Carraro front axle troubleshooting


Problems

Wheel vibration, front tire resistance, broken stub axle.
Steering difficult, the vehicle keeps on moving straight forward when the wheels are turned.
Differential does not function, it gets jammed when steering.
Excessive transmission noise.
Excessive tyre wear.
Friction noise.
Vibration when driving forward, intermittent noise.

Possible causes

Incorrect installation / Defective axle
Re-install. If differential tests after assembly are not satisfactory, repair or replace the differential.

Overload / incorrect weight distribution
Remove excess weight and distribute the load as indicated by the instruction supplied by the vehicle manufacturer.

Different wheel turning radii 
If the radius of one wheel is smaller than that of its counterpart, partial wheel slippage can result when force is applied. The other wheel, with larger radius, will support the entire load. Replace the tire or adjust the pressure to obtain the same radius for both tyres.

Broken stub axle
It is not recommended to drive with a broken stub axle. The vehicle can only be moved a few meters (engine stopped and at no load).

Warped stub axle
Replace the stub axle concerned.

Differential jammed
Abnormal differential operation or broken or seized-up control mechanism. Check the differential assembly and all its components. On vehicles with a high steering angle, this failure can cause jerky operation, difficulty steering or excessive tire wear on narrow turns. Reduce the steering angle to a minimum and reduce speed when vehicle begins to jerk.

Incorrect wheel alignment
Check the axle assembly and wheel bearings.

Broken or worn axle components
Check the condition of the ring gear, pinion, bearings, etc. Replace defective parts.

Dirty particles in the axle housing or incorrect assembly of certain components
Detect dirty particles. Check the assembly of different axle components.

Incorrect bevel gear shimming: transmission components worn (transmission gearing, pivot balls, etc.). Shim or replace the concerned parts.

Product misuse
Refer to the instructions provided by the vehicle manufacturer.

Front axle troubleshooting

Problem - Ring gear teeth damaged on external side
Cause - 1. Excessive load on teeth in relation to design load.
            2. Incorrect backlash (excessive clearance).
            3. Loosening of the pinion nut.
Action required - Replace the ring gear and pinion. Carefully follow the recommended adjustment operations for bevel gear clearance.

Problem - Ring gear teeth damaged on internal side
Cause - 1. Jerky load
            2. Incorrect shimming of teeth (insufficient clearance).
            3. Loosening of the pinion nut.
Action required - Replace the ring gear and pinion. Carefully follow the recommended adjustment operations for bevel gear clearance.

Problem - Ring gear teeth and pinion teeth worn or damaged
Cause - 1. Insufficient lubrication.
            2. Contaminated fluid.
            3. Lubrication incorrect or containing diluting additives.
            4. Pinion pin clearance misadjusted and poor contact between pinion and ring gear caused by wear to the pinion bearings.
Action required - Replace the ring gear and pinion. Replace the bearings, ensuring the correct positioning of the ring gear, pinion and bearings preloads. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Ring gear teeth and pinion teeth overheated. Check that the teeth have not lost their colouring.
Cause - 1. Prolonged operation at excessive temperatures.
            2. Incorrect lubrication.
            3. Low oil level.
            4. Contaminated fluid.
Action required - Replace the ring gear and pinion. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Pinion teeth corroded
Cause - 1. Excessive use.
            2. Insufficient lubrication.
Action required - Replace the ring gear and pinion. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Axle beam warped
Cause - 1. Vehicle overload.
            2. Vehicle accident.
            3. Jerky load
Action required - Replace axle beam.

Problem - Bearings worn or corroded
Cause - 1. Insufficient lubrication.
            2. Contaminated fluid.
            3. Excessive use.
            4. Normal use.
            5. Loosening of the pinion nut.
Action required - Replace the bearings. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Oil leak at seals
Cause - 1. Prolonged use at excessive oil temperature.
             2. Incorrect assembly of oil seal.
             3. Damaged lip seal.
             4. Contaminated fluid.
Action required - Replace the seal and mating surface if damaged. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Input flange splines excessively worn
Cause - 1. Excessive use.
            2. Loosening of the pinion nut.
            3. Pinion shaft clearance.
Action required - Replace the flange. Check the wear on pinion splines. If necessary replace the ring gear and pinion.

Problem - Pinion teeth broken due to fatigue. Check if the rupture is straight (jagged)
Cause - 1. Excessive use.
            2. Prolonged overload.
Action required - Replace the ring gear and pinion.

Problem - Pinion teeth and ring gear teeth broken
Cause - 1. Differential parts at breaking load.
Action required - Check and replace other differential parts if necessary.

Problem - Pinion splines of sun gear excessively worn (excessive backlash)
Cause - 1. Excessive use. Replace the pinions throughout the differential.
Action required - If necessary, replace the stub axle.

Problem - Thrust washer mating surface worn or scratched
Cause - 1. Insufficient lubrication.
            2. Incorrect lubrication.
            3. Contaminated fluid.
Action required - Replace with a new washer if scratched or if thickness is under 0.1mm. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Taper roller bearing internal diameter worn
Cause - 1. Excessive use.
            2. Excessive pinion axial clearance.
            3. Insufficient lubrication.
            4. Contaminated fluid.
Action required - Replace bearing. Check pinion axial clearance. Use suitable lubricants, top up level when required and change the lubricant as indicated in the recommended maintenance schedule.

Problem - Stub axle warped or broken
Cause - 1. Excessive use or vehicle overload.
Action required - Replace the defective stub axle.

Problem - Stub axle broken at wheel side
Cause - 1. Wheel support loose.
            2. Axle beam warped
Action required - Replace the defective stub axle. Ensure that the axle beam is not warped. Ensure that the wheel support is not worn or misadjusted.