How the 6-speed Gazelle NN gearbox works, what it does and when to service it


As you know, the gearbox of any car is one of the most important components in the transmission structure. The main functions of the gearbox are to convert and transmit torque from the internal combustion engine to the drive wheels.

The quality of the transmission directly affects the health of the vehicle, as well as the comfort and safety of the driver and passengers. It must be remembered that even small deviations from the norm in the operation of the gearbox require detailed diagnostics. Otherwise, a minor malfunction can lead to costly repairs.

We also note that each box, due to its design features, requires an individual approach. In this article we will look at the Gazelle gearbox, as well as what features the GAZelle gearbox has, since this car is widespread in the CIS.

What are the faults of the Gazelle gearbox?

Gazelle gearboxes are rightfully considered one of the most reliable and durable, but even they can become unusable due to high loads. In order for the replacement of the Gazelle gearbox to go without a hitch, you must know the hardware of the car, study the diagrams, be careful and patient, and also follow the safety rules and understand the principle of operation of the Gazelle 4x4 gearbox.

Gazelle repair may be required in some cases:

  • difficulty changing gears. This snag occurs due to the lack of fluid in the cylinder or due to the presence of air in the hydraulic drive. In addition, you can check the locking bolts, which often need additional tightening, as well as the transmission intermediate shaft. You can observe how the device jerks in neutral, and the transmission howls. Another sign is that in 4th gear, fifth or second, the device makes a howl, a lot of noise;
  • The gearbox engages with noise and crackling noise when starting. In this case, the synchronizer blocking ring on the transfer case could be worn out or deformed. Also check the power take-off. It is advisable to replace the blocking ring or power take-off box, and to ensure that the new element fits in without problems, use lapping paste. In addition, check the condition of the input shaft, how the mortar works, whether the car is noisy in neutral;
  • random shutdown of the manual transmission. If you notice such a problem, first of all check the fastening nuts to the clutch housing, as well as the condition of the gazelle gearbox linkage. In addition, the couplings could wear out (worn out teeth), as well as the locking springs (they can either wear out or weaken). You may also need to adjust the intermediate shaft and input shaft;
  • the appearance of extraneous noise. In order to get rid of them, it is necessary to replace bearings or damaged gears, add oil to the crankcase or check its alignment with the crankshaft.

To repair a Gazelle gearbox, you must know everything about the structure of the transfer case, because disassembling the gearbox is not an easy task. This is also necessary to determine the type of failure. The most popular reason for Gazelle owners to replace the gearbox is oil leakage. It occurs due to worn out seals or bushings, worn out gaskets, as well as poor sealing of the plugs. In this case, you will need to add or change the oil in your car, as well as replace the bushing.

Design and principle of operation

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As with any car, the Gazelle’s gearbox performs the most important functions of the transmission. It converts and transmits torque to the wheels from the engine. Therefore, a lot depends on the quality of operation of this unit. For example, the comfort and safety of people, because any malfunction of the gearbox carries the risk of accidents.

The small Russian car is equipped with a manual 5-speed gearbox. Despite the manufacturer's assurances that it is durable and unpretentious, most owners claim the opposite. The reliability of the unit is poor primarily due to constant excessive loads, since commercial vehicles can be operated for 24 hours straight.

The main elements of the checkpoint are:

  • double crankcase;
  • gears;
  • main shafts and intermediate;
  • synchronizers, balls, springs;
  • gear shift mechanism.

The crankcase is made of aluminum alloy for lightweight purposes. It consists of two parts: front and rear with extension. They are securely connected with 10 bolts through a 0.33 mm paronite gasket. To ensure alignment of the shaft ends and rod holes of the switching mechanisms, they are centered with special bushings pressed into the crankcase.

The shafts are equipped with other unique parts. For example, the secondary shaft is limited from axial movements by retaining rings and special thrust half-rings. A collar is also provided. The input shaft is equipped with a drive gear for the speedometer drive. All shafts, including the intermediate one, have gears, and at the ends there are roller or ball bearings and retaining rings/half rings. A special place is occupied by bushings, fixing pins, spring washers and 0.2 mm shims. The drive and driven shafts are connected at their ends to the engine crankshaft and crankcase. The intermediate shaft is located inside the box body.

The gear shift mechanism, in addition to the lever, is equipped with springs, a seat, seals, a thrust cone, and bushings. There are a lot of washers, plugs, and dowel pins. Speeds are switched using forks - there is a separate one for fifth gear and reverse gear. The locking device or fuse consists of two plungers and a locking pin. To prevent accidental engagement of reverse gear, a separate bushing with a spring is provided.

How to replace a gearbox on a Gazelle

How to remove the box? Replacement of the gearbox is carried out on an overpass or inspection pit. First, drain the oil from the crankcase. Now we remove the cardan. To do this, arm yourself with a file and put a notch on the connecting unit and the continuation of the gearbox on the gazelle. Now remove the support fasteners using keys thirteen and twelve. Using keys seventeen and fourteen, remove the fixation of the cardan to the flange of the main gear gear. We remove the shank and insert a rag into the hole. Now we need to get the lever to install the gearbox. To do this, we get rid of the cover and the top of the lever inside the cabin, unclench the bushing, remove the rubber cushion, floor seal and cover, cap and the lever itself.

Next, disconnect the speedometer from the transmission along with the rear light switch. Now you can remove the transfer case. How to disassemble the gearbox housing? To do this, get rid of the fixation of the exhaust pipes and bracket, disconnect the transmission from the clutch housing, and create protection from a wooden block for the cylinder head. We proceed to removing the transverse fixation of the transfer case and remove the device. Be careful as its weight can reach 30 kg. Install a new element. Be careful not to damage or miss the stepped transfer case.

Now we begin assembling the Gazelle gearbox. The box is assembled in the reverse order. Please note that the shafts must be installed at the same time; to do this, tie them up in advance. Inspect the input shaft, shank, bushing, crankcase, output shaft and all gears. Wash them in kerosene or diesel fuel. If there are signs of rust, sand it down. The fasteners are coated with sealant, and the elements are coated with transmission oil.

Before installing the splines, lubricate them with CV joint-4, and while assembling the cardan, make sure the marks match and pay attention to the gear ratio. It is an important indicator of the adequate operation of a mechanical device. After repairing the Gazelle gearbox, replenish the amount of oil in the crankcase.

Published on August 27, 2016

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Recommendations for extending the service life of the unit

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Without proper care, the Gazelle gearbox quickly breaks down. Some explain this by the mismatch of the unit for a truck. As you know, the box used here, albeit modified, is from a passenger car. Therefore, the slightest overload or prolonged operation has an extremely negative effect on the resource. Already by the 80,000th mileage, gears begin to fly out, crackling and noise appear.

Other recommendations:

  • do not load the car above the norm of 1.5 tons;
  • drive on good roads, avoiding gravel and complete off-road conditions;
  • monitor the clutch, refill technical fluids on time.

Repairing and disassembling the Gazelle gearbox is not an easy task, but following the instructions, you can handle the operation yourself. If something doesn’t work out, you can always take the box to a service center or call a specialist to your home.

Checkpoint performance test on site.

Raise the rear wheels of the car (jack up and place the rear axle of the car on supports), start the engine and slowly engage the gears one by one (create an imitation of the car’s movement). Test the performance of each transmission for about one minute. WHAT WILL IT GIVE!? Firstly because the gearbox parts have been thoroughly washed, then the initial operation of the gearbox will be dry, despite the fact that the oil has already been filled (oil will not get into all the gaps at once, if you pay attention, only the intermediate shaft is in an oil bath, and it is the oil distributor in the gearbox, in As a result, the operation of the primary and secondary shafts is dry, although where gears and bearings were available, they were lubricated during the assembly process), and when the vehicle is operating without load, it will allow the oil to be painlessly distributed inside the gearbox system, and secondly, in case of unforeseen circumstances (sudden output failure of any element, breakdown, etc.) the operation of components and assemblies will be without load, which will avoid more serious breakdowns.

The most common symptoms and troubleshooting methods

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Despite the structural simplicity of the unit, repairing a Gazelle gearbox with your own hands involves serious work. Without the proper knowledge and skills, it is better not to touch the unit, so as not to make it worse. To replace damaged parts, the box must be dismantled and disassembled.

There is a noise in the box

Most often, a sign of a mechanical malfunction is a dull hum or crunch, indicating weak fixation or destruction of the bearings. An unpleasant cracking sound is also possible, indicating damage to the synchronizer rings. Often the box howls, and in completely different ways. The strength of the sound and its character depend on the speed of movement, the specific gear, and the duration of driving.

It is noteworthy that the characteristic noise does not always indicate a gearbox malfunction. Especially if the elements of the box have recently been replaced. In this case, the howling will only be a sign that the parts have not yet gotten used to it. Often, the crunching of the gearbox is confused with malfunctions of the clutch or other related units. And any experienced Gazelle driver will confirm that until you disassemble the box, the specific cause of the noise can only be determined with a 50 percent probability. But a competent bulkhead will help you immediately find the problem area. Before this, of course, you need to check the oil level. If it's ok, you need to disassemble the gearbox. Anything can turn up during the troubleshooting process. For example, there may be a mismatch in bearing markings, missing washers, or incorrect sizes.

Difficulty shifting gears

If it becomes difficult to change gears, this indicates one of the problems:

  • synchronizers or gears of a certain gear are worn out;
  • the lever or other switching mechanisms are damaged - most often the fork;
  • problem with the clutch - it does not engage completely, the pedal drive cable is loose, the driven disc is damaged.

It also happens that it is difficult to change gears on a warm engine, but when it is cold everything goes like clockwork. The point here is that initially there is a thick layer of lubricant between the synchronizer thrust ring and the gear. After the temperature rises, the oil liquefies, the ring and gear are rubbed almost dry, and the coupling rests against the teeth of the ring. Either a high-quality grip, such as HOLA, or another MTF compound will help.

Speeds do not turn on

In this case, you need to urgently check the fluid level in the clutch reservoir. It is possible that a leak has occurred through a damaged main circulation center or control center. It is possible that air has entered the system, then you can get by with a little blood by expelling it through the fitting.

If the fluid is ok, then the problem is with the gearbox, or more precisely, with the switching mechanism. More often the fork breaks down - it bends or is pierced by the rod, and then it becomes impossible to engage a certain gear. It is not uncommon for the tide-limiter on the synchronizer to grind off.

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