Tom Niemczewski wrote: > A speedometer that is within 10% of actual speed is considered VERY > >accurate! And guess what... 99% of speedometers will actually show 10% more >than your actual speed. > >The thing that can affect the reading would be different tires than those >used originally at the factory. Even if the size is correct. Tires from >different manufacturers differ in size. That will affect the speed as well >as odometer reading. The smaller the tire the higher the reading will be. In >your case where the odo is lower than you expected and speedo is higher I >would say that it's perfectly fine. The speedo is perfect and odo in your >OTHER car is probably going faster than it should. > >I hope this helps > >Tom Niemczewski >vin 6149 (in Poland!) >tomciodmc@xxxxxxxxxxxxxx >www.deloreana.com <- home of the convex mirrors - available now > > > This really depends on the make and model of the car, and can vary even from car to car itself. However. I think that a nearly 5mph differece going at only 30ish speeds is a bit much. I know most of the mechanical speedometers in the vehicles i've driven in the past have usually differed by that much at highway speeds (70mph or so) not at 30. I know my 98 dodge intrepid is nearly spot on, showing 69.8 on the gps with the speedometer showing 70, but it's speedo is entirely electric, no mechanical parts in it beyond the pickup in the transmission, and it's probably hall-effect. I can think of only 3 things that are changable to affect displayed speed. 1) tire size, you'd have to go larger diameter to get a more correct reading if the numbers posted are correct. 2) angle drive. Not sure exactly what differences can turn up here. but if one or both gear diameters aren't right then it will effect output shaft speed, which will send the speedo the wrong wheel rpm to the speedo. 3) the speedo itself. I guess if you had a stroboscope and a way to drive the speedo out of the car, you could just do the math using the correct tire sizes for the front. (which would be a circumference of 72.9 inches, or 869 rotations per mile, by the way) So assuming the angle drive has a gear ratio of 1:1 (I don't know if it does or not. Haven't looked that up) you'd simply drive the speedo input at 869rpm and the speedo should, if accurate, read 60 mph. Of course doing this would just tell you where in the system the oddness in speed is coming from. not help you correct it. I know of no way of adjusting these speedo's mechanically. I've never had reason to ever dismantle one. I guess the first and easiest thing to do would be to make sure your front driver's side wheel was inflated to the proper air pressure, then use a tape measure and measure it's circumference. If it's less than 73 inches, then your tires are at least part of your problem. If it measures right, or relatively close anyway. your problem probably is the speedo, unless others can note differences they've found in different angle drive ratios. -- Chris VIN# 03209 http://badger.brazi.net/index.pl/delorean -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.362 / Virus Database: 267.13.4/175 - Release Date: 11/18/2005 To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/