Brake Skimming: A Smart Alternative?

The Art of Brake Disc Resurfacing: Skimming vs. Replacement

In the world of automotive maintenance, the question of whether to replace or resurface brake discs is a recurring one. While the prevailing trend leans towards replacement, particularly for everyday vehicles, the practice of brake skimming, or resurfacing, offers a compelling alternative with significant benefits. This article delves into what happens if you skim brake discs, exploring its advantages, disadvantages, and its place in modern vehicle servicing.

The Problem: Brake Judder and Disc Thickness Variation (DTV)

One of the most common and frustrating issues drivers face is brake judder. This manifests as a vibration or pulsation felt through the brake pedal and steering wheel when applying the brakes. A primary culprit behind brake judder is Disc Thickness Variation (DTV). DTV occurs when the brake disc surface is not perfectly flat, leading to uneven contact with the brake pads.

According to industry data, brake faults contribute a significant percentage to MOT failures. While the RAC suggests around 10%, the Driver and Vehicle Standards Agency (DVSA) places this figure considerably higher, at up to 17%. This highlights the critical importance of maintaining healthy braking systems. Replacing worn brake discs is becoming as routine a service requirement as fitting new spark plugs.

The Dominant Approach: Replacement

For the majority of common cars and light commercial vehicles, replacing brake discs is the default and often the most cost-effective option. The competitive market means a new set of discs for an axle can be purchased for well under £60, depending on the vehicle's make, model, and the chosen disc manufacturer. This price point makes it difficult for many workshops to justify the cost of resurfacing.

In stark contrast, brake resurfacing can cost between £120 and £200. This price difference makes the exercise seem illogical to many customers when a new set of discs is so affordable.

Why Consider Brake Skimming? The Environmental and Performance Case

Despite the cost disparity, there are strong arguments in favour of brake skimming:

• Environmental Benefits: The most obvious attraction is the environmental aspect of recycling perfectly serviceable components. Instead of discarding potentially good metal, skimming allows for its continued use, reducing waste and the energy required to manufacture new discs.
• Ensuring True Running: Brake lathe manufacturers, like Tecalemit Garage Equipment, highlight that resurfacing brake discs while they are still mounted on the hub (on-car skimming) ensures the disc runs true to within a fraction of a hair's thickness. This process compensates for normal axle wear and any misalignment caused by impacts such as kerbing or pothole damage.
• Addressing DTV: As mentioned, DTV is a common cause of brake judder. Adam Hilton, sales and marketing director at a leading brake lathe manufacturer, points out that skimming can easily fix this issue. However, most brake disc manufacturers only recommend replacing both discs and pads as the solution.
• Extended Component Lifespan: Typically, brake discs last 2-3 times longer than brake pads. Hilton suggests that when a workshop replaces only the pads, it's the ideal opportunity to skim the existing discs. This not only improves braking performance but can also increase the revenue generated from the service visit.

The Waste of Good Metal

James Hallet, CEO of EBC Brakes, observes a significant amount of perfectly usable brake discs being discarded. "Digging through the metal bin at most brake service providers, we find a massive number of discs that are still well above manufacturers’ specifications and could have easily been resurfaced," he states. "The cost of collecting, shipping, and recycling all this material is enormous when you consider that they could be resurfaced and kept in service instead.""

Added Revenue for Workshops

The potential for workshops to generate additional revenue through brake skimming is considerable, though it depends on various factors, including labour rates and the efficiency of the skimming process.

Hilton estimates that an average skimming job takes around 30 minutes. With an average labour rate of £80 per hour, charging £40 per axle for skimming is considered a realistic figure. Considering that the lease cost for professional on-car brake lathes, such as the Pro-Cut X9, can be just over £40 per week, the equipment can quickly become self-funding.

Table 1: Cost Comparison - Skimming vs. Replacement

Customer Perceptions and Warranties

One advantage that customers often value with new discs is the manufacturer's warranty. For instance, brands like febi bilstein offer warranties of up to three years on their brake discs. In contrast, guaranteeing the quality and longevity of a brake skim is typically at the discretion of the individual garage performing the service.

Skimming New Discs: Matching Hubs

Beyond fixing existing issues, there's a case for skimming new discs. Adam Hilton explains that the primary benefit here isn't necessarily to eliminate potential DTV but to ensure the disc is perfectly matched to the hub. "Most discs are now mounted directly onto the hub, but there can be variances within the hub," he states. "By skimming the discs on the car, this variance can be removed without needing to replace the hub." This meticulous approach can prevent subtle vibrations that might not be immediately apparent.

James Hallet further argues that replacing discs alone can sometimes be a short-term fix. He points out that even a wobble of less than 0.003 inches, which is imperceptible to the naked eye, can lead to future braking issues. He also highlights potential problems with regenerative braking systems in low-mileage electric vehicles (EVs), which can sometimes cause pedal feel irregularities. Hallet warns that aftermarket replacement discs can vary significantly in quality, and resurfacing the original discs removes the risk of installing inferior components.

Will Skimming Work for Your Workshop?

The success of offering brake skimming services often depends on the workshop's clientele and local market. Phillip Bird of PJ Bird in Billericay, Essex, shared his experience. Initially, his brake skimmer was profitable because a local high-end prestige car dealer routinely had their stock's brake discs skimmed for cosmetic reasons and to ensure optimal performance. However, with the dealer's relocation, the equipment saw less use. Bird notes that his workshop offers a service few others in the area provide.

Pro-Cut, a company that has been manufacturing brake lathes since 1999, observes that some prestige dealerships have even invested in their own skimming equipment. This is done to reduce pre-sale preparation costs, recognizing that brake resurfacing is becoming as essential as alloy wheel refurbishment for presenting vehicles in their best condition.

The Future of Braking Services

As Adam Hilton concludes, "Motoring is undergoing one of the most significant changes ever seen as we move away from fossil fuels. While how we power vehicles will change, how they stop will likely remain the same." Brakes represent a crucial area where independent garages can still offer valuable, specialized services. "Brakes may be one of the few areas garages can still service, so it’s essential that workshops up their game in what has perhaps become an overlooked source of income. Having the right skills and equipment will be crucial for a workshop’s survival.""

Frequently Asked Questions (FAQs)

What is brake judder?

Brake judder is a vibration or pulsation felt through the brake pedal or steering wheel when braking, often caused by unevenness in the brake discs.

Can skimming fix brake judder?

Yes, if the judder is caused by Disc Thickness Variation (DTV), skimming can effectively restore the disc's flatness and resolve the issue.

Is brake skimming cheaper than replacement?

The cost of skimming itself can be higher than the parts cost of replacement discs for common vehicles. However, when considering the environmental impact and the potential to avoid premature replacement of discs, skimming can be a more economical and sustainable choice in certain circumstances.

How long does a brake skimming service take?

A typical on-car brake skimming service can take approximately 30 minutes per axle.

Are there any risks associated with brake skimming?

The main risk is if the discs are already below their minimum thickness specification, in which case they cannot be safely skimmed. A competent technician will always check this before proceeding. The quality of the skim also depends on the equipment and the technician's skill.

Should I skim new brake discs?

Skimming new discs can ensure they are perfectly matched to the hub, especially if there are slight manufacturing variances, potentially preventing future vibrations.

Do manufacturers recommend brake skimming?

While many manufacturers' service recommendations focus on replacement, the underlying principle of ensuring discs are flat and true is universally accepted for optimal braking performance. The industry is slowly acknowledging the benefits of resurfacing.

If you want to read more articles similar to Brake Skimming: A Smart Alternative?, you can visit the Brakes category.