DIY corner/car scales

Might need a set of corner scales for an upcoming project. Don't need huge accuracy just ballpark cause I'm thinking of making a FWD mid engined and wouldn't mind being able to get "close" to the weight balance I want. Implying I don't need 1kg accuracy here, not setting up coilovers or anything, my friends ones don't go high enough and I'm not spending a fortune for a simple check, I could definitely guess it pretty well but I'd rather have some kinda check so I don't land up with a porsche.

Had a couple ideas, my first was 4 bathroom scales locked together with a plate to distribute load. The other was this using simple physics

http://i231.photobucket.com/albums/ee178/jslade_usa/Weight1.jpg

Thoughts, something obvious I've missed, other ideas! Unless someone wants to sell me some flash proper racing 600kg ones for $50 :P

If all you need is 'good enough' then you can do it with one set of bathroom scales. Measure each wheel in turn, with the other three at the level the one on the scales is at. So in effect you have three little stacks of boards, and the scales.

Would bathroom scales take that sorta weight!

No that is why I'm suggesting using torque or perhaps 4 with a load spread. Most are rated ~150kg. Times by 4 and you have a decent load rating. Or on the other hand make a 1/4 multiplying torque arm like in the pic and you reduce the effective load on the scales.

The ideas would definitely work in theory but maybe someone else has done something like this and has a suggestion, always worth asking before going out on a limb.

AH ok. I guess I was thinking minis, and the ones I have used recently go to 200.

The difficulty with the torque arm is getting all four wheels at the same height. If they're not, the load distribution changes. Also the flex shown in that pic will make accuracy difficult. Good idea though, just needs refining.

Failing that, go to local scrap yard or transfer station, and park one wheel at a time on their scales ;)

Mate, so assuming he could make 3 little adjustable levelling fixtures of some description . and use something that did not distort like that plank will . is this quite an accurate way of obtaining corner weights! I guess the proof in the pudding would be turning an adjustable spring seat or something and seeing how much you have to turn it before it registers on the scales. Or try placing a known weight on top of the tire! And above all . always use the same scales so you get consistency. Thoughts!

American ones would.

Heh, 'merican bathroom scales will be the same as the ones the rural vet has.actually Aussie too, aren't they now fatter than the yanks!

Anyway, as far as I can see, if you have:

- a way of getting the scales to register a weight when all four tyre contact patches are level
- either scales that can handle the weight, or a stable, repeatable way of reducing the weight on the scales (like the lever)
- scales that are proven consistent in the weight range you are using (don't even have to be accurate, just consistent)

Then I don't see why this shouldn't work. I like the idea, and would give it a go myself if I didn't have other things to sort on the car first. I love messing around with home made caster and toe-in gear etc. That's one of my next jobs so I don't shred my yummy new rubber.

The tricky bit will be getting the contact patches level and in the same place on that lever. I'm wondering if a wheel with no tyre, or even a hub with no wheel might be more accurate/stable! The tyre patch being a cm or two either way on the lever could have a big effect, so how do you decide which point of of the contact patch to measure from.whereas if it was the bottom ball joint or something it would be more exact.

I like this idea, even if I made a steel fixture that bolted to the hub or had a couple stops to make the wheel settle in the same place. Or even as you say a ball joint, just drill a nice big hole for the nut to settle into so it's in position then weld that to a nice hunk of square steel that won't flex.

Might have to buy a set of scales to suit and try it now :)

Yeah, I like nutting this sorta stuff out too. I have an LB1 Laser Level (Beacon Type) that is capable of getting things down to a knats cock. I've used it for checking chassis's on the bench and it works great. I'd use that to get level. I'd use something involving a large(ish) bolt diameter to adjust whatever fixture is made up for the 3 non-scale corners. I'd use some decent thickwalled box as the lever and devise a simple system involving stops of some sort to ensure same placement and repeatability. If someone developes this . share with a pic.