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

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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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.

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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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

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

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

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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Respect mine and I'll respect yours.

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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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Here is a chart that Phil 850 made up.

hello thanks for the help. i had a 3;44 ratio, now i put in 3;1 a lot better for the highway.

3.1 is a great ratio for highway use.

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