Help : Digital bathroom scales for corner weights

[Craig Powers]

I currently use analogue bathroom scales when weighing my car and setting up corner weights. Digital scales are becoming more commonplace and can handle higher weights. A fellow competitor wants to buy 4-off digital scales and is seeking advice.

Has anyone successfully used digital bathroom scales? Many have an auto on/off and auto calibrate/zero feature which makes them hard to use. For example, the scales could potentially time-out and power off before you can read them. Or they may not zero properly. I expect that I will have to modify the scales so that I can power up and zero all four at once. Recommendations of bathroom scale manufacturers / models, and modifications are most welcome.

Does anyone have any experience of this?

As a club racer I am looking for a budget solution. Buying racing corner weight scales is a) out of my budget and b) goes against my clubmans ethos. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Regards,
Craig Powers, UK

[MRT_Xii]

For a while our team used 4 digital platform scales like the digiweigh DW-63. I think we found them on ebay for something like 70$ each and they can take up to 400lbs and are accurate enough. Most of them have a 9V plug so you don't have to use a battery if there is an outlet close. Those particular scales will not turn off or re-zero by themselves.

Off course having 4 individual read-outs is a bit annoying and the repeatability is not perfect but it will put you in the ballpark.

On the other hand, when one scale broke 2 years ago we had no choice but to buy another full set as the exact model we had was discontinued and there is no way you can find parts for them. The load cells are much smaller than those you would normally find on automotive scales so beware of shocks and impacts.

I'd like to point out that there are a lot of used automotive scale sets on ebay and they are quite affordable. The quality difference is night and day. For a little bit more money Longacre has some inexpensive basic sets that will do much more than the platform scales and will last a lot longer.

We adopted the "buy right cry once" attitude and got a nice set of Intercomp scales. I do not regret a single penny that we paid for them.


Good luck!

[Charlie]

Thanks for the review MRT.

I have been looking at scales and $1200 for a pro set is just too rich for me at the moment.

I found the 4 DX-63 scales for $191 shipped from Overstock.com. That's a pretty dang good deal, and once I get a chance to try them out, I'll try to remember to post a review.

[PatClarke]

Craig, you missed an opportunity. You should have asked Santa for a set ;-)
Pat

[Kirk Feldkamp]

When I bought my scales a few years ago, I was able to find a $1200 (retail) Longacre set for $900 shipped, brand new on eBay. On a whim, I just looked at RacingJunk dot com, and there is a used set of Longacre scales for $750, and the guy is "willing to negotiate". There are always deals out there to be had, you just have to look in the right places!

-Kirk

[VFR750R]

I'd look into refrigerant scales
w w w. ntxtools .c o m/network-tool-warehouse/MTC-98210-A.html

I've used one at work for measuring cranks and they have are way more accurate and have more resolution than most bathroom scales. The one above is very similar to the one we use at work and even has a leveling bubble and adjustable feet.

[VFR750R]

Look into refrigerant scales

We have one at work that we use for measuring crank weight and other medium weight stuff that has great accuracy and resolution compared to most bathroom scales.

Our is a
MasterCool Air Conditioning Tools
MTC 98210-A
Accu-charge Refrigerant Scale

it even has a leveling bubble and adjustable feet so you could compensate for uneven shop floors.

[Craig Powers]

Hi Pat,

Good to see you on this forum too.

Actually I am OK with my analogue bathroom scales. They are accurate enough for my purposes (see below, *). Having been educated by Allan Staniforth & the Rev Barry Whitehead I have a clubman’s outlook and seek cheap solutions to each and every problem. Every $ or £ saved can be spent on tyres.

However my close friend wants to buy a set of cheap bathroom scales and is attracted to digital readout and the higher load range of digital scales. Analogue scales are getting progressively replaced by digital scales; there is less choice available.

(*) In my opinion the main measurement inaccuracy is due to stiction in the suspension which affects ride height and corner weight distribution. We address this by bouncing and jittering the suspension to let the car settle. I also briefly lift each wheel in turn with a scissor jack to ensure that there is no sideways tyre scrub force acting on the scale that could compromise the reading. Used wisely and carefully the bathroom scales are accurate enough.

I have a pair of 30 stone (420lb) scales for the rears and a pair of 20 stone (280lb) scales for the fronts. This gives adequate range for my 740lb OMS and allows me to bounce the chassis without overloading the scales.

My friend has a 1700cc Ford crossflow powered Westfield (Lotus 7 look alike) so needs stronger scales than I use. I am unsure of the car weight but he is looked for a range up to approx 400lb / corner. I will keep this thread active and report back to him on any recommendations from the FSAE teams.

Thanks to all contributors, so far.

Craig Powers

[Michael Royce]

Craig et al,
I don't know about stiction in the suspension, but one of the biggest errors can come from not having all four scales on a true plane. Just think, if the wheel rate is say 400 lbs/in and one pad is 1/8 inch off plane, the error is 50 lbs!

The other thing that some tend to forget, as a friend and I did one night while setting up his Sport 2000 car, is that you have to have the sway bars disconnected. And then when you hook up the second end, it has to go on without any preload.

[Craig Powers]

Hi Michael,

I totally agree. Important advice.

Luckily Rev Barry has a good flat set-up floor at his house. He made sure that a wet, sloppy concrete mix was used when the garage was built and consequently the floor is flat and level. I always take my car there for set up.

Best wishes,
Craig

[Peter7307]

Craig,
given you are watching the costs closely perhaps a shared purchase may be the way to go since the corner weighing is not something you need to do all the time?

A second thought is to check consumer magazines for reviews on these things...and don't automatically assume digital will be more accurate than analogue for this item.
Some of these things are off by major amounts.

Peter.

[Richard Pare]

To save some money, you only need 2 scales to do the job. Use them on the front to get their weights even - the rear weights will follow.

Of course, the 4 corners need to be the same height from side to side. Don't bother too much about getting the rears the same height as the front - a small difference isn't going to be measurable in its effect on the weight distribution.

Also, most bathroom scales are pretty flimsy, so it is advisable to reinforce the top surface with something. 1/2" or 3/4" plywood works well.

Also, try to get the tires as close to the center of the scale face as you can - getting too offset towards one edge or the other will usually throw the accuracy off, especially with mechanical scales.

[martinsteve]

It's true that every one looks for anything in there budget only. one of my friends who is searching for Weighing Scales purchased it from digitalscalesaz.com in his budget and now he is totally satisfied with it and enjoying the scales.

scales (http://www.digitalscalesaz.com/)