Genuine Mazda Connecting Rod Big-End Bearing Set – Multiple Sizes • LFY1-11-SE0A

Genuine Mazda Connecting Rod Big-End Bearing Set – Multiple Sizes

Genuine Mazda connecting-rod big-end bearing set for Mazda MX-5 Mk3 NC models with compatible 1.8-litre L8 or 2.0-litre LF MZR petrol engines.

The bearing shells fit between the four connecting rods and the crankshaft journals. They support the rotating connecting rods on a controlled film of pressurised engine oil while maintaining the specified running clearance around each crankshaft journal.

Each selected variant provides a complete engine set containing the upper and lower bearing shells for all four connecting rods. This equals four bearing pairs or eight individual bearing shells.

Three sizes are available. The standard set is intended for an unground crankshaft with journals remaining within the original Mazda specification. The 0.25mm and 0.50mm options are undersize bearing sets for crankshafts that have been professionally reground to the corresponding repair dimension.

Critical sizing advice: The bearing size must be selected from accurate crankshaft-journal measurements and the finished journal diameter. Do not select an oversize or undersize bearing merely to compensate for general wear. Incorrect bearing clearance can cause low oil pressure, bearing seizure, excessive knocking or complete engine failure.

Engine-generation note: These LFY1-series bearings are identified as the earlier-style MZR connecting-rod bearing set. For a standard catalogue replacement, the listing should be treated as primarily applicable to the earlier MX-5 Mk3 NC1 engine arrangement. Later or previously rebuilt engines should be identified by the removed bearing set, connecting rods, crankshaft measurements and engine-build specification before ordering.

• Part type: Connecting-rod big-end bearing set
• Common names: Con-rod bearings / big-end shells / connecting-rod metal set
• Location: Connecting rods to crankshaft journals
• Engine family: Mazda MZR L8 / LF
• Engine applications: 1.8-litre L8 and 2.0-litre LF petrol engines
• Connecting rods serviced per set: 4
• Bearing pairs supplied: 4
• Individual bearing shells supplied: 8
• Quantity of sets required per engine: 1
• Standard size available: Yes
• 0.25mm undersize available: Yes
• 0.50mm undersize available: Yes
• Connecting rods included: No
• Connecting-rod bolts included: No
• Crankshaft included: No
• Engine oil included: No
• Brand: Genuine Mazda

Available variants:

• Standard – Mazda Part No. LFY1-11-SE0A
• 0.25mm undersize – Mazda Part No. LFY1-11-SF0A
• 0.50mm undersize – Mazda Part No. LFY1-11-SFXA

Standard bearing specification: MazSpec lists an approximate bearing thickness of 1.504mm, bearing width of 16.599mm, connecting-rod housing diameter of 50.025–50.046mm and standard crankshaft-journal diameter of 46.980–47.000mm. These figures should be checked against the applicable Mazda workshop data and the measured engine components before assembly.

Possible signs of worn connecting-rod bearings:

• Deep knocking noise that follows engine speed
• Knocking that becomes more noticeable under load
• Low engine-oil pressure
• Metallic debris within the engine oil or oil filter
• Scoring or discolouration on the crankshaft journals
• Excessive connecting-rod bearing clearance
• Bearing material transferred onto the crankshaft
• Damage following oil starvation or engine overheating

Fitment advice: Confirm the engine family, connecting-rod design and removed bearing reference before ordering. Engines may have been rebuilt previously using a reground crankshaft or alternative internal components, so vehicle model and registration year alone cannot determine the required bearing size.

Size-selection advice: Measure every connecting-rod journal using a calibrated micrometer. Inspect for taper, ovality, scoring and heat damage. Standard bearings must only be used where the journals remain within the standard service specification. A crankshaft requiring machining should be professionally ground to the exact repair size corresponding to the selected 0.25mm or 0.50mm bearing set.

Bearing-clearance advice: Confirm the finished oil clearance using precision measuring equipment or an appropriate bearing-clearance checking method. Do not assume that a new bearing set automatically produces the correct clearance.

Replacement advice: Where one bearing has failed, inspect all four connecting rods, every crankshaft journal, the oil pump, oil pickup, lubrication passages and the complete engine oil supply system. Installing new shells onto a damaged crankshaft is unlikely to provide a durable repair.

Other items to consider: Inspect or replace the connecting-rod bolts, piston rings, main bearings, thrust bearings, oil pump, oil pickup, sump gasket or sealant and crankshaft oil seals. Fresh engine oil and a new oil filter are essential after assembly.

Useful tools / consumables: Engine stand, calibrated micrometer, bore gauge, bearing-clearance measuring material, calibrated torque wrench, angle gauge, clean engine assembly lubricant, lint-free cleaning materials, fresh engine oil and a new oil filter.

Difficulty guide: DIY Difficulty: Specialist / Advanced. Accurate crankshaft measurement, bearing-clearance assessment, component cleanliness and correct connecting-rod bolt tightening are essential. Incorrect assembly can cause immediate and severe engine damage.

Why Genuine Mazda? Genuine Mazda connecting-rod bearings match the original shell width, locating-tab position, oil-clearance specification, bearing profile and connecting-rod housing geometry. Correct bearing dimensions and material construction are critical to maintaining a stable oil film and protecting the crankshaft journals.

What’s in the box: One complete Genuine Mazda connecting-rod big-end bearing set in the selected size, containing four upper and four lower bearing shells for all four connecting rods.

Installation notes: Fully clean the connecting rods, caps, crankshaft journals and lubrication passages before assembly. Keep every connecting-rod cap paired with its original rod and maintain the correct orientation. Measure each journal and connecting-rod housing, then confirm the selected bearing size and finished oil clearance. Install the bearing shells dry into clean housings, ensuring the locating tabs are seated correctly, then apply clean engine assembly lubricant to the bearing surfaces. Fit the rods and caps without damaging the journals and tighten the connecting-rod bolts using the applicable Mazda sequence, torque and angle procedure. Confirm that the crankshaft rotates smoothly after each rod is installed. Prime the lubrication system before first start and verify oil pressure immediately.