Overhauling Hydraulic Brake Calipers

Few people would deny that the braking system is the most safetycritical part of a car. Rob Marshall focuses on how the most costly parts, the calipers, can be removed, remanufactured and refitted.

How the pros tackle refurbishing calipers before selling to us as remanufactured parts.

Not many CM articles are based on the author making a mistake. Having bought and fitted an inexpensive remanufactured brake caliper online several years ago, I was somewhat shocked to find that it had developed a dangerous leak from its piston, barely six months after being installed. The car was grounded immediately, and the caliper was dismounted and boxed-up, ready to be sent back to the reconditioner for replacement. Unfortunately the exercise was futile, because by then the company had gone bust, meaning that its warranty had also gone up in smoke.

To whose standard?

Due to the high cost of replacement components from main dealers, a whole industry has grown around overhauling original parts. These vary from small components, such as ECUS, through to steering racks and engines. From a braking perspective, parts such as wheel and master cylinders,are fairly inexpensive to buy – both from OE (Original Equipment) car manufacturer suppliers such as TRW, ATE, or Bosch, and also from aftermarket companies that comply with the same standards. Not only are genuine brake calipers expensive to buy but their almost constant exposure to pressure, moisture, heat, dirt, stress and vibration mean that they are also popular parts to fail, with corrosion, fluid leakage, or the seizure of moving parts being the most common issues.

With neither formal, nor legal, differentiations existing within the aftermarket braking industry between the terms ‘reused’, ‘reconditioned’, or ‘repaired’, there is no set procedure that a company should follow to ensure that calipers, overhauled on an exchange basis, are safe. The industry is also unregulated. To keep costs down, for example, certain critical

components such as pistons might be reused, when in fact those parts are suitable only for the scrap bin.

While Shaftec established itself in 1979 as an expert in driveshafts, its attention expanded into brake calipers from 2007. The Birmingham-based company refers to its own work as ‘remanufacturing ’, as its marketing exponent Joe Toakley explains:

“We use the term ‘remanufacturing’, because we replace virtually every single component – only the main casting and, occasionally, the handbrake levers are the only parts that remain. Even then, they are refurbished to be better than new.”

Toakley explains that my personal experience with a leaky brake caliper was likely to be caused by lacklustre factory processes. He explains that all Shaftec calipers are remanufactured in-house at its base in Hockley, near the

centre of the city. This ensures that all quality processes are easier to monitor and control. For example, every caliper is barcoded to identify the employee that handles a particular part. Additionally, every single caliper is pressure-tested; in some factories, only selected calipers within a batch are checked.

Remanufactured vs new vs second-hand

With safety-critical brake calipers, be wary of being lured into false economy. As they are in demand from Shaftec and its competitors, many car breakers are aware that used calipers have a value. Therefore, it is possible for you to buy a set of secondhand replacement parts which are in worse condition that those fitted to your car.

As CM discovered, when both front calipers were seized on our budget-buy

Chrysler PT Cruiser (July 2019 issue), the difference in cost between buying a set of guaranteed reconditioned calipers from a quality supplier (Pagid brand, via Euro Car Parts in our case), compared to sourcing a set of used items from a scrapped car, was surprisingly small.

A further option is for you to clean, split, inspect and service the calipers at home, using proprietary seal repair kits, which might include the piston as well. This is feasible on less complex calipers and was detailed in our July 2015 issue. However, seized calipers can be damaged irreparably by DIY methods to free them, reducing their value to that of scrap. Additionally, certain parts tend to be unavailable to repair more complicated mechanisms that include both mechanical and Electric Parking Brake (EPB) systems, meaning that obtaining an exchange caliper is likely to be the

most efficient option in terms of both time and cost. This involves using either a postal exchange service, or swapping your old caliper with a remanufactured item from a local motor factor, which may mean that you could have your car back on the road the same day.

When exchanging your old caliper for a remanufactured Shaftec item, you will pay a surcharge on top of the replacement caliper cost. This is not unusual. Surcharges are very common and Shaftec is not the only company that uses them. Once your old part has been inspected and verified as suitable for remanufacturing, the surcharge is refunded. Therefore, ensure that you take your old caliper off carefully; do not damage the casing. After all, without having your old unit to remanufacture, Shaftec’s business would be unworkable. Shaftec told CM that, while surcharges are important to ensure adequate stock inventory, customers and the motor trade tend not to like them – but the company has responded by using its buying power to keep surcharges down to between £10 and £20 per caliper.

Yet, Shaftec warns that any aversion to surcharges might lead you to consider instead buying new, non-oe calipers that are starting to appear in the aftermarket. As the castings do not appear to be made from the same materials as those used by OE calipers (the reduced weight is a big giveaway), Shaftec cannot guarantee that they are of the same quality. This may have fitting implications. Softer metal can mean a greater risk of stripping the threads where the hydraulic union or bleed screw is fitted. There might also be (albeit unproven to our knowledge) operational and longevity compromises. Should you consider a new ‘copy’ caliper, ask for evidence about its quality control and warranty. In any case, Shaftec considers new calipers too variable in quality for it to remanufacture.

The following procedures show not only Shaftec’s remanufacturing processes (demonstrating the focus on quality that is required of such safety-critical parts) but also the most common type of calipers on British roads, and how they work.

This poorly reconditioned/repaired caliper developed a serious brake fluid leak after only six months of use. Not all companies’ definitions of a ‘safe’ replacement part are the same.

The less expensive floating calipers are mounted to carriers and, through a set of sliders, can move relative to the disc. One piston acts on one pad only; as it does so, the equal and opposite force generated allows the caliper to slide inboard, forcing the outer pad in contact with the other side of the disc. The picture shows one of the caliper slider bolts being tightened.

Fixed calipers are bolted to the vehicle directly and cannot move. Each brake pad’s movement is controlled by its own dedicated piston(s), an identical number of which feature on the opposing side.

You have less risk of damaging a brake pipe union if you use a dedicated brake pipe spanner to disconnect the lines, prior to removing a caliper.

When removing and refitting the caliper, neither allow the flexible hose to become twisted, nor use it to support the caliper’s weight.

Use a dedicated piston rewind tool, instead of improvising with pliers. This reduces the chance of damaging your replacement caliper’s pistons and gaiters. Pictured is Laser Tools' 3835 brake caliper piston rewind kit.

Certain Electric Park Brake (EPB) designs have a motor and associated gearing bolted to the carrier. Some manufacturers are integrating EPB with stability control systems for extra safety. Picture courtesy of Brembo.

Carriers on floating calipers are fixed to the vehicle and the calipers are fixed to the sliders, new examples of which are pictured.