tweetdriver63 wrote:Bottom line on the 160 or 170 question in the Elan is really about how accurately you want your speed displayed. As I mentioned before, that's even what Metal Monkey says on their website.
http://www.metal-monkey.co.uk/acatalog/ ... Turbo.htmlFrom personal experience, I can say unequivocally, you will have a more accurate speedo if you go with the 160 face.
Thanks for your comments Chris. I wonder whether 16" rims and tyre options have contributed to inaccuracy on your side of the pond.
I'm on my 3rd Elan SE in UK and haven't found any particularly inaccurate but Speedo accuracy seems a real 'can of worms' these days. The UK Road Vehicles (Construction & Use Regulations) required an accuracy of + or - 10% above 10mph and my Lotus Eclat was built to that but was revised in 1986 to comply with an EU Directive and changed to 0% (never show less than actual speed) to plus 10%+4km/h above actual speed. There's a UN Document that covers all signed up countries too. From the number of drivers who sit in the overtaking lane doing 62 or 63mph on a dual carriageway I'd guess that a lot of cars are like all 3 of the Subaru Foresters I've had. At 63mph actual (by Satnav) speedo says 70mph so 10% fast on OE 215/55/17 tyres. The first Forester came on aftermarket alloys with Goodyear 215/50/17 NCT's which added a further 3.2% error and I could only get 225/50/17 snow tyres which add 1.7% error, according to some internet 'Tire Size Comparison Calculator' s. I've also read that the variation between a new tyre with 8mm of tread and one close to the legal limit will add a 2% error on a 14" rim, so only marginally less error on a worn 15". For the Forester I use a RoadAngel SatNav to give me accurate speed & set cruise control by it, plus it gives speed camera, accident black spot, approaching school, and other useful audible warnings. The SatNav confirms my wife's Ford Focus ST170 speedo is spot on, around 70mph anyway, as is a Ford Galaxy based motorhome we've got, so at least Ford UK are giving us sensible information.
My first Elan (Calypso Red '91) boosted to .7bar, for reasons unknown. On a cool damp overnight drive through France to get to the '96 Monaco GP I was the only car on the motorway at 3 a.m and saw 150mph indicated on the speedo and the revcounter showing just over 7k. 7k to 8k is a red box on the revcounter so I thought I'd be OK but I got a hell of a shock when the engine cut - front tyres squealed, seat belt operated to stop me hitting the screen and engine came back in and I was doing 110mph, so I lost 40mph in an instant - never want to do that again. I didn't know about the electronic rev limiter than cuts ignition and fuel pump at 7,200rpm but found out the hard way. When I got home I looked through the Manual's to investigate it and found gearing info says 5th is 20.9mph/1000rpm so 7.2k limiter will cut at 150.48 mph so the speedo in that one was certainly very accurate at the top end but it was before I had a SatNav for reference so don't know about mid-range accuracy.
I bought a pair of 2nd hand 15" SE wheels with used tyres and always carried a 'proper wheel' as a spare on trips through France - doesn't take up a lot of extra room and so convenient when needed. When the red Elan was involved in an accident with a whitevan man using his mobile phone and was going to be written off those wheels went on it and two with almost new Avon ZZ3 tyres came off.
I eventually found a Pacific Blue '91 SE with 34,000 miles for the money I'd got for the red Elan on 130,000 miles but this came with Bridgestone, Yokohama, Pirelli and a 'budget tyre', all 205/50/15 with decent tread but very different tread patterns. I fitted the Avons on the front, removed the two from the rear and lined up these 4 odd ones side by side to choose which to refit and was amazed that the heights were all over the place, so the rolling radius would be completely different and effect on accuracy of speedo would depend on which were fitted where. Different manufacturer's carcasses seem to have different profiles even though all quoting 205/50/15!
I decided I'd treat the new car to another pair of Avon ZZ3 so all 4 were the same and went to my friendly local tyre dealer. He couldn't do ZZ3's but could do 4 Goodyear Eagle F1 GS02's with a similar tread pattern and offered a bargain price as he planned to resell the old odd ones, which were hard to get. I noticed that when the tyres were stripped some had very concave tread when deflated and some looked the same as when inflated. Very strange as I thought they'd all be 'neutral contour tyres'. I came home and fitted the Eagle F1's all round and then realised that I'd now got 6 directional tyres so the choice of which to carry as a spare needed me to know what side I'd get a puncture -
I fitted a RoadAngel Satnav in that Elan by putting a bracket in the well behind the three 52mm gauges and have it set to give a full screen speedometer roundel that I can see in my peripheral vision whilst still looking at the road ahead, like a "head-up display" so use it all the time. Checking the Elan speedo against it confirms that's reasonably accurate too but takes longer to read . (Putting SatNav in that position means I can't reach it without pulling in and undoing my seat belt so I'm never tempted to do anything with it when driving.) French Law changed in 2012 and having a RoadAngel in my car is now illegal and I can be fined €1,500 and have the car & Satnav confiscated even if it's not in use but just in the car!!!!
15 months ago I bought what I think is the last SE to come out of Hethel - a low mileage Pacific Blue registered 22/12/93, and have checked the speedo against the RoadAngel SatNav and the Speedo app in my iPhone and that one isn't far out either. It's just 4mph fast everywhere - shows 30 at 26mph and 74 at 70mph so if I can get the needle back on the spindle in just the right position after I've fitted the new faces I should have an accurate speedo ... ha ha, bet that's easier said than done !
Phil
it is now spot-on @ 100 km/h 
