We did this a couple of summers ago. I just found the pictures we took on an old PC and thought they might make a useful how to guide for fellow Turbosporters.
Step 1
Get down to Tesco and buy yourself 2 x value bathroom scales. They were £4 each at the time and I doubt they are much more now.
Each scale weighed up to 150 kg giving us a max measurable weight of 300 kg per corner or 1200kg total. The car we were measuring is a stripped out track / fast road toy so we were confident it was under a ton.
If you think your car is going to be more than 300kg per corner you will need to buy three. Remember to allow for the drivers weight.
If you are planning on doing a lot of corner weighting and adjustments I recommend you buy eight (still only £32). You will see why in a bit.
Step 2
Because we are tight and only wanted to buy two scales we had to search around for some wood.
From memory I think the scales are 2” high and we used a 3” x 2” bit of timber to spread the load over them both. This meant we could use three bits of 4” x 4” to bring the car up to level while we measure one corner at a time. If you bought scales for all corners you would not need the wood and the whole process would be much quicker.
Step 3
After a bit of rolling around on the drive and jacking up and down we had a measurement for each corner with the driver in place.
To check the accuracy of our method we weighed all the corners again with an empty car. We then weighed Colin the driver (feather weight 64kg). I then added empty car weight and driver weight up and it was the same as the car plus driver when they measured together!!
We then made the appropriate adjustments to the coil overs to balance the car.
Step 4
While you have your jacks out you can also use the scales to measure the unsprung weight on each corner.
We simply undid the top shock mount and then rested the wheel on one of the scales. I know technically a bit of the coil over is sprung weight but it is accurate enough for us.
Measure the front and back wheels as they will be different.
Why would you want to measure un sprung weight I hear you ask? At the time this car was stupidly over sprung. The coil overs were supplied with springs for a road car with full leather interior and possibly five passengers (1270- 1500kg). This car only weighed 937kg so was a real struggle to drive on anything but a billiard smooth road and would bash and crash over the smallest bumps. Traction was also poor off the line.
Using the un-sprung weight you can use Staniforth’s calculations to work out wheel frequency and from there select appropriate spring rates.
With the new reduced spring rates the car handled much better and was far more drivable.
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