Automotive Timing Belt

Automotive timing belts are precision synchronous belts used to maintain accurate timing between the crankshaft and camshaft in internal combustion engines. Positive tooth engagement with the timing pulleys keeps valve timing synchronized without the slip associated with friction-drive belts, supporting stable engine operation and consistent power transmission.
TRANSCO supplies automotive timing belts for passenger cars, SUVs and light commercial vehicles, including OE replacement and aftermarket applications. Available constructions include CR or HNBR rubber compounds, fiberglass or aramid tensile cords, wear-resistant nylon tooth fabric and multiple automotive tooth profiles. Belt selection can be matched by vehicle and engine information, OE number, belt code, tooth count, width, profile, sample or technical drawing.

Key Features:
Precise synchronous timing
Low-elongation tensile structure
HNBR/CR compound options
Wear-resistant nylon tooth facing
OE and profile matching

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What is an Automotive Timing Belt?

An automotive timing belt, also called an engine timing belt, car timing belt or cambelt, is a toothed rubber synchronous belt that links the crankshaft and camshaft so the engine valves open and close at the correct point in the combustion cycle. Unlike an accessory belt, it is part of the engine timing system and must maintain accurate tooth-to-pulley engagement and stable pitch length during repeated high-speed operation.

A timing belt is different from a serpentine belt or accessory drive belt. A serpentine belt drives external accessories such as the alternator, air-conditioning compressor and, on some engines, the water pump. The automotive timing belt controls internal engine synchronization. Correct OE matching is therefore based on the vehicle and engine code, OE or cross-reference number, tooth profile, tooth count, belt width and required material specification.

Why choose TRANSCO Automotive Timing Belt?

Precision Molded Tooth Geometry: Accurately molded tooth profiles engage with crankshaft and camshaft pulleys as a positive synchronous drive, helping maintain stable valve timing without relative belt slip. Controlled tooth geometry and pitch are especially important for reducing meshing error, abnormal tooth wear and timing deviation.

Low-Elongation Tensile Structure: Fiberglass tensile cords provide high tensile strength with low elongation, helping the belt maintain stable pitch length and tooth position under repeated engine loads. Aramid tensile members are available for selected applications requiring higher strength or lower elongation.

HNBR and CR Rubber Compound Options: HNBR compounds are suited to demanding engine environments where improved heat, ozone and ageing resistance are required, while CR compounds are available for standard replacement specifications. Compound selection can be matched to the vehicle application, operating temperature and OEM requirement.

Wear-Resistant Nylon Tooth Fabric: Polyamide/nylon fabric covers the working tooth surface to reduce friction and abrasion during repeated pulley engagement. The fabric protects the tooth flanks, supports smoother meshing and helps control wear and operating noise over continuous timing cycles.

Stable Tooth Load Transfer: The molded tooth rubber and tensile-cord structure work together to transfer pulley tooth loads through the belt while maintaining tooth shape under cyclic tension and bending. Stable load distribution helps reduce localized tooth deformation and supports consistent synchronous engagement.

Flex-Fatigue Stability for Engine Timing Cycles: Automotive timing belts repeatedly bend around crankshaft, camshaft, tensioner and idler pulleys while remaining under controlled tension. The combined rubber, cord and tooth-fabric construction is designed to resist repeated flexing and maintain dimensional stability during continuous engine timing operation.

Technical Standards

① IATF 16949:2016 Automotive Quality Management : Automotive timing belt production is controlled under an IATF 16949:2016-certified automotive quality management system, supporting process control, product traceability, defect prevention and consistent manufacturing quality for automotive applications.
② Automotive Belt Dimensions & Tooth Geometry: TRANSCO automotive timing belts can be manufactured and dimensionally inspected according to ISO 21342:2019 and applicable requirements of GB/T 12734-2017, covering tooth geometry, pitch, belt width, pitch length and dimensional tolerances for automotive synchronous belt drives.
③ Physical Property Verification: Automotive timing belt physical properties can be tested according to ISO 12046:2025 and GB/T 10716-2012. These methods provide technical verification for synchronous belts used in camshaft, fuel-injection-pump, balance-shaft and other engine timing drives.
④ Fatigue & Dynamic Durability: Belt fatigue performance can be evaluated according to GB/T 18183-2017, supporting verification under repeated bending, tensile loading and continuous synchronous transmission conditions.
⑤ Material & Environmental Performance: Where required by the application, rubber compounds can be evaluated for accelerated ageing and heat resistance according to ISO 188:2023 and for resistance to oils or specified service liquids according to ISO 1817:2024, or the current applicable edition. Acceptance criteria are defined by the approved belt compound and OEM/customer specification.

How to choose Automotive Timing Belt?

Confirm Vehicle and Engine Information : Provide the vehicle brand, model, production year and engine code. Different engines within the same vehicle family can use different timing belt lengths, widths and tooth profiles.
Check the OE Number or Belt Code : For replacement timing belts, the OE number, original belt code or reliable cross-reference number is the fastest way to narrow the match. A sample belt or technical drawing can also be used when the marking is unavailable.
Verify Tooth Count and Belt Width : Tooth count and belt width must match the engine timing system. For example, 137 ZBS 25 indicates 137 teeth, a ZBS tooth profile and a 25 mm belt width.
Match the Tooth Profile : The tooth profile must correspond to the pulley groove geometry. Common TRANSCO automotive profiles include MR, MY, YU, RU, ZA, ZB, ZBS, ZAS, S8M, ZLB and RPP. Incorrect profile matching can cause poor meshing, noise or accelerated tooth wear.
Select the Rubber and Cord Specification : Choose CR or HNBR according to the engine environment and OEM requirement. Fiberglass cord is standard for stable low-elongation timing performance, while aramid reinforcement is available for selected customized or higher-load applications.
Confirm Kit and Custom Requirements : For aftermarket programs, confirm whether the order requires the timing belt only or a kit with tensioners, idlers and, where applicable, a water pump. Also specify logo marking, private-label packaging, quantity and market requirements.

Quick Selection Checklist

Vehicle / Engine	Brand, model, year and engine code
OE Reference	OE number, belt code or cross-reference number
Tooth Profile	MR, MY, YU, RU, ZA, ZB, ZBS, ZAS, S8M, ZLB, RPP or approved custom profile
Tooth Count	Required number of teeth
Belt Width	OEM/standard width in mm
Material	CR rubber, HNBR rubber or customized compound
Tensile Cord	Fiberglass or selected aramid construction
Application	Passenger car, SUV, van, light commercial vehicle, OHC/DOHC engine timing system
Kit Requirement	Belt only, tensioner/idler kit or water-pump kit where applicable
Customization	Logo marking, private-label packaging, sample/drawing development

Construction

Belt Back : CR or HNBR rubber forms the belt back and protects the tensile layer from engine-compartment exposure and repeated flexing. Compound selection is matched to the required heat, ageing and environmental resistance.
Tensile Cord : Fiberglass cord is the primary load-carrying member, providing high tensile strength, low elongation and stable pitch length. Aramid cord can be used for selected higher-load or customized requirements.
Tooth Rubber : Precision-molded tooth rubber forms the required automotive tooth profile and transfers load between the timing pulley and tensile layer. Accurate tooth geometry supports stable engagement with crankshaft and camshaft timing pulleys.
Nylon Tooth Fabric : Polyamide/nylon fabric protects the tooth surface during repeated engagement, reducing friction and abrasion while supporting smoother meshing and lower operating noise.

Model Specifications

Profile	Pitch Pb (mm)	Tooth Height ht (mm)	Overall Belt Height hs (mm)

MR	9.525	3.54	5.69
MY	8.00	3.06	5.21
YU	8.00	3.11	5.20
RU	9.525	3.56	5.70
ZA	9.525	1.91	4.10
ZB	9.525	2.29	4.50
ZBS	9.525	2.76	5.06
ZAS	9.525	2.32	4.50
S8M	8.00	3.05	5.30
ZLB	9.525	2.70	5.05
RPP	9.525	2.25	4.50

Applications


Camshaft Timing Drives : Used to synchronize the crankshaft and camshaft in OHC and DOHC gasoline or diesel engines, maintaining correct valve timing through positive tooth engagement.	Fuel-Injection-Pump Drives : Suitable for engine systems that use a synchronous belt to drive the fuel injection pump at a defined relationship to crankshaft rotation.

Balance-Shaft Drives : Used in selected engine layouts where a synchronous belt controls balance-shaft timing to support smooth engine operation.	OE Replacement & Automotive Aftermarket : Available for passenger cars, SUVs, vans and light commercial vehicles, with matching by OE number, engine code, tooth count, width and tooth profile for replacement and private-label programs.

Packing and Shipping

Frequently Asked Questions

An automotive timing belt synchronizes the crankshaft and camshaft so the engine valves open and close at the correct time. Its toothed positive-drive design maintains a fixed timing relationship between rotating engine components.

A timing belt controls internal engine timing between the crankshaft and camshaft. A serpentine or accessory drive belt powers external accessories such as the alternator and air-conditioning compressor, and on some engines the water pump.

Typical TRANSCO constructions use CR or HNBR rubber, fiberglass tensile cord, optional aramid reinforcement and polyamide/nylon tooth fabric. The exact construction depends on the OE specification and operating environment.

HNBR is selected for timing-belt applications that require improved heat, ozone and ageing resistance in demanding engine environments. The required compound grade should still be matched to the specific OEM or customer specification.

Fiberglass cord combines high tensile strength with low elongation, helping the belt maintain stable pitch length and tooth position during repeated engine timing cycles.

Nylon tooth fabric reduces friction and abrasion at the tooth-pulley contact surface, protects the molded teeth and supports smoother, lower-noise engagement during repeated rotation.

In this designation example, 137 is the tooth count, ZBS is the tooth profile and 25 is the belt width in millimeters. Actual coding conventions can vary by manufacturer, so the OE number or original belt marking should also be checked.

Confirm the vehicle model, production year, engine code, OE number or original belt code, then verify tooth profile, tooth count and belt width. A sample or technical drawing can be used when the original marking is unclear.

Depending on the product specification, automotive timing belts can be dimensionally verified against ISO 21342:2019 and GB/T 12734-2017, physically tested according to ISO 12046:2025 and GB/T 10716-2012, and fatigue-tested according to GB/T 18183-2017. Material ageing and liquid resistance can be evaluated using applicable ISO rubber test methods.

Yes. TRANSCO supports OE-number and sample/drawing matching, custom belt marking, private-label packaging, material selection and selected profile or size development for distributors and aftermarket programs.

Timing belt programs can be matched with tensioners, idlers and, where applicable, water-pump components according to the target vehicle application and sourcing requirement.

Replacement intervals vary by vehicle and engine design. Follow the vehicle manufacturer's specified service interval and inspect related timing-drive components during maintenance; do not use a universal mileage interval for all engines.

Provide the OE number or belt code, vehicle/engine information, tooth profile, tooth count, belt width, quantity, target market, packaging requirements and any logo or marking requirements. A sample or drawing can be supplied for custom matching.

Automotive Timing Belt Manufacturer