 18mths in total with holidays etc). Agree with all talk of cables etc. Mine's broken twice and it isn't always easy getting it fixed without putting more miles on the car. I know have a Stack dash so no longer have the problem (like the cycle jobs it works off sensors. But is a tad more pricey smile.gif). Link to comment Share on other sites More sharing options...
kenny. Posted August 8, 2001 Share Posted August 8, 2001 Andy, 8k a year........you must live in the tropics........I thought I was hard doing 800 a year......froze my balls off for 650 of them too!!!!! Kenny HPC Link to comment Share on other sites More sharing options...
murph7355 Posted August 9, 2001 Share Posted August 9, 2001 Sorry Kenny, can only assume you're a big wuss. I do 850 in one sitting (well, 4 if petrol stops count)! Dorking has probably never been called tropical before, but as a Northerner who has emigrated darn sarf I guess it is, relatively speaking. You need some therapy. May I suggest a summer tour round Europe or a trip to Eire. You'll never have had so much fun in the car and it'll get the mileage up.... Link to comment Share on other sites More sharing options...
kenny. Posted August 9, 2001 Share Posted August 9, 2001 Bit insulting wasn't it?...no need for that! I'm all upset now! Kenny HPC Link to comment Share on other sites More sharing options...
murph7355 Posted August 10, 2001 Share Posted August 10, 2001 Sorry Kenny. I *did* say I'm a Northerner (bit direct we can be smile.gif). Another suggestion - thermal underwear. Just don't let your mates see you wandering into Damart or let your other half see you in it! Link to comment Share on other sites More sharing options...
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