Hydraulic pump question

[urq20v]

Since the hydraulic pump in my RR has two circuits,brakes and steering,is it common for the brake circuit to lose pumping pressure with age before the steering circuit?I ask because I have been chasing a brake power problem for a while and it does not appear to be the bomb or the servo.The pump is not overly noisy and the steering is fine.
Rex

[Greg_S]

I guess you have throughly bled the fluid & changed it? have you also check the master cylinder?

[urq20v]

I have fitted a new master cylinder and bled the system with new dot 5.1 fluid.At high speed,the brakes work very well (Porsche Boxster conversion) but at low speed after a thrash they can feel totally useless!

[Greg_S]

what pads are you using?

[urq20v]

Im using the standard Porsche pads.They could be the problem I surpose,but the brakes used to work fine at any speed.There is definitly a pressure problem with the hydraulics,the red light comes on after a few pumps of the pedal but the bomb and servo have been replaced.Im getting the car ready for MOT/DVLA etc after bringing it over from NZ and want everything right.

[PeteRR]

I'd lay my suspicions on the hydraulic pump. Sounds like it's having a hard time keeping up the pressure charge demand.
Unless your new accumulator is faulty! (doubtful, but worth checking out maybe).

If you've not used the car for a few days does the light stay on for a couple of mins when first starting?