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Diff ratio applications
https://www.ausmini.com/forums/viewtopic.php?f=2&t=99947		 Page 1 of 1
Author:  Bill B [ Fri May 01, 2020 4:14 pm ]
Post subject:  Diff ratio applications
I am dismantling an early rod-change gearbox.
The diff pinion/crownwheel fitted is 18/62 which is 3.44 ratio.

What later minis beside Cooper S, used this ratio? It would not have suited 998cc motors on 10inch wheels.
Author:  drmini in aust [ Fri May 01, 2020 4:30 pm ]
Post subject:  Re: Diff ratio applications
Every rod change box I have worked on was 3.44.
Including 998.
Big wheel Mokes would have had a 4.13 or 4.26, I'm not sure which.
Author:  Bill B [ Fri May 01, 2020 4:41 pm ]
Post subject:  Re: Diff ratio applications
I'll take that as an answer. Thanks drmini.
Author:  CPOCSM [ Fri May 01, 2020 8:45 pm ]
Post subject:  Re: Diff ratio applications
Bill B wrote:
I am dismantling an early rod-change gearbox.
The diff pinion/crownwheel fitted is 18/62 which is 3.44 ratio.

What later minis beside Cooper S, used this ratio? It would not have suited 998cc motors on 10inch wheels.


Have the very combo you mentioned in my Leyland mini s and was great on the open highway between Canberra and Sydney every fortnight and it screamed along in the 110kph stretches and was revving just shy of the 4000rpm. A little noisy in the cabin but plant the foot and it just took off. I personally reckon it is a good combo for city and highway driving but a good stereo was a godsend on those trips to Sydney and back. Downside was winter morn8ngs and always, without fail, iced up at the second or third overpass near Goulburn. Always had a bottle of warm water before I left home in anticipation of the spluttering...once de-iced, didn’t have an issue. Mind I was running a dellorto dhla 40 so was prone to the cold. Mind also I did love that induction roar...gold...:)
Author:  Bill B [ Fri May 01, 2020 9:16 pm ]
Post subject:  Re: Diff ratio applications
CPOCSM wrote:
Bill B wrote:
I am dismantling an early rod-change gearbox.
The diff pinion/crownwheel fitted is 18/62 which is 3.44 ratio.

What later minis beside Cooper S, used this ratio? It would not have suited 998cc motors on 10inch wheels.


Have the very combo you mentioned in my Leyland mini s and was great on the open highway between Canberra and Sydney every fortnight and it screamed along in the 110kph stretches and was revving just shy of the 4000rpm. A little noisy in the cabin but plant the foot and it just took off. I personally reckon it is a good combo for city and highway driving but a good stereo was a godsend on those trips to Sydney and back. Downside was winter morn8ngs and always, without fail, iced up at the second or third overpass near Goulburn. Always had a bottle of warm water before I left home in anticipation of the spluttering...once de-iced, didn’t have an issue. Mind I was running a dellorto dhla 40 so was prone to the cold. Mind also I did love that induction roar...gold...:)


A few years ago a friend fitted a genuine cooper S gearbox with S ratios to a 998cc and found the motor didn't have the torque to run in top gear under normal circumstances. Maybe this rod change gearbox has different input ratios to compensate. Will compare teeth.
Author:  timmy201 [ Fri May 01, 2020 9:26 pm ]
Post subject:  Re: Diff ratio applications
Some later cars in the UK were fitted with a 998 and 2.95 final drive. They would be a real slug!
Author:  drmini in aust [ Fri May 01, 2020 9:32 pm ]
Post subject:  Re: Diff ratio applications
@cpocsm
Rob, my Dellorto used to do this. So I welded a bit of 1/2" OD alloy tube across the back of the manifold flanges and piped the fresh air heater water through it. Also made brass bolts to hold the carby on.
Hasn't iced up since. :)
Author:  DavidE [ Sat May 02, 2020 10:04 am ]
Post subject:  Re: Diff ratio applications
Bill B wrote:
I am dismantling an early rod-change gearbox.
The diff pinion/crownwheel fitted is 18/62 which is 3.44 ratio.

What later minis beside Cooper S, used this ratio? It would not have suited 998cc motors on 10inch wheels.


My pretty much standard Deluxe has been upgraded to a 3.44, from its original 3.76. No problems with that.
Author:  Stibbsy [ Sat May 02, 2020 12:24 pm ]
Post subject:  Re: Diff ratio applications
Matty Reed gave me a quick lecture on diff ratios recently after I got a ticket for 68kph in a 60 zone. He recommended the 3.7 where that sweet spot of engine revs is just at the right speed.
Author:  Ian_B [ Sat May 02, 2020 8:12 pm ]
Post subject:  Re: Diff ratio applications
Yep my first job A mate there was a tech and sold me a pristine Austin Mini for 50 bucks We put an 1100 in it as the 850 was buggered and yep it was very zippy It wasnt 3.4 like my S
Author:  Ian_B [ Sat May 02, 2020 8:16 pm ]
Post subject:  Re: Diff ratio applications
And stupid me lost that Austin with its oval tag and thick body steel.
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