How To Check & Change Brake Linings

This guide captures ‘bygone’ advice on how to Check and Change Brake Linings on Classic Cars. 

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.

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Introduction

From a safety viewpoint, the most important part of any vehicle is the braking system. So it is important that brakes are correctly adjusted and maintained. And that when the linings wear down they are promptly replaced.

Replacing drum brake shoes is a ‘fiddly’ job often requiring patience. But it is worth persisting with because it can save you a considerable amount of money.

The adjustment of drum brakes involves keeping the brake shoes at the correct distance from the drum. On many cars this adjustment is automatic, but on those cars which have manual adjustment, it should be checked every 1,600 km (1,000 miles).

On all types of brake, whether the adjustment is automatic or manual, the drums should be removed and the linings checked for wear every 8,000-10,000 km (5,000-6,000 miles).

The linings must not be allowed to wear down to the rivets or where bonded shoes are fitted below 1.5 mm from the metal shoe.

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Preparing To Free The Brake Drum

Before the drum can be removed it may be necessary first to slack off the brake shoes, as these sometimes bind on the drum.

This is especially true of manually adjusted brakes, but quite often automatically adjusted brakes need to have their shoes slackened off too.

If you find that the shoes are gripping the drum the adjuster will have to be located and slackened off.

As the type of adjuster fitted varies enormously among makes of car and even among models in the same range, the owner’s handbook should be consulted to identify the type of adjuster fitted to your car and the procedure to be followed to slacken it off.

Failing this, the drum should be carefully inspected for signs of an adjusting nut, screw or recess in either the front or back of the drum. The table below describes the most common types of adjuster and how they can be adjusted.

After having slackened off the adjuster the drum should be easy to remove. Remember when working on the back brakes that the handbrake should be released first.

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How To Free A Stuck Brake Drum

The drum can either be separate from the wheel hub or combined with it.

If the brake drum has two retaining screws in between the wheel bolts, or a locating flange which holds the inside edge of the drwn to the hub, then it is separate from the wheel hub.

This type of drum is removed as shown below.

If there is no sign of either screws or flange, then the drum is integral with the wheel hub.

To remove a brake drum which is integral with the wheel hub you need first to prise out the grease cap from the centre of the hub.

You will then see a nut with castellations held in place by a split pin. After removing the pin and nut, you should then remove the spacing washer and the outer tapered roller bearing, keeping all components in their order of removal so that you know which parts to replace first when it comes to reassembly.

Some cars have a rear drum assembly which can be removed only by using a puller:

The puller is fitted to the wheel studs with the wheel nuts replaced to hold it in position. The centre bolt of the puller is then tightened down progressively until the drum and hub slide off the stub axle.

If you do not have a puller you can still remove the drum and hub assembly by replacing parts of the drum, and using the wheel to give extra leverage. You should, however, take care to exert even pressure around the wheel to prevent the distortion of any component.

Disconnect The Handbrake Linkage

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What To Inspect on Brake Linings

The linings must not be allowed to wear down to the rivets, or, where bonded shoes arc fitted, below 1.5 mm from the metal shoe.

The drum should also be inspected for wear, distortion or heavy scoring.

If the drum is damaged it should be re­placed, as it will greatly affect the effectiveness of the brakes and drastically reduce the life of the shoes.

When buying new brake shoes it is essential to get the correct replacement . So you should make a note of your car’s make, model and year, or, better still, the chassis number, and quote them when buying replacement parts.

Always renew brake linings on both the back wheels, both the front wheels, or on all four. For, since new shoes will grip more efficiently than old ones, replacing shoes only on one side or corner of the car would lead rothe car slewing to one side when heavily braked. To adjust, examine and replace drum brake shoes these steps need to be followed

• First the adjuster should be slackened off so that the drum can be removed and examined.
• Next, the shoes should be checked and re­placed if necessary.
• Once this has been done the drum should be replaced and the brakes adjusted.

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How To Remove Brake Shoes

Before removing the brake shoes note the positions of all the components so that you will be able to reassemble them correctly.

If problems do occur, the drum on the other side of the car can always be dismantled and used for reference.

Remember though that one side is a mirror image of the other so some components will be reversed.

The brake shoes can be retained on the backplate by three different methods. Two use springs and the third uses a clip.

Depending on the type of spring fitted, com­press the spring and twist it or compress the spring and twist the dish washer (as shown below).

The clip type can be removed by pulling the clip downwards.

All the subsequent stages of brake shoe removal and replacement are basically the same for ail makes of drum and are covered below.

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Check Brake Cylinder Movement

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How To Refit & Adjust Brake Shoes

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Notes On Drum Brake Adjustment

Automatically adjusting brakes adjust themselves in a number of different ways depending on the type fitted.

Some adjust themselves after the brake pedal has been depressed once, others require the handbrake to be operated several times.

Less common types even require being operated several times.

Less common types even require the car to be driven backwards and then stopped. In order that they are adjusted correctly the method of adjustment must be known and this information should be in the owner’s manual.

So the only attention that new ones need is to be centralized and this is done simply by pumping the brake pedal once or twice.

The procedure for adjusting manually adjustable drum brakes whether fitted to the front or rear of the car is the same regardless of the type of brake adjuster fitted.

The idea is get the brakes close to a final adjustment then to centralize them (at which point they will loosen again), and then to complete the adjustment.

What you do is:

• First, having determined which type of adjuster is fitted to yoU1· car, screw the adjuster in until the drum is locked-that is, until you cannot turn it.

• Second, U11do the adjuster slowly until you feel or hear it click twice; the drum should now be free to turn.

• Third, centralize the brakes by pumping rhe brake pedal a couple of times

• Fourth, repeat stages one and two.

If the adjuster does not click, note the amount the nut or screw needs to be turned for the drum to turn freely.

It is important to adjust all the brakes by the same amount so that the braking will be smooth and even.

Do not worry if the shoes bind on the drums a little. It is only because they are new.

It is better to leave them slightly in contact with the drum than too loose. If they are a shade tight they will soon wear down to the correct fit. But if they are loose they could be dangerous (There will be more travel in the brake pedal before the brakes ‘bite’)

With either type of brake, once the work has been completed the car should be very cautiously road tested. New shoes may give the brake pedal a spongy feel at first, as they take some time to bed in.

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Regards SCOTTY

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