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Crankshaft Identification

MINI Crankshaft Identification   
This list should cover any forging numbers you can find on any Mini  A Series or A + crankshaft, from a 1959 thin tail 850cc to the 1275 MPi 2000, we have included various tuning crankshafts including the Turbo and of course the ultimate Mini Cooper S ones. We have not listed part numbers as it depends on the bearing types and can be confusing. Sometimes the same forging number can be produced using a different grade of steel, machined to different sizes and or heat and chemically treated using a different process, so would have a different part number and or application. As a guide from a longevity and performance point an EN16T steel  crankshaft is pretty good, but the 970, 1071 and pre 1969 1275cc Cooper S Crankshafts were EN40B steel which is in itself very strong but benefits further from the chemical heat process of Nitriding, which hardens the surface even more.

Contrary to popular belief all Mini A series and A+ crankshafts are forged steel, if they were cast iron or steel  they would break all too easily. 

Various tuning companies produce other forged or billet crankshafts for the Mini, mostly  for the 1275 engine blocks, from  1275cc to around 1500cc. They are generally for motorsport to help make up to a class limit, (eg, Hillclimb and Sprint regulations have a class break at 1400cc currently). Some are short stroke and some are longer than the standard 1275 of 81.3mm, these are covered in the capacity section, as a general rule, they  do not have forging numbers on them, and may only have the stroke length punched into the surface.

Forging                       CC     Notes

22A62 & 63               850    1959-62 oil fed primary gear, 1.375" thin tail
22A298                      850    1962-3, 1.375" thin tail
12A670                      850    1963-84 with 1.5" dia. tail
AEG515                     850    Special Tuning Tufrided
12A375                      997    1961-2 Cooper oil fed  primary gear, 1.375” thin tail

12A298                      997    962-63 Cooper with 1.5” dia.tail
12A595                      998    Early EN16T
12A1451                   998    Later EN16T pre A+
12A1451                    998     A+ spec
12G82                       1100     A series EN16T
AEG330                    970    EN40B Nitrided,  non-cross drilled
AEG171                    1071    EN40B Nitrided,  non-cross drilled
AEG315 / 316           1275    1964-66 Cooper S, EN40B Nitrided, non-cross drilled
AEG479 / 480           1275    1966-69 Cooper S, EN40B  Nitrided, cross drilled
AEG623                    1275    1969-71 Cooper S, EN16T, Tuftrided
12G1287 / 88           1275    Non-S, EN16T with 1.625" dia. big ends
12G1505                  1275    1969-71 Cooper S with 1.625” big ends                                                                                
12G1683                  1275cc    12G1505 forging, non-S, EN16T with 1.75" dia. big ends, Tuftrided
CAM6232*                1275cc    Rolled fillet radius bearing journals, A+ with 1.75" dia. big ends
This crankshaft was used in all Mini 1275cc A+ engines including the Mini ERA Turbo and the MG Metro Turbo. It is now impossible to know with any degree of certainty but, it appears that early Turbos had just the standard spec, EN16T, non-heat treated type fitted. Later examples certainly appear to have been heat-treated, probably an up-to-date, emissions-friendly version of 'Tuftriding' (a recognised ICI registered process) - possibly a forerunner to Nitro-Carburising. These crankshafts have a distinctly charcoal-grey/black finish - mostly detectable on the webs, water pump/alternator pulley end and in the rolled fillet radii. The later being fairly 'deep' and very even.

* AEG515 - 850cc - Special Tuning Competition Crankshaft, Tuftrided

* 8G2733 - 998cc - ?
* 12A595 - 998cc - Early EN16T spec
* 12A1451[R] - 998cc - Later, pre-A+ EN16T spec
* BHM1436 - 998cc - A+ spec, 1985 onwards (12A1451 forging)

* 12G2827 - 1071cc - South Africa spec, 1,75" big ends

* AEG1392 - 1275cc - Cross drilled, wide thrust gap, small journals

* 12G1817 - 1275cc - n/a (verm. Clubman 1275GT)
* 12G1505* - 1275cc - Non-S, EN16T with 1.75" dia. big ends
* 12G1683 - 1275cc - 12G1505 forging, non-S, EN16T with 1.75" dia. big ends, Tuftrided
* CAM6581** - 1275cc - Metro Turbo early (controversy if nitrided or not runing)
* CAM6232** - 1275cc - Rolled-fillet radius on bearing journals, A+ with 1.75" dia. big ends

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