Weighing a car with a bathroom scale.

[godzillarb]

I realize that most people just take their cars to the dump or whatever to get a vehicle weight. This is fine for most, but not me. I want to know the corner weights and weight distribution. I also don't want to pay someone to use their race scales. Anyways, I did some searching around on google and this is what I found:



Might look stupid but should work. The key is not killing the bathroom scale with your over weight car. To do this you use a 4 foot board that is marked every foot. The car should sit on the 3' mark, thus putting 75% of the weight on the ground and only 25% on the scale. Also, to ensure proper readings the car should be sitting as level as possible, basically the other 3 wheels should be at the same height as the one you're weighing.

Take the reading on the scale and divide by .25, and BAM! Corner weight.

I haven't tried this, but will be giving it a shot when I get home from VA. I got my Jetta weighed professionally a couple months ago (only because it was free) so I'll be able to see just how accurate this method is.

If someone else posted this idea before, my apologies. Every time I tried to use the search button it gave me an error.

[racepar1]

That is not a reliable way to get any sort of weight measurements from the car. All the tires have to be in the EXACT same position on the boards and the boards have to be the EXACT same length and the pivot point (the angle iron used in the pics) have to be in the EXACT same position. Also the car is not level, which is VERY important for accurate corner weights. There is no reliable way to half ass corner weighting. You either need a COMPLETELY level floor and 4 heavy duty scales or a set-up platform and 4 heavy duty scales. Search for an affordable solution on websites like coleman racing's or google "longacre". Longacre makes all kinds of racecar set-up tools.

[jspaeth]

I would agree.........this is a cool idea, but in terms of practicality, there is not way you are going to be able to do it precisely enough for it to even matter, unless your corner weight are outrageously terrible.

[luftrofl]

Originally Posted by godzillarb

Also, to ensure proper readings the car should be sitting as level as possible, basically the other 3 wheels should be at the same height as the one you're weighing.

That strikes me as something that is much easier said than done. If you're off by just a small amount, your measurements will be basically worthless.

[derk]

.... that looks soooooo mickey mouse.

[godzillarb]

Originally Posted by derk

why dont you just pay to get it properly corner balanced.... jesus.

The whole idea was to be able to measure, adjust weight, remeasure, and so on. I really doubt if the guys at a race shop would be cool with me camping out for a day and tinkering with the weight balance of my car.

The guy in the picture really half-assed it, no question.

Oh well, it might be a hopeless endeavor but just out of curiosity I'll weigh my Jetta using a similar method and cross check it with my print out from the professional scales.

[S14DB]

Would have to think to pay someone to corner weight would be cheaper than 4 scales and all that other crap.

[racepar1]

Originally Posted by godzillarb

The whole idea was to be able to measure, adjust weight, remeasure, and so on.

To be able to do this ^^^ with a set-up like that would be almost impossible. You simply cannot trust any information you get from that set-up. If you really wanna corner weight yourself you absolutely HAVE TO spend some money on a proper set of scales. There ARE budget options here, you just need to do some research.

[racepar1]

Originally Posted by S14DB

Would have to think to pay someone to corner weight would be cheaper than 4 scales and all that other crap.

That all depends on how often you want to corner weight. I wouldn't mind corner weighting my car every 2 to 3 track events as I am constantly changing the set up here and there.

[godzillarb]

Originally Posted by racepar1

There ARE budget options here, you just need to do some research.

Yep yep. I did, cheapest set of pads I found were $750ish. Maybe I'll be able to find a used set.

Looks like I'll do some calling around to find out where I can get my car on a set of real scaled when I get home. I'm doing a bunch of weight relocation so I might as well put it on the right side.

Thanks for the advice though

[gotta240]

The thing you posted has been done for a long time by budget racers. The one you posted is very ghetto though. A better and more accurate system can be made from metal. Instead of setting the car on a POINT you must make a mini ramp with two pieces of metal that HOLD the wheel exactly at one point.


such as



Pivot______I TIRE_I_______________Scale
.
Dont let these people discourage you. Most of them have probably never corner balanced their own car or know how expensive it gets when changing your suspension set-up and needing a new balance EVERY track day. Although the set-up i mentioned above is not accurate to the pound, it is 13939399239239 percent better than doing NOTHING...like most people on this site do.

[cdlong]

Originally Posted by godzillarb

Take the reading on the scale and divide by .25

or, you know, multiply by 4. a little easier to do in your head.

conceptually it works just fine. in practice, it's a little harder as stated, but it still gives you a very good idea. especially if you're changing stuff every weekend and don't want to pay each time you change something.

depending on how much your car weighs, which corner, and the range of the scale, you could adjust it for more accuracy. i.e., if the corner in question weighs 600 lbs and the scale goes up to 300lbs, you could put the tire in the middle.

[Sil-Abc]

take an engineering statistics class ull learn that method is way off. the weight distribution is all bad, wood will bend, pivot points will always be different. overall, bad idea but at least its an idea. honestly, just save up and get it done right. my 2 pennies

[ALEXTHESUS*PECT]

not reliable enough to trust.

[S14DB]

Why not get some 1,000 lbs scales? Prolly be as much as 4 bathroom scales and all the parts of that rig.

http://www2.northerntool.com/product-1/22929.htm
http://www.1800scales.com/High-Capac...form-1000.html

[racepar1]

Originally Posted by S14DB

Why not get some 1,000 lbs scales? Prolly be as much as 4 bathroom scales and all the parts of that rig.

http://www2.northerntool.com/product-1/22929.htm
http://www.1800scales.com/High-Capac...form-1000.html

There is your answer! ^^^

[gotta240]

Because that costs 800 to 1000 bucks for 4. The way i described in my post cost under 200 and is fairly accurate.

[racepar1]

Originally Posted by gotta240

Because that costs 800 to 1000 bucks for 4. The way i described in my post cost under 200 and is fairly accurate.

If "fairly accurate" is good enough for you then go for it! That is simply not good enough to satisfy me. I want exactly accurate and will settle for nothing less. If I can get something that is exactly accurate for under $1200 I would consider that a bargain.

[jholman05]

Why do you need 4?, just get some make some blocks the same height as one of those $200 scales and weigh each corner individually, mark it down and adjust accordingly.

[Wabash9000]

why not just put 4 scales under all four tires. 16 scales...

idk seems all very getto but very 240.

[babowc]

^lol.
funny!

how much does a bathroom scale cost??.. 30?

[gotta240]

OH PAAAAALLLLLEEEEEEEEEZZZZZEEE. Unless your car is a 100,000k race car and you are a PRO driver, you will not notice a 20lb difference in a scale. I'm not even saying this to insult you or to be a dick, but honesltly, i've seen your car and you would be better off spending that 1000 bucks extra in upgrades and not worrying about the .5 percent difference in corner weights due to a "NOT PERFECT" scale.

Now honestly, lets quick the bullshitting. How many times did you corner balance your car last year?

Originally Posted by racepar1

If "fairly accurate" is good enough for you then go for it! That is simply not good enough to satisfy me. I want exactly accurate and will settle for nothing less. If I can get something that is exactly accurate for under $1200 I would consider that a bargain.

[S14DB]

Damn, I'm not a race car driver. Time to buy some rota's and sleeve coil overs...

Just cause your not a pro driver doesn't mean you have to half ass things.

[g-via]

Originally Posted by S14DB

Why not get some 1,000 lbs scales? Prolly be as much as 4 bathroom scales and all the parts of that rig.

http://www2.northerntool.com/product-1/22929.htm
http://www.1800scales.com/High-Capac...form-1000.html

1000 lb bathroom scales?!

ahh....you'd only need that in the states! LOL jk, jk, i know most of you guys are in the US....eh....

[racepar1]

Originally Posted by gotta240

OH PAAAAALLLLLEEEEEEEEEZZZZZEEE. Unless your car is a 100,000k race car and you are a PRO driver, you will not notice a 20lb difference in a scale. I'm not even saying this to insult you or to be a dick, but honesltly, i've seen your car and you would be better off spending that 1000 bucks extra in upgrades and not worrying about the .5 percent difference in corner weights due to a "NOT PERFECT" scale.

Now honestly, lets quick the bullshitting. How many times did you corner balance your car last year?

I've done it twice since november and it could use another shot as I wanna lower it some more and change my alignment settings just a bit. Don't insult my car. If you really wanna talk shit let's take it to the track. Just because it looks ugly doesn't mean that it isn't well modified and maintained. I am absolutely positive that if we put our cars up on racks right next to eachother mine would be cleaner and better maintained.

[crzycav86]

This method will work. It might be 10% off(just a guess), but you can make it work.

First, like has been mentioned, you need to raise the other 3 wheels by the same amount.

Second, you need to subtract half the weight of the wood, and subtract the weight of the metal bracket sitting on the scale.

Third, instead of assuming that you've got the wheel 75% away from the scale, find out exactly how far it is bymeasuring where the middle of the wheel sits(from one end), and dividing it by the distance between the two metal mounts.

Fourth, if you want an accurate corner-weighting, you need to load up the driver's seat with weights. (equal to your weight)

Fifth, If the car weighs 3000 lbs, approximately a 1/4 is on each wheel, that's 750 lbs. If your scale reads up to 250, you can locate the wheel 66% away from the scale without maxing it out. The scale will read more accurately the closer you can get the wheel to it. On the same token, a longer piece of wood will help you measure more accurately. Just make sure it doesn't break.

Hope that helps.

[cdlong]

Originally Posted by Sil-Abc

take an engineering statistics class ull learn that method is way off. the weight distribution is all bad, wood will bend, pivot points will always be different. overall, bad idea but at least its an idea. honestly, just save up and get it done right. my 2 pennies

i took an engineering statics class, and did the calculations, the method is fine. wood will bend, but that doesn't matter, it is statics after all. pivots points will not always be different if you set it up properly. it's aready been stated that the picture is a ghetto setup and can easily be improved upon to make an accurate system. actual weights don't really matter anyway, only the relative weights.

stop giving the guy shit for a sound idea.

[McRussellPants]

Doesnt work.

Car isn't Level.

Motion Ratio would be wrong every time.

Gotta 240 Sucks at cars.

Weird Cross weight is totally noticeable.

Borrow someones scales or pay 100$ to get it done at a raceshop.

[crzycav86]

Originally Posted by Sil-Abc

take an engineering statistics class ull learn that method is way off. the weight distribution is all bad, wood will bend, pivot points will always be different. overall, bad idea but at least its an idea. honestly, just save up and get it done right. my 2 pennies

I don't know which engineering school you went to, but I learned how this works in STATICS.

The rest of what you said doesn't explain anything. Care to elaborate on what you learned in statistics?

[kognition]

I think that the issue you are having is paying someone who has invested the odd thousand bucks for legit scales. If you want to legitimately weight and scale your car (corner balancing), you must use the right equipment. Weighing your car really is a waste of time unless you are corner balancing it at the same time.
At the end of the day, you will never know if the bathroom scale is being truthful. My wife says hers always lies anyway.
Corner balancing is usually anywhere from 50 to 100 bucks, depending on the shop.
You will be amazed at how well a properly corner balanced car will handle.