Rear axle gearbox VAZ 2107 - design and repair

Features of VAZ-classic rear axle gearboxes

All VAZ classic cars are rear-wheel drive, the vehicle moves using the rear axle, which is the drive axle. The VAZ rear axle gearbox is the most important part in the transmission; it is where the main gear is located.

• 1 Device
• 2 Differences in VAZ rear axle gearboxes
• 3 Gearboxes on machine 2107
• 4 Replacing the rear axle gearbox of VAZ 2106, 2107
• 5 Defects in the gearbox
• 6 Adjusting the VAZ rear axle gearbox
• 7 Repair or replacement, which is better
• 8 Locking the rear axle gearbox VAZ 8.1 Related articles:

Common faults

In most cases, disassembling the gearbox is required to replace the oil seal. Like all rubber gaskets, it often begins to leak because:

• loses elasticity over time;
• may have a manufacturing defect;
• was initially installed incorrectly.

In particular, the following signs indicate problems with the oil seal:

• oil stains are periodically detected at the rear axle;
• a backlash (always radial) is formed at the gearbox shank.

The latter also indicates wear of one bearing or several at once.

An atypical noise coming from the trunk will also tell you that the rear axle is faulty. It is important to find out at what speed it occurs. For this:

• accelerate to 20 km;
• continue to accelerate smoothly to 90;
• record the engine speed at the moment the noise appears;
• release the gas, but do not engage the gear;
• When braking with the power plant, pay attention to the nature of the sounds.

The following test accurately indicates that the gearbox is broken:

• accelerate the VAZ-2107 to 100 km;
• set to “neutral”;
• turn off the ignition.

If you still hear a hum, then the gearbox is to blame.

Where is the gearbox located?

On the "sevens", as on all representatives of the rear-wheel drive family, the gearbox is located at the rear, under the bottom of the car. It connects the cardan to the VAZ 2107 axle and causes the wheels of the car to rotate. Rotation occurs thanks to axle shafts engaged in the gearbox, which, due to the technical features of the rear axle of the VAZ 2107, will have to be removed later. If the car is lifted, or when viewed from a garage pit, the gearbox is simply impossible not to notice.

Signs and malfunctions of the classic rear axle gearbox

Replacing a gearbox with your own hands is a labor-intensive process, which includes not only the purchase of a new unit (quite expensive), but also time costs. Therefore, before you start, you need to make sure that the gearbox is faulty. You can define the signs like this:

• gradually accelerating the car, listen carefully and remember at what moment the noise appears;
• while driving, start engine braking (remove your foot from the gas pedal at speed), at this time listen to the gearbox and note the moment the noise appears;
• accelerate the "seven" to hundreds, switch to neutral and turn off the engine - listen to how the gearbox behaves while coasting.

“If the bridge is noisy both in neutral and at speeds, the gearbox has nothing to do with it. If the hum occurs only at speed (regardless of the number), repairs, or, as a last resort, replacement of the gearbox are inevitable.”

When the signs are identified, it is necessary to carry out another check:

• park the car, secure the front wheels with shoes;
• jack up the rear so that the bridge hangs over (it is necessary that the wheels come off the surface);
• start the engine and accelerate the “seven” to the point at which noise occurs, while the wheels should spin without load.

If the noise has not changed, then the gearbox is clearly in good working order and it is not the cause of the trouble. Here other drive units are checked. Well, if there is no noise when driving without a load, then we are talking about worn gears of the gearbox, which make noise only when driving with a load.

The “seven” gearbox itself is a fairly reliable unit that can withstand a period of 100 to 300 thousand mileage, and there is no need to even look into it. Gears, gear spacer, differential adjustment - all these problems arise during improper operation:

• the use of oil with a low viscosity level, as well as failure to comply with the terms of its replacement;
• operating the “seven” with an amount of oil insufficient for this;
• During movement, the bridge is subject to extreme loads (frequent and unsuccessful slips).

Gearbox removal process

In order to repair or replace the rear axle gearbox of a VAZ 2107, you first need to remove it from the car:

1. Drain the oil. This, by the way, may be a reason to replace it.
2. Separate the flanges of the cardan and gearbox. To do this, you need to unscrew four bolts and nuts. At this time, it is necessary to fix and immobilize the cardan with a screwdriver or by holding the brake pedal. After unscrewing the nuts, you need to tie the cardan to the muffler. You can simply hang it, but this can also lead to negative consequences for the cardan.
3. Remove the axle shafts, because without this the gearbox cannot be removed. At the same time, you can inspect the seals, and if they are worn out, replace them. This will save time and prevent possible malfunctions.
4. Separate the beam and gearbox by unscrewing all eight bolts that secure it. When unscrewing the latter, it is necessary to hold the gearbox so that it does not fall. The bolts are unscrewed - carefully remove the gearbox.

Repair and adjustment of the VAZ 2107 gearbox

Before you start repairing the gearbox and its subsequent adjustment, you need to have certain skills, backed up by skills, observe all the nuances and subtleties of this process, and also strictly follow the technological nuances of the process. Therefore, if a person starts work for the first time, then it is better to abandon this idea. In addition, you must have all the necessary tools:

• pullers;
• stands;
• a set of keys, screwdrivers and other accessories.

Replacement procedure

Before proceeding with dismantling the gearbox, drain all oil from it. Remember - never reuse old grease.

In order to free the rear axle, put the car in neutral.

Further:

• raise the rear with a jack;
• The cardan joint, carefully held with a pry bar (so that it does not turn during the process), is disconnected from the drive gear;
• unscrew the 4 nuts securing it;
• taking a flat screwdriver, disconnect the flange;
• the cardan is suspended on a rope, secured to the bottom of the car;
• twist the nut that secures the drive gear;
• remove the washer;
• the flange itself is dismantled;
• turn off the brakes and unscrew the wheels.

Since it is impossible to replace the gearbox without removing the axle shafts, dismantle them too.

After this, all that remains is to remove the gearbox itself. It is disconnected from the beam by unscrewing 8 bolts.

Whatever the reason forces you to disassemble the rear axle, always check the condition of other moving elements along the way. As previously noted, oil seals most often become unusable.

The main bearings also often wear out due to high loads. If visible defects are found on these elements, they must be replaced. By the way, this element is designed to ensure the correct gear ratio of the power unit. For those who intend to start tuning their “seven”, it is useful to know that installing a superior gear directly into the gearbox allows you to lower the above-mentioned indicator and, therefore, increase the speed. For 2107, the highest allowed number is 4.4.

About gearbox adjustment

If the driver finds out that the main pair of gears in the rear axle is completely worn out, he will have to change this pair. But you won’t be able to simply change the gears, since there are gaps between the gear teeth that will have to be adjusted. Here's how it's done:

• a special adjusting washer is installed under the drive gear (they are sold in sets, and the thickness of such washers varies from 2.5 to 3.7 mm);
• an adjusting sleeve is installed in the gearbox shank (these sleeves are also sold in sets; you can find them in any spare parts store);
• the washer and bushing must be selected so that the shaft on which the drive gear of the gearbox is mounted rotates without play when turned by hand. After the desired bushing has been selected, the nut on the shank is tightened;

Gearbox repair

When making adjustments and repairs to the rear gearbox, you must have certain skills, as well as follow technology. A mandatory requirement is that you must have special tools, pullers and stands at your disposal. If you do not have all these tools, then it is better to have the rear gearbox repaired by a professional.

If you have never tried to repair rear gearboxes, but really want to do it, it is better to first learn from experienced mechanics. Disassembling the VAZ-2107 axle gearbox is not difficult, but this is a vehicle component that requires very high-quality maintenance. You shouldn't skimp on this.

Differential device

The planetary gear is mounted on the differential housing. The differential consists of two axle gears, two satellites and a pin. The main, most common differential malfunctions are wear of the pinion pin (play) and wear of the splines on the axle gears.

On a car, the play of the pin of the satellites can be determined by turning the driveshaft by a quarter or more; if there is no play, then the shaft practically remains in place when you try to turn it in one direction or another.

It's also worth noting that there is never any noise coming from the differential. When moving forward (in a straight line), the differential rotates as one unit and it turns out that there is simply nothing to make noise there.

The cause of noise from the rear axle gearbox when gas is added and the noise disappears after releasing gas is (almost 99.9%) wear of the teeth of the main pair. This is clearly visible on the removed gearbox. The forward side of the teeth has significant wear, while the reverse side shows little wear.

If, after disassembling and troubleshooting the parts of the main pair, wear of the teeth is detected, then no repair will help and it will simply be a waste of time and money. Only the main pair needs to be replaced.

Home-couple

The gears of the main pair are selected at the factory based on contact patch, noise and other parameters and are marked. For example, on the planetary gears it is stamped - VAZ 2103 (model), 10 41 (gear ratio), 4091 (pair number). The main pair number 4091 is also marked on the bevel gear.

After marking these parts, they became the “main pair” and are not installed one without the other, that is, “family”. “- 6” is also marked on the “tip”; this is an amendment for assembling the main pair in the gearbox. When troubleshooting a differential, its bearings are also checked for wear and, if necessary, replaced. Bearing wear is often caused by unprofessional replacement of the gearbox seal.

For example, after replacing the oil seal, tighten the shank nut without observing the tightening torque (pull as much as possible) and the force is transferred not to the spacer sleeve, but to the differential bearings.

These are supports on rotating axes and shafts, which receive loads and transfer them to various structures...

As a result, after a short run after replacing the shank oil seal, noise from the gearbox appears. Only in this case, the “hum” noise in the gearbox is constant and unlike the noise from worn teeth of the main gear. In this case, the hum is constant, regardless of whether gas is added or released.

Rear axle gearbox assembly video

During assembly, the gearbox is adjusted according to 4 parameters:

1. Selection of the adjusting ring

Parameters from 2.6 to 3.5. The ring serves to adjust the depth of engagement of the teeth of the “tip” and “planetary gear”, which is strictly specified. This is where the “correction -6” is needed for this main pair, which was mentioned above. Of course, this amendment will be individual for each main couple.

In this video, the main pair will be adjusted using a special device. It is clear that the vast majority of motorists do not have such a device and this is just a clear example of adjusting the engagement depth parameter. An option will also be given for adjustment without a “device”.

A “device” with a micrometer is also installed on the device, simulating the gear of the main pair. The indicator shows zero. Then the indicator leg is transferred to the bearing bed and in this case the indicator shows a value of 3.25, which is not good, since it should be within the range of 3.0. On the second landing plane it turned out to be 3.45. The arithmetic mean is 3.3. To adjust, we will use the correction at the “tip” - “-6”. In this case (– 3.3) + (-6) = 3.36. The thickness of the adjusting washer required is 3.36 mm. Using a micrometer, select the washer of the required thickness.

Note. When the shank bearing wears out, it begins to rotate on the “tip” body. As a result, the bearing end, adjusting washer and shank gear bodies wear out. It turns out that when replacing the shank oil seal, even with the correct tightening torque, the adjustment of the depth of engagement of the teeth of the gears of the main pair is lost and the “howl” of the pair is ensured, as is its early failure.

Let's return to the gearbox assembly...

2. Adjusting the preload of the shank bearings

The shank bearing sits on the “tip” and a NEW spacer sleeve MUST be installed. The video clearly shows that the new bushing is smooth without any deformation, while the previously installed one is deformed. What happens is this: When the shank nut is tightened to the prescribed torque (from 12 to 26 kgf), the bushing takes on the tightening force and, when deformed, works like a spring, creating tension. The tightening force for the VAZ 2107 gearbox nut is significant and the shank must be secured against turning.

In the video we see what kind of “device” the master uses. It is necessary to tighten the shank nut until there is no play. When the nut is tightened correctly, the shank should rotate with a resistance force of 0.3-0.4 kg, therefore, the bearing preload is correct. This assembly rule applies to old (used) bearings.

The differential with bearings is installed and secured with covers (tightening torque is about 8 kgf) and the adjusting nuts of the differential bearings are tightened.

3 and 4. Simultaneous adjustment of the thermal clearance of the main pair and the preload of the differential bearings

For these purposes, another “device” with two indicators is needed. Using the adjusting nuts in the video and everything is shown well, we move the planetary gear towards the teeth of the “cone” to achieve the required clearance. Factory clearance adjustment data is from 0.08 to 0.12 mm. However, such a gap is provided for the new main pair (“tips” and “planets”). The gap is checked in 4 planes by turning the gear. The gap for the working main pair after adjustment is 0.13-0.14 mm.

After making the adjustment, the adjusting nuts are locked with special plates for this purpose, with one or two “antennae”. This completes the assembly and adjustment.

Video of adjusting the engagement depth of the main pair

In this case, it is necessary to select the thickness of the adjusting washer.

So: Instead of the device, we install the “original” shank and tighten the nut until it stops lightly, leaving a gap. The differential with planetary gear assembly, bearing caps are installed and their mounting bolts are tightened.

When replacing the shank oil seal, a number of incorrect actions are allowed, which ultimately lead to premature failure of the gearbox. Before releasing the shank nut, according to the technology for performing the work of replacing the oil seal, it is necessary to remove the axle shafts (which is almost never done, since the amount of work will increase many times). Although according to the price list, the removal of the axle shafts will most likely be included in the list and a fee will be charged for this, since this is required by the plant’s technology for replacing the oil seal. This is a necessary condition, since the axle shaft will create resistance when tightened and correct adjustment will simply be impossible to achieve.

Before releasing the shank nut, it must be secured against turning and the tightening force of the nut must be checked with a torque wrench, around 12 kgf. Before installing the oil seal, if its outer surface is not rubberized, then you need to use a sealant to guarantee it. Thus, a mark of 0.15 mm on the gearbox stocking will be sufficient to pass oil through the outer surface of the oil seal.

Back to assembly...

The adjusting nuts are installed, and the gap on the main pair is pre-selected (the final working gap is 0.08 to 0.12 mm). Then paint is applied to the teeth of the planetary gear from an aerosol can and, using a shank, it is necessary to make several movements in different directions in order to fix the contact spots in the paint.

Now, having turned the planet gear back, you can clearly see the contact patch on its teeth with the teeth of the pin. The contact patch (in this case) shows that the adjusting washer on the shank is thicker than the required thickness. We slightly tighten the shank nut, thereby moving its bearing, which makes it possible to move the gear teeth towards each other, that is, as if “reducing” the thickness of the adjusting washer. Using the differential bearing adjusting nuts, we set the approximate gap (reducing it slightly).

Then we again apply paint to the teeth of the planetary gear and again begin to rotate the shank (or gear) in different directions to print the contact patch between the teeth. It can be seen that the contact patch has risen a little, but still not enough and it is necessary to tighten the shank nut a little again. Similar actions with paint and turning the gear must be carried out until the contact patch is located exactly in the middle of the teeth, and the sound of the turning teeth becomes quieter.

After correct (final) adjustment, the sound will be almost inaudible.

Remember to tighten the differential bearing adjusting nuts every time you tighten the shank nut. As a result, the contact patch was located exactly over the entire surface of the teeth. It should be noted that this is the condition for the location of the contact patch for old (working) pairs. For new main pairs, the contact patch, as mentioned above, should be located in the center of the teeth.

Further. The planetary gear mounting covers are released and the differential is removed. The shank nut is unscrewed and removed. Since the shank was installed only with a bearing without an adjusting washer, there was a gap between the bearing and the shank gear where the washer would fit. This gap is measured with a set of feeler gauges, thereby calculating the required thickness of the adjusting washer.

It turns out, as in the case of using instruments and accessories, the size for the required adjusting washer was also 3.36 mm. The shank bearing is removed, an adjusting washer (3.36mm) is installed, the bearing is put in place and the gearbox is assembled. The shank is installed, the shank nut is tightened, min. 12 kgf. The differential with planetary gear is installed, the covers and bolts are tightened, but not completely.

By the way, the lids should not be mixed up. The adjusting nuts of the differential bearings are installed and the gap on the main pair is pre-set. Then the differential cover bolts are finally tightened. The gap in the main pair is finally adjusted and the adjusting nuts are secured.

Correct assembly

When using old parts, only the oil seal and spacer sleeve are changed. When replacing elements of the main pair, it is necessary to use a new spacer washer for the shaft gear and bearing. The washer is selected according to the size, which can be found on the shaft itself. The adjustment ring is mounted and pressed with an attachment onto the inner bearing race.

Requires installation of a spacer sleeve. It is placed in the crankcase. A new oil seal is installed. Next, put on the flange and tighten everything with a new nut. When installing new bearings, the nut must be tightened with a force of 16-200 kgf meter. After running-in, the force will drop to 6. When using old bearings, tightening occurs in the same way as the oil seal.

The differential is assembled and installed in place. If the semi-axial gears had axial play, then thickened washers are installed. After this you can screw on the lids.

A specialized wrench is made to adjust the bearings.

The main pair is adjustable. The nut must be tightened from the main gear until the gap disappears. The shtangel will help measure the gap.

Then the second nut is tightened and tightened a couple of teeth. The first nut has a gap of 0.08-0.13 mm. It will be noticeable if you pick up the gear: a faint knock of teeth will appear.

While controlling the gap, slowly tighten both nuts until they increase by 0.2 mm. This ensures that the bearings are tensioned correctly.

Next, the gear is turned by hand and backlash is tested. If it is the same in different positions, then locking plates are installed, tightened with bolts. If this is not the case, then they say that the differential box is deformed, and therefore it needs to be replaced.

Diagnostics and causes of malfunctions

The fact that the gearbox is in a faulty condition is indicated by the appearance of a characteristic noise (hum) when the vehicle is moving. To accurately determine the gearbox malfunction, there is the following experiment.

You need to accelerate the car to 25 kilometers per hour and gradually pick up speed, starting from this mark. If suspicious hums appear, be sure to record the speed at which you hear them.

Once you reach the desired speed, slowly release the gas pedal and apply engine braking. Again, listen for extraneous noises and pay attention to the speed at which they appear or disappear.

Certain noises should appear and disappear at the same speed. If this happens, it means that the rear axle gearbox is in a faulty condition. However, to be 100 percent sure, be sure to put the car on the parking brake, put the gear in neutral and try to gain speed, if the noise appears again, then the problem is not in the rear axle gearbox, and if there is no noise, then you can be sure that it is rear axle gearbox.

The cause of malfunctions, most often, lies in the use of low-quality oil, loss of its viscosity, as well as its complete absence. In addition, the gearbox may fail due to failure of oil seals, bearings and special gears. Sometimes, the cause of a rear axle gearbox failure is a broken axle shaft.

How does it work?

There are three differential operating modes in total. So, his work is aimed at moving in a turn, along a road and in a straight line. In the latter case, the car's wheels have equal resistance. Torque from the driveshaft (or final drive) is transmitted to the differential housing. The satellites rotate with it. The latter run around the axle gears and thus transmit torque to the two driving wheels in equal proportions. And since the satellites on the axles do not rotate, the gears of the axle shafts move at the same angular speed. The speed is equal to that of the driven shaft of the main gear.

The operating principle of the differential is slightly different when the car is cornering. So, in this situation, the wheels will rotate at different angular speeds. What is closer to the center of the turn has more resistance than the outer disc. What happens in this case? The differential begins to transmit torque with different forces to the axle shaft. Thus, the rotation frequency of the outer gear increases, and that of the inner gear decreases. The sum of the revolutions of both gears is equal to twice the speed of the driven gear of the main drive.

Now consider a situation where a car is moving on a slippery road. So, in a certain area, one of the wheels begins to slip, encountering more resistance. The differential gears rotate the second wheel at increasing speed. Surely you have seen more than once how a stalled car slips with only one wheel when the second one is stationary. This is the job of the differential. However, its function is not at all aimed at deteriorating the vehicle’s cross-country ability. Thanks to this element, the car corners more steadily. At the same time, the tread on the tires does not eat up, since the discs rotate equally.

Important nuances in work

1. When driving the oil seal using a mandrel, do not overdo it. Apply gentle blows and control the depth of the oil seal. If you hit it hard, you can easily damage the oil seal;
2. Before installing the oil seal, lubricate the rim and sealing edge with fresh oil;
3. Before installation, inspect the flange for wear in the area where the sealing lip of the oil seal meets. If there is a “groove,” the flange must be replaced.

As you can see, the process of replacing the VAZ 2107 gearbox seal is quite simple and does not take much time. The most important thing in this job is to properly tighten the rear axle flange nut.

vote

Article rating

Checking the serviceability of the shank oil seal

The first sign that it is necessary to replace the shank oil seal on a VAZ 2107 is the presence of traces of lubricant, dust and dirt on the outer part of the rear axle. Determining the presence of leaks on the rear axle is not difficult. To do this, you need to climb under the car and inspect the bridge.

If the oil seal is worn significantly, a puddle of oil may be found under the car. If the problem is not resolved in a timely manner, oil may leak out of the bridge, which will lead to its rapid breakdown. Despite the fact that the cuff is a small part in a car, its serviceability plays a very important role.