Frequently Asked Questions

A heavy-duty brake caliper is a key braking component that slows down or stops the vehicle by pressing the brake pads against both sides of the brake disc. In pneumatic disc brake systems, the force generated by the brake chamber is transmitted through the lever and internal mechanism of the caliper to the tappets. Once the inner brake pad comes into contact with the disc, the caliper housing moves along the carrier and presses the outer brake pad against the disc as well.

The reliability of a complete brake caliper used in truck, bus, and trailer applications depends on the proper and coordinated operation of the housing, carrier, mechanism, tappets, pins, boots, and automatic adjustment system.

Depending on the model, a complete brake caliper consists of the caliper housing, carrier, pins and bushes, protective boots, lever, mechanism, gears and automatic adjustment components, tappets, covers, brake pad retaining components, and, where applicable, a brake pad wear sensor.

In addition to complete brake calipers, TTT-auto manufactures caliper repair kits, mechanism components, pins, tappets, carriers, sheet metal components, and rubber and silicone parts for these component groups. This enables the compatibility of the critical parts that make up the caliper to be evaluated within the same manufacturing and quality approach.

A brake caliper repair kit is a set of components designed to restore the safe operating function of a caliper by replacing specific worn or damaged parts. The contents of the kit may vary depending on the caliper model and the level of repair required. Different kits may include pins, bushes, boots, seals, O-rings, covers, tappets, mechanism components, brake pad retainers, or fastening elements.

For this reason, the term “complete repair kit” does not refer to the same set of components for every model. Before placing an order, the kit contents, caliper model, and OEM reference should always be checked together.

The decision should be based on the level of damage to the caliper. If the caliper housing and carrier are still in a condition suitable for safe use, and the damage is limited to specific components such as pins, boots, tappets, or mechanism parts, an appropriate brake caliper repair kit may offer an economical and effective solution.

If there is a crack in the housing, severe deformation, irreparable bearing-seat wear, damage to critical mounting surfaces, or extensive corrosion, replacement of the complete brake caliper should be preferred over refurbishment. Since TTT-auto manufactures both complete brake calipers and brake caliper repair kits, the required solution can be evaluated according to the level of repair needed. However, the final decision should be based on a physical inspection carried out by trained service personnel.

To select the correct product, the caliper brand and model, OEM number, vehicle make and model, axle position, left- or right-hand side, carrier type, and sensor option should be evaluated together. If the reference number on the existing part cannot be read, photographs and critical dimensions may also help support the identification process.

TTT-auto performs cross-reference matching for complete brake calipers and brake caliper repair kits using its extensive OEM reference database and product development infrastructure. However, selecting a product based only on the vehicle model may not always be sufficient. On heavy-duty vehicle brands such as Renault Trucks, Mercedes-Benz Trucks, Volvo Trucks, DAF, MAN, IVECO, HOWO SITRAK, and BYD, different brake calipers may be used within the same vehicle family depending on the production year, market, or axle configuration. Likewise, across different brake system families such as Knorr-Bremse, WABCO, Meritor, Haldex, and Bendix, as well as Meritor Z-CAM brake applications, product selection should not be based solely on external appearance.

The OEM number is one of the most reliable references for identifying a part’s design family, dimensions, mounting configuration, and application. Two brake calipers or repair kits that appear visually similar may differ in shaft diameter, pin length, carrier hole center distance, sensor type, or mechanism design.

TTT-auto’s R&D department analyzes OEM samples using 3D scanning, comparative modeling, and technical measurement methods. This approach enables product development to be based not only on visual similarity, but also on dimensional and functional compatibility.

TTT-auto may offer brake caliper repair kits that are originally supplied by the OEM with a specific set of components in alternative configurations tailored to different service and repair requirements in the aftermarket. In some cases, the kit contents are reorganized according to specific needs and assigned a different TTT-auto product reference. Such alternative kits may not have an exact OEM equivalent. In these cases, matching is carried out not only by OEM number, but also by evaluating the OEM reference of the main kit, the caliper application, the kit contents, and the technical specifications of the individual components together.

On the TTT-auto website and in its catalog, the contents of each brake caliper repair kit are clearly presented together with the corresponding part codes and quantities. Distinguishing technical details, such as pin diameter and length, are also specified in the product information. Alternatives that do not have a separate OEM kit equivalent are identified through their own TTT-auto product codes and detailed content lists. This makes it easier to distinguish between visually similar kits and select the correct product.

Components included in the kits are also listed individually in our product range under separate product codes and can be supplied separately from the complete kit. This allows customers to purchase only the components they actually need instead of buying a complete kit containing unnecessary parts. This user-friendly catalog structure reduces confusion, simplifies product selection, and helps lower costs by avoiding the purchase of unnecessary components.

To identify and match a brake caliper when the OEM reference is unreadable or unknown, the make and model of the vehicle from which the caliper was removed should first be provided, together with the axle information whenever possible. It should also be specified on which axle of the vehicle the caliper was installed and whether it was used on the right- or left-hand side.

Clear photographs of the caliper taken from different angles, any readable numbers or markings on the part, and certain critical dimensions are also required. In particular, the center-to-center distance between the mounting holes on the carrier and the dimensions of the mounting points are important for accurate identification.

TTT-auto’s expert team compares the information provided in detail with its extensive OEM reference database and existing product records to help identify the correct product. Additional photographs or measurements may be requested when necessary.

No. Visual similarity alone does not mean that parts are interchangeable. Even a small difference in pin diameter, boot seating geometry, tappet height, thread profile, coating thickness, or rubber material can directly affect the operation of the component. Using an incorrect part may cause the caliper to seize, disrupt the operating clearance, or lead to uneven brake pad wear.

For an accurate assessment, the OEM reference, technical drawing, measurement results, and application information should be evaluated together. If there is any uncertainty, the part should not be forced into place during installation and should be verified with the manufacturer or technical support team.

It is not recommended. Even if they appear to be compatible with the same caliper model, mechanisms, tappets, pins, bushes, boots, and other components from different aftermarket manufacturers may vary in dimensional tolerances, material properties, hardness, coatings, and operating characteristics. Using a TTT-auto component together with a mechanism part from another aftermarket manufacturer may adversely affect operating clearance, force transmission, and component service life.

The compatibility of the components used in TTT-auto complete brake calipers and brake caliper repair kits is verified on a product-specific basis. For this reason, TTT-auto parts should only be used together with OEM parts that match the relevant OEM reference or with other compatible TTT-auto components. Parts from different aftermarket brands should not be mixed within the same caliper. Before installation, the product code, kit contents, and caliper application should be verified through TTT-auto catalogs or the technical support team.

Air disc brake calipers can be used on different axles of heavy commercial vehicles such as trucks, tractor units, buses, trailers, and semi-trailers. Caliper design may vary depending on axle capacity, brake disc diameter, brake pad dimensions, brake chamber connection, and operating conditions.

TTT-auto develops complete brake calipers and related products for heavy-duty vehicle applications worldwide, including Renault Trucks, Mercedes-Benz Trucks, Volvo Trucks, DAF, MAN, IVECO, HOWO SITRAK, and BYD. This does not mean that a single caliper is suitable for every make and model; the final product selection should always be verified according to the caliper model, vehicle application, and OEM reference.

TTT-auto manufactures aftermarket complete brake calipers, brake caliper repair kits, and related components for brake systems such as Knorr-Bremse, WABCO, Meritor, Haldex, and Bendix. In addition, TTT-auto also manufactures products for Meritor Z-CAM brake systems. Product coverage may vary depending on the model, vehicle application, and product group. Current compatibility information should therefore be checked in the catalog or product database.

Renault Trucks, Mercedes-Benz Trucks, Volvo Trucks, DAF, MAN, IVECO, HOWO SITRAK, and BYD are vehicle manufacturers, while Knorr-Bremse, WABCO, Meritor, Haldex, and Bendix are brake system brands. This distinction is important when selecting the correct brake caliper. Brand and model names are used solely for product comparison and application identification purposes. TTT-auto is an independent aftermarket manufacturer.

Common symptoms include excessive heat at a single wheel, delayed brake release, the vehicle pulling to one side during braking, uneven or tapered brake pad wear, abnormal noise, restricted caliper movement on the carrier, rapid brake pad wear, and incorrect readings from the wear sensor.

These symptoms are not always caused by the brake caliper alone. The brake chamber, compressed air line, brake disc, brake pads, or installation errors may produce similar symptoms. Therefore, during fault diagnosis, the complete brake assembly at the affected wheel should be inspected, including the brake caliper, brake chamber, disc, pads, and compressor connections, rather than focusing only on the component showing the symptom.

A brake caliper may fail to release due to corrosion or contamination on the pins, damaged boots, incorrect or incompatible grease, binding on the carrier sliding surfaces, a malfunctioning automatic adjustment mechanism, tappets that do not return properly, or a brake chamber that fails to release air pressure.

The first step is to check whether the compressed air supply to the brake chamber is being released correctly in order to determine whether the problem originates from the brake chamber and compressor system or from the mechanical movement of the caliper. With the brake pads removed, the caliper should be checked for free movement in accordance with the manufacturer’s instructions. The condition of the pins and boots, the brake pad seating surfaces, and the internal mechanism should also be inspected.

Uneven wear between the inner and outer brake pads may indicate that the caliper housing is not moving freely enough on the carrier. Faults in the pins, bushes, or boots; corrosion on the brake pad contact surfaces of the carrier; excessive play; or mechanism-related issues may lead to tapered wear.

The brake pad itself may be the result of the problem rather than the root cause. During inspection, the brake pad thicknesses should be compared, the carrier and pin system should be examined, free caliper movement should be verified, and any signs of overheating or uneven contact on the brake disc surface should be assessed.

Worn pins and bushes, loose or incorrectly torqued connections, a damaged brake pad retainer, a broken spring, excessive brake pad movement within the carrier, or the use of unsuitable components may cause play, knocking, or metallic noise.

Replacing only the brake pad retainer may not be sufficient unless the source of the noise is identified. Radial and axial play in the pin and bush system, carrier surfaces, mounting bolts, and brake pad hardware should be inspected in accordance with the service criteria specified for the relevant model.

Brake caliper pins typically corrode when water, salt, and mud enter the assembly due to a torn or improperly seated boot. Using the wrong type of grease may cause rubber components to swell, attract contamination, or restrict pin movement. In some caliper designs, certain pins must not be lubricated; therefore, model-specific service instructions should be followed instead of applying a general lubrication rule.

TTT-auto machines brake caliper pins in its own production cell and subjects them to appropriate heat treatment, grinding, and surface coating processes. However, even a high-quality pin cannot perform properly if the boot is damaged or the component is installed incorrectly.

The automatic adjustment mechanism maintains the correct operating clearance between the brake pad and the disc as the pad wears. If the mechanism is not functioning properly, braking response may become weaker, the clearance may remain excessive, or, conversely, the brake pad may continue to drag against the disc. Abnormal resistance at the manual adjustment point, irregular movement, or failure to maintain the adjustment may also indicate a malfunction.

The mechanism should not be forced during adjustment, and the inspection procedure specified for the relevant model should be followed. TTT-auto verifies whether the caliper mechanisms it manufactures operate within the specified torque range using a dedicated mechanism torque testing device.

If the wear level remains fixed, does not correspond to the actual brake pad thickness, gives intermittent warnings, or produces no signal at all, the sensor, wiring, connector, and sensor cover should be inspected. The issue may not originate solely from the electronic sensor; it may also result from the movement inside the caliper not being transmitted correctly to the sensor.

The sensor should be tested throughout its operating range using an appropriate test device, and its compatibility with the relevant caliper model should be verified. It is not correct to assume that the sensor is functioning properly simply because no visible damage is present on the cable or connector, nor should the caliper be replaced based solely on a dashboard warning.

Using the wrong caliper model, mixing up the right- and left-hand calipers, installing a caliper whose internal mechanism is not compatible with the vehicle’s brake system, using unsuitable brake pads, incorrect brake chamber adjustment, or problems in the compressed air line may cause different braking forces on the two sides of the axle. Correct installation of a new caliper does not necessarily mean that the brake system on the opposite side of the same axle is operating properly.

It should be verified that the installed caliper is compatible with the vehicle and axle, that the correct right- or left-hand version has been selected, and that the carrier and wear sensor are suitable for the relevant caliper model. It should also be confirmed that the mounting bolts are tightened to the correct torque, the caliper housing moves freely on the carrier, the brake pads and disc are in good condition, and the brake chamber operates correctly. If necessary, the braking forces on both sides of the axle should be measured and compared.

Brake caliper pins allow the caliper housing to move smoothly and in a controlled manner on the carrier. When the inner brake pad is pressed against the disc, this system enables the caliper housing to slide in the opposite direction and engage the outer brake pad as well. Wear or binding within the pin, bush, and boot assembly may prevent the braking force from being distributed evenly between the two brake pads.

Brake caliper pins must be suitable for the relevant caliper model not only in terms of dimensions, but also in terms of material, hardness, grinding quality, and surface coating. TTT-auto manufactures brake caliper pins in robot-assisted CNC production cells and applies the relevant surface treatment after heat treatment and grinding processes.

Boots, seals, and O-rings help prevent water, salt, dust, and mud from reaching the pins, tappets, and mechanism areas. Even a small tear or improper seating may allow corrosion to develop inside the caliper and cause costly mechanical components to seize.

During installation, it should be checked that the sealing lips of the boots are fully seated in their grooves and are not twisted or cut. TTT-auto’s in-house production of rubber and silicone components enables material selection, molding, dimensional control, and process control to be managed according to the specific caliper application. These processes are carried out within the framework of the IATF 16949:2016 quality management system, which covers the production of disc brake calipers and brake caliper repair kits.

No. The grease must be compatible with the rubber compound, operating temperature, water resistance requirements, and metal surfaces. Petroleum-based grease or grease containing unsuitable additives may cause certain rubber-based components to swell or soften. Excessive grease may also attract contamination, prevent the boot from seating correctly, or create hydraulic-lock-like resistance during assembly.

In addition, certain pin or bush locations in some caliper models are designed to operate dry. The caliper manufacturer’s latest service instructions should therefore be followed regarding the type and quantity of grease to be used, as well as the specific areas where it should be applied.

The tappet transmits the axial force generated within the caliper mechanism to the back surface of the brake pad. Smooth and even movement of the tappets is important to ensure that the brake pad is pressed against the disc in a parallel and uniform manner. If the tappet surface, boot, or threaded connection is damaged, force distribution may be affected and uneven brake pad wear may occur.

TTT-auto carries out machining, heat treatment, grinding, and application-specific surface treatments such as electroless nickel plating for tappets and pins within its own production infrastructure. Proper installation of the protective boot is just as important as the surface quality and dimensional accuracy of the component.

The brake caliper mechanism converts the movement transmitted from the brake chamber into a high clamping force and compensates for brake pad wear through the automatic adjustment system. Depending on the model, the lever, eccentric mechanism, bridge, gear components, and tappets are among the main elements of the mechanism.

The dimensions, hardness, tooth profiles, and operating torque of these components must be compatible with one another. TTT-auto manufactures the gear components used inside the caliper on precision CNC gear machining equipment and verifies the assembled mechanism through torque testing.

The carrier secures the caliper to the axle, ensures that the pins operate along the correct axis, and keeps the brake pads in the proper position. Deviations in hole centers, pin bores, or brake pad contact surfaces may affect caliper movement, brake pad wear, and braking force.

TTT-auto machines carriers and caliper housings in separate production cells. The hole centers of the manufactured carriers are 100% inspected using optical measurement equipment, and the measurement records are linked to production traceability data. This measurement and traceability approach is supported by TTT-auto’s IATF 16949:2016-certified quality management system.

Rubber components used in brake calipers are exposed to demanding environmental conditions such as temperature changes, moisture, salt, dirt, and continuous mechanical movement. Unsuitable materials may harden, crack, swell, or lose their elasticity over time. This can compromise their sealing and protective functions, creating conditions that may lead to failures in pins, tappets, and the caliper mechanism.

TTT-auto manufactures silicone and rubber components in its own production facility. For suitable caliper applications, premium-grade VMQ silicone rubber is used to provide high resistance to heat and ozone. Although the material offers strong temperature resistance, the operating limits of the finished component should always be evaluated according to the technical specifications of each individual product.

The brake caliper housing must maintain its dimensional stability while withstanding high mechanical loads. The chemical composition, graphite structure, tensile strength, and yield strength of the casting material directly influence the durability and machinability of the housing.

TTT-auto uses GJS-600 / GGG-60 grade ductile cast iron for brake caliper castings. During the casting process, samples are taken from the molten metal for chemical analysis using a spectrometer. Additional inspections include sand analysis, hardness testing, microstructure verification, and tensile testing. Control records related to raw materials and the casting process are monitored through the traceability system within TTT-auto’s IATF 16949:2016-certified quality management system.

Hot forging provides a suitable manufacturing method for components that require high strength and impact resistance by enabling steel to be shaped under controlled conditions. Proper material selection, temperature control, and deformation flow help ensure structural continuity and achieve the required mechanical properties.

TTT-auto’s hot forging facility is designed to process steel components ranging from 0.2 kg to 35 kg. Forged components are subjected to inspections such as magnetic particle testing, hardness testing, chemical analysis, and three-dimensional dimensional inspection.

Heat treatment is applied to brake caliper components to provide the hardness, strength, and wear resistance required for their specific operating conditions. Controlled heating and cooling of steel improves the strength of the component and increases its resistance to impact. Carburizing hardens the outer surface of the component to reduce wear while helping the core retain the toughness needed to resist impact and fracture. The appropriate heat treatment for pins, tappets, and mechanism components should be selected according to the steel grade, component geometry, and operating load.

TTT-auto performs hardness inspections after heat treatment and records the results within its quality documentation system.

Coatings and surface treatments protect components against corrosion and wear while also influencing friction characteristics and surface durability. Depending on the application, different processes may be used, including electroless nickel plating, alkaline zinc plating, zinc phosphate, manganese phosphate, cataphoretic coating, black oxide coating, or electrostatic powder coating.

Electroless nickel plating is applied to pins and tappets, while alkaline zinc plating is used for pin caps. Components to be painted first undergo a phosphating process and are then coated with electrostatic powder paint. All of these processes are carried out on TTT-auto’s own surface treatment lines. Painted products demonstrate resistance of approximately 300 hours in salt spray testing. The test duration may vary depending on the coating specifications of the product.

If there is a crack in the caliper housing, severe deformation, pin bore wear exceeding the permissible repair dimensions, damaged mounting threads, deterioration of critical carrier surfaces, or extensive corrosion in the mechanism area, a repair kit may not be sufficient. Previous incorrect repairs or unauthorized interventions such as welding may also prevent the caliper from being safely revised.

The purpose of a repair kit is to renew specific worn components; it is not intended to make a structurally damaged caliper housing safe for further use. In such cases, replacement of the complete brake caliper should be considered.

The brake caliper is a safety-critical component, and assembly should be carried out by personnel experienced in heavy-duty brake systems, using the correct equipment and in accordance with the technical requirements of the product. Removed components should not be mixed; bores and seating areas should be cleaned; the caliper housing, carrier, and mechanism should be inspected for damage; and boots and seals should be fitted using suitable tools without causing damage.

Long and short pins, covers, bushes, and sensor variants must be used in the correct positions, and grease should only be applied to the specified areas. Single-use bolts or bolts that must be replaced should not be reused. After assembly, caliper movement and functional checks should be performed.

Insufficient torque may cause the connection to loosen and lead to misalignment, while excessive torque may damage the bolt, threads, or caliper housing. The required torque value should not be estimated based solely on bolt diameter; it should be applied in accordance with the relevant caliper manufacturer’s service specifications.

On TTT-auto’s dedicated assembly line, carrier-to-pin connections in particular are tightened to the torque values recommended by the OEM using electronically controlled equipment, and the results are recorded for traceability. This process control is an important part of production monitoring in accordance with TTT-auto’s IATF 16949:2016-certified quality management system.

After assembly, the caliper should be checked for free movement on the carrier, correct operation of the automatic adjustment mechanism, equal movement of the tappets, proper seating of the dust boots, free movement of the brake pads within the carrier, correct tightening torques, and, where applicable, proper operation of the wear sensor. The operating clearance and other relevant measurements should be compared with the model-specific service limits.

TTT-auto’s assembly and testing infrastructure includes braking force measurement, caliper mechanism torque testing, and high-cycle mechanical endurance testing.

TTT-auto’s production standards are based on the combined application of OE references, technical drawings, material specifications, and product-specific control plans. The chemical composition, hardness, and microstructure of GJS-600 / GGG-60 ductile cast iron are verified, while forged and heat-treated components undergo material, hardness, and crack inspections. Machined components are checked using methods such as CMM measurement, 3D laser scanning, optical measurement, surface roughness testing, and coating thickness measurement. The hole centers of manufactured carriers are inspected 100% using optical measurement equipment, and the results are recorded through MES software.

Completed brake calipers are subjected to mechanism torque testing, braking force measurement, movement and dimensional checks, and high-cycle mechanical endurance testing. The quality process is carried out in four stages: incoming quality control, in-process quality control, final quality control, and outgoing quality control. This structure is supported by TTT-auto’s IATF 16949:2016-certified quality management system, which covers the production of brake calipers and brake caliper repair kits for disc brake applications.

Dimensional compatibility cannot be verified simply by taking a few measurements with a caliper. The caliper housing, carrier hole centers, pin axes, brake pad seats, and mounting surfaces must be evaluated together. 3D laser scanning, CMM, and optical measurement systems make it possible to record dimensional deviations between the OEM sample and the developed product.

TTT-auto performs comparative modeling by 3D scanning OEM samples during product development and records dimensional inspections against technical drawings through MES-based control plans during production. This approach ensures that TTT-auto’s extensive OEM database is supported by physical measurement data and process records.

New product development begins with identifying the application and OEM reference, followed by sample measurement and 3D scanning, analysis of material and surface properties, CAD modeling, prototype production, dimensional inspections, and functional testing. Even if laboratory tests are successful, the product’s performance under real vehicle operating conditions should also be evaluated.

TTT-auto conducts on-vehicle tests of newly developed prototype complete brake calipers by installing them on vehicles with the support of authorized service personnel and under the supervision of its engineers. The test results are then documented together with feedback from the service team and vehicle drivers.

TTT Otomotiv A.Ş. is certified to IATF 16949:2016 and ISO 9001:2015 quality management system standards for the production of brake calipers and brake caliper repair kits for disc brake applications. The company is also certified in accordance with ISO 14001:2015 Environmental Management System, ISO 45001:2018 Occupational Health and Safety Management System, and ISO/IEC 27001:2022 Information Security Management System requirements.
These systems are reflected not only at the certification level, but also throughout operational processes from raw material acceptance to production and shipment, including incoming quality control, in-process quality control, final quality control, and outgoing quality control. Through ERP- and MES-based production tracking, process and quality records related to complete brake calipers, brake caliper repair kits, and associated products are managed with full traceability.

TTT-auto’s in-house manufacturing capabilities include machining, casting, hot forging, induction and heat treatment, sheet metal pressing, surface treatment and coating, electrostatic powder coating, rubber and silicone production, assembly, and testing processes. Surface treatments such as electroless nickel plating, alkaline zinc plating, manganese phosphating, and zinc phosphating, as well as component washing, passivation, and protective oiling processes, are also carried out in-house.

Production is organized into product-focused cells for caliper mechanisms, pins and tappets, levers, caliper housings and carriers, mechanism gears, sheet metal components, and tooling and fixtures. Through robot-assisted CNC machines, automated gear machining, dedicated assembly lines, and specialized testing equipment, the critical components that make up complete brake calipers and brake caliper repair kits are managed within the same integrated manufacturing and quality system. Caliper products for brake systems such as Knorr-Bremse, WABCO, Meritor, Haldex, and Bendix, as well as Meritor Z-CAM brake products, are also machined, inspected, and tested within this integrated production structure.

TTT-auto operates on a production site comprising 10,000 m² of open area and 26,000 m² of enclosed manufacturing space, with 410 production employees, 16 quality control personnel, and 12 R&D employees. Its machining infrastructure includes CNC lathes, twin-turret CNC lathes, CNC vertical machining centers, and CNC horizontal machining centers. The machinery park is further supported by robot-assisted production cells, gear shaping and hobbing machines, grinding equipment, induction systems, presses, washing and passivation lines, as well as CMM, 3D laser scanning, optical measurement, spectrometer, and hardness testing equipment.

TTT-auto’s foundry is equipped with 1-ton INDUCTOTHERM melting furnaces, providing a casting capacity of 165 tons per month and approximately 2,000 tons per year. The automatic molding line can produce castings ranging from 1 kg to 50 kg, with a maximum capacity of up to 97 molds per hour. The hot forging facility is designed to process steel components ranging from 0.2 kg to 35 kg. This integrated machinery infrastructure helps TTT-auto maintain a low level of external dependency in the production of complete brake calipers and brake caliper repair kits.

Cast and hot-forged components involve different production risks; therefore, the same inspection methods are not sufficient for both processes. In TTT-auto’s GJS-600 / GGG-60 ductile iron production, samples are taken from the molten metal for chemical analysis using a spectrometer. Sand analysis, hardness testing, microstructure verification, and tensile testing are also carried out. A spectral analysis device capable of analyzing 32 elements is used to monitor elements such as carbon, silicon, manganese, nickel, and chromium, which directly affect material properties.

For hot-forged components, key inspections include material chemical analysis, hardness testing, magnetic particle inspection, and three-dimensional measurement. These controls, carried out after forging, heat treatment, and machining, help prevent surface or internal defects, dimensional deviations, and undesirable mechanical properties from progressing to subsequent stages of production.

When a customer complaint or technical feedback is received, relevant technical data is first collected, including the product code, batch information, OEM reference, vehicle and caliper application, quantity affected, and supporting photographs or videos. Historical production records in the ERP and MES systems are then reviewed in detail together with raw material inspections, measurement results, assembly torque records, final inspections, and functional test results where applicable. Feedback concerning complete brake calipers, brake caliper repair kits, pins, or caliper wear sensors is evaluated by experienced personnel from the quality, technical, production, and sales teams.

Customer complaints and suggestions are handled with care in order to determine the root cause and provide the customer with a prompt, clear, and traceable response. Based on the findings, a technical explanation, corrective or preventive action, and an appropriate resolution plan are prepared. The conclusions are also communicated to the relevant production cell and incorporated into control plans, ensuring that customer feedback becomes an integral part of the continuous improvement process.

TTT-auto’s after-sales support is not limited to complaint handling. Aftermarket service centers, distributors, and fleet customers are supported by the sales and technical teams in areas such as complete brake caliper or brake caliper repair kit selection, OEM cross-referencing, vehicle application, pin, carrier, and wear sensor variants, as well as assembly and usage-related questions. Requests concerning brake systems such as Knorr-Bremse, WABCO, Meritor, Haldex, and Bendix, as well as Meritor Z-CAM brake applications, are evaluated using OEM and product data. Reference numbers, photographs, videos, and measurements provided by customers are compared against TTT-auto’s extensive database and engineering resources.

Each request is recorded and forwarded to the relevant specialist departments, while the customer is kept informed throughout the evaluation process. Where necessary, technical explanations, visuals, inspection results, and solution options are shared. By maintaining coordinated communication between sales, quality, production, and technical departments, TTT-auto provides customers in the global heavy-duty aftermarket with prompt, clear, and traceable after-sales support.