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| Diff Ratios https://www.ausmini.com/forums/viewtopic.php?f=2&t=90992 |
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| Author: | DM72GT [ Mon Nov 09, 2015 1:30 pm ] |
| Post subject: | Diff Ratios |
hello im new to the mini club. i need help with some diff ratios? i have a 1972 clubman gt with the 1275 engine. when i do 100kph it revs at 4000rpm. i was thinking of going a higher ratio like a 2.95 or a 3.1 ? i do most is highway driving. any one with these ratios can u let me know what rpm your mini dose at 100kph? thanks |
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| Author: | timmy201 [ Mon Nov 09, 2015 1:51 pm ] |
| Post subject: | Re: Diff Ratios |
Are you sure your speedo/tacho are reading correctly? A 3.76 diff will give you 60mph at 4000rpm A 3.44 is 60mph at 3650rpm A 3.1 is 60mph at 3250rpm A 2.95 is 60mph at 3100rpm From: http://www.guess-works.com/Tech/ratio.htm |
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| Author: | gtogreen1969 [ Mon Nov 09, 2015 2:34 pm ] |
| Post subject: | Re: Diff Ratios |
Have you checked your tacho against another rev meter like a timing light/dwell meter? Have you checked your speedo against a GPS? The tacho in my car was reading 300rpm high at 4000rpm and my speedo was off a bit, and my exhaust is very noisy. I originally thought I had a 4.1 ratio because of the engine scream and high tacho reading. |
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| Author: | TheMiniMan [ Mon Nov 09, 2015 2:58 pm ] |
| Post subject: | Re: Diff Ratios |
taller gearing just wrecks accelleration tho i wouldn`t bother going anything over a 3.4:1 ratio (which is probably what you have in there) unless you have "PLENTY" more grunt than the usual. |
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| Author: | 1071 S [ Mon Nov 09, 2015 3:39 pm ] |
| Post subject: | Re: Diff Ratios |
That might be true but those of us that don't live in the Big Smoke - and so rarely indulge in Traffic Light GPs - really find our 3.1s (70+ @ 4000) quite useful... Cheers, Ian |
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| Author: | slacko [ Mon Nov 09, 2015 7:47 pm ] |
| Post subject: | Re: Diff Ratios |
I have a 3.4 diff in my car I have a smiths tacho ( never been checked against any thing else ) 2200 rpm = 60 kph 3100 rpm = 80 kph 4000 rpm = 100 kpm give or take 100 rpm the speed readings are taken from my very old navman Mark |
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| Author: | Kennomini [ Mon Nov 09, 2015 8:59 pm ] |
| Post subject: | Re: Diff Ratios |
I have a 3:1 in my 1275 mini and I love it. In lower power minis it'd be a bit slow going. |
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| Author: | drmini in aust [ Mon Nov 09, 2015 9:03 pm ] |
| Post subject: | Re: Diff Ratios |
I run a 3.647 with 10" A008s. 110KMH on the TomTom = ~4700rpm on new Autogage tacho. It sounds a bit busy, and as I have 1st gear traction problems a 3.44 is going back in it this Xmas. |
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| Author: | gtogreen1969 [ Mon Nov 09, 2015 9:50 pm ] |
| Post subject: | Re: Diff Ratios |
Here is a chart that Phil 850 made up. Phil 850 wrote: I used the data for the 3.44 cooper diff in the Orange mini manual.
I then just calculated what the other ratios would come out at. It may not be perfect but should be very close.  |
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| Author: | DM72GT [ Fri Dec 18, 2015 6:23 pm ] |
| Post subject: | Re: Diff Ratios |
hello thanks for the help. i had a 3;44 ratio, now i put in 3;1 a lot better for the highway. |
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| Author: | Convertible Mini [ Sat Dec 19, 2015 5:03 am ] |
| Post subject: | Re: Diff Ratios |
3.1 is a great ratio for highway use. |
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