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| how would a close ratio box with 3.1 Fd drive like https://www.ausmini.com/forums/viewtopic.php?f=2&t=76065 |
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| Author: | kiwiinwgtn [ Thu Mar 22, 2012 7:55 pm ] |
| Post subject: | how would a close ratio box with 3.1 Fd drive like |
Hi I was discussing with my neighbour about Mini gear boxes and he has a close rato gear box and intends on putting a 3.1 diff into it. I am sure a read some where this is not a good idea as it makes first to second to short can any help me answer this question correctly Ta Kiwiinwgtn |
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| Author: | GT mowog [ Thu Mar 22, 2012 7:58 pm ] |
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to make it relative, what the engine and it's spec? |
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| Author: | kiwiinwgtn [ Thu Mar 22, 2012 8:02 pm ] |
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good point 1330 cc with a 286 cam a plus engine and box |
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| Author: | dodge [ Thu Mar 22, 2012 8:06 pm ] |
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depends on ur driving reqs, it will run sweet on the hwy |
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| Author: | kiwiinwgtn [ Thu Mar 22, 2012 8:10 pm ] |
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what about changing up and down thru the gears will you lose / gain anything.. |
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| Author: | michaelb [ Thu Mar 22, 2012 8:13 pm ] |
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Please define "close ratio" I have just fitted a 3:1 diff in my project which is designed for a supercharger but not yet fitted. The gearbox is a late clubman type so not sure of ratios but I have found that once the car is moving it is great and it seems to have dropped the revs in top gear by around 800, so cruises at 100kph at around 3500rpm The only issue currently is starting on very steep hills but nothing a few Extra revs won't solve. And eventually the supercharger should solve this issue. The change between each gear including 1 to 2 seems ok Hence my original question Maybe one of the technical gurus will have a better explanation? |
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| Author: | kiwiinwgtn [ Thu Mar 22, 2012 8:19 pm ] |
| Post subject: | |
It is a factory close ratio helical gear set A+ it uses a different lay gear and first motion shaft from standard Kiwiinwgtn |
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| Author: | GT mowog [ Thu Mar 22, 2012 8:33 pm ] |
| Post subject: | |
kiwiinwgtn wrote: It is a factory close ratio helical gear set A+
it uses a different lay gear and first motion shaft from standard Kiwiinwgtn Same as Cooper S MKII. I have a few of the same - unobtainuim - sets. IMO, the diff would be too tall, but I like them nippy off the line. I ran a 3.2 with a similar spec engine for a while. Great on the longer trips and definitely livable around town, but hard pushed getting better than 15 000 KM from a clutch. Just a little too slow off the line for my liking. I have found - after also trying a 3.6, a 3.44 is about the best for it. |
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| Author: | kiwiinwgtn [ Thu Mar 22, 2012 8:39 pm ] |
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Thanks GT you answered my question it effects the off the line speed Ta Kiwiinwgtn |
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| Author: | GT mowog [ Thu Mar 22, 2012 8:47 pm ] |
| Post subject: | |
No worries. If you look closely at the cars that these Tall diffs were fitted to, most, if not all, had 'twin line' gear sets. These were the oposite of the close ratio sets, ie, 1st gear in a Cooper S set is 3.2:1, the Twin Line sets are 4:1 ('standard' sets being 3.54;1). They used these wider sets to 'make up' for the tall diffs. And these were in stock engines with tame cams. Big cams and tall diffs don't mix on a 4 speed gearbox. |
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