Advice 1: How to determine spring stiffness

Spring is a component of the car's suspension, which protected the car from irregularities in the road, but also provide the desired height of the body above the road, which greatly affects the handling of the vehicle, comfort and payload capacity. As a result of the tests for each vehicle select the optimum stiffness of the suspension springs under certain traffic conditions.
How to determine spring stiffness
If you experience "breakdowns" suspension spring is too soft. In such situations, the drivers become unstable in control. Ideally, the spring force must be equal to the value that prevents excessive body roll.
Stiffer springs require the cars prepared for racing. In different types of races using the same car involves the installation of springs with different stiffnessYu. Pay attention when passing any corners for body roll that, when properly selected springs should be no more than two or three degrees.
For the front and rear suspension pick spring stiffness pairs. However, it is not immediately possible to achieve the desired height of the suspension, because the spring sits and at some point may "get lost" that's really bad. This is due to lack of bearing capacity, even at full compression, but with the stiffnesss, providing the necessary height of the suspension. This is determined always easy: between the spring windings should be a gap of less than 4 mm.
Choose the springs so that when refilled the car the gap between the turns of the springs was slightly more than 6.5 mm. it is Desirable to set the soft springs, even though they will give a roll of the machine within acceptable limits. To use stiff springs, based on the opinion that they reduce the roll of the car, improving handling, as a rule, incorrect.
Check the stiffness of the spring by a product code or for applying labels or stamping paint). Also determine the stiffness of the springs using the hand pump, floor scales and measuring line in kilograms per centimeter.
On everyday scales fit a piece of wood (thickness 12 mm) square at the larger end of the spring, and the top is a spring. Then, on the upper end of the spring is placed a second piece of wood is measured length of the spring. With a press of the spring compress to a certain size (e.g. 30 mm) and take readings of the weights, thereby computing the stiffness.
The pressure on the spring is measured according to the testimony of the weights, but this method of determining the stiffness of springs is dangerous as the spring can fly off at a sufficiently large distance.

Advice 2 : How to check the springs

Severe blows on the body of the axle beam when driving a loaded truck, shortness of traffic control talking about external manifestations of wear or breakage of the rear springs or front suspension. To avoid this, it is necessary to periodically test the springs, and how to do it?
How to check the springs
All springs depending on length and load 3425 N (350 kgf) is divided into two classes: class "A", the length of which is more than 278 mm and class "b", the length of which is less than or equal to 278 mm. In this case, coil springs "class b" on the outside of the coils are painted over with black paint, and a class "A" is not painted over at all.
Before testing, all parts should be thoroughly rinsed. Sleeve, protective coatings and rubber parts don't forget to protect from solvents. Then inspect every detail of the springs for cracks, mechanical damage and wear.
You need to check the length of each of the rear springs or front suspension in a free state, if the length of the spring is less than the maximum allowable standard value, then it must be replaced. Remember that the standard is equal of 44.00 mm length of a spring under a load of approximately 216 H of 35.00 mm and the length of the spring under load 451 N is 27,20 mm.
Now test the elastic characteristics of the spring itself by its control points, before tentatively holding it to the contact of the turns with each other. Then see whether there is deformation of the rear springs or front suspension, if it is, then it means that there is a reason its performance, so you need to replace the spring.
Then you should check spring for Squareness. If any crooked areas exceeds the upper limit standard value is 1.5° or less, it means that the spring has broken its properties and should be replaced.
There is another old method of checking springs. For this between two metal straps with bolts in the middle should hold the old and new springs and gradually tighten the nut of the bolt. If they are compressed to the same extent, so that the old spring is in good condition.
And finally, check the condition of the rubber support pads springs, rear or front suspension. In case of malfunction replace them with new ones.
Useful advice
If you need replacement springs, they should be replaced at the same time on both sides of the car.
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