As the UK's leading supplier of replacement commercial vehicle transmissions parts, H L Smith have a wealth of information about parts and maintenance of your commercial vehicles.

If you have a problem you need to resolve, try our FAQs. If you can't find what you're looking for, please contact us and we'll  get back to you as soon as we can.

What are the likely causes of an oil leak?

We recommend that you check the following:

• A blocked breather  - could cause pressure in axle case, leading to a leak.
• A worn propshaft ,and the resultant vibration, can result in a leak from the pinion oil seal.
• Check axle oil levels are not over full.
• Differential lock air system  -could be leaking into unit, pressurising the axle.
• You might have a damaged pinion oil seal.

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What might lead to excessive noise?

It depends on the type of noise, for example, a knocking noise indicates missing or damaged gearing, wheras a whining noise indicates bearing and crown wheel and pinion
wear; it can also indicate lack of oil.
Take an oil sample. The presence of any metal debris would indicate an internal problem.

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Loss of drive problem

Areas to check:

• Half shafts for worn or broken splines.
• Crown wheel and pinion for missing or damaged teeth.
• Planetary set for worn splines or broken gears.
• Coupling flange – pinion splines for wear.

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Crabbing around corners

Check the planetary set for seized or damaged gears

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