Note position of the tire on a wheel disk (for a smaller visibility a tag it is applied on metal from the inside of a wheel)

Reproduce vibrations, be convinced that they are connected with the speed of the movement (you reproduce vibrations on several transfers of KP).

Write down an interval of speeds in which there are vibrations.

Check influence of braking on vibrations:

– in the field of speeds of emergence of vibrations slightly brake the car (to a contact of brake shoes with a disk) and define existence or lack of change of vibrations, supporting the speed of the movement.

Check influence of change of torque of the engine (the movement "vnatyag" at inclusion of the lowest transfers):

– in the field of speeds of emergence of vibrations change engine loading (for creation of traffic conditions "внатяг", then upon transition to the lowest transfers) and define influence of this change on vibrations.

Define from what of suspension brackets there is a vibration and number of impulses for wheel turnover of the table of speeds of emergence of own fluctuations of suspension brackets.

This check consists in determining the speed of emergence of own fluctuations of suspension brackets by artificial creation of an imbalance (receiving one impulse for a wheel turn) on one of lobbies, then on one of back wheels.

The best decision is use at this check of other car (the same model, but it is not obligatory with the same engine).

Establish an additional balancing small weight weighing 50 g on one of forward wheels and note its situation (the provision of a small weight on a circle of a disk of a wheel does not matter). Leave former small weights or a small weight on the place.

Execute road test and write down an interval of speeds in which vibrations appear. The result corresponds to the speed of emergence of own fluctuations of a forward suspension bracket of the checked car.

Remove an additional small weight from a forward wheel and establish it on one of back wheels.

Again execute road test and write down an interval of speeds in which vibrations appear. The result corresponds to the speed of emergence of own fluctuations of a back suspension bracket of the checked car.

Compare result of check 1 to check 2 and define what of suspension brackets is a source of vibrations, and number of impulses for a wheel turn.

Defect of an internal design of tires is the possible reason of vibrations. Such defect is externally imperceptible. For its identification it is necessary to rearrange forward and back wheels (to put the left wheels at the left, right – on the right), previously having written down an interval of speeds of vibrations when performing check 1, and again to execute check 1. If at this new test the interval of speeds of emergence of vibrations changed and began to correspond to the speed of emergence of own fluctuations of other suspension bracket (see the table 4.3 "Speed of Emergence of Own Fluctuations of Suspension Brackets"), defect means it is connected with tires or with balancing of wheels.

NOTE With defect of a design of the tire on a wheel usually establish balancing small weights of big weight (50 g and more on one party of a disk of a wheel). Reliability of results of check 3 is based on a difference between speeds of emergence of own fluctuations of forward and back suspension brackets.

Fig. 4.8. Vibrations of a forward or back suspension bracket at one impulse for a wheel turn