Simon
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| posted on 15/4/05 at 10:41 PM |
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Corner weighing
Might be a bit mad, but having seen the prices of corner weight scales, thought I'd look elsewhere.
Picked up the Argos catalogue and found some bathroom scales for £3.29 each. Max 120kg
Ordered four off, including delivery is £18.11.
Should only need 2 for rear and all for front.
Any tips? Eg. Did I read that to weigh car like this that whichever end on scales, the other needs to be lifted by same amount.
Cheers
ATB
Simon
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craig1410
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| posted on 15/4/05 at 11:32 PM |
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Simon,
Yes I think you need to keep the car level to get a true reading although I'm not sure just how much of an error you would get from say a
2" lift at each wheel. I suppose if you were able to calculate the variance as a pecentage you could apply a correction factor to correct each
reading afterwards. This would certainly simplify the whole operation if it was possible.
I'll be very interested to hear how you get on as I might need to do something similar myself soon.
Cheers,
Craig.
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Ian Pearson
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| posted on 16/4/05 at 07:22 AM |
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quote:
I'm not sure just how much of an error you would get from say a 2" lift at each wheel.
Planning on weighing my car this way. As far as I'm aware, as long as the all wheels are the same height, the readings should be as accurate as
the scales.
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zetec
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| posted on 16/4/05 at 07:25 AM |
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I'm thinking of doing the same. I was going to get 2 sets and do one wheel at a time. As said you will need to keep the car level and I was
going to make some blocks for the other wheels the same height as the scales from 4"x2". Try and do it with the driver in the car. I
can't see why it won't work just fine as you are not too interested in the accuracy of the scales, just the fact they they show the same
reading for each wheel.
Good luck.
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Mix
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| posted on 16/4/05 at 08:09 AM |
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The principal used for weighing aircraft is exactly that.
Level the aircraft using jacks
Record the weight at each jack
Calculate the total weight, CofG, longitudinal and lateral moments.
I'm not sure what Zetec means by the scales showing 'the same reading for each wheel', I would expect the readings to all be
different especially between the rear and front wheels.
Mick
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alister667
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| posted on 16/4/05 at 08:39 AM |
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I'm not sure 120Kg max is enough. I did my corner weights with me sitting in the car and the rear corners weighed in around 160Kg (with my
lardy ass in the car!) each.
The fronts came in around 120. I used 1 (heavy duty) scale and 3 pieces of wood the same hieght as the scales.
The scales I had ran out of figures in around 150Kg, but measured OK past that.
It was a pain moving the scales about, I admit using 4 scales would be a lot handier.
When I got the car to the track a few months after doing that the handling was transformed - it was well worth it.
All the best
Ali
http://members.lycos.co.uk/alister667/
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craig1410
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| posted on 16/4/05 at 11:48 AM |
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I agree about the 120Kg's not being enough but I think Simon was intending using two scales each side on the front and one each side on the back
although from what you have said perhaps he will need two each side at the back also.
Both Simon and I have Rover V8's fitted which puts more weight at the front than you will get with a BEC. I'd expect 55% front to 45% rear
distribution and perhaps just over 725Kg's total including 75Kg driver so that should be around 400Kg's front and 325Kg's rear by my
estimates. If that is accurate then we will indeed need two scales each corner linked with a wooden beam or similar to spread the load.
Cheers,
Craig.
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Fifer
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| posted on 16/4/05 at 12:18 PM |
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Just thought i'd throw this in. Measuring corner weights is indeed a good move to get car set up, but, you need to consider ride heights (height
from floor to fixed points around car) when adjusting each corner. Get a book on setting up suspension and you will soon be driven round the bend (no
punn intented).
The bathroom scales worked for me by the way, you can get higher reading ones although they cost more.
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andkilde
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| posted on 16/4/05 at 01:24 PM |
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If the scale isn't up to the task you could also whip up a lever arm jig out of scraps.
Would reduce the reading on the scale in the ratio of the arm lengths.
As others have said, you'd need to block everything up level.
Cheers, Ted
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dozracing
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| posted on 16/4/05 at 03:24 PM |
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Hi Simon,
Why not come over to Dartford and i'll set the car up for you, use proper corner weight scales, camber gauge and tracking equipment, and get it
right for you.
Kind regards,
Darren
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Deckman001
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| posted on 16/4/05 at 06:12 PM |
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Careful Darren, Dartford isn't far for lots of us 
Jason
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Simon
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| posted on 16/4/05 at 09:57 PM |
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Cheers for the comments chaps.
Darren,
Funny you should say that - one of the reasons for weighing the corners is so you can supply me with some different springs. My car is sitting
to low, so using scales (weight), protractor (spring angle) and ruler (compression) I'm hoping that you'll be able to give me an idea on
springs. Eg without weighing, my spring bases are 20 turns from "longest", under load springs are 4.75" long, unloaded 6.25"
long and spring angle is approx 44 degrees. Another thing, car sits with 4" ground clearance and need another 3/4" to level rear
wishbones.
I'm hoping once weighed you'll be able to help.
I drafted an email (unsent) a couple of weeks ago but figured some data would be required. Should have scales Monday, so will weigh in evening and
contact you shortly thereafter.
ATB
Simon
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Simon
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| posted on 18/4/05 at 07:40 PM |
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Well peeps, scales arrived and I've weighed it.
Heavier than I thought, so here's the numbers
Front: 360 kg - 51.43%
Rear: 340 kg - 48.57%
Total: 700kg - 100.00%
So there you go!
Darren,
Did you see comments above or shall I send you an email?
ATB
Simon
PS Here's a badly edited pic of my car
 
Rescued attachment 2005_0418Image0007.JPG
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craig1410
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| posted on 18/4/05 at 10:36 PM |
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That's quite a bulge in your bonnet... 
Was that weighed with driver or was it just the car? Also, are there any bits missing including things like coolant, oil, fuel etc? The front/rear
balance seems quite good even if it is a bit heavier then expected.
Cheers,
Craig.
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Simon
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| posted on 19/4/05 at 08:19 PM |
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Craig,
Weighed without me - just car, ith about a gallon of fuel. Engine oiled, but not water.
Only things to go on car are header tank and plumbing (5 - 10 lbs?) and n/s harnesses.
Hoping to have a session on the bonnet this w/end to get it looking like the photo, and have now got to widen front wings
Not sure about the bulge, sort of spoils the lines, but I can't afford a weber at the moment so it's staying.
ATB
Simon
[Edited on 19/4/05 by Simon]
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kb58
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| posted on 20/4/05 at 12:52 AM |
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I recently went through this same thing, with my mid-engine Mini coming in at about 714kg... without driver. Sorry, but when doing corner weights is
no time to be leaving yourself out of the equation. Go back and do it again with yourself in the car and 1/2 fuel load. It's not to simply
weight the car, that's why it's called corner weighing. The point is to make sure your diagonal weight percentages identical...
that's why we're using adjustable springs... right?
[Edited on 4/20/05 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Fifer
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| posted on 20/4/05 at 07:39 AM |
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Sorry to repeat my message above, but dont forget ride heights. Even if you get the corner weights looking good, if your ride heights are miles out
it will handle like a pig. It's a combination of both you are looking for.
700kg ! just as well you will have plenty power to hand !
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craig1410
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| posted on 20/4/05 at 08:49 AM |
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Simon,
Have you considered turning the bonnet bulge around so that the open end faces backwards? That's what I intend to do to cover my SU's with
K&N's. My thinking is two fold:
1. The bulge should look less obtrusive when facing backwards because of the natural lines of the bonnet. I intend to have my bulge starting just in
front of the bonnet-nosecone joint and rising quickly (45 degree angle) to about 2" above the joint to allow room for my alternator and dizzy. I
will then let it rise at a steady rate backwards to the required height above the carbs (about 4" total to clear the dashpots). Finally I will
turn the edges of the scoop inwards at the top and sides to make the actual aperture look a bit smaller than it is.
2. It won't act like a bloody great air brake! I believe that the Locost already scoops too much air in through the nosecone so I thought it
would be better to let it out again through a rear facing scoop rather than try to scoop more air in. This should improve aerodynamics or at least not
make them any worse...
Well that's the theory, make of it what you will... I hope to start on this shortly once I have finished fitting my side panels and got the foam
rubber in place around the edges of the engine bay. That will define the final natural height of the bonnet and I can then start carving a bonnet
scoop out of PU foam sheeting which I bought from CFS.
I'll keep you posted,, drop me an email if you wish to discuss.
Cheers,
Craig.
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kb58
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| posted on 20/4/05 at 02:05 PM |
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About the air intake. There is high pressure at the base of the windshield/windscreen because all the air piles up there. Because of that it's
a great place to get air for the engine. So yes, point it backwards.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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kb58
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| posted on 20/4/05 at 02:09 PM |
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quote:
Originally posted by Fifer
Sorry to repeat my message above, but dont forget ride heights. Even if you get the corner weights looking good, if your ride heights are miles out
it will handle like a pig. It's a combination of both you are looking for.
700kg ! just as well you will have plenty power to hand !
Good point! When I set corner weights the first time I got it "right", then had to start all over when I remeasured ride height. The
secret is to adjust diagonal corners by the same amount. Also be aware that turning the collors won't have much effect, until you get near the
proper point where those corners begin taking up their share of the load, the it gets very sensitive, 1/8 turn will make a big difference at that
point.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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locoboy
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| posted on 20/4/05 at 02:57 PM |
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being a novice to this kind of topic i am interested in how you can 'balance' or 'set' the corner weights without adjusting
the ride height?
These two things seem to have been talked about as if they are two completely different animals - is this so?
ATB
Locoboy
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Fifer
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| posted on 20/4/05 at 03:13 PM |
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Bottom line is yes.
Imagine your car chassis bottom rails are exactly 6 inches from the ground at four points around the car at each corner. If you weighed each wheel you
would probably find that they would vary, the total of course being the total weight of the car.
If you place a sand bag, the weight of the driver in the driver seat, this would lower the right side of the vehicle a small amount.
The ride heights would now be different.
Now level the car again using the spring tension and weigh it again, again the corner weights might be diferent but you can work on these to try to
get a ballance so that the fronts are near the same and the backs are near the same.
Obviously, you will only get them nearly the same unless you are very lucky, so, next job could be, move battery to adjust the weights, move fuel
tank, move engine, move anything etc etc to get the ride heights and weights as close as possible.
On a seven type car, you will not get them exact (and if the car is completed, you are snookered to make big weight shift changes) but assuming the
weights are close and the ride heights are close, the diference in handling will be great.
IMHO 
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locoboy
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| posted on 20/4/05 at 03:22 PM |
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Thanks, much clearer now.
I was sat here thinking once its level then surely the only way to change the corner weights is by moving stuff about! or..........making it un level!
ATB
Locoboy
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Simon
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| posted on 20/4/05 at 11:02 PM |
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Chaps
Re the corner weight thing, agree entirely, but the main reason for weighing initially was so I can get some more appropriate springs. Once they are
on, I'll probably take the car to Darren, give him lots(?) of money and let him have all the aggro.
As for bonnet scoop, the bonnet/scoop were made in one piece and laminated to the nosecone, so I ain't changing it yet. A point worth
considering is that the engine will swallow such huge quantites of air, I'll probably need to keep the brakes on to prevent "creep"
while stationary Seriously, will be remoulding next summer (2006) as one piece (doing it properly!!) and should have a nice weber 500 and pancake
sitting under a flat (ish) bonnet, especially as I've just saved quite a few quids by buying some 2nd hand alloys - as seen in pic above off -
off a Corsa!!!!!!!!!!
Really don't want to start changing things as I have under a weeks work left (though done 10 mins here and 10 there - so another three
months)
ATB
Simon
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barraw
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| posted on 21/4/05 at 10:33 PM |
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There's an easy and cheap way of getting the front and rear weight - take it to the local public weigh bridge. I took mine there, it cost £4
and they gave me a slip showing 300kg front and 250kg rear and total 550kg.
Also I picked up a good tip from a Des Hamill's book 'Suspension and Brake Tuning' - to balance the car left to right, use a jack
and a 2" steel ball bearing to jack it up from the centre point. Good book - from Amazon.co.uk
Cheap and does the trick.
cheers
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