This is the OEM size 85mm crankshaft. Maruha developed this in response to Mazda discontinuing the OEM genuine crankshaft but features several design improvements over the standard crank. One of the biggest is the extended pulley boss at the front of the crank. The oil pump, timing belt and front pulley are all attached right on the very edge of the crankshaft and over time, this edge can become fatigued resulting in uneven wear of both the pulley and the crankshaft. Once worn, this will unbalance the front of the crankshaft putting major strain on some of the most critical components of the engine. Maruha have solved this by extending the crank out 14mm from the OEM pulley, setting all the load of the belts and oil pump away from the edge and providing a solid surface for this load to be transferred from.
Maruha’s 85mm crank is also around 1kg lighter than factory. With the 1.6 engine often being favoured for its free-revving qualities, this shedding of weight will lead to the 1.8 engine feeling as revy as ever while maintaining the added torque the extra displacement brings.
When building a fresh engine, one of the major considerations should be how long you’ll want the engine to last. Even complete rebuilds normally use a second-hand crank, but there may be issues even the most experienced mechanic cannot find. This is the main issue Maruha sought to address with this 85mm replacement crank; if you’re completely refreshing a stock engine or building one to take power, you’ll want to build it to last as long as possible as crank issues will require the entire engine to be disassembled. A new crank provides much-needed assurance that an engine can easily last hundreds of thousands of miles more.
- Cast and machined from 43040 Chromoly Steel
- Several design improvements over the OEM crankshaft
- Compatible with OEM rods, pistons, main & rod bearings
- Retains standard displacement