Solving Starter Motor Problems

How To Fix Starter Motors on Classic Cars

This guide captures ‘bygone’ advice on How to Solve Starter Motor Problems on a Classic Car. This post is the Introduction post in a Series on Starter Motor Problems. The further sections cover :

To see all my ‘bygone’ advice guides please visit Classic Car Maintenance DIY Guides.

Remember folks these are ‘bygone guides’ … useful but the safety and personal protective equipment measures are reflective of bygone awareness. Stay safe.





Common Starter Motor Problems

Below is a quick diagnosis chart for most common starter motor problems. All of which will be covered in detail within Starter Motor Problems .

Common Starter Motor Problems

How do Starter Motors Work

It is important to understand the elementary function of the starter motors before attempting any work on it. As with most electrical devices, most faults are caused by poor connections but in the case of the starter there are additional mechanical complications.

The starter motor is connecteed to the battery via a switch. When the switch is closed, current passes to the field coils and causes their soft iron cores to become magnets, while at the same time a second magnetic field is formed in the armature.

The interaction between these two magnetic fields causes the armature to rotate.

Because of the torque required to turn over a cold engine the starter operates through a reduction gear with a ratio of about 10: 1. This means that it cannot be permanently in mesh with the engine.

Otherwise it would have to rotate at speeds in excess of 35,000 rpm. It therefore is fitted with an engaging and withdrawal mechanism.


Different Types of Starter Motor

There were two common types used on Classic Cars. A Pre Engaged Starter Motor and an Intertia Starter Motor .

The drive slides in to mesh with teeth on the rim of the flywheel and is either operated by a lever with a solenoid plunger or an automatic device known as an inertia drive ( originally called a Bendix drive after the company who first produced the unit).

The solenoid-operated drive is known as a pre-engaged type as the current to the windings only passes after the gears are engaged. It is more reliable than the inertia drive and gives better starting in difficult conditions since the gears are not thrown out of mesh when the engine fires.


Exploded Diagram Of A Pre Engaged Starter Motor

Exploded Diagram Of A Pre Engaged Starter Motor

Exploded Diagram Of An Interia Starter Motor

Exploded Diagram Of An Interia Starter Motor

LUCAS Starter Motors On eBay


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