June 17, 200521 yr comment_51093 I'm trying to work out my speedo calibration at the moment, and I'm not sure if I'm missing something, or if I haven't been to school for too long, or maybe I'm right and my original speedo is very off. Basically, I'm assuming my speedo is calibrated for a 4.11 diff. I'm now running a 4.77. I have a terratrip, so have speed readings from that, and basically I know that in comparison to my current speedo, it reads a bit like: real speed - speedo 60 - 80 70 - 90 85 - 110 100 - 130 110 - 140 Or something like that anyway. Now, ignoring that information, I tried to work it out from a mathematical point of view. So I'm guessing it would be: (speedo reading) = ((real speed) x 4.77) / 4.11 Is that right? I tried to match it up against the graph that my in-gear-calculator-excel-file-thing makes, and it seems right. But this formula brings up: real speed - speedo 60 - 69 70 - 81 85 - 99 100 - 116 110 - 128 These readings are quite different to what I'm getting at the moment, unless my current speedo (assuming I was running a "stock" 4.11 diff) is about 10km/h out? When I was running the stock 4.11 diff I did remember comparing it to the Terratrip and thinking it was pretty much on the money... And if my speedo readings are right, then the speedo would be calibrated for a 3.67 diff... Unless... The T50 gearboxes I've been using have had different speedo gears in them? Maybe that's it. Cause I've changed gearboxes since too... Report
June 17, 200521 yr comment_51111 you have to allow for the rolling Circumference of the tyre as well. i think!!!! Report
June 17, 200521 yr comment_51112 That shouldn't affect the calculation if he's using the same wheels & tyres as when using the different diff. But if they're different, then yes, you are right. Report
June 17, 200521 yr Author comment_51142 Nothing else has changed apart from gearbox and diff. Same wheels and tyres. Report
June 17, 200521 yr comment_51151 Both the speedo gears you gave me are the same. 21x9 I think.... Report
June 18, 200521 yr comment_51179 ok, i know the early k40 was 5x20 the early starlet k50 was 6x19=12mph off the later starlet k60 efi is 7x19=19mph off these only apply to daisy...... :P Report
June 18, 200521 yr comment_51188 use a tire-to-speed calculator. but don't go off tyre size, measure the actual raduis or circumference of the tyre, i've found my "185/60"s are more like a 185/62 or /63, though no doubt that will change as the tyre wears more Report
June 18, 200521 yr Author comment_51207 I'm still using the same tyres as I was before :P Except now they're kinda balder than they were before... Report
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now