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PostPosted: Wed Dec 21, 2016 12:03 pm 
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Joined: Thu Jun 24, 2010 8:01 pm
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Location: Dunfermline, Fife
My point exactly, and Diff ratios are specific to events. One car may have run at Le Mans and done the Targa Florio - It won't have used the same diff, and I know which I'd go for!

:D

Al


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PostPosted: Sat Dec 24, 2016 1:44 am 
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Joined: Fri Jun 25, 2010 10:47 pm
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http://www.marcos-oc.com/project50/gallery.html


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PostPosted: Sat Dec 24, 2016 9:26 am 
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How much lighter would the Marcos have been over a cooper s. If there is a big weight difference a 2.9 would pull no problem. The biggest problem with fitting a tall diff is the gap gets bigger between the gears so the rev drop might take it off cam. I would imagine they would have used a CR gear set to reduce this gap.


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PostPosted: Sat Dec 24, 2016 11:20 am 
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Joined: Mon Feb 03, 2014 3:33 pm
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There is a significant difference in the weight of a Marcos over a normal mini shell, with my Mk1 race car it isn't too difficult to lift the back end on my own, in fact it's the easiest way to move it in the tight space in the garage. Albeit the grp on my car is a lot thinner than I have seen on other cars and is allegedly one of a small number of lightweight shells produced by Marcos in '66. I would guess that the Le Mans shell is the same.
I am certain that the front and rear subframes would also have been lightened on the LeMans car, but have no proof, the body of the Marcos is extremely rigid with the amount of marine ply that is bonded into the shell so the subframes add very little to this.


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PostPosted: Sat Dec 24, 2016 12:28 pm 
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Location: East Sussex
I don't think the weight saving would make any real difference to top speed, it will however improve : acceleration, braking and cornering ability, which will improve lap times but I'm sure aerodynamics play a much more important role.


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PostPosted: Sat Dec 24, 2016 5:18 pm 
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I would think that aerodynamically it would be significantly better as well?


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PostPosted: Sat Dec 24, 2016 6:15 pm 
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Joined: Fri Jan 07, 2011 9:26 pm
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Location: Scotland
rpb203 wrote:
I would think that aerodynamically it would be significantly better as well?

Definitely much less aerodynamic drag from a MM shell compared to a Mini. For two reasons, first the drag coefficient is a lot less than a Mini, and second the frontal area is less.

That's why 95-100bhp in the Le Mans Mini Marcos was good for 146mph on the Mulsanne Straight. If you put the same engine in a Mini you might get something like 115 mph?


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PostPosted: Sat Dec 24, 2016 6:26 pm 
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Just had a quick look and the weight difference could be anything between 200-250 kgs. But I agree it would make very little difference to the top speed. You would just get to the max speed quicker, so the high diff would be less of a problem with the weight loss!


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PostPosted: Sat Dec 24, 2016 7:48 pm 
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Location: East Sussex
Certainly, up to a point, but I think in practice the battle with weight is well and truly over by the time you're deep into the torque curve and a couple of hundred kgs is nothing compared to poor aerodynamic performance. Reduction of frontal area is again only a starting point, take the Mini and Metro comparison as an example where the mini frontal area is smaller and the weight is greater for the Metro, but the overall areodynamics of the Metro and general performance is far superior with a like for like engine transmision package, the Metro wins in every department. If I remember correctly Ian Hargreaves did such a test back in the early eighties with an engine spec similar to the one he built for me and the results were published in CCC, anybody got a copy ?


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PostPosted: Sat Dec 24, 2016 10:02 pm 
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The ways to overcome a high diff would be rated like this:

1: Fit a lower one :lol:
2: Fit a more powerful and torque engine :twisted:
3: Loose 1/3rd the cars weight :shock:
4: Improve the cars aero :P

Remember I am talking about overcoming a high diff not achieving top speed.


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