Category Archives: Apec

Discs – how low should you go? – Apec Bulletin

It’s fairly obvious when brake pads become too worn and thin to be safe – but what about brake discs? There seems to be some confusion in the trade, even at MOT and VOSA level, about when disc thickness is too low to be safe.

The correct minimum thickness for any brake disc is the one specified by the motor vehicle manufacturer. Any thinner, and the disc will no longer deliver the braking performance the manufacturer intended.

Hot and bothered

Disc thickness specification isn’t arrived at by chance. It’s the result of numerous calculations covering key criteria, principally heat dissipation, and caliper/pad retention. Clearly, the thicker the disc, the more material there is to dissipate heat. Once the disc is thinner than specified, it will fail to shed heat sufficiently under prolonged heavy braking or in a full-on emergency stop. The discs anneal, the pad material starts to break down and braking performance is seriously compromised.

Failure is a real risk

The problem with caliper/pad retention is that when the disc is too thin, the pistons in the caliper push out the pads further to make contact with the disc. If the pads are also thin, this can mean the caliper overextends; the pistons aren’t properly supported and either apply pressure unevenly or won’t retract. The result is brake drag or lock, which can generates enough heat to make the brake fluid evaporate, leading to total brake failure. Another possibility is that the piston no longer seals with the caliper, leading to loss of brake fluid and again, eventual brake failure (worst case scenario).

If the disc is very thin or the braking very aggressive, the friction ring can shear away from the hub, resulting in probable brake failure and loss of control.

Dangerous to drive

Driving a car with discs below the manufacturer’s recommended thickness is unpleasant, as well as dangerous. It can cause vibration and shaking at the steering wheel, and disconcertingly long brake pedal travel. Brake fade occurs much more quickly and, as we’ve seen, the risk of complete loss of braking is considerably increased.

Don’t take risks with discs

It only takes moments to measure and check disc thickness. Most discs will have the minimum thickness stamped on the hub or edge, or you can simply look it up on the Apec website:

www.apecbraking.co.uk.

This shows you the vehicle manufacturer’s recommended thickness (as supplied by Apec) and the safe minimum.

Discs are relatively inexpensive, so considering the possible consequences, the answer must always be: if in doubt, replace.

Caliper Core Rejections – Apec Bulletin

Recently we have noted an increase in the number of Caliper returns that have had to be rejected due to the mounting holes having been cut or damaged at the point of removal.
(examples shown)

These units are unusable and therefore cannot be accepted back for credit against the surcharge.

Please ensure that when taking back an exchange caliper, the unit is inspected for damage and rejected at source where necessary.

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BRAKE GREASE – Apec Bulletin

screen-shot-2016-10-31-at-15-08-04Apec Brake Grease helps you do the most professional job on new brake installations. Its specially formulated copper- free lubricant assists the smooth movement of braking components, and minimises noise.

Apec Brake Grease effectively withstands water and high temperatures, and is fully compatible with ABS brakes.

Apec Brake Grease is manufactured to the same high standards as the rest of the Apec Braking range, to provide quality you can trust.

 

 

 

 

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The importance of replacing Brake Fitting Kits – Apec Bulletin

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Old worn out-parts causes:

  • Tension of springs significantly reduced.
  •  The old parts break or are lost.

 

Old worn out-parts increases the risk of:

  • Brake noise (the brake pads and clip rattle}.
  • Unequal and disproportionate wear on the brake pads and a risk of damaging the disc.
  • Unequal brake effect which reduces brake stability and safety.

 

Old worn out-parts causes:

  • Tension of springs significantly reduced.
  • The old parts break or are lost.

Old worn out-parts increases the risk of:

 

  • Brake noise (the brake shoes rattle}.
  • Unequal brake effect which reduces brake stability and safety.
  • The brake shoes drag on the drum, which is damaged.

Poor handbrake performance:

  • If you have an adjuster bar fitted, check for wear at abutment point with shoe as this can cause poor adjustment.

Put the Brakes on Noise – Apec Bulletin

screen-shot-2016-10-31-at-14-41-10Car manufacturers have made enormous advances in refinement. Today’s family cars offer NVH (Noise, Vibration and Harshness) levels that would have been impressive for luxury models 30 years ago.
One of the key focus areas for manufacturers is eliminating brake noise. Complete caliper, disc and pads assemblies are tested in specialist sound booths to detect noise generation over a range of speeds and conditions.

The role of shims

Most brake noise is caused by vibration between pads, caliper and discs, and pad manufacturers deal with this by using shims to locate the pad correctly in the caliper. As brake caliper design has become more sophisticated to meet motorist’s increasing expectations for braking performance and quiet operation, so shims have evolved too.

Advanced manufacture

Today shims are made from metal, composites, rubber and even fibreglass. Shim shapes have also become more complex, to aid positive location. However, the shim must still stay attached to the pad, otherwise noise will still occur. Manufacturers use various techniques to make sure the shim is firmly fixed.

Some shims are attached by phenolic resin and compressed against the pad’s back plate at approximately 150°C. Some are simply riveted, while others are fixed by pins and pressed into recesses in the back plate. This latter type allows the pad to compress more when cold, minimising noise, without allowing too much compression when hot, which could lead to excessive brake pedal travel.

Directional fittings

Metal shims may have cut-outs, allowing the caliper piston to pitch the pad at an angle to the disc to aid bedding-in and eliminate noise. These shims may have arrows on them; it’s essential the arrow follows the direction of disc rotation to prevent noise. This is also true of pads with chamfers at one end; these should be at the leading edge, against the direction of rotation. Some brake pads have multi-directional chamfers, designed specifically for vehicles with known noise problems.

Good workshop practice

What does all this means for the workshop, dealing with a car that had silent brakes when new but has now covered thousands of miles? It’s vital to make sure the shims can still do their job. Don’t forget they will have endured exactly the same heating, cooling and pressure cycles as the pads, so if the pads are worn, the shims will also be past their best.
Most pads supplied by Apec Braking are already fitted with shims, and as these are to OE specification, you can be sure they are fit for purpose. Where pads have separate shims, the shim needs to be re-tensioned
so it still locks firmly to the pad. Apec Braking offers a complete range of accessories such as springs, to provide correct tension, prevent uneven wear, and silence those complaints about noise.

Renault Clio Sport 172 / 182 Brake Disc Fitment – Apec Bulletin

Please be aware that when changing the rear discs on the Renault Clio Sport 172 / 182 01-05, there are spacers that sit behind the Brake Discs on the rear stub axle. When removing the used discs please ensure that you check to see whether the spacer has remained in place and has not come off with the used disc, as this is required for the fitment of the new discs.

NB: The spacers are not supplied with the Brake Discs.

Failure to refit these spacers will result in premature bearing failure and possible damage to the rear stub axles.

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New spacers are available from Renault Main Dealers only. Deflector C2 – OE Number 60 00 073 518

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What causes brake judder?

Judder is one the most annoying faults that can occur with braking systems, and if a customer comes in complaining about it, you can be sure they definitely want a cure. They’ll probably describe pulsing through the brake pedal or shaking through the steering wheel whenever they brake. The cause is almost always that the brakes are suffering from DTV: Disc Thickness Variation.

FEB 2012 Apec Car EdDTV means the outside and inside disc surfaces are no longer parallel, so the pads are pushed into the thinner areas and kicked back out by the thicker areas. This violent movement is transmitted back through the caliper pistons and brake fluid to the pedal, where it soon annoys the drive.

Why does it happen?
There are four main reasons for DTV: poor quality manufacturing, incorrect fitting, sticking calipers and bad driving.

Keep it clean
Incorrect fitting could then be the culprit. Make sure the hub is completely clean before you fit a new disc. Even the tiniest spec of dirt or rust causes an inboard-outboard movement that increases towards the outer edge of the disc. It probably won’t be apparent when the owner drives away, but with repeated brake applications either the disc wears unevenly, or brake pad material is deposited unevenly. Both have the same effect: judder.

A sliding fit
So we come to sticking calipers. This tends to be a less common source of judder, but it’s worth checking for. If the caliper slide pin or guidepost pin is rusted, dirty or bent, the caliper won’t ease back from the disc when the brake pedal is released, causing the pads to rub against the disc. This leads to an uneven build-up of pad material and hot spots on the disc, both resulting in judder.

 

Driving lesson

So what about bad driving? No customer will want to admit it, but if they’ve been careless about bedding-in new pads or discs, they’ve laid the foundations for future judder.

Apec pads make bedding-in easier because the High Pressure Treatment (HPT) process (like that pictured below) used during their manufacture reduces the time required for bedding-in. However, it’s still necessary to treat the brakes gently for the first few hundred miles, and here’s why. Bedding-in transfers an even layer of pad material to the discs, providing a consistently smooth surface that means the whole pad will contact the disc on each application, without creating high spots on the pad or variations in disc thickness. That’s the ideal scenario. Braking hard before this ‘protective’ layer has built-up means the transfer of material will be patchy and uneven, again leading to the dreaded DTV.

FEB 2012 Apec HPT Ed

Apec’s advice for technicians

1. Make sure the disc and the hub are both scrupulously clean before you fit them.
2. Ensure that the caliper slides freely on its pin.
3. Lastly, try to persuade your customers that a little patience during bedding-in is well worthwhile if they want to avoid ‘the shakes’.

 

 

 

Why you should never compromise on the quality of brake hoses

Perhaps less publicised, but of no less importance to a vehicle’s braking system, is the humble brake hose. These perform a simple yet deeply important function: the transfer of brake fluid to the brake caliper or wheel cylinder, forcing a brake pad onto disc. In other words, the behind-the-scenes work between the depression of the brake pedal and the vehicle stopping.

Why the requirement for a hose change?
Car owners generally expect to replace brake discs and pads during a vehicle’s lifetime, in general, due simply to wear. Thankfully the deterioration of brake discs and pads is usually associated with very clear, tangible signals, such as noise on application, reduced performance and visible disc and pad abrasion.

However, the majority of vehicle owners are simply unaware that ‘wear’ also applies to brake hoses, with numerous reports stating that many owners will never change, or even think to replace the component. Perhaps this is not solely the fault of the end user; it would appear that very few garages and mechanics regularly recommend hose replacement before its absolutely necessary, or prior to some degree of failure. As a general rule brake hoses have a life cycle of around five years, and while this can change dependent upon use and climatic conditions, at some stage all will require replacement.

Warning signs

Fitting-picThere are a number of reasons why brake hoses deteriorate, which includes a multitude of factors such as the temperature of the caliper and brake drum, the aggressive nature of braking fluid, the consistent movement of the hoses during driving, a hose’s susceptibility to varying weather conditions and changes in temperature and the corrosion associated with road salt. The fact is brake hoses lead a hard life, and as such, must be viewed as wear and tear items in the same vein as the other major components of the braking system.

When a brake hose deteriorates it will start to allow water permeation due to the hydroscopic nature (attracting water) of brake

fluid. As the water ratio increases within the brake fluid, the boiling point of that fluid lowers dramatically; in fact just 4% of water content within the brake fluid could cause the fluid to boil, which in turn switches to a gas state. As gas is less dense and more compressible than liquid, so drivers will feel their brake pedal start to travel further while braking performance is reduced or eliminated entirely. This could happen progressively or (if a crack or tear appears) instantaneously – the effects of which does not bear thinking about.

This condition, known as ‘Vapour Lock’, can prove to be extremely dangerous and the signs that lead to it are visible only through a detailed visual and physical inspection.

Signs of impending failure include wet or pasty areas (usually around the back of the fitting ends), bubbles or blistering across the surface of the hose, small cracks on the outer layer as well as chafe marks. Less obvious signals also include soft or easy to bend as well as hard or brittle hoses, and, from the driver’s seat, a spongy or less resistant brake pedal feel.

Aftermarket challenges
In recent times both the VAG group (Volkswagen, Audi Seat and Skoda) and Vauxhall have adopted increasingly elaborate brake line systems that run in parallel along each side of the vehicle’s axle and these use a veritable jigsaw of pre-bent steel metal piping within their construction.

In essence this is in order to deter aftermarket brake specialists from replicating the design, and while Apec is one of the few who has been able to integrate this more detailed specification and production into its manufacturing process and product range, supplying brake lines that match this new OE specification precisely, there are some companies that are unable to do so, instead supplying flexible tubing (or even metal tubing) that requires alteration and bending on site.

 

Apec’s alternative
Hose-ImageManufactured on advanced, automated production lines to exacting tolerances, all Apec hoses feature a multi-layered construction to offer exceptional resistance to heat, the ozone and weather conditions. Additionally, rigorous testing procedures include assessment of corrosion within the brake hose itself, as well as analysis of leakage, whip and burst pressure trials up to 200 bar, volumetric expansion and brake fluid compatibility testing.

Apec has unique approach to braking component

Over the years, the ‘Apec approach’ has helped us to build on a reputation for providing, quality, value and service to our customers. As a company, our view has always been that with critical components, such as brakes, it is vital to match the original manufacturer’s levels of performance, safety and comfort – a message that seems to be the buzzword in the IAM at this point, but is no less pertinent as a result.

Combining these standards with competitive prices means that car drivers benefit from uncompromising stopping power plus exceptional value for money – a combination that’s especially welcome in a challenging economic climate.

Consistent standards

In Europe, friction braking parts are regulated by the R90 standard, which stipulates that performance must be +/- 15% of the OE specification. In Apec’s opinion, that standard is actually too low; instead, we design our products to provide the closest possible match to the OE part. This is achieved by using high quality materials and consistent, precision manufacturing techniques.

Robotic production process

A good example of this comes in the shape of Apec brake pads. Manufactured in a state-of-the-art facility in Europe, these pads use a complex and closely controlled mix of friction materials, formulated to provide highly effective braking across a range of operating temperatures and loads.

The friction material is also environmentally responsible, as it’s free from heavy metals, such as lead, antimony and copper – well in advance of the EU’s target date for removing these elements.

The pads are produced in automatic presses, with computer controlled temperature, pressure and time cycles. The use of this highly accurate robotic production process continually ensures the friction material is heated and pressurised for precisely the right period, so each finished pad meets the exact specification set by the R&D department. The process works to such close tolerances that thousands of pads are automatically rejected each year, even though they may only vary from the set standard by the smallest amount.

Under pressure

The pads also benefit from HPT – a High Pressure Treatment process only encountered in the high quality sector of the industry. The process heats the friction material surface to 650°C, while applying one tonne pressure, ensuring it’s evenly cured to a depth of 2mm. This improves initial braking, considerably reduces the bedding-in period and noise, and prolongs pad life by eliminating crystallisation of the friction material.

It’s also kinder to the environment, as the harmful gases normally released into the atmosphere on first brake application are contained and treated within the factory.

Attention to detail

The attention to detail doesn’t stop there, though, as we also offer a comprehensive selection of accessories, such as fitting kits and wear leads.

There’s sound reasoning behind this: After only a year’s use, brake pad springs can lose up to 50% of their tensile strength, becoming loose and causing uneven wear, unbalanced braking and noise. By fitting new springs and shims when replacing the discs and pads, technicians can restore even high mileage braking systems to the original manufacturers’ performance levels.

Apec 2

Committed to continual R&D

One crucial factor in our success is the emphasis that is placed on the continual research, development and testing of all braking parts.

An annual commitment of millions of Euros allows constant monitoring, evaluation and incorporation of new technology, improving and developing products by using the latest research results and industry advances.

This investment means Apec continues to be at the forefront of braking, with products that are claimed to far exceed R90 and other European legislation.

Testing regime

As you can see from some of the details outlined in this article, nothing is left to chance. As a result, the brakes undergo rigorous testing, with samples taken randomly from the Apec production line and subjected to extreme scrutiny, with testing on dynamometers and closed, controlled test tracks.

The brake pads also have to prove their capabilities during repeated descents of one of Europe’s toughest public roads: the notorious Glossglockner pass. Even though the pads will endure many hundreds of applications during the test, their temperature must not exceed Apec’s strict limits, and they must still demonstrate safe stopping ability at the end of the final descent.

Apec 3

Service to match

These high standards apply to all of our products, consisting of brake pads and discs, shoes and drums, accessories and the hydraulic range, which includes master cylinders, wheel cylinders, calipers and DOT approved hoses.

They’re also evident in the renowned levels of customer service that are provided, and, with proximity close to the M4 and M5 motorways for rapid distribution, Apec’s huge warehouse carries such extensive stocks that enables delivery of 98% of the listed items the next working day.

Technicians can be confident that the range will be constantly updated and parts will be available for a new model as soon as six months after its initial launch. Furthermore, mechanics can request emails of parts updates or look them up on the Apec website.

Over 6,000 parts

With one of the largest braking ranges for the aftermarket, comprising over 6,000 parts and covering 99% of all cars and LCVs in the UK and Ireland, whatever the expectations of factors, technicians and motorists, Apec aims to exceed them.