Hi guys,
I was wondering of anybody knows exactlay where the CoG of the VX220 is?
Due to a project I´m working on I need the information of the HIGHT and the WEIGHT DISTRIBUTION.
I really appreciate your help!
Cheers,
John
Center Of Gravity?
Started by
Josi0785
, Dec 01 2011 01:56 PM
17 replies to this topic
#2
techieboy
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Posted 01 December 2011 - 02:10 PM
Wont an exact CoG depend on the individual car?
#3
VX Boyd
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The VX220.
My work.
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Posted 01 December 2011 - 02:16 PM
Uni project?
I did one on a caterham about determining the CoG of a caterham.
CoGs, can differ if you're after an exact amount from one indicidual to another.
You need two measurings of the mass at each corner, one set with the vehicle compeltely flat - which won't be hard to find, a few people have done this. But to work out the height of the CoG you'd need the corners weighed with the vehicle angled - I doubt many people have done this.
Edited by VX Boyd, 01 December 2011 - 02:17 PM.
#4
MellowYellow
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Posted 01 December 2011 - 02:17 PM
Wont an exact CoG depend on the individual car?
and the build of whoever is driving it.....they may have a large ass!
#5
techieboy
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Posted 01 December 2011 - 02:20 PM
Wont an exact CoG depend on the individual car?
Yep, the CoG of mine definitely isn't on the centre line (or anywhere near) of the car when I'm sat in it and any amount of tweaking of the ride heights won't allow for that.
#6
Korkey
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Posted 01 December 2011 - 02:45 PM
Wow! This is a big ask.
I would be amazed if anyone has found it yet.
I had to do this once on a race car which I produced, a long time ago now.
The center of gravity is a single point where all of the vehicle's weight is centered. When hung from this point it would be in equilibrium if no force was acting upon it.
It is far easier to think of this point in threee planes in which it can be measured.
Longitudinal axis..... wheelbase.
Lateral axis.......track width.
Vertical axis.......height above the ground.
To determin the first element......by weighing each of the four corners.......add the front wheel weights together and divide by the vehicle weight.
The resulting % shows us where the balance point is along the wheelbase of the vehicle.
EXAMPLE.
If the weight of the front wheels is 400Lbs and the rear is 600Lbs the total vehicle weight is thus 1000Lbs. The percentage of total weight upon the front wheels is thus 40%. The first balance point of the vehicle lies along the wheelbase, at a point 40% of the total distance from the centre of the rear wheels.
If the wheelbase is say 100 inches then the "point" will be 40 inches from the centre of the rear wheels moving forwards.
The lateral COG is found in the same way. Comparing left to right weight. And it will fall exactly upon the centre line of the track width if the weights are equal.
Now we have 2 of the 3 points.
The third point is the more difficult one.
Elevate the rear, say, 2 feet above the ground ( must use a flat floor here ) whilst weighing the rear corner weights. Once they are equal to the front weights, by raising or lowering then we have the HEIGHT of the COG and thus with the other information the cars COG point.
Regards.
Korkey.
Edited by Korkey, 01 December 2011 - 02:48 PM.
#7
2.2_na
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Posted 01 December 2011 - 03:23 PM
the build of whoever is driving it.....they may have a large ass!
I'd imagine that a 'large' driver would be a significant factor / influence.
#8
techieboy
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Posted 01 December 2011 - 03:45 PM
Think I read it was roughly +5mm on the ride height on the drivers side for a 75kg driver somewhere on here or SELOC on presumably standard rate springs. Mine was corner weighted with me in it last time I had it done properly but didn't ask what changes they'd had to do to allow for me. 
#9
VX-GT
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Posted 01 December 2011 - 04:14 PM
If it is just data for a college/uni project, I would talk to Simon Roberts of Cornering Force Ltd (sorry simon hope you don't mind)
If it is to support kinematics on ones own car then measurement using korkey's technique will suffice
#10
Ouchie
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Posted 01 December 2011 - 05:17 PM
An extra jack?Think I read it was roughly +5mm on the ride height on the drivers side for a 75kg driver somewhere on here or SELOC on presumably standard rate springs. Mine was corner weighted with me in it last time I had it done properly but didn't ask what changes they'd had to do to allow for me.
#11
Josi0785
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Posted 01 December 2011 - 05:28 PM
Ya, it is a uni project. The point is they have already been taking off some parts like engine and the body panels. So measuring the weight of the car is not gonna work.
Somebody of you guys must have the awnser for an original VX 220, don´t you? So I would be totally fine with the weight distribution and hight of the CoG of the original VX220 (Doesnt matter which trim or version).
THX,
John
#12
VX-GT
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Posted 01 December 2011 - 05:42 PM
in that case try Simon RobertsYa, it is a uni project. The point is they have already been taking off some parts like engine and the body panels. So measuring the weight of the car is not gonna work.
Somebody of you guys must have the awnser for an original VX 220, don´t you? So I would be totally fine with the weight distribution and hight of the CoG of the original VX220 (Doesnt matter which trim or version).
THX,
John
#13
hairy
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Posted 01 December 2011 - 06:24 PM
Somewhere around the jacking points, mine (and others) will "float" on axle stands.
#14
jules_s
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Posted 01 December 2011 - 10:48 PM
Hairy has it...
A standard VX will balance on the two central jacking points...mine does and i've seen turbos do it too
#15
VX-GT
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Posted 01 December 2011 - 11:23 PM
This only represents one fulcrum point whch is the section through the vertical lateral planeHairy has it...
A standard VX will balance on the two central jacking points...mine does and i've seen turbos do it too
what about the vertical longitudinal plain and (more difficult) the horizontal plane
#16
2.2_na
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Posted 02 December 2011 - 02:35 AM
Somewhere around the jacking points, mine (and others) will "float" on axle stands.
That's assuming you don't have a Tim King 'esque
#17
VX Boyd
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The VX220.
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Posted 02 December 2011 - 10:23 AM
I don't suppose you're at herts uni? I know they had a couple of dead VXs that never got used for anything in my time there.
#18
RobNA
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Posted 02 December 2011 - 06:42 PM
This only represents one fulcrum point whch is the section through the vertical lateral plane
Hairy has it...
A standard VX will balance on the two central jacking points...mine does and i've seen turbos do it too
what about the vertical longitudinal plain and (more difficult) the horizontal plane
We have done the test to get the CoG at work, seeing the car on the flat patch, but with the rear wheels on ~3 feet stands is amusing
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