MED EN40B STEEL BILLET CRANKSHAFT - INLINE
The MED crankshaft is CNC machined from EN40B steel billet and nitride hardened, with extra large C-shape counterbalance webs to reduce potentially damaging harmonics. It is designed specifically for the inline (Midget/Sprite) A-Series engine.
1.625" size big end journals with counter-bored webs reduce weight and further enhance the counterbalance effect. An improved counterbalance helps to reduce the 'whip' often encountered with the three main bearing A-Series crankshaft, to improve longevity and performance at higher RPM levels.
This crankshaft is ideally suited to Appendix K historic Midgets and Sprites where a more traditional stroke length and big end size must be retained. It would also suit high performance road, rally and trackday builds.
- CNC machined from EN40B steel billet
- 81.33mm standard stroke
- 1.625" big end journals
- 2.000" main journals
- Extra large C-shape counterbalance webs
- Counter-bored big ends for further weight reduction
- 100% crack detection and material certification
- Extra long keyway for crank pulley
- Nitride hardened journals
- Balanced to within 1 gram
As used in our inline race engines, from five-port to eight-port and 16-valve. With hundreds of crankshafts sold worldwide over the past decade, this remains the best value EN40B steel billet crankshaft available for the 1275 inline engine.
Please note - the timing gear end has a carefully machined radius for extra strength - please be sure that your timing gear sprocket has a matching radius or damage will be caused on assembly.
We also offer a complete crankshaft kit package with a choice of pistons and MED steel conrods. If you're not restricted by race regulations, you may be interested in upgrading to the more radical MED Multiweb crankshaft kit, which further improves the counterbalance effect.
Please see the additional information tab for frequently asked questions.
Why is an MED steel crankshaft better than a standard type?
Most factory crankshafts were made from lesser grade EN16T, as opposed to certified EN40B steel billet. The counterbalance effect is also far greater with this design, so it is both stronger and better balanced.
An improved counterbalance effect helps to reduce the 'whip' often encountered with the three main bearing A-Series crankshaft, to improve longevity and performance at higher RPM levels.
Whilst standard crankshafts can be effectively re-worked to improve their counterbalance effect, it is not possible to add material, only subtract. You're also unlikely to know the history of a second-hand crankshaft - it could be over 50 years old!
Do I need to use steel main caps?
Ideally, yes. We would highly recommend an MED four-bolt steel main cap set, AFS studs and line-boring of the block when upgrading to a steel crankshaft. On a road car, an MED centre main strap kit may suffice, but it's not the ideal arrangement when using a such a high-end crankshaft.
Which conrods and bearings do I need?
The big end journals are sized at 1.625" as per the original Midget/Sprite engine, so original conrods will fit. However we would highly recommend upgrading to a set of MED steel conrods for extra strength and reduced weight.
Main bearings are standard 1275 size, big ends are Midget/Cooper S as above, and thrusts are the standard 1275 type. To make things simple we can supply a complete crankshaft kit with everything you may need.
Is this a standard replacement?
Yes, although you ideally it's best to use steel main caps, as mentioned above. Otherwise this is a direct replacement for the standard-type crankshaft and does not require any special machining of the block or gearbox.
Can you make me a custom steel crankshaft?
Unfortunately with the design, drawing and machining costs involved in producing a custom design crankshaft, it would prove too expensive. However, we have developed our crankshaft designs over many years using decades of A-Series engine experience, so you can be assured of the best possible setup for the vast majority of applications.
What's better, billet or forged steel cranks?
This is an area of much debate. In use we have found no tangible difference in strength and reliability between the two manufacturing techniques. We prefer machining crankshafts from billet, as this allows for regular design development without needing to make a new forging tool each time, which would not be economically viable.
Does this come with any certification?
Each crankshaft is supplied fully balanced with certification, 100% crack detection and certification of material and heat treatments. Critical detail inspection reports are also supplied.