Weighing your car on bathroom scales

[ashaughnessy]

I've just purchased four sets of bathroom scales from my local department store, ten pounds each. They are rated up to 130Kg. Plenty for my car, as I reckoned it only weighed 505Kg.

After lots of messing about, I finally got them to read accurately. I had to spend plenty of time getting them flat on the floor (well, reasonably flat and reasonably level). I also had to make sure each tyre's weight was spread evenly across the scale surface - I used a plank on each scale. I also put a greased metal plate under each front tyre so that when the car is lowered onto the scales, a bounce on the front got the weight settled nicely - the greased plate allowed the wheels to spread out as they settled on the suspension.

The end result was just what I expected it to be.

Also, although the scales are only rated to 130Kg, if you go past this they keep on going round the clock. Don't know when they'd stop but I reckon you might be OK up to 150Kg per wheel.

I wouldn't trust them for suspension setup, but if you want to measure total weight I reckon it's OK and pretty cheap. Handy if you want to measure how much ballast you need to get up to minimum weight for a race.

BTW - with no doors, no passenger seat, no FIA petty strut and no fuel, I can get below 500Kg. I was quite pleased about that!

Anthony

[oilyhands]

Being a tightwad I reckon you could do the same with just one pair of scales and some blocks of wood of the appropriate thickness, might take a bit longer though.

 

Oily

[ashaughnessy]

I think using just one set might produce a systematic error. You might find that the corner at which you had the scales always shows lighter or heavier than the three corners with the blocks, so the total always shows lighter or heavier. Using four set eliminates this error, though there are still plenty of ways for the scales to read wrong.

The back wheels seemed pretty accurate, due to the solid axle forcing the weight of the wheels vertically down.

The front wheels caused problems. The droop of the suspension brings the wheels together and when you drop the car back onto the scales, this produces an outward force that seemed to make the scales read wrong by very large amounts (+ or - 50Kg). Using the greased plates helped this.

Anthony

[oilyhands]

You have cunningly discovered my method for deceiving the wife over my weight. If I lean over and put all my weight on my right leg on the bathroom scales it takes about 10lbs off..

 

Oily

[stevefoster]

I have done this and posted about it a while ago.

 

It works, I have set up 4 or so cars and we are all happy.

 

What do you use to stop the scales being destroyed by the front suspension droop splaying out the scales?

I borrowed a roller plate... works a treat.

 

To corner weight you MUST have a flat floor or the diagonals will be pressured unevenly and you will never get it right.

 

There is a spread sheet to help adjust what by how much... I can mail off web if anyone wants it.

[Allan Haighton]

Even cheaper. Get a set of 8 scales at £4 each from Argos - up to 120Kg each. Spread the weight over two at each corner using a plank.

Oh - and expect very funny looks when you insist on having all scales the same type

(different scales can have the same catalogue number).

[stevefoster]

I got my Ek's scales (Swedish make) from B&Q for £4 each and yes i did get funny looks when taking 8 to till.

 

I made what I will descibe as bridges for each wheel to sit on in favour of a simple plank.

[Baby Bucket]

Steve can you email me your spreadsheet that helps calculate the adjustment.

 

Many thanks,

 

Peter

[C7JFM]

Me too for the spreadsheet please ?