Coil over question

My Model A coupe project came with coil over shocks already installed. Is there a way to determine the spring rate? The rear is so stiff it feels like there are no springs at all. The slightest bump will jar your teeth. I would like to soften the ride a little if possible but a I need to figure out what I've got first.
Thanks ahead of time.

 

Most of the manufactuers we have bought coilovers from use a small spot of paint on one end and the color of the paint is the spring companys color code which tells spring rate. We have just started using a new coilover co which actually has the rate printed on the spring.

 

Find a local circle track racer/shop..They usually have a coilover spring checker...In just a few minutes they can check the spring rate for you...You also need to know the actual weight on each corner of the car...Most race shops also have scales to do this, in order to set up their race cars...They could scale the car and calculate the needed spring rate

just my $0.02 worth
Stan

 

You don't need to know the spring rate. You need to weigh your car and do all the math. That is the correct way in the first place, not done by the builder. You will be able to determine the spring rate along the way.

Weigh the car on a proper set of scales to get the weight at each corner. A good circle track or drag race shop should offer this service cheap enough. You can do it one wheel at a time with a conventional scale of 500 lb or so capacity and 3 blocks of the same height. Move the scale from corner to corner with the other 3 wheels on blacks the same height as the scale. Then measure the length of the springs at curb weight, static. pull them out and measure the free length. The inches shortened under weight divided into the corner weight will give you spring rate. (400 lbs on a corner, compressing a spring 2 inches = 200 lb rate)
You really need to determine the compressed length you want with the weight you have on the corner. That will give the rate you need to order.

If you can't go through all this, take a spring out and put it between a scale and a weight. Determine the # pounds to compress the spring 1". Have fun with that. I like barbell weights with a pipe through the middle of the spring and the weights. Remember to deduct the weight of the spring and pipe if they all sit on the scale.