evo3500
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| posted on 1/3/06 at 08:06 PM |
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XR4x4 diff
Hello bec owners I am making a new kit protoype vehicle useing bike power.
I am using an Aprillia rsvr v-twin engine,wheel size probably 205/50/15,If i use a Sierra XR4X4 rear diff what kind of engine rpm will it do at M/way
speed 70mph.Anyone know how to calculate this
dont know if this helps in manual says
6th gear primary reduction is 0.851 to 1 (23/27T)
Thanks Simon
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froggy
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| posted on 1/3/06 at 08:32 PM |
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might be wrong here but im using a tl1000 twin in my kitten and i worked out that with 15" wheels i would be getting 10mph per 1000rpm in top
as the reduction on twins is a little worse than on 4cyl bike engines, my mates rsv was fairly evenly matched rev wise to my tl on the road . im
keeping the 10" wheels on my kitten so ive cobbled up a overdriven chain drive setup to give my car 13mph per 1000rpm on 10" wheels using
a 3.5:1 diff.
i struggled to get my head round it but if you figure that the final reduction on the bike which is say 17th front sprocket and 38th rear would give
you a "diiff" ratio of 2.25:1 driving a 17" wheel which you will replace with a 15"wheel and a 3.62 diff youve lost nearly
30%(guess) of your gearing straight away hence people use 17" rims and tallest diffs ie 3.14 7" sierra and freelander 3.2,s HTH
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smart51
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| posted on 1/3/06 at 09:27 PM |
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My R1 with an XR4x4 rear diff makes 10.2 MPH / 1000 RPM in 6th. It varies from bike to bike. I considered an RSV Mille and from memory the gear
ratios are quite good. I'll look up the data on my other computer tomorrow.
To work it out yourself, 195/50/15 tyres cover 1.76 metres per revolution. your 1000 RPM on your bike is divided by its primary reduction ratio, its
6th gear ratio and by 3.62 for your diff. there are 1609.344 metres in a mile. bit of arithmatic. Bingo.
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RichieC
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| posted on 1/3/06 at 11:35 PM |
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APRILIA RSV
Primary 1.935
1st 2.500
2nd 1.750
3rd 1.368
4th 1.091
5th 0.957
6th 0.852
Assumed rev limit 10500
Not sure if the RSVR was any different in ratios, I dont think so but could be wrong, but Id estimate around 6500 RPM, assuming a top end of 118
MPH.
[Edited on 1/3/06 by RichieC]
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smart51
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| posted on 2/3/06 at 08:21 AM |
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Edited to include RichieC's correction (oops)
The data I have on the RSV Mille is a bit different. 10,500 RPM rev limit BTW, 11,000 for 2004. 195/15/50 tyres, 3.62 diff
2002
ratio top speed
primary 1.55
1st 2.41 51
2nd 1.78 69
3rd 1.37 90
4th 1.11 111
5th 0.97 127
6th 0.85 144
70 @ 5000 in top
2003
primary 1.935
1st 2.267 43
2nd 1.632 60
3rd 1.300 76
4th 1.091 90
5th 0.96 102
6th 0.885 111
70 @ 6600 in top.
I would suggest that smaller wheels (lighter) or a 3.92 diff would suit the 2002 engine.
I am told that later engines are better for reliability.
www.mcnews.com.au/NewBikeCatalogue/2002/Aprilia/Tuono/Default.htm
www.sportrider.com/bikes/2003/146_03_apr_mille/
www.motorsports-network.com/Aprilia/2004/mille04.htm
[Edited on 2-3-2006 by smart51]
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RichieC
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| posted on 2/3/06 at 08:38 AM |
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Early RSVs were 10500, this was raised to 11000 from 04 onwards (from the bottom link you posted "In fact the rev limiter has been upped to
11,000 rpm from 10,500 revolutions." )
Not that it makes much difference. Again, I cant speak for the RSV-R.
[Edited on 2/3/06 by RichieC]
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evo3500
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| posted on 3/3/06 at 01:55 PM |
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Thanks for all the replies clears things up a bit.what is the best Sierra model, option for bec to give resonable cruising say 5000 6000 rm 70
-75mph,other than the ultra rear diesel diff and is most commonly available ?
Thanks Simon
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smart51
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| posted on 3/3/06 at 03:40 PM |
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Most sierras are 3.62. Some are 3.92, a few 3.38 and very few were 3.14. If you can make your car work with a 3.62 then your laughing. 3.38s are
rarer and more expensive but if needs must...
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