Piooly
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| posted on 21/4/15 at 11:14 PM |
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Help?? Design weight calculation?
hi guys, I have Atlast sort of finished the car and I want to book my IVA test today using the online application. I need some help on what to put on
the weights section. I have read the manual and am a little unsure as the book shows a 4 seater etc. Mine is a lotus seven by the way with V8 engine.
Actual weights are as follows, this includes a full tank of fuel but no passengers or luggage -
My front axle weight is 410kg
My rear axle weight is 438kg
So 848kg all in.
Yes my lotus is a bit heavy but it's running a v8, full roll cage, 65 litre fuel tank and it's got a lot of trim and bits in it. Last
thing I want to do is fail my test for listing the wrong weights on my car plate and application. I understand I have to add 65kg per seat and 7kg per
seat for luggage. do these all get added to the rear axle weight as the seats are at the rear of the car in a seven? If anyone can put this in plain
English I would be very grateful.
Thanks.
Ps, pictures to follow soon..
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Angel Acevedo
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| posted on 22/4/15 at 02:32 AM |
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Even though they will be rear biased, part of the weight will fall on the fronts.
I'd apply a simple "regla de tres" sorry, the name in English escapes me.. To find out the relationship of how much goes to each
axle.
HTH
Beware of what you wish.. for it may come true....
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theduck
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| posted on 22/4/15 at 02:09 PM |
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This is all to do with design maximum weight and is used for calculating the required braking forces on the brake test.
For your VIN plate you only need:
Manufacturer
VIN number
In that layout.
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The Black Flash
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| posted on 22/4/15 at 08:12 PM |
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You pretty much need to guess. All you can really do is take the actual weight and divide the passenger+luggage weight equally across the axles, then
add a bit more as a safety margin. Don't forget the weight of fuel! It's not crucial, as long as the design weight is greater than kerb
weight + passengers + luggage. (Though the IVA man said that if it wasn't they'd just change the form so that it was).
Be careful though - the brake tests are done on the design weight. This caught me out as mine was something like 1000 kg, although the car is just
over 600 in reality. My handbrake failed, even though on the MOT rollers (which measure actual weight) it passed fine.
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ettore bugatti
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| posted on 22/4/15 at 09:04 PM |
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Cool, that you know the actual weights.
Easiest way was to measure it with a full tank and 75kg worth of sand bags.
You could actual get a very accurate guesstimation.
This picture tries to explain it:
So if you imagine a reference line thru your front axle then you can draw the CoG line at 52% of your wheelbase. Let's call this X
Now measure the distance from your hip point position to the front wheels (centre, obvious), it is called Y.
The sum you have to do is:
848*X+150*Y=Z
then
Z/(848+150)=your new CoG line distance measured from front wheels
And from that gives your new front/rear weight distribution.
Anyway, Just shout your wheelbase
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