£20 DIY Corner Weight Measurement

[Roy Kemp]

Just managed a couple of hours in the workshop. Been meaning to get the corner weights measured for a while, so have had a bit of time to thing about how to do it without handing over the car to a competition prep company or shelling out a fortune for proper corner weight scales. So... The Kemp Method. You will need:

8 pieces of 30mm thick decking board, cut to 320mm long. 4 need bevelled edges.

1 Salter Max Bathroom scale, rated to 250kg, or equivalent.

Arrange as shown, the bevels used for getting the car on and off the wooden step more easily, so are placed at the rear.

Then, one corner at a time, replace the front wooden step with the scales and roll the car forward.

I took three measurements on each corner, and worked out an average:

NSF = 184.0 / 184.0 / 183.5 = 183.83kg

OSF = 167.1 / 167.1 / 167.6 = 167.43kg

NSR = 167.0 / 166.3 / 166.3 = 166.53kg

OSR = 167.4 / 166.6 / 166.2 = 166.73kg

So, this gives a total weight of 684.53kg, and a front/rear split of 351.27/333.27kg, which works out at 51.3% front to 48.7% at the rear.

Buggered if I can figure out why the left front is so heavy. Could be an un-even ness in the garage floor, or maybe the right front spring is stuffed? But, either way, I'd have expected to see the difference reflected in the diagonally opposite corner.

Anyway, that's how to get your corner weights (and puzzle yourself with the results) for twenty quid.

[James Doulton]

Roy, I think that I'd try turning the car around to see if you get the same difference again.

[Roy Kemp]

Just thinking some more, and over the passengers side of the engine you've got starter, alternator, most of the water pipes, exhaust system including a heavy cast manifold, etc. Over on the left you've got a little carb and inlet manifold.

Even my heavy power steering column is on a big cross-brace so would add some weight to both sides, not just the drivers.

So the extra 17kgs on the right front is probably not all that daft.

[James Doulton]

I used 4 scales from Tescos for £4 each. They were only up to 130Kg each so I used two for each wheel with a plank to spread the load. I weighed one end at a time with wooden blocks under the other wheels to keep the car level (which was probably unnecessary given the accuracy of the scales). My Melos had a Pinto with a 4 speed Escort box. I got a figure of 623Kg with an empty fuel tank and radiator, so very similar to Big Vern's.

I adjusted my scales using my own weight and calibrating against a couple of digital scales.

My Melos was 10Kg heavier on the Near Side Front, probably because the Pinto was an inch or so offset. Front rear balance was 52.0% front, which should change to nearly 50:50 with fluids added. Adding me as driver moves about 4% of the weight to the rear.

[Roy Kemp]

Cheers Vern - but I'd have expected a CVH engined car to be lighter than a Pinto'd one. Maybe my big burly MT75 box adds a few kilos! No idea what my fuel load is either - the sender is on the bench awaiting some jiggery pokery.

Tony - I did look into some £4 argos scales but not sure if I could have been bothered with the extra joinery. Not sure if these scales will be up to the task of corner weighting my Peugeot 205 though!

[Big Vern]

That's pretty much the way to do it but it would be worth checking the scales at the high end as they can often be quite a way out. For info we corner weighted an Pinto engined melos on calibrated corner weight scales at 672kg with half full tank.