http://www.nyssa.ltd.uk/Y10/aqui fica o excerto
Following the debut of the Lancia Prisma 4WD and the Lancia Delta HF 4WD at the 1985 Turin Motor Show, in 1986 Lancia presented the Y10 4WD with a four wheel drive system that could be engaged by the driver using electropneumatic actuators to engage the rear wheels. The 999cc FIRE engine was used, but with power raised from 45bhp to 50bhp to cope with the additional weight. The suspension was changed along with the gear ratios, and special 4x4 tyres were fitted as standard.
The Y10 4WD boasts all the typical virtues of the basic model - innovative line, compact size, lots of room, elegant interior - but now with something new: agility and totally safe handling on any road surface. The totally new system adopted for the Y10 4WD preserves the superb (145kph) performance and comfort of the front-drive model in normal conditions, but enables the driver to engage the rear wheels for trouble-free driving over poor grip surfaces such as unmade roads, mud, snow and ice.
Electropneumatically powered, the system permits the disengagement of the drive shaft and rear wheels from their respective half-shafts and the gearbox so that the real differential is not engaged when the Y10 4WD is operating in front wheel drive mode.
Prior to the Y10 4WD, Lancia launched two other models onto the four wheel drive market, the Delta HF 4WD and the Prisma 4WD, both with permanent four wheel drive. In contrast, Lancia opted for engagement 4x4 on the Y10 4WD as more suitable for the specific characteristics of the model.
The Y10 after all, is a dynamic, nippy little car that dashes through the city traffic, zips along the motorway and scampers up narrow, twisty mountain roads.
The adoption of four wheel drive is designed to preserve the Y10's characteristic mobility even in extreme conditions. Bad weather, a sudden snowfall, an icy uphill road, a storm that suddenly makes the road surface slippery: none of this presents a problem any more.
For this purpose and in view of the Y10's (low) power output, permanent four wheel drive seemed superfluous. After all, it takes up space, adds weight, absorbs power and costs more. So Lancia opted for engageable 4x4 but with some advanced technical features in the Lancia tradition.
In fact traditional 4x4 engagement presents one major disadvantage. When the rear wheels are disengaged the half shafts, differential and drive shaft together remain engaged. This 'passive' movement generates friction hence extra fuel consumption, vibration and noise.
Something quite new amongst small cars, the system designed by Lancia for the Y10 4WD eliminates all such problems. The driver just presses a button on the dashboard to isolate half shafts, differential and drive shaft from the power take off on the gearbox and the rear wheels, bringing them to a halt. In this way the connections are not interuppted and the car converts back into a front wheel drive car. This type of drive offers advantages such as better fuel economy, less vibration, less noise and less wear of transmission components.
Transmission:
The Y10 4WD consists of the following parts:
4x4 engagement/disengagement button on the dashboard to the left of the steering wheel and linked to a dial presenting a stylised diagram of the system with two yellow lights, one per axle. The first LED is always illuminated, the second lights up when the rear wheels are engaged.
an electropneumatic engagement/disengagement system composed of the following parts:
- a vacuum tank linked to the pipe that joins the brake servo to the intake manifold, a one-way valve maintains the vacuum
- solenoid valves in a special container in the engine bay to check the vacuum in the actuators
- Pneumatic actuators for engagement of the synchronised connection of the drive shaft to the gearbox outlet and the 'free' rear wheels by means of front-toothed sliding sleeves.
Synchronised connection at the gearbox outlet by pneumatic actuators
Operation
Here is the sequence of 4x4 engagement operations when the button is pressed:
- the main actuator on the gearbox triggers the connection mechanism; the drive shaft starts to move entraining the differential and then the half shafts.
- the rear actuators come into play, wheels and half shafts unite.
Sequence of 4x2 to 4x4 operation
The whole operation takes no more than a few seconds. The whole thing is automatic with the great advantage of total disengagement of the transmission thanks to the 'free' wheels.
Efficiency and Safety
Lancia has taken particular care to ensure that the system remains effective even in extreme conditions.
The four wheel drive can be engaged and disengaged with the engine running whether the car is parked or is in motion.
A special device automatically prevents engagement at over 55 kph but the command memorises the driver's intention so that engagement happens automatically as soon as the car's speed drops below 50kph with no need to press the button again. Once engaged, the rear wheels remain engaged, even above 55kph.
In order to prevent the free wheel actuators being stiffened or blocked by snow, ice or mud so that the rear wheels cannot be engaged, four wheel drive is automatically engaged each time the engine is switched off and then automatically disengaged when it is switched on again.
Other New Technical Features
The Y10 4WD differs from other versions in the range by the inclusion of several rechnical features rendered necessary by the adoption of four wheel drive and the car's expanded operational capabilities.
Engine. This is the FIRE 1000 engine with the power output raised from 45 to 50 bhp at 5500 rpm. The maximum torque is 8 MKG at 3000 rpm with the very flat torque curve desirable for 4x4 driving. The ignition is of the electronic breakerless type.
Gear Ratios. The selection of the correct gear ratio is vital for a car that has to operate as a 4x4 and tackle difficult road conditions. The Y10 4WD has a shorter final drive than the front wheel drive Y10 Fire (5.455:1 as against 3.733:1) while 5th gear is longer (0.73:1 as against 0.78:1), the remaining gear ratios being unchanged. This makes for improved pick up in 1st gear, extra sparkle in the middle ratios and a top speed of 145 kph (as with the Y10 Fire) but achieved in 5th rather than 4th gear.
Suspension. The classic Y10 Omega suspension has been replaced by a rigid rear axle with longitudinal leaf springs in order to accept the four wheel drive components.
Other New Technical Features (continued)
Tyres. The Y10 4WD runs on Pirelli asymmetrical 4x4 tyres. The tread, consumption and struture were specially designed for the Y10 4WD with the aim of optimising road holding in the wet and power in poor grip conditions as well as providing the comfort of normal road tyres.
Characteristics of the '4x4' tyres:
- asymmetric tread design: it is the outer strip of the tread that takes the most stress on bends or at high speed, so the outer blocks of rubber are arranged to give high grip on fast surfaces. The inner strip is designed to give maximum longitudinal traction on slippery surfaces. Water is eliminated efficiently and the tyres are very quiet.
- compostion: designed on the basis of rally experience the compostion has a high friction coefficient for extra traction and efficient braking in poor grip conditions while providing the same tyre life as a normal tyre.
The Y10 4WD in Figures
Engine FIRE 1000
Capacity 999 cc
Max power output (EEC) 50 bhp at 5500 rpm
Max torque 8 mkg at 3000 rpm
Length x Width 3.39m x 1.54m
Kerb Weight 850 kg
Top Speed 145 kph
Acceleration 0-1000m 38 seconds
EEC Fuel Consumption 5.2/7.0/7.0 litres/100 km
Maximum climbable gradient 4x2 36%; 4x4 43%
Towable weight 900 kg
