[berni29]

Hi There

My friend has a lovely RR Shadow II that has a recent brake issue. It was his grandfathers car and he went with at the age of 14 to pick it up. He knows the car very well in terms of its behaviour but is not so mechanically minded. I am, but do not know Rolls Royce. The car had a couple of calipers and pipes replaced last year, and the reservoir cleaned out. Now the weather is nice he got the car out and the brake pedal goes to the floor, and the brakes operate in a switch like manner. Before starting the car today I pumped the brake pedal maybe 20 times until a hissing noise (the servo?) stopped, and the pedal did not harden at all. On examining the reservoir glass there were many air bubbles on the glass. They were not present yesterday.

Does anyone know what is the likely culprit causing this behaviour? I was hoping the brakes simply needed bleeding, but I am starting to think it is more than that. On a normal car the pedal will harden when pumped if there is air present in the system. But this is not a normal car!

Many thanks in advance

Berni

 

[Wraithman]

First, RR brakes do not require conventional "pumping" to bleed them. The brake pedal is merely part of a long handle that opens 2 brake distribution valves at over 2200 psi. It builds it's own pressure from 2 brake pumps and stores it in 2 accumulators.
If the car sat for a very long period, I can assure you the car is unsafe and needs extensive brake and hydraulic repair to make it safe. The system is complex, requires above average mechanical know how, almost 2 dozen rubber hose replacements and on.

 

[guyslp]

You are indeed that these are not anything like "normal cars" when it comes to the braking and hydraulic systems.

Who, if I may ask, did the work you describe on the car? It sounds like the system was not properly bled after all that work was completed. See: "The Collection" thread: SY Brakes & Hydraulics - Diagnostics and Maintenance, and specifically the entry on how to flush and bleed the system the easy way.

 

[Jean7]

And depending on the year of your Shadow you may have a master cylinder or not.....low and high pressure or only high pressure....
You should study this also : Rolls-Royce Silver Shadow - Hydraulics

 

[berni29]

Hi Guys

Thank you for your advice. An amendment! The car is a 1977 last of the Shadow 1's!. Here is a copy of the work that was done to the car last year or so.

I have not attempted to bleed the brakes yet. The pumping with the engine off was just to see what happened with the pedal feel.

The bubbles in the reservoir really worry me!

Many thanks again

Berni

 

[berni29]

Hi

Picture of bubbles........

 

[shadow 11]

That looks like corrosion on the zinc plating rather than bubbles.

 

[Jim Walters]

As Shadow II says those are corrosion bubbles in the reservoir coating, not bubbles in the fluid. Common to see this and not a concern. Do the "brake pedal pump down test", found with a search of this site. That will determine the state of charge of the accumulator spheres, which I note on your invoice were not rebuilt or checked last year. You must run the engine to have brake pressure, and the accumulator spheres provide you with a reserve of brake pressure when the engine is off. If low or no nitrogen in the spheres you will have no brakes with the engine off.

 

[KennyK]

On a shadow II, the brake pedal "feel" is produced by two pieces of rubber (one on the rat trap's frame, the other on the pedal lever) bump against each other. Without those rubber pieces, the brake pedal will just act as an on/off switch. Get a diagram from rrtechnical.info, get under the car, remove the cover of the rat trap and take a look. It may be that one or both of the rubber blocks has either perished or fallen out of place.

 

[AlanD]

Berni, where are you in UK? I am in Somerset and have rebuilt several Shadow brake systems. Want some help/advice?

Alan D.