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| Speedo and wheels https://www.ausmini.com/forums/viewtopic.php?f=2&t=88665 |
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| Author: | man+van [ Thu Feb 19, 2015 1:35 pm ] |
| Post subject: | Speedo and wheels |
Hi all, I am getting stuck back into my mini, Re-shelling my van as the rust got a bit bad. Now my van has a A+ 1275 in it, dont know diff ratio i assume std A+. I purchased it with 12inch wheels and the speedo was correct. Then i went to 10s and it is out. Now how do i get the speedo correct? change speedo drive? The speedo gauge has SNT3328-31 and 820 below it. With my spare 1100 motor in the speedo is correct. Also i know there was a wheel thread on here a while ago but cant find it as i want to know what wheels these are and where i can get a set of wheelnuts from. Thanks and im sure i will have more questions |
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| Author: | Hobson [ Thu Feb 19, 2015 2:00 pm ] |
| Post subject: | Re: Speedo and wheels |
Keen to know, I need to do the opposite, I know mine is out by about 5 at 100km/h cause it was never set for the 12 inch wheels. Edit : most seem to go with a gps anyways. |
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| Author: | timmy201 [ Thu Feb 19, 2015 2:09 pm ] |
| Post subject: | Re: Speedo and wheels |
Well: 145/80R10 = 486mm diameter 165/70R10 = 485mm 145/70R12 = 508mm 165/60R12 = 503mm 175/50R13 = 505mm The biggest difference is 4% between the biggest and smallest ones.. You'll need to know your gearbox type, diff ratio and speedo tpm and you can work out the speedo gear with this: http://www.guess-works.com/Tech/ratio.htm The wheels are Tasman/Dunlop D1. |
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| Author: | simo74 [ Thu Feb 19, 2015 2:46 pm ] |
| Post subject: | Re: Speedo and wheels |
check this out in the 'How To' section viewtopic.php?f=25&t=88644 could be BWA's or Tasmans but sure someone more knowledgeable than me will tell you |
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| Author: | man+van [ Thu Feb 19, 2015 3:22 pm ] |
| Post subject: | Re: Speedo and wheels |
Thanks Timmy, Hmm i remember it being out by a bit. Maybe it wasnt correct with 12s. been 5yrs since i drove it. I will have to pull the diff cover when i get the front subframe out to count the crown and pinion teeth. Thats the thread i was thinking of Simo aewsome, Thanks. |
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| Author: | 1071 S [ Fri Feb 20, 2015 8:38 am ] |
| Post subject: | Re: Speedo and wheels |
Don't forget there are two separate instruments in that big round gauge in the dash... Calibrating the speedo is no big deal (if you have a suitable expert). Basically, you change the distance between the drive and driven plates in the back of the gauge. Its not a DIM (do it myself:) job but the local instrument shop doesn't charge much. The odometer is different and needs the correct speedo drive gears in the gearbox - or an intermediate (geared) box between gearbox and instrument. Otherwise the mental maths are pretty basic. A 10% change in final drive ratio (3.44 to 3.1 for example) will change the speedo/odo readings by 10%. Cheers, Ian PS If you have the engine out you don't need to pull the diff to measure the final drive. Take the clutch cover off, mark the flywheel and diff output flange, make sure you'e in top gear and count how many revolutions of the flywheel are need to rotate the diff output one complete turn.... The difference between a bit over three turns (3.1), almost three and a half (3.44) or almost four (3.76) will be obvious. |
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