DIY corner weighing scales?

[MR22ZZ]

Been thinking about setting up some corner weighing scales for home to aid with coilover setup when I play around with ride heights.

the cheapest set-up I can find is ~$1700, so that got me thinking. http://www.gmpracingproducts.com.au/...cale-72594.php
What about grabbing 8 high load ~180kg bathroom scales, like these... http://cgi.ebay.com.au/Glass-top-Bat...item53e2227b96

then make up some load distributing platforms so you car proportion the load across 2 of the scales at each corner.

Then all you need to do is add up the numbers of the twinned scales to work out the load on that corner, then it's easy to work out load distributions across the car. I could also set up a spreadsheet that would do all the calcs for you pretty easy just by plugging up the numbers from each corner.

about $300 and a small amout of time and there is a set of corner weights ready to roll.

Ideas, problems with my thinking?

[Duk]

It's a brilliant idea!
Obviously you'd need to have a very flat piece of ground to do the measuring on. And driving the car onto the scales without wrecking any thing may require a small ramp at each corner.
I think if you (or someone else) bought a pair of those or similar scales, set them up with a bridge piece and then sat the other 3 wheel onto blocks of a similar size so the car was basically level, then the concept could be proven with minimal outlay.

[oldcorollas]

one problem with bathroom scales, you gotta tap them on, then they zero, then they weigh.. but don't stay on for ages..

which would be a real pain when trying to weigh a car...

[wilbo666]

Yeah they are expensive...

Seen the older school lever style ones? I recall seeing plans at some stage in the past...


One thing that I thought would have been cool when the Wii Fit came out was to use 4 of them and link it via wireless....I initially thought they might be up to the task seeing as fat yanks / people could be buying them and using them... alas turns out they aren't rated for fat people / quarter of a car

http://cgi.ebay.com/ebaymotors/Manua...item1e5cb314a8


Cheers
Wilbo

[MR22ZZ]

It's a brilliant idea!
Obviously you'd need to have a very flat piece of ground to do the measuring on. And driving the car onto the scales without wrecking any thing may require a small ramp at each corner.
I think if you (or someone else) bought a pair of those or similar scales, set them up with a bridge piece and then sat the other 3 wheel onto blocks of a similar size so the car was basically level, then the concept could be proven with minimal outlay.

I was thinking more jacking the car up to slide the scales under the wheels so they are positioned perfectly.

I like the idea of trying it out with 2 scales to test, could easilly support the other corners with axel stands.
We need some new bathroom scales anyway so it would be no loss if it doesn't

Stu, I hadn't thought of the auto off delay on the scales, I'll have to investigate this.

I'm sure there are analogue options available and cheaper.

Wilbo, yeah I've seen that setup, but don't like the lack of accuracy you get from having to factor for the canter-lever.

[Billzilla]

Just get some of the older style spring scales, not the electric ones. You can make them accurate enough by working out how roughly much weight will be on each corner, then dividing it by two to get the reading that each scale will see, then adding that weight to each scale and using the zero adjuster on it so they all read the same in the weight range you'll be checking.

[Duk]

I was thinking more jacking the car up to slide the scales under the wheels so they are positioned perfectly.

Yeah, I figured that that approach would be suggested as well. The reason I mentioned ramps is so that the suspension would be properly settled when you are taking measurements. You know how the car isn't sitting down correctly on its suspension when you let it down off the jack? Same thing here could give inaccurate readings.

[MR22ZZ]

the coilovers don't have a large range of travel so the suspension it pretty close to settled anyway when it's dropped.

Bill, yeah the analogues seem to be the go, but it's more a case of finding them with at least 150kg load capacity... the higher the better.

[Mr Ed]

one problem with bathroom scales, you gotta tap them on, then they zero, then they weigh.. but don't stay on for ages..

which would be a real pain when trying to weigh a car...

Hahahahahahahahaha! You should change your name to genYcorollas.

The normal cheap old analogue scales are the obvious choice for this.

[Hiro]

For the FSAE car we used normal bathroom scales (obviously since the car only weighed 300kg you'd need bigger ones for a road car), the tyres sat on a board which sat on tiny ball-bearings which sat on another board which sat on the scales so we could adjust the coilovers on the fly to get accurate corner weights (the boards and ball-bearings allowed the suspension to shift camber/toe/caster etc without distorting the tyres)....also helps when you can pick the whole car up with 4 beefy guys at the corners, but the principle is the same.

[oldcorollas]

Hahahahahahahahaha! You should change your name to genYcorollas.

The normal cheap old analogue scales are the obvious choice for this.

you're an idiot Ed.

the consistency between different sets of digital scales is very good.
beteen different analogue ones can be pretty poor.

if you are checking the last couple of kg difference, it will be much harder on analogue than on digital

[Mr Ed]

:facepalm:

Problems with your statement:

1. Analogue scales are plenty accurate, definitely within a kg
2. A kg difference over the weight of a car wont mean anything anyway
3. Any significant inaccuracy across 8 sets of scales will cancel itself out
4. Digital scales wont work anyway for other reasons (as you said)

How will it be harder to check the difference on analogue scales anyway? Do you have trouble telling the time on an analogue clock too?

[Sam_Q]

I bought a 240V powered grocers scales rated at 300kg for this purpose. I plan on making cutting up 3 spacers to have an equal height for the other corners of the car.

I just found a link to the same model:

http://cgi.ebay.com.au/INDUSTRIAL-EL...item439f26508e

I just didnt attach the post

[TERRA Operative]

Wat about load cells? Wouldn't be too hard to hook them up to a PIC or the like to get readings.

Dunno how much load cells are worth, but the electronics would be pretty cheap.
Something like this would work.
http://cgi.ebay.com.au/S-Type-Load-C...item3cae7c4022

[MR22ZZ]

the industrial scales, I'm looking at spending the price of one of those on the complete set of mine.

Terra, those load cells are interesting, but can imagine it would be a hell of a lot of fucking around with labview (or something similar) to get a program worked out for it. If juts running them of a standard display I have no idea what the calibration would be like on those. Way to much of a ground-up setup for what I'm looking to do.

Do-able but way to much time and stuffing around for the simple backyard system.

I do like the idea though, the time to get it running properly, not so much.

EDIT: actually the list of products that the load cell mob sell is pretty impressive. http://www.onlyweighscales.com/
Cheers