RR Classic brakes ( or lack of)

[coachman]

Good evening fellow green oval fans :- I am /was feeling pleased with myself for having eventually fitted a coilspring conversion to my RR Classic ,aided by a set of `short ` coil spring compressors .

I fit the springs ( never again ) I also fitted new pads and pins frnt and Rr ,the caliper pistons were quite free to say car had been stood 2 yrs .

I then fitted the road wheels ,the calateral damage so far is 2 lost ( somewhere safe )wheel nuts and a flat tyre ,( not bad for me ),

I then started the engine ,such music mmm.Prior to starting the engine I had managed to `roll ` the car ,quite freely for a big car , BUT with the engine running the brakes came on ,and have stayed on .

There is a `buzzing `coming from under the bonnet ,sounds like an electric motor .My thoughts ( among many ) are that I should have disconnected something when I took the air suspension off .PLEASE DOES ANY ONE HAVE AN ANSWER . i AM SO NEAR YET SO FAR .

The ultimate in all this is ,my daughter is getting married later in the year and I intend for this NIAGARA GREY car to be used as wedding car .If I can refurb ,polish ,MOT ,and make ready then it will be good .coachman .

[duncmc]

The buzzing I guess is your ABS pump. Now that you have started the engine and got the ignition on, power has allowed the pump to pressurize the ABS brakes.

The ABS pump should turn off once it has got up to pressure, ideally after 30-40 secs. Mine currently takes a bit longer (maybe a minute or so) but it needs bleeding properly again.

The ABS modulator blocks can develop sticky valves in them after being stood for a long time, which could allow the brakes to stick "on". The modulator is the master cylinder effectively.

Of course I have assumed you have ABS, but I would expect it because you had air suspension.

[coachman]

The buzzing I guess is your ABS pump. Now that you have started the engine and got the ignition on, power has allowed the pump to pressurize the ABS brakes.

The ABS pump should turn off once it has got up to pressure, ideally after 30-40 secs. Mine currently takes a bit longer (maybe a minute or so) but it needs bleeding properly again.

The ABS modulator blocks can develop sticky valves in them after being stood for a long time, which could allow the brakes to stick "on". The modulator is the master cylinder effectively.

Of course I have assumed you have ABS, but I would expect it because you had air suspension.

Thank you OLD HAND I knew somebody would have an idea .But what do I disconnect if anything .coachman .

[duncmc]

Ok, sorry if I am about to teach you to suck eggs;

Your ABS pump is mounted on your drivers side inner wing between your coolant expansion tank and the brake reservoir.

It looks like this;

Can you feel vibration from this pump when you switch the ignition on? If so does it eventually stop after a few minutes on its own, or does it keep running? If it keeps running just post on here and then we can help you figure out what is wrong.

For the MOT, you can't just unplug something to get rid of the noise I am afraid, you would get an ABS warning light come on and the brake effort would be too low I suspect.

Did you disconnect the Air suspension compressor when you removed the air suspension? The pump is under the sill next to the control valves.

[Bowie69]

Brake effort is almost NOTHING without the pump, scarily nothing when you don't realise it has failed!

[duncmc]

Brake effort is almost NOTHING without the pump, scarily nothing when you don't realise it has failed!

I can personally confirm that too. I had an ABS pump burn out in 1994/5 whilst driving round Eastnor with the Range Rover Register due to a stuck ABS pump relay.