Design feature of the rear axle of the UAZ-3151, -31512, -31514, -31519

UAZ vehicles are equipped with two types of rear axles - with a single final drive or with additional wheel reduction gears

Axle with a single final drive consists of a cast-iron crankcase split in a vertical plane and steel tubular casings of the axle shafts pressed into it, additionally fixed by welding.

Two parts of the crankcase are tightened with eight bolts through a gasket.

The main gear with differential is located on the right side of the crankcase and forms the axle gearbox.

The final drive gear is installed in the crankcase on double roller angular contact and roller radial bearings located on both sides of its ring gear

The driven gear is bolted to the pinion box

Gears - bevel with spiral tooth, gear ratio - 4.625

The satellite box consists of two parts connected with bolts

It is installed in the crankcase on two tapered roller bearings

The box contains two pinion axles, four pinion gears, and two side gears with thrust washers

The splined ends of the axle shafts enter the splined holes of the side gears

Flanges are made at the outer ends of the axle shafts, which are connected to the wheel hubs with ten bolts

Each hub is mounted on the shaft housing on two identical tapered roller bearings

Five bolts are pressed into the hub, to which a stamped steel wheel with a bore diameter of 15 or 16 inches is fastened with flare nuts

Adjustment of the bearings and engagement of the final drive gears is done by changing the thickness of the spacers between the inner rings of the pinion bearing and the number of washers at the inner rings of the satellite box bearings

The hub bearings are adjusted by ring nuts mounted on the threaded ends of the axle housings.

The gearbox is lubricated with gear oil poured into the crankcase.

For filling and draining oil, there are holes closed with plugs with conical threads.

The hub bearings are lubricated with grease embedded in the internal cavities of the hubs.

To prevent leakage of oil and grease, as well as the ingress of dust, the rear axle is equipped with cuffs installed on the shank of the drive gear and in the wheel hubs.

There is a breather on the axle housing to relieve excess pressure inside the axle.

The rear axle with wheel reduction gears is similar to the one described, but has the following differences:

• - the final drive gear is cantilevered on two tapered roller bearings with a spacer sleeve between them;
• - the gear ratio of the main gear is reduced to 2.77 and corresponds to the dimensions of the main gear housing have been significantly reduced;
• - at the ends of the casings of the axle shafts, wheel reduction gears with a spur gear of internal gearing are installed (gear ratio - 1.94)

In this case, the drive gear of the gearbox is installed on the splined end of the axle shaft, which is supported by ball and roller bearings

The driven gear is integral with the driven shaft. It is splined to the drive flange of the wheel hub.

The wheel gear housing consists of two parts, bolted together through a gasket

The wheel reduction gear is lubricated with oil poured into its crankcase and has holes with plugs for filling and draining oil, like the central reduction gear

Thanks to the use of wheel gears, the vehicle's ground clearance is increased by 80 mm, which increases the vehicle's cross-country ability.

Oil change in the rear axle reduction gear

It is advisable to change the lubricant after a trip while the oil is warm

We install the car on a viewing ditch or lift

Cleaning the filler and drain plugs of the reducer

We substitute a container to drain the oil from the gearbox

Unscrew the gearbox drain plug with a 12 hexagon and drain the oil into a container

We clean the cork from metal particles and twist it into place

Unscrew the filler plug with a 12 hexagon

Pour fresh gear oil into the gearbox with an oil syringe to the level of the lower edge of the filler hole

We wrap the cork in place and tighten it.

If the used oil is dark in color and metal particles are visible in it, before filling in fresh oil, we flush the gearbox, for which, after draining the old oil, pour into the gearbox about 0.5 liters of a mixture of gear or engine oil with 20–30% kerosene or diesel fuel

Having wrapped the cork, we hang out one side of the car (until the wheels are off the ground) and turn on the front axle

Start the engine and turn on the first gear for 2–3 minutes, after which we completely drain the flushing oil and fill the gearbox with fresh gear oil, up to the lower edge of the filler hole

Similarly, we change the oil in the wheel gears (for vehicles with wheel gears)

Possible malfunctions of drive axles and methods of elimination

Increased driving noise

Increased lateral clearance in the meshing of the final drive gears due to:

- Wear of the gear teeth of the final drive

Replace worn gears

It is not necessary to adjust the position of the gears to compensate for wear, since the required contact in the meshing of the gears is achieved only at a certain relative position

- Wear of the bearings of the final drive gear

Adjust or replace worn bearings

- Differential bearing wear

Replace worn bearings

- Loosening the bolts of the driven gear to the differential

Tighten the driven gear bolts

- Incorrect adjustment of the main gear engagement on the contact

Adjust the gearing in the absence of tooth wear (for UAZ-3151 drive axles)

- Damage to differential parts (wear of gear teeth, rubbing surfaces of the satellite box and other parts associated with them).

In this case, noise appears when turning or slipping one of the wheels

Replace worn parts

- Reduced oil level in the final drive housing

Add oil to the crankcase up to the lower edge of the oil filler hole

Oil leak through the cuff of the final drive gear

- Wear of the cuff or the surface of the flange of the driveshaft to the final drive gear

Replace the collar together with the flange