A vital component of any vehicle's underside are its front and rear axles.

Axles are central shafts connected to the wheels, moderating the engine's power to drive the car either forward or backwards.

With the notable exception of three-wheeled vehicles-   private and sports cars come with front and rear axles as standard.

In addition to turning the wheels, axles play another significant part in improving the vehicle's overall stability by supporting its weight.

There are two formats of axles-  Live axles and Dead axles.

The rear axle does the hard work, delivering power to the driving wheels.

 In two parts, known as half shafts, connected through the differential, this common category of the rear axle is described as "live".

Live rear article rotates in line with the wheels of the vehicle.

The front axle shares the weight burden, as well as steering the vehicle. The front axles will also absorb any jolts suffered through being driven through less than perfect road surfaces.

 Because they have to deal with the unexpected front axles are usually sturdier than the back, produced using either carbon or nickel steel.

The role of  the  front axle is simpler to  the rear - to  take its share in bearing the weight of the vehicle as well as facilitating its  steering and absorbing shocks caused by road surface variations

Front axles usually fall into the "dead" category because they never rotate.

Specific models can be fitted with a live front axle, designed to transmit the vehicle's driving power through a transfer gearbox to the front wheels.

Some of Colin Chapman's early Lotuses used this design.

A live front axle differs from a dead front axle as it has insufficient strength and rigidity to carry the vehicle's weight.
The axle beam's ends are secured to short ( stub axles)  using kingpins to overcome this issue. Stub axles are produced using alloy steels containing chromium and molybdenum.

Axles are made up of two main segments- beams and track rods.

Axle Beams ( also known as rigid axles or solid axles) were the axle of choice in post-war UK and European cars, gradually replaced at the end of the Sixties by independent suspension. 

Comprising a single beam or shaft, the axle beam has the vehicle's wheels attached at either end by the  (king pin). This form of rigid axle was conducted by leaf springs or individual steering arms connected with the frame.

The advantage of the rigid style of axle design is its simple construction coupled with its ability to provide parallel guidance to the wheel.

What brought about its demise was the axle beam's considerable weight and bulk, making adding springs a challenging proposition

Track rods are fitted to each end of the steering rack and adjusted to a preset tracking level. Consisting of an inner and outer track rod with the inner track rod attached to the steering rack and pinion while the outer track rod is connected to the steering knuckle on the wheel.

Track rod ends are flexible steering links in the form of a small ball joint connecting the tie rods to the steering knuckles that play a significant role in steering a vehicle.

In typical  Fifties and Sixties models, both the front and rear axles came fitted with constant-velocity ( CV) joints that made for smoother turns and driving on an uneven surface while boosting the car's acceleration capabilities.

When looking at a classic car with any eye for restoration, the potential problems  to look  for in the front and back axles include:

  • Wear in the track rod end ball joints is indicated if the vehicle's tires display a feathered wear pattern.
  • Loose track rods will cause excessive play, bad wheel alignment and substandard control. If, during a test drive, the car is challenging to steer, this is an indication that the track rods may need to be replaced.
  • If a  steady clicking, tapping or whirring noise can be heard as the vehicle accelerates or is cornering, it is an almost sure sign that the outer CV joint is faulty.  If a loud clunking sound is heard as well as the clicking noise, it can be taken as read that the inner CV joint requires replacing.

The clunking and clinking noise is being caused by excessive movement of the CV joints.

Another sure sign that all is not right with a car's axle is when the driver experiences vibration when handling the steering wheel.
These vibrations are a symptom of either a damaged or worn axle or CV joint  that is causing the axle assembly to move off-balance gradually

Any problems or even possible problems with a vehicle's axles should never be ignored as they could rapidly render the car unstable and unsafe to drive.

As is the case a classic car's steering, brakes and suspension, where the vehicle's safety may be compromised, any diagnosis and subsequentrepair must be carried out by professionals who have the know-how and equipment to return the car to the position where it is completely roadworthy.

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A guide to acquiring, restoring and maintaining UK or European Classic Cars of the Fifties and Sixties- as well as a recollection of the iconic cars of the era and the visionaries that produced them.;