Nickp
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| posted on 4/1/14 at 08:40 AM |
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Haynes BMW gearing...
Just took the rear cover off the Sierra diff that came with my Haynes. Looks like it has an LSD and is a 3.62.
I was bored so thought I'd work out the gearing using my BMW 323i gearbox.
Using 205/50/15 tyres and revving to 7Krpm the max speed in each gear will be-
1st 31mph
2nd 53mph
3rd 80mph
4th 109mph
5th 133mph
Seems quite reasonable to me and fair to say it won't be exploring the upper limits of 5th too often, but will give a 4krpm cruising speed of
76mph.
The engine's going to be a nice torquey 2.8 M52 that will rev to 7K but realistically it's not going to be spending much time up around
there, unless I have a death wish!! I reckon 1st gear might be pretty much redundant for all but the quickest of getaways or the steepest of hills. I
think 3rd will be very useable 
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snapper
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| posted on 4/1/14 at 09:08 AM |
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With a torquey 2.8 I would think it could pull a 3.38 or 3.14 easily this giving more usable 1st a better 2nd for pub bragging 0 to 60 and much better
touring in fifth
I think you'll spin up first and second to frequently
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Nickp
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| posted on 4/1/14 at 09:25 AM |
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quote:
Originally posted by snapper
With a torquey 2.8 I would think it could pull a 3.38 or 3.14 easily this giving more usable 1st a better 2nd for pub bragging 0 to 60 and much better
touring in fifth
I think you'll spin up first and second to frequently
You're probably right, but that's what I've got so it's having it (unless anyone has either of the above and fancies a swap)
I can always swap it later when the mood suits.
[Edited on 4/1/14 by Nickp]
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ReMan
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| posted on 4/1/14 at 10:46 AM |
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Out of interest, what is the std diff ratio?
www.plusnine.co.uk
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Nickp
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| posted on 4/1/14 at 11:04 AM |
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quote:
Originally posted by ReMan
Out of interest, what is the std diff ratio?
2.93 in the 323i apparently.
With a 3.14 it'd hit 61mph in 2nd and be doing 3600rpm @ 80mph but have a theoretical top speed of 153mph!! 
It would be a better option but I'm not going to bust a gut (or the bank) to get one.
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SteveWallace
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| posted on 4/1/14 at 06:44 PM |
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I have a BMW 2.8 engine and gearbox and a 3.62 LSD, but I have slightly larger wheels as I'm building a Viento so prompted by you Nick, mine
translates into
1st 33mph
2nd 56mph
3rd 84mph
4th 113mph
5th 141mph
A pity its a bit short of 60mph in 2nd so it will be interesting to see what the 0-60 time difference is between starting in second and changing
compared with starting in 3rd.
Not far off finishing now, but the chance to test it will depend on my IVA date and the weather. BMW cars are near useless in ice and snow so I
really don't fancy trying a BMW powered kit car in those conditions!!
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Nickp
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| posted on 4/1/14 at 08:44 PM |
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quote:
Originally posted by SteveWallace
I have a BMW 2.8 engine and gearbox and a 3.62 LSD, but I have slightly larger wheels as I'm building a Viento so prompted by you Nick, mine
translates into
1st 33mph
2nd 56mph
3rd 84mph
4th 113mph
5th 141mph
A pity its a bit short of 60mph in 2nd so it will be interesting to see what the 0-60 time difference is between starting in second and changing
compared with starting in 3rd.
Not far off finishing now, but the chance to test it will depend on my IVA date and the weather. BMW cars are near useless in ice and snow so I
really don't fancy trying a BMW powered kit car in those conditions!!
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