AWD: The Impreza WRX STI uses Driver Controlled Center Differential (DCCD), the most performance-directed type of Symmetrical AWD. A limited-slip, planetary gear-type center differential provides a performanceoriented 35:65 front/rear power split.
AWD: The Impreza WRX STI uses Driver Controlled Center Differential (DCCD), the most performance-directed type of Symmetrical AWD. A limited-slip, planetary gear-type center differential provides a performanceoriented 35:65 front/rear power split.
An additional benefit of this arrangement is that the mechanical valve damps out some of the unwanted oscillation in the brake pedal as the ABS pump runs. Because of this, the F valve used on the ABS-2SL system is no longer needed and has been eliminated from the circuit.
ABS Operating Modes:
To illustrate the four operating modes of this ABS system, we’ll assume that the ECU is operating only the solenoid for the right rear brake circuit. Recall that this circuit also affects the left rear brake circuit through the mechanical valve.
Normal Braking:
• Driver depressing pedal
• ECU passive (monitoring)
• Zero current in solenoid valves
• Pump off
• Plunger piston full right, pressure port open
• Master cylinder pressure supplied to all wheel cylinders
Pressure-Reduce:
• Pump pressure raising pedal
• ECU controlling solenoid valves and pump
• Full current in the right rear solenoid valve
• Pump running
• Plunger piston moves left, closes pressure port; system balances the two rear wheel cylinders.
Pressure-Hold:
• Pedal firm
• ECU controlling solenoid valves and pump
• Half current in the right rear solenoid valve
• Pump Off
• Pressure port closed
• Plunger piston is stationary, maintains reduced pressure in the right and left rear wheel circuits.
Prior to the Legacy RS turbo, Subaru had never enjoyed the experience of distributing a genuine performance car. Of course, there had been the 4WD turbo RX and Vortex, but neither could crack 10 seconds for the 0-100km/h sprint – although they were very reliable. The RS was the gun version of the first Legacy series released in 1988 and discontinued in 1994. The RS (Rally Sport) model was aimed squarely at world rallying, with many of its components and concepts carried over to the dominating Impreza WRX.
The center Viscous LSD on the MT models initially starts out with a 50/50 torque split, front and rear, and will up the ratio towards the end with more traction. The manufacturer doesn’t give a final figure, so the max split is either 65/35, or could even venture as high as 95/5, since the A/T model has a different system that is marketed at a 65/35 maximum split. A higher ratio would explain some of the handling characteristics at the limit. The rear differential is also a Viscous LSD model.
The BC/BF is unique in having an Air – Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy’s have all used air to air intercoolers.
In late 1998, Subaru UK officially imported 16 22Bs (described below), and passed them on to Prodrive for modification. The UK cars differ from the privately imported 22Bs, not just in their 3 year factory warranty, but with revised gear ratios more suited to UK roads.
This was achieved by changing the final drive ratio from 3.9 to 4.44 to lengthen the gearing. Cosmetically, the car got the headlights from the ‘99 model, UK rear light clusters and driving lights (not fog lights!) were fitted where the normal 22B has blanking plates. From the back, you can tell you’re looking at one of the rarest cars in the world by the “Type UK” and “Prodrive” stickers. The price was £39,950, and demand for the cars was overwhelming.
Interestingly, Subaru UK were not able to put their 16 cars through the Single Vehicle Approval scheme because the maximum of 50 privately imported 22Bs had already been registered in 1998. Consequently the Type UKs were registered in 1999. The cars do not meet European Type Approval regulations for noise and emissions.
Sometimes if you spent more than five minutes posting facebook and instead searched on google you might understand the World Rally Champion anti-lag system that’s used on Subaru’s rally cars.
It gets to a point were none of these people should own a turbocharged Subaru. True anti-lag systems are expensive and require extensive tuning and kills turbos which translates into a lot of money which none of these people have.
