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Peter Scott TryHard South Australia UZZ32 Active V8
Posts: 133 Reg: 08-2005
Rating: Votes: 2
Tuesday, June 12, 2007 - 08:49 pm, by: Peter Scott(Planetsoarercom)
The Soarer has an Electro-hydraulic braking system (the ones with TRC). Quote: ELECTROHYDRAULIC
On vehicles with integral anti-lock brake systems where the master cylinder is part of the hydraulic control assembly (Teves Mark 2 ABS, Bosch III ABS, Delco Powermaster 3 ABS, Bendix 10 and Jeep ABS), an electric pump with a nitrogen pressurized accumulator is used to provide power assist.
With these systems, power assist is provided by pressure stored in the accumulator. We're talking LOTS of pressure here, from 675 up to 2600 psi depending on the system and application. When the driver steps on the brake pedal and the pushrod moves forward, it opens a valve inside the master cylinder that allows stored pressure from the accumulator to enter a cavity behind the piston assembly. This pushes the piston forward and applies the brakes.
A pressure switch on the master cylinder monitors the stored pressure in the accumulator, and closes a switch to turn on the electric pump when pressure drops below a preset minimum. It then turns the pump off when pressure is back up to where it should be.
Problems with this type of power brake system will usually be due to a bad pump motor, a leaky accumulator, or internal problems in the master cylinder assembly. Because it's all part of the ABS system, electrical problems with the pump motor or pressure switch as well as low fluid level or low pressure will usually trigger a fault code and activate the ABS warning light. To find out what's wrong, you'll have to hook up a scan tool or use the appropriate diagnostic procedure to pull out the trouble codes. Accurate diagnosis here requires referral to the applicable shop manual.
The electric pump and accumulator can usually be replaced separately if there's a problem, but the master cylinder and hydraulic control unit are replaced as an assembly (which is very expensive!).
The most important thing to keep in mind about servicing these systems is to always depressurize the accumulator before working on any part of the brake system or opening up any plumbing. The pedal needs to be pumped 30 to 40 times with the engine off (or until an increase in pedal effort is clearly felt) to bleed off all the pressure from the accumulator.
End Quote.
The Soarer nitrogen accumulator unscrews from the master cylinder with a special tool to grab those two notches on top. I made a quick nasty tool to get mine off - it worked but is looking a bit sad now.
Motorcycle shock suspension specialists can recharge this accumulator. Krooz tune in Melbourne and the Shock Doc in Adelaide spring to mind. The gas port screw is replaced with a hex head screw and copper washer, gas injected past the loose threads the tightened - similar to how I did my UZZ32 accumulators years ago. 1000 psi nitrogen is the likely goal pressure (based on other references). Gas leaked out once and it will leak out again. But how long will it take? Re-gas is cheap. Best bet is to get the accumulator professionally unscrewed (needs quick machine of rolled lip), new seals on the internal piston and regassed. Peter Taplin is the only guy I know doing this service.
