Welcome again to the newest section of the MyRV Magazine- Campfire chat, smell that smoke, feel the warm glow. Pull up a chair, grab a beer, wine, or softy and let’s talk about your rig, places you have been and places you want to go. What is it about a campfire that draws everyone in?
After the first issue of MyRv we had reader Phil Scott from Cooma write to us saying he wanted and asked for more technical issues to be featured in the mag. So the first campfire chat revolves around brakes and upgrades, so I didn’t have to look to far to find a specialist in the industry John Lawson joined me for our first campfire chat.
About John Lawson & His Career Please tell us about your career. How did you decide to become an automotive brake mechanic specialist? The love of working on cars has inspired me to take a job as a mechanic. I was exposed to the field early on, as my family were heavily into the automotive industry. temperature of the pad is probably the main criteria.
It made me realize that working, as a mechanic was right for me. I decided to specialise in automotive braking and clutch components
What do you enjoy most about your job and about the field in general? The job is a challenge of figuring out what is wrong with the car and making effective repairs. The field in general is rapidly changing in all areas, and I enjoy keeping up with the latest innovations and staying on top of the field. Car and truck manufacturers build to a price; sometimes there is a better way.
STEVE – Before we get into brake upgrades, are there any must do’s for people looking to just replace their disc pads, some people say if the rotors look good, just leave them.
JOHN – A lot manufacturers today design pads and rotors to wear, I know the idea of rotors designed to wear may sound strange to some, but that’s the way we are heading, in Europe you always replace the rotors with the pads, because they work and wear in conjunction with each other. But to answer your question, refacing the old rotors is a must if they fall into the minimum thickness requirements.
STEVE – -Lets talk about a simple but effective brake upgrade for your vehicle, after all stopping a recreational vehicle, probably heavily loaded or towing, quickly – can mean the difference between your safety and a costly and sometimes tragic accident”.
JOHN -“Before you worry about a brake upgrade, remember the rest of your braking system has to be working correctly, and that includes tyres, brake master cylinder, rear wheel cylinders (if fitted with drums), your pads and “brake rotors should also be in top condition. Obviously most modern cars and light commercial vehicles are subject to wear and should be regularly inspected, especially pre trip. Last week I had a Patrol owner come in for a brake inspection, its brake pads were well down and in need of replacement. His rears were ok because you will normally go through two sets of front pads, to one set of rears. He opted for a complete change and upgrade on the fronts.”
STEVE – “With a variety of rotors available. Any recommendations?”
JOHN – Smooth-faced rotors are generally standard equipment on all but performance vehicles, while fully drilled and slotted rotors can be seen on race and rally vehicles.
STEVE – Why do slotted or drilled rotors work better than a smooth-faced rotor?
JOHN – The slots or holes improve the dissipation of water, dust and road grime from the contact area. This increases brak¬ing effectiveness. When a pad clamps onto a rotor, the heat generated produces gas that forms between the pad and rotor- (gassing out). Gassing out lifts the pad off the rotor, which decreases your braking efficiency. Drilled and slotted rotors enable that gas build-up to escape, improving the brak¬ing performance of the pads and rotors.
Rotors that are fully drilled are very common at the performance end of the market, however they suffer at times from cracking between the drilled holes in a 4X4 application because of the extremes they suffer, water and mud on a red hot rotor does not go down that well and the rotor can be weakened.
STEVE – Is there a compromise!
JOHN – For the Patrol we had in last week, I recommended, a set of (RDA) Rotor Drums Australia grooved and dimpled rotors, RDA offers a great range of directionally slotted brake rotors in Australia, the rotors are coated with zinc and gold-passivated to help avoid corrosion and have a full sweep groove pattern across the disc face. They have the advantages of a normal slot¬ted or drilled rotor and are marked as ‘left’ or ‘right’ for ease of identification and fitment.
STEVE – Ok, so what about the pads.
JOHN – The pads can make a dramatic difference to break performance, you have to choose the pads most suited to your vehicle and your situation, do you tow? The pad composition varies according to the particular series of pads used, what the brake pad has been designed for, and its operating temperature. It is impor¬tant to choose the right pad for your vehicle and what you are using it for. The correct operating
Kevlar-impregnated brake pads are popular. EBC (European Brake Corporation) produces a range of Kevlar-impregnated pads suitable for light commer¬cials right through to racecars. Pads produced in Europe need to comply with ‘Reg 90’, which identifies their pads as having met those criteria. As you’d expect, EBC pads have the Reg 90 logo.
Brake pads can endure operating temperatures of up to 800°C -900°C but it’s more important for average daily use that the pads have good cool braking character¬istics. For example, EBC’s 4000 Series brake pads don’t work well below an operating temperature of 150’C and are suited for race or rally cars.
I fitted a set of EBC’s standard Kevlar range of pads which have an operating range from 0*C to around 400’C to the Patrol. If the owner did a lot of towing in his 4X4 I would have recommended pads, which offer operating tempera¬tures from 0’C to 650’C.
STEVE – How long will a set of brake pads last?
JOHN – Well, as I said earlier, rear pads will normally last longer than front pads as the fronts do most of the work. However, ABS and stability control are changing many of these age-old formulas, auto vehicles will go through pads faster than a manual vehicle.
STEVE – How long do you need the vehicle for this work?
JOHN – The whole brake change¬over job takes a couple of hours. It really depends on whether we decide to change the front wheel bearings-, which I would usually recommend.
STEVE – You often hear conflicting stories and theories about bedding in brakes, help us out here.
JOHN – We might drop in Rotors & Drums Australia Pty Ltd Tech Bulletin –#8
It pretty much covers the bedding in process.
RDA – Our recommended bedding in method as shown on our boxes and fitting sheets is as follows again; –
When a vehicle has had both new rotors and/or just new pads fitted, there are two processes or objectives, to getting the brake system to operate at optimal performance.
The first step is to make sure the disc face is clean of all oils/anti rust or any foreign matter like previous brake pad material. If the rotors are not being replaced, then it is imperative that the disc is machined, prior to the fitment of new pads- without exception.
The second step is heating (not cooking) the brake rotor and pads, to transfer the pad material evenly, onto the rotor face. This step involves performing a series of stops, so that the brake rotor and pad are heated steadily, to allow the transfer of pad material onto the brake rotor friction surface. The friction surface should be clear of all oils, which are used to stop the rotor from rusting, before being fitted to the motor vehicle. Whilst these will be burnt off, they risk transferring and possibly polluting the brake pad material and will definitely lead to a longer bedding-in process.
Whilst performing a series of brake applications to transfer the pad material, care should be taken to not come to a complete stop, as this can lead to the transfer of pad material unevenly on the disc at the point where the pad comes to rest on the friction surface. A typical program of 8-9 brake applications, from 60km down to 10km p/hour, without any cool down in between would be sufficient. For performance pad materials, a further two sequences of ten stops will be required after a cooling down period between each cycle, to ensure that the pads have reached the required higher operating temperature to allow for the pad material to transfer effectively.
At all times during the bedding in process, care should be taken to not apply the brakes in a harsh manner or decelerate from high speeds, as this will corrupt the transfer of materials and lead to uneven material build up on the rotor surface, which in most instances will require machining to regain a flat rotor surface for optimal operation.
STEVE – What is the noticeable difference with the upgrade?
JOHN – They offer better and more aggressive break feel, especially at slow speeds. Absence of squeal or shudder at speed, while at higher speeds the brakes will work much better, pulling up quicker no matter what the temperature or operating conditions. The improvement in braking distances is around three metres at lOOkm/h.
STEVE – Lets talk cost
JOHN – Ok – well if we look at say a Landcruiser 100 series or Prado, Pajeo Patrol etc, the pads will cost roughly $135 – to $160 a set, a first class pair of rotors are about $350. Fitting is extra.