VR master cylinder

[chrisdoesitbetter]

hi everyone, i have a low and hard brake pedal. my gregories manual thinks it could be the master cylinder. i have not bled the brake fluid yet, but im thinking its a problem beyond jsut air in the system. my question, looking at the diagram on an abs equipped model, the only difference is a valve within the spring. im wanting to know what master cylinders will fit my car (for example VN or VS) and how much brand new and second hand they roughly cost. my car has abs and is v6 built in 94.

 

[RX25SE]

If you still have a low pedal after you have bled the brakes, clamp each of the brake hoses and see if the pedal firms up.
If it doesn't then the master is faulty.

I would recommend fitting the correct part listed for your year/model.
Price? No idea, sorry.

 

[Brett_jjj]

Sometimes on ABS equipped vehicles if the ABS isnt cycled when the brakes are bled,trapped air in the ABS modulator can make the brake pedal spongy.Some scantools, (Tech 1 and Tech 2) have the ability to cycle the ABS when brake bleeding.As a last resort you can try to lock up the brakes on grass or gravel which will cycle the ABS and hopefully let the trapped air through to the wheel cylinders so it can be bled out.

 

[moff_man]

you can not cycle the abs while doing a brake bleed, i did mine on the weekend using tech 1 and its not listed, i think from memory the vs one can but vr's cant

i also have a hard pedel but its not low, im broke at the moment so im not even bothering with dignosing it, also it passed blue slip like that and it still stops the car.

vr abs master SHOULD (im not saying it is) be the same as vs abs but if you are going new i would ask for one for your model and year

 

[Brett_jjj]

you can not cycle the abs while doing a brake bleed, i did mine on the weekend using tech 1 and its not listed, i think from memory the vs one can but vr's cant

Both the VR Tech 1 cartridges dont have the actual ABS brake bleed menu like the VS cartridges have, but you just go into the ABS tests menu and cycle the solenoids whilst doing the bleeding.Its suprising how much air can be trapped in the ABS modulator.Some of the USA cartridges dont have the ABS brake bleed menu either,most do though.For the ones that dont it just says to cycle the solenoids.Its unbelieveable how much extra stuff the USA Tech 1 cartridges can do compared to ours,they can adjust the speedo for accuracy,they can test the sound systems and the speakers,reprogram the BCM's and ECU's ,Australian cars got none of that until the Tech 2 came out..Even the Tech 2 is out of date over there now,it cant even "natively" read the newer on board diagnostic CAN (Controller Area Network) systems unless theres a CANdi (diagnostic interface) module attached to do the interfacing, (the CANdi module is a bit like the OBD11 interface module that was available for the Tech1. This allows the a Tech 1 to read OBD11 diagnostic systems at the time when it was changing over from OBD1 to OBD11)..GM dealers are using laptops over there in the US now to do their diagnostics.

 

[chrisdoesitbetter]

thanks brett, i dont have a tech tool. ill try rx's technique first then go from there.

 

[Brett_jjj]

If you end up doing no good with it ,try locking up the brakes a few times on some grass or gravel somewhere and then re bleed the brakes.This will cycle the ABS which will let any trapped air go through the ABS modulator,see how they feel then.Also the hard pedal could be a faulty brake booster, you can check the brake booster is working by putting your foot on and off the brake pedal a few times and then hold it in firmly,then start up the engine,the brake pedal should sink in a bit,if it doesnt then the booster is not working.

 

[RX25SE]

Low but hard pedal makes me think its not trapped air, but something like pad knock off, siezed caliper slides etc.


All this talk of air trapped in ABS units interests me. I have never had to cycle a Bosch system to sucessfully bleed the air out. (Bendix system must be cycled).
I understand the Bosch system can be cycled, just never had to do it.

 

[Brett_jjj]

All this talk of air trapped in ABS units interests me. I have never had to cycle a Bosch system to sucessfully bleed the air out. (Bendix system must be cycled).
I understand the Bosch system can be cycled, just never had to do it.

A lot of people dont worry about it as the pedal feel is usually fine for the average driver and most people probably dont notice any difference.Im just fussy when it comes to brake pedal feel and travel.Ive done a couple of ABS equipped VR/VS's now like this and the pedal feel is a bit better than if its not done at all.Id say thats why the brake bleed menu was included in the Tech 1 VS cartridge menu.Holden must have had a few complaints about spongy brakes on ABS equipped VP/VR's.My VS does not even have ABS thank god.I dont go much on it .Most VS's that Ive seen have it fitted.