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cheap corner weighting kit
rodgling - 20/9/15 at 09:11 PM

Have just invested in some of these:

150Kg/300kg Heavy Duty Digital Postal Parcel Platform Scales Weigh Post Office

Seems like good value compared to "proper" kit, and should do the job nicely - will report back results.


loggyboy - 20/9/15 at 09:47 PM

Shame they dont do a 400kg version as really fancy some for rhe clio.


Brian R - 20/9/15 at 10:27 PM

The exact same ones we use. They're fine. Not as robust as the real sets but more than up to the job for a seven type car.

Make a set of blocks up the same height to roll the car off the pads whilst suspension fiddling/jacking up etc.

Stock up on spare batteries too. ;-) You'll go to use them after a while and they'll be flat!


Daddylonglegs - 21/9/15 at 08:23 AM

They certainly look like a great alternative

As for the batteries going flat, there seem to be more and more gadgets on the market that drain battery life even when not being used. I've found the best thing is to just pop a piece of card in between one end of a battery and the contact to stop that happening. As the scales won't be used that often (I would guess) then it's no big deal to just remove the card when you need to use them.

Just my 2p worth


dij - 21/9/15 at 08:34 AM

I have the same ones, they are a little tall but do the job well enough.
It does help if you have a measured weight to set the "tare" on them before use (zeroing)


Toys2 - 21/9/15 at 10:04 AM

Assume that I know nothing about checking corners weights

Do you have 1 set of scales and move them around or need 4 sets?

If using 1 set, would you then have 3 blocks to sit the other wheels on?

Thanks


dij - 21/9/15 at 10:06 AM

You usually use 4 sets


AlexXtreme - 21/9/15 at 04:07 PM

would't one be enough and move it round between wheels?
If necessary rest the other wheels on wooden blocks of the same height to keep the car level


Lander - 21/9/15 at 05:19 PM

In theory you could use one and blocks the same height but it will take so much longer, changing one corner can easily affect the other 3 too.


AlexXtreme - 21/9/15 at 06:50 PM

if the heights are the same then how can the weight change...? agreed it will take longer however I cant see myself checking the weights very often


Lander - 21/9/15 at 07:46 PM

If you adjust one corner it can alter the other 3 slightly. Your idea will work to get it roughly right.


Toys2 - 21/9/15 at 09:29 PM

Thanks for the responses, after writing it, I did wonder if moving the car during set up wouldn't be the best idea
Though I suppose if you had 1 scale and 7 blanks, it could work without too much trouble....
The car on the scale and 3 blanks, then roll the car onto the 4 other blanks, swap the scales and roll it back


killerferret666 - 22/9/15 at 09:48 AM

At the IVA one of the scales was broken so he only weighted each corner a time but had it on both scales.

I think the difference would be very small if done on a per axle basis. It would definitely give you a good guide and if you weighted it the same way for future weighing (if stripping weight) that would give you an accurate difference in weight.


Ugg10 - 22/9/15 at 11:35 AM

quote:
Originally posted by killerferret666
At the IVA one of the scales was broken so he only weighted each corner a time but had it on both scales.

I think the difference would be very small if done on a per axle basis. It would definitely give you a good guide and if you weighted it the same way for future weighing (if stripping weight) that would give you an accurate difference in weight.


I think for getting all up weight the 1 scale/3 block approach would be fine. But for setting up corner weights every time you change one corner all four should be checked and therefore having to move the scale round all four corners each time you turn a suspension platform would be a right PIA.


Edwardo - 23/9/15 at 06:55 PM

Just wanted to say thanks for the link rodgling

I bought a pair of these after reading your post, they arrived tonight and seem to be brilliant value for money so have just ordered the other 2.

Many thanks again
Tony


hornetV2 - 2/10/15 at 01:36 PM

Looks like a good Locost alternative

I no longer have access to a set of Intercomp scales, so these would be very handy. The Intercomp scales used to weigh a lot and so were difficult to transport around. These look to be much lighter, so could anyone let me know how heavy they are?


Edwardo - 2/10/15 at 01:40 PM

I can get the exact weight when I get home for you if you like. But if you’re just looking for a rough idea they are easily as light as my bathroom scales.

Cheers
Tony


hornetV2 - 2/10/15 at 02:06 PM

Hi Tony

No need for the exact weight, your approximation is fine

Each Intercomp scale used to make me grunt when I lifted it, so these will be a fraction of the weight.


Fandango - 5/10/15 at 07:18 PM

Think I will invest in a set of these.

In the meantime I have a set of (very expensive) ones on loan.

Can anyone point me to an online tutorial for setting corner weights. I am just about to do my first trackday, and have (with an 85kg driver);

LF144
RF125
LR147
RR166

With no driver I have;

LF144
RF105
LR123
RR126

Total weight of 498,so happy enough with that.


hornetV2 - 6/10/15 at 07:00 AM

People can go on for ages about how to corner-weight a car but for general circuit work in a car that is not symmetrical (like a single seater) the idea is to get the diagonal totals to equalise within a few Kg of each other. This way you maximise the grip (and get the car to feel the same) during the transient changes (turn-in to a corner and accelerating out of a corner).

I assume you want the best from the car with just yourself in it and your current diagonal totals are:

LF + RR = 310kg
RF + LR = 272kg

As you can see your diagonal totals differ by 32kg, which is too much.

Think of yourself sitting on a four legged bar stool and one of the legs is shorter than the other three, so if you shift your weight diagonally the chair will rock along the diagonal with the shorter leg (and you will spill your beer), and nothing will happen the other way. So using this analogy you now need to vary what weight the suspension is seeing on your car, so either push the RF and LR further into the ground by raising the spring platforms, or reduce the load on the LF and RR by winding the spring platforms down.

IMPORTANT - YOU ARE NOT SHIFTING WEIGHT AROUND THE CHASSIS, ONLY CHANGING WHAT THE SUSPENSION IS REACTING AGAINST

Another thing to bear in mind is to ensure any anti-roll bars are disconnected prior to doing any measurements and soften any adjustable dampers. When reconnecting the anti-roll bars, do it at the preferred weight of the car (driver sat in) and ensure the drop links are adjusted so the bolts just slide in.

To answer earlier questions, having four scales makes this a relatively simple process, having just one and three blocks can make it a days work!

The above is just a simple guide to a very complex subject, so you may need some pop-corn for the debate this may kick off!


hkp57 - 6/10/15 at 07:57 AM

Good web page here

https://robrobinette.com/corner_weight_calc.htm


Fandango - 6/10/15 at 11:56 AM

quote:
Originally posted by hornetV2
People can go on for ages about how to corner-weight a car but for general circuit work in a car that is not symmetrical (like a single seater) the idea is to get the diagonal totals to equalise within a few Kg of each other. This way you maximise the grip (and get the car to feel the same) during the transient changes (turn-in to a corner and accelerating out of a corner).

I assume you want the best from the car with just yourself in it and your current diagonal totals are:

LF + RR = 310kg
RF + LR = 272kg

As you can see your diagonal totals differ by 32kg, which is too much.

Think of yourself sitting on a four legged bar stool and one of the legs is shorter than the other three, so if you shift your weight diagonally the chair will rock along the diagonal with the shorter leg (and you will spill your beer), and nothing will happen the other way. So using this analogy you now need to vary what weight the suspension is seeing on your car, so either push the RF and LR further into the ground by raising the spring platforms, or reduce the load on the LF and RR by winding the spring platforms down.

IMPORTANT - YOU ARE NOT SHIFTING WEIGHT AROUND THE CHASSIS, ONLY CHANGING WHAT THE SUSPENSION IS REACTING AGAINST

Another thing to bear in mind is to ensure any anti-roll bars are disconnected prior to doing any measurements and soften any adjustable dampers. When reconnecting the anti-roll bars, do it at the preferred weight of the car (driver sat in) and ensure the drop links are adjusted so the bolts just slide in.




To answer earlier questions, having four scales makes this a relatively simple process, having just one and three blocks can make it a days work!

The above is just a simple guide to a very complex subject, so you may need some pop-corn for the debate this may kick off!



Many thanks for your excellent input. Could be a busy day at Oulton Park for us, next week!


johnH20 - 6/10/15 at 05:12 PM

Anyone tried these scales out yet? Mine arrived this morning and I could not resist having a go. I have some slightly disturbing results:
- My two scales are 3 kg different when weighing me - approx. 80 kg.
- One of the scales initially produced some erratic results including residual readings of up to 54 kg when a 200 kg load was removed ! After excercising the scale some 10 times it seemed to stabilise with a net figure of 1 kg after load removal.
- When compared to my previous weighings using multiple mechanical bathroom scales the results were:
Front Rear Total
- Bathroom scales 230 385 615
- New electronic scales 219 373 592
- Norwich IVA 230 400 630
I have no idea which is right in absolute terms. My readings are all an average of 5 at each wheel taken as pairs. The IVA readings were made outside as a one off and the reading seemed to flicker with the state of the breeze. I am sure my weighing technique can be improved as I did not take excessive care over levelling but my data sets are consistent within themselves.
So my car ( fully tanked ready to go ) weighs somewhere between 592 and 630 kg . Take your pick!
I need to take more measurements but I have a suspicion that the 'dodgy' scale may have a non linear characteristic at the higher loads relative to the other in which case I will send it back. So the warning is take care when using this bargin equipment!


johnH20 - 6/10/15 at 05:54 PM

As an aside why does my carefully formatted post get centred in this way! Is it me or Fozzie ?


rodgling - 6/10/15 at 07:34 PM

Just tried mine with a weight of around 23 kg. Two read 21.7, two read 22.7, not great (about 4.4% different).

Anyone know how to access the calibration function? The high quality manual suggests holding down the Mode button but this doesn't work for me?


Edwardo - 6/10/15 at 10:09 PM

When mine first arrived I checked them with my weight against our pretty accurate bathroom scales. They all read very slightly differently but all were within about 0.2kg of the 81.2Kg reading on the bathroom scales - so was happy with that.

First thing I weighed in the garage was the fully dressed Injection Pinto engine+gearbox which is out of the car at the mo. Weighed it 3 times and each time got 186kg-188Kg which sounds about right from trawling the net (140Kg'ish for engine+40Kg'ish for box).

I found that a house brick was pretty much a spot on match height wise for the scales - so popped a couple under each wheel and rolled the car on and off. Again tried this about 3 times and got pretty much the same reading each time on the displays, which when totalled up didn't seem ridiculous as total weight at all.

I think with this you have to bear in mind the price of the scales. To be fair they are never going to be spot on accurate like the proper equipment.

I'm very happy with mine as I'm not planning to be getting heavily into corner weighting (no pun intended). All I really wanted to know is roughly whether my cheap low end kit car is going to be a 650kg fatty or a 700Kg+massive disappointment. Even if these cheap scales are 15-20kg out (hopefully they are more like only 5-10Kg out) - it still gave me a good idea which is what I wanted.

Cheers
Tony


snapper - 7/10/15 at 06:21 AM

Corner weighting a car by definition will change the Wright by moving the suspension up and down using available adjustments ( simple terms) by changing the Wright pressing down on 1 scale the Wright is shifted across the car
The gauge show an increase or decrease
You haven't changed the Weight of the car so the weight must go somewhere
To one of the other corners
Which one?
Move the single scale to each corner and weigh again
And again
And again
Trust me use 4 or book a room in advance to the latest asylum


hornetV2 - 7/10/15 at 06:31 AM

Hi John

Please keep us posted how you get on with the scales. As you say, it seems you may have one dodgy scale.


rodgling - 7/10/15 at 08:41 AM

The seller got back to me with some updated instructions on how to calibrate the scales:

1. Keep pressing the MODE button first, and then press the ON/OFF button to turn on the device untill the screen displays 000000.

2. Release the button, the screen will display E-00, press the MODE button again, the screen will display E1-25 (E2-50, E3-100).

3. Put on the corresponding weight( for 25, put a 25KG weight). When the screen display GOOD and turn off automatically, it means that the correction is finished.


Gave this a quick try on one of mine and it seems to work. Now I have the problem of finding a calibrated 100 kg weight... (actually I don't really mind too much as long as they all over- or under-read by the same amount)

Hope this helps.


johnH20 - 7/10/15 at 11:20 AM

Update. Prior to attempting any recalibration as above I did a further simple exercise this morning - weighing myself 10 times on each scale. Total spread of readings on my 'good' scale was 1.1 kg, spread on my ( previously ) 'dodgy' scale was 2.2 kg. Average for the former was 82.1 and for the latter 81.5. These numbers correlate with my mechanical bathroom scales ( 3 sets ). This is probably as good as I can expect on this equipment.
What is a bit baffling is the initial erratic reading of my 'dodgy' scale. I cannot understand why 'running in' an electronic device should have an effect but it seems this is what has happened in my case. I plan one further test to double my body weight with added sand bags to see if there are discrepancies at higher loads. Watch this space.


cosmicicecreamman - 7/10/15 at 11:39 AM

quote:
Originally posted by snapper
Corner weighting a car by definition will change the Wright by moving the suspension up and down using available adjustments ( simple terms) by changing the Wright pressing down on 1 scale the Wright is shifted across the car
The gauge show an increase or decrease
You haven't changed the Weight of the car so the weight must go somewhere
To one of the other corners
Which one?
Move the single scale to each corner and weigh again
And again
And again
Trust me use 4 or book a room in advance to the latest asylum


Totally agree!!!

You will also need to ensure your surface that you are putting each scale on is level. A spirit level is not accurate enough - build a water level, label each corner and the corresponding scale to ensure that scale always goes to the same corner, and shim under each scale until they are perfectly level.

You will also need to disconnect anti roll bars to ensure there are no external loading affecting the corner weight reading.


johnH20 - 7/10/15 at 01:36 PM

Update 2. My last check done, me and the sandbags. Each bag weighed separately for a combined 82 kg. Weighed together 84 kg plus me (82 kg ) weighed 167 kg ( average of 2 scales ). So some nonlinearity there but not too serious. I have repeated all yesterdays car weighings with scales now seemingly stabilised after yesterdays erratic results. After ignoring the first result in a series, which always seems to be off, I can get repeatable results in a series of 5 within +/- 1 kg over 200. I seem to have a discrepancy of 5 kg between scales at this point, so that seems to be the limit of accuracy with this equipment.
My conclusion is this is good enough for our kind of activity. I still don't know what the absolute accuracy is in the absence of suitable calibrated weights, but in corner weighting we are looking for differences so I am not too troubled. I now have to get down to the real work.


hornetV2 - 7/10/15 at 02:12 PM

Thanks John

I agree for the cost of these items, they provide a reasonable check. Fandangos car was 32kg out, so if these can get you to within a few Kg, then they are worth it.


mark chandler - 7/10/15 at 03:04 PM

I doubt you would ever notice a 5kg discrepancy, drop a wheel by a couple of mm and you will see that, so unless the roads you drive on are glass flat it will not show up.