INTRODUCTION - CRANKSHAFT AND FLYWHEEL

1.9 JTS, 2.2 JTS

SPECIFICATIONS

Made from cast iron, the crankshaft is supported by five main journal bearings, supported by crankcase bearings with eight counter-weights.

The steel flywheel is fitted on the eighth counter-weight which, together with the rpm sensor, produces the signal for the speed of the crankshaft and the position of T.D.C.

The crankshaft is connected to the twin mass damping type flywheel described in ASSEMBLY 18 together with the clutch.

1. Crankshaft

2. Flywheel

3. Flange for flywheel attachment

3.2 JTS

Crankshaft

It is made from forged, micro-alloyed steel; the bearings do not have any surface treatment but are rolled and polished.

The crankshaft is supported by four main journals, sustained by bearing supports and balanced by counter-weights. The flywheel for the rpm sensor is made from steel and is an interference fit at the back of the shaft.

The shaft thrust clearance is adjusted through the third main journal. As can be seen in the diagram, the housing for the thrust washer is located in the third main journal.

For the maintenance operations, it is advisable to grind the crankshaft main journals and the crankpins producing the recommended undersize (see TECHNICAL DATA).

Engine flywheel

The dual mass, DVA (dual mass vibration-damping flywheel), has one mass integral with the crankshaft and the other on the gearbox mainshaft with an interposed flexible torsional damping system.

The resonance points, located between 800 and 2200 rpm with conventional systems, are shifted toward lower rpms outside the service range.

1.8

CRANKSHAFT

This is steel and rests on five main bearings. Shaft axial clearance is governed by two half-rings housed in the middle main bearing.

Eight counterweights balance the crankshaft rotary masses with precision.

A set of channels runs along the length of the crankshaft to lubricate the main journals and crankpins.

FLYWHEEL

Made from cast iron with a ring gear in tempered steel, it is suitably balanced.

There is a phonic wheel and the engine rpm sensor ring between the flywheel and the crankshaft rear flange.