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- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1975-1977 3.0L Turbo (930)
Main Bearing Set 0.25mm Oversize Inner - Standard Outer
Main bearings support the crankshaft within the crankcase
and provide the accurately controlled running clearance required for reliable
lubrication and smooth crankshaft rotation. This set is intended for engines
requiring a 0.25mm oversize inner bearing specification and is supplied with 12
bearings plus 2 thrust bearings.
Fits:
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1975-1977 3.0L Turbo (930)
Diagram Ref No 23 and 24
Specification: 0.25mm oversize inner / standard outer
Contents: 12 bearings + 2 thrust bearings
What Do the Main Bearings Do?
Main bearings support the crankshaft as it rotates within the engine. Pressurised oil creates a lubricating film between the crankshaft journals and bearings, reducing friction and wear.
The thrust bearings also control axial movement of the crankshaft.
Why Do Main Bearings Wear?
Bearing wear can result from:
- High engine mileage
- Low oil pressure or oil starvation
- Contaminated engine oil
- Incorrect bearing clearances
- Crankshaft journal wear
- Engine overheating
- Previous internal engine damage
The cause of abnormal bearing wear should always be identified during an engine rebuild.
Why Use 0.25mm Oversize Bearings?
This is not a standard-size bearing set.
The 0.25mm oversize inner specification is intended for an engine where the crankshaft has been measured or machined to require this corresponding bearing size.
Accurate crankshaft and crankcase measurements are essential before ordering. Oversize bearings should not be selected simply because the existing bearings are worn.
When Should Main Bearings Be Replaced?
Main bearings should be inspected during an engine rebuild and replaced if they show scoring, excessive wear, surface damage, incorrect clearance or evidence of oil starvation.
Crankshaft journals, bearing housings, oil passages and thrust surfaces should also be inspected before assembly.
Main Bearing Sets
Correct main bearing selection is essential when rebuilding an air-cooled Porsche flat-six engine. The bearings support the crankshaft, maintain the required oil clearance and help ensure reliable lubrication throughout the engine.
This OE Match 0.25mm oversize inner main bearing set is designed for Porsche 911 2.7 and 930 Turbo 3.0 engines requiring this specific bearing dimension.
Always measure the crankshaft journals and crankcase accurately before selecting standard or oversize bearings. Design911 supplies Porsche main bearings, thrust bearings and associated engine rebuild components for classic air-cooled Porsche applications.
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91110190250
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- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 718 2.0L Manual (300 Bhp) 2017>>
- Porsche Boxster 718 2.0L PDK (300 Bhp) 2017>>
- Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
- Porsche Boxster S 718 2.5L PDK (350 Bhp) 05/2017>>
- Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
- Porsche Boxster T 718 2.0L PDK (300 Bhp) 01/2019>>
- Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12
- Porsche 997 MKII Turbo 2010-13
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
- Porsche 991.1 GT3 3.8L (475 Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500 Bhp) 2015-16
- Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Targa 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19
- Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
- Porsche 992.1 Carrera 2 3.0L 2019-24
- Porsche 992.1 Carrera 4 3.0L 2019-24
- Porsche 992.1 Carrera 2 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 2S / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 2S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Targa 4 3.0L 2020-24
- Porsche 992.1 Targa 4S / GTS 3.0L 2020-24
- Porsche Cayman S 3.4L 987C 2005-08
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman 718 2.0L Manual (300 Bhp)
- Porsche Cayman 718 2.0L PDK (300 Bhp)
- Porsche Cayman S 718 2.5L Manual (350 Bhp)
- Porsche Cayman S 718 2.5L PDK (350 Bhp)
- Porsche Cayman T 718 2.0L Manual (300 Bhp)
- Porsche Cayman T 718 2.0L PDK (300 Bhp)
- Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
- Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
Fits:
Porsche 996 3.6L 2002-04 engines M96.03
Porsche 997 2005-08 3.6L / 3.8L engines M97.01 / M96.05
Porsche 997.2 2009-12 3.6L / 3.8L engines MA1.01 / MA1.02
Porsche 997.2 Turbo 2010-13 3.8L engines MA1.70
Porsche 987 Boxster S 3.4L >>2006 engines M97.21 / M97.22 (RS SPYDER)
Porsche 987.2 Boxster 2.9L 2009-2012 engines MA1.20
Porsche 987.2 Boxster S 3.4L 2009-2012 engines MA1.21
Porsche 987C Cayman S 2006-08 engines M97.21 / M97.22
Porsche 987C.2 Cayman 2009-12 engines MA1.20
Porsche 987C.2 S Cayman 2009-12 engines MA1.21
Porsche 981 Boxster 2012-2016 engines MA1.22 / MA1.23 / MDB.XA (Spyder)
Porsche 982 Boxster 2017-2021 engines MDD.PA / MDD.PB / MDD.NC
Porsche 981C Cayman 2014-2016 engines MA1.22 / MA1.23
Porsche 981 Cayman GT4 2016 engines MDB.XA
Porsche 982C Cayman 2017-2021 engines MDD.PA / MDD.PB / MDD.NC
Porsche 991 2012-16 engines MA1.03 / MA1.04 / MAB.03 / MAB.04
Porsche 991 Turbo 2014-16 engines MA1.71
Porsche 991 GT3 2014-16 engines MA1.75 / MA1.76
Porsche 991.2 2017-19 engines MDC.HA / MDC.H / MDC.JA / MDC.J / MDC.KA / MDC.K
Porsche 991.2 Turbo / GT2 2017-19 engines MDA.BA / MDB.CA / MDA.B / MDB.C / MDH.NA / MDB.CB
Porsche 992 2019-21 3.0L engines MDKC / MDKCA / MDKK / MDKKA
Click picture for large parts diagram.
Diagram Ref No 24.
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0PB105638
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100 Plasigauge strips per box
PLASTIGAUGE PL-A is widely used in the measurement of clearance in plain automotive bearings. Measurement of clearance in big-end bearings can be achieved without dismantling the crankshaft.
For measurements of: 0.001″ to 0.007″ (0.025mm – 0.175mm)
Suitable for use at temperatures between 0°C and 35°C
Contents:
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PLA007
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3G Mineral Grease: To coat journal prior to use of Plastigauge
3G Silicone Grease: To apply to surface of shell
Lubricants to assist with the measurement of clearance in automotive bearings.
Plastigauge Precision Clearance Gauges
Kit includes:
1 x Plastigauge PL-A box
1 x Plastiguage Mineral grease
1 x Plastiguage Silicone grease
PLASTIGAUGE PL-A is widely used in the measurement of clearance in plain automotive bearings. Measurement of clearance in big-end bearings can be achieved without dismantling the crankshaft.
3G Minerak Grease: To coat journal prior to use of Plastigauge
3G Silicone Grease: To apply to surface of shell
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This kit is comprised of the following items:
