In today's test we will talk about the most important drive in a car - the gas distribution mechanism drive, or timing. We will test timing belts for the most popular car on the Russian market - Lada Granta with an 8-valve engine 21116 and its modifications (a belt with a rounded tooth, having 113 teeth and a width of 17 mm).
The tests will take place in two stages: bench and resource.
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All about belt drive systems
The first is divided into several tests, but the results of the resource test will be known only by the end of summer. So, let's see.
During a search in stores, it turned out that in our region you can buy this belt from only three manufacturers: ContiTech, Gates and Trialli .
The first two belts can be purchased separately, only Trialli is sold as a repair kit with a tension pulley.
Price: 800 rubles
The belt is in branded cardboard packaging, on the box there is a sticker with a QR code. The kit includes a sticker that indicates the date of replacement and mileage, as well as which of the components - roller, belt, pump - were replaced. This is convenient: you won’t have to struggle to remember when the last belt replacement was made and what exactly was replaced. In addition to branded and general designations, the belt is marked with a batch number.
Signs of belt wear
As we have already noted, it is necessary to regularly monitor the condition of the timing belt. This will allow you to notice its damage even before it completely fails, damaging engine parts. The first sign will be significant wear and tear on the material. If this is the case, then you run the risk of slipping or breaking if there is a significant load on the car, as well as with high air humidity. It follows that wear occurs, as a rule, when the position of the tension roller and pulley deviates, as well as when the bearing temperature is high or its unsatisfactory operation. You can notice this by the fact that the material will be worn out and fabric debris will stick out from it. The third sign suggests the presence of cracks or peeling. The more such damage, the higher the chance that the belt will break very soon. Problems are also typical for situations where the back surface of the belt has a low elasticity index and significant hardness. This will also give away the characteristic shine of the belt. This will not allow it to make good contact with the pulley. During use, the belt may lengthen. If this parameter has become too large, then it is worth replacing the belt with a new one, especially since its elastic abilities will be significantly reduced. And, of course, if the belt position deviates from the specified one, this will indicate a situation where the tension roller components may fail.
The timing belt was removed for inspection and still works, but the owner decided to replace it
In this case the belt is still in good condition
Test method
Strength tests of belts were carried out in the testing laboratory of PJSC NPO on R-10 and MR-05 tensile testing machines.
Frost resistance and life tests were carried out in the testing laboratory of NPO Talis.
The testing of timing belts was carried out according to TU 38.1051912-90 “Toothed belts with a parabolic tooth profile for VAZ car engines.” The factor of the parabolic profile standard for belts with a rounded profile in this case is not significant, since the tested belts are actually intended for the good old “eight” engine, which means that the forces transmitted by the timing belt remained at the same level.
The first test was to check the bending resistance of the belts. This test uses a smooth pulley with a diameter of 50 mm. One belt of each type undergoes an artificial aging procedure, which is carried out as follows: the belt is placed in a heat chamber with a temperature of 120 degrees and maintained for 70 hours. The other belt is frozen along with the pulley at -45 degrees for 24 hours.
Afterwards, the belts are removed and bent over a smooth pulley with the teeth outward by 180 degrees. Tears and cracks are not allowed in the bend zone. The frozen belt bends on a pulley that was previously cooled along with the belt.
All belts passed this test.
At the next stage, we checked the strength qualities of the belts.
First, the belts were tested for breaking force. According to the standard, the minimum tensile strength of a belt should be at least 8 kN/cm for a new belt and 7 kN/cm for a belt that has undergone artificial aging. Thus, with a belt width of 17 mm, the minimum breaking force should be at least 13,600 N, and for artificially aged belts - at least 11,900 N.
This test is carried out as follows: the belts are installed with the teeth outward on smooth cylindrical pulleys and stretched at a speed of 50 ± 15 mm/min until breaking on a R-10 tensile testing machine.
The breaking force test results are shown in Table 1 .
As can be seen from the test results, all belts have a good margin of cord strength (from 1.43 to 1.8 before aging and from 1.68 to 2.1 after aging). The strongest cord turned out to be the Continental CT 1164 belts: it can withstand loads of up to 2.5 tons.
But in a belt, the strength of the cord is not the most important indicator. Therefore, as a second strength test, the tooth resistance to tearing off of new and artificially aged belts was checked. This figure must be at least 92 kgf for each centimeter of belt width - both new and old. Knowing that the width of the tested belts is 17 mm, we obtain a force of 156.4 kgf.
This test is carried out using a special device that has a toothed pulley with a tooth profile corresponding to the belt being tested. The device contains a calibration spring, which presses the belt through a metal plate to the toothed pulley with the required force, in our case it is 119 N. The belt is cut, one end is installed in the device so that the fifth tooth from the top of the cut belt falls into the pulley socket. The lower end is fixed in the clamp, and the MP-05 tensile testing machine pulls it down.
The results of this test are shown in Table 2 .
On new belts, the teeth did not cut off: the rubber is still plastic, the tooth simply deforms and jumps. But with aged belts, tooth shearing occurs on their “hardened” teeth - this is what happened with the Continental CT 1164 and Trialli GD 790; Gates 5670XS had a tooth deformation and it jumped. The test results show that all belts have a good shear strength (from 1.95 to 2.43 before aging and from 2.1 to 2.51 after aging). The timing belt from Trialli turned out to be the most resistant to tooth shearing.
Some people may find it strange that strength increases after artificial aging. This is explained by the properties of heat-resistant rubbers that are used to make belts: with prolonged heating, their internal bonds are strengthened.
According to statistics, replacing timing belt tension rollers occurs more often than replacing the belt itself. Therefore, it is worth periodically listening to see if there is noise from the rollers, because a failed roller will ruin the timing belt, no matter how good it is, which can lead to expensive engine repairs.
General information timing belt
In any car, the gas distribution mechanism allows for timely intake and release of the working mixture and exhaust gases, respectively. This mechanism includes a camshaft, as well as various valve drive parts, like the valves themselves with springs, as well as guide-type bushings. If we talk about the timing belt, then it is a special element that works as a connecting link. Thanks to it, synchronous operation of the camshaft and crankshaft is ensured. Finding such a belt is not at all difficult. All you have to do is open the hood, after which the belt will appear to your eyes. True, this “special unit” will be protected by a special casing, which should prevent the entry of dirt and protect it from other mechanical influences. Externally, the timing belt has a toothed inner surface and a rubber base. Unlike other types of belts, it spans multiple pulleys at once.
Lada Granta camshaft drive diagram
Camshaft drive diagram: toothed pulley of the engine crankshaft; coolant pump timing belt pulley: tensioner roller or automatic tensioner; rear timing belt cover; camshaft timing belt pulley; timing belt; tide on the oil pump cover; A - mark on the crankshaft toothed pulley; B — mark on the oil pump cover boss; C - protrusion on the rear timing belt cover; D - mark on the camshaft toothed pulley In addition to the two named shafts, the belt combines several more units, such as a water pump (pump) and so on. If the rollers or pump are damaged, this suggests an increased rate of belt wear, which reduces its service life many times over.
Resource test
To determine the service life of belts, there are special stands, one of which is located in the laboratory of NPO Talis LLC. This stand completely replicates the geometric arrangement of the units (pulleys and belt tension rollers) that come into contact with the drive belt when operating the engine; more precisely, when creating this stand, standard units were used, which are installed on internal combustion engines produced by VAZ. The stand is universal and provides the ability to install belts that are used for both 8-valve and 16-valve engines of front-wheel drive cars produced by AvtoVAZ. Also, by replacing the pulleys, it becomes possible to test belts with both trapezoidal and semicircular tooth shapes.
The belt is driven by a toothed pulley, which rotates a 7.5 kW electric motor - it acts as a crankshaft, causing all drive units to rotate using the timing belt. The belt is tensioned using the standard timing belt tension roller. The role of the camshaft is performed by an electric brake, which, when braking, creates a resistance of 27.5 N/m - this is a five-fold overload of the force that, during normal operation, is transmitted by the timing belt in an 8-valve engine. Thus, we turn every hour of belt running on the stand into five hours of work on the car.
According to the test method TU 38.1051912 “Toothed belts for VAZ engines,” the belt must have run for at least 100 hours, which turns into 500 hours of run time during normal engine operation. To fully simulate operating conditions, the space in which the timing belt operates is covered with a casing with thermal insulation installed in it, and the working area is heated to a temperature of +90 degrees - this requirement is not found in either the specifications or in any of the test methods known to us, but we decided make the job more difficult for the belt. When braking, the electromagnetic brake converts all incoming rotational energy into heat - and requires cooling, so an autonomous pressure cooling system is organized for the electric brake, which takes up no less space than the stand itself.
Test results
None of the timing belts we tested presented any surprises—all of them honestly worked the required 100 hours on the bench. When inspecting each timing belt after testing, no damage was found that could indicate imminent failure of any of the belts.
Recommendations from Lada Granta owners
Many Lada Granta owners, especially those equipped with 16-valve versions of power units, recommend not waiting for the coveted 60 thousand km mark. This is due to the possibility of using low-quality components, which can cause wear of the replaced elements after a mileage of 20 thousand km.
This fact encourages many “Grantavods” to resort to using products with good quality, and many of them, when asked which timing belt is better, answer that from . But we note that there are counterfeits of spare parts of this brand, and therefore it is recommended to purchase items only from trusted suppliers.
Installation of all shafts according to marks
First check that the gear is in neutral.
There is a rubber cover on the crankcase body closer to the clutch assembly. It needs to be removed. The point is to achieve alignment of the marks on the flywheel and in the scale slot. When this is done, fix the flywheel with a screwdriver.
Of course, it is easier to perform such an operation with two people. Know that the desired position of the shaft corresponds to the alignment of marks AB and CD (see figure).
The crankshaft itself must be rotated to the right using a 17 or 19 key (motor 11183).
The meaning of this is illustrated in the photo. The alternator belt must be removed.
The alternator belt blocks access to the timing drive parts. You will have to loosen the fastening and remove this belt.
Use a 13mm wrench to loosen the lower mounting bolt. Then unscrew the upper fastening nut and remove the bolt. The generator casing is pressed against the engine and the structure is secured with wire. The belt can now be removed. Installation of the alternator belt is carried out in the following sequence:
1
.
Secure the generator; 2
.
Throw the belt over the pulleys, as shown in the photo; 3
. Having engaged 5th gear, roll the car back.
Please be aware that reusing the alternator belt is a last resort. It would be better to buy a new part.
