timex
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| posted on 30/11/07 at 02:55 PM |
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Corner weight`s, How??
Can anybody explain how to set up the corner weights in simple easy to understand steps.
Thanks, Phill
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Guinness
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| posted on 30/11/07 at 03:12 PM |
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Put the car on 4 scales, put a few bags of sand the same weight as the driver in the drivers seat. Muck about with the suspension 
This may be more help though!
http://www.grmotorsports.com/news/012005/understanding-corner-weights.php
Mike
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mookaloid
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| posted on 30/11/07 at 03:52 PM |
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quote:
Originally posted by Guinness
Put the car on 4 scales, put a few bags of sand the same weight as the driver in the drivers seat. Muck about with the suspension
Mike
ROFL 
"That thing you're thinking - it wont be that."
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higgsti
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| posted on 30/11/07 at 04:14 PM |
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http://7faq.com/owbase/ow.asp?FlatFloorSetup
another which might help .corner weights should always be done with the drivers weight in the drivers seat either in person or as ballast and also
with fuel i find it best with half tank
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simes43
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| posted on 30/11/07 at 06:22 PM |
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Adjusting platforms to deliver/distribute weight across axles is difficult and can create a very odd set of ride heights around the car.
A major tip would be to not bolt, weld or position anything that can be housed in another place (safely) before the car has been corner weighted.
To create a rake angle for instance and keep it while you are adjusting all the platforms is very difficult to achieve
Put another way, a significant adjustment on the platforms is required to gain or loose 6kg of a corner, compared to actually relocating the battery
around the car (even a red top 20 at 6kg makes a huge difference)
Another tip is to make sure your tyre pressures are exactly what you run. A 1lb of pressure difference will change a corner weight reading.
Oh and once the car is corner weighted and four wheel aligned, you will need to make sure that the rear geometry is still correct. Ride height will
change the panhard and trailing arms.
Find a race team with a four wheel corner mode system and pay them. Its the only accurate way of setting a car up.
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Bob C
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| posted on 30/11/07 at 06:58 PM |
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With a BEC I was able to use bathroom scales. What you're basically trying to achieve is front right + back left = front left + back right.
right to left and front to back is determined by the distribution of masses in the car. So you can easily move the back higher - just adjust both
spring seats up the same! Yes put the equivalent of your weight in the driver's seat.
To use the bathroom scales I had to lose a bit of weight which I did by taking the wheels off & balancing it on the brake discs. The other
advantage of this is that it takes away any variation due to tyres & pressures.
It was easy and quick to get the mismatch down from over 35kg to under 3. And it was repeatable too. And the car is noticably better for it,
previously the lightly loaded tyres were prone to spin or lock.
Yes pay a garage a small fortune if you want, or buy a couple of sets of bathroom scales & DIY. In spite of what folks (on here) say theyre
accurate enough - particularly as its a relative reading you're interested in not absolute. If your car's too heavy rest it on a
floorboard on 2 scales and add the readings.
And you only need to measure one axle at a time.
You DO need a flat floor - preferably level!
Bob
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mark chandler
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| posted on 30/11/07 at 07:21 PM |
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I,m with bob here, nice set of 4 scales from B&Q for less than £20.
I calibrated mine before starting, accuracy of weight is not important just that they all display the same weight when loaded, so dropped 3 x 25litre
bottles of water and zeroed, I guess this is around 75kg.
You need a very flat floor, within 1mm really or the values go out the window.
My mate sat in mine when we were doing it, from leaning back to leaning forwards in the seat made 7 kg change on the front wheel.
I also tried swapping the scales around, but they all came out within a couple of Kg of each other so in my case money well saved ! + I can do it
again next year when things have settled.
Regards Mark
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simes43
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| posted on 30/11/07 at 08:18 PM |
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And then you have the car four wheel aligned using a four wheel laser system.
Accurate measurement of castor, camber , front and rear, set back , kpi, thrust angle, etc etc.
Any change will alter another....
The reason for using technology for car set up is that every adjustment can be understood and the impact seen across the whole car. Both corner and
cross weights for instance.
Or you use a piece of string and a spirit level. They go nicely with bathroom scales.
Important point. please dont use a local garage who have no experience (or interest) in setting up a car, even if they have the kit.
A small race team will understand what dynamics you are looking to introduce and or avoid.
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Bob C
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| posted on 30/11/07 at 08:26 PM |
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"Or you use a piece of string and a spirit level. They go nicely with bathroom scales. "
LOL horses for courses mate. We've allegedly built our cars for £250 haven't we...???
Are we after the last nanosecond in a lap time or something a bit less embarrassing on the high street? You pays yer money etc. etc.
However I reckon a home builder with tesco scales will do a better job 95% of the time than an unknown, questionably trained, intellectually
challenged grease monkey who just wants to get home.... ;^)
Bob
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simes43
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| posted on 1/12/07 at 08:37 AM |
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The main problem is the knock on effects of raising and lowering the chassis.
Even with Longacre scales its tricky to get right and the suspension geometry always changes.
If I get the set up wrong, I am off the pace, you guys are mainly on the road which is a much more dangerous place to have an incorrectly set up
car.
Could I suggest that the first set up is done using technology, the second using the cheaper methods? If you note down the changes, then they could be
put back.
I will find out how much Regency in Cambridge would charge for a full alignment and corner weight using their Sun and Longacre kit.
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procomp
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| posted on 1/12/07 at 11:21 AM |
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Hi simes 43 you are banging your head on a brick wall. Many people on this site woulld never entertain getting the job of setting the car up properly.
They would rather drive around in the belife that they have done it correctly on four bathroom scales and it must be right.
Every car that i have seen done this way and has then been checked properly has been so far out it is a pointless exercise.
I know it costs money but for the sake of £200 . You can get the car fully setup - corner weighted - castor checked - chassis alingnment checked -
springs tested - All 4 dampers dynoed and balanced- ect ect.
You have to ask why one of the most important areas of the car That costs 6k is always overlooked and never given proper consideration for the sake
of £200. It is a bit of a joke really.
Sorry that turned in to a rant but it seriously baffels me.
Cheers Matt
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