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Discussion Starter · #1 ·
2 Brake Pressure light shining brightly today thank you.

Are there any simple things I can check to start off with.....could it be fluid level????

The glass check levels look ok but of course I cant start it because the battery is flat. After 4 mins of running to these level change significantly?

many thanks.

I've an idea I might be busy on here. :?
 

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You say you can't start it, so I presume you mean you're getting the two brake pressure lights on when you just turn the ignition key on (without the motor running)?

If so, and it's been a week or so since it last ran, then that could be more or less normal. The accumulators will keep a charge for a couple of days, but the brake/height control system isn't usually 100% tight and so over time the accumulated fluid leaks through and back to the reservoir. If the lights go out within a short time (15 seconds?) after starting the engine, then everything is probably up to snuff.

Note: on the SSII/T2 (at least), the fluid level is a separate warning light.

Jeff.
 

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there may be trouble ahead

If you can give bit more info then can probably help.
Does the light goes reasonably quickly when engine running ?
does light come on if you press pedal with engine running?
need to check fluid levels with engine running for 5 minutes to allow height control to sort it self out Only top up with RR 363 brake fluid
 

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Discussion Starter · #4 ·
Sorry.....My rambling isn't very clear.

I drove the car yesterday and all was Kool and the Gang.

I started the car today with a jump pack (battery flat) and the " 2 brake pressure" light is illuminated.

Drove the car for a few cautious miles and parked her up. Decided to check the level a couple of hours later but needs to run and wont start till I get new battery.

Brakes seemed to operate OK though I didn't stand on them but the basic operation appeared to be the same as before (no change in pedal feel)
 

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Viper,

I say this not to be depressing or cruel, but if you own a car from Crewe there will be trouble ahead. The only question is how much. Shadows in particular seem to be "perpetual project" cars even when they are in excellent shape.

Just FYI, you will not ever notice a change in pedal feel in these cars like you do with a conventional braking system. The brake pedal does nothing more than opening a valve to let hydraulic fluid under pressure go where it needs to go. The whole "Oh, heavens, it's slowly (or quickly) sinking to the floor" experience just doesn't happen. That's what makes the potential danger from bad accumulators even worse.

I had posted the prior information several years ago but cannot find it via a search, so I'm posting it again. Doing the "Brake Pedal Pumping Test" is a quick and dirty way to determine if there are issues with the accumulators. If you have your pressure lights coming on in under 30 pumps (and some people would say 40) then you probably need to rebuild your accumulators and accumulator valves. Once you restart the car it should not take any more than 30 seconds for both pressure lights to go out if things are working as designed. However, if they go out instantly then suspect you have a burst accumulator diaphragm.
The formal diagnostic steps are for isolating the location problems in the whole system.

-----------------------------------------
Testing the Rolls-Royce/Bentley SY Series
[Shadow/T & Shadow II/T2] Hydraulic System

1. Make sure the system is *COMPLETELY* depressurized. The easiest
way to do this is to turn the key to the RUN position *without*
starting the car. Pump the brake pedal 50 to 70 times until the
Brake 1 and Brake 2 pressure warning lights come on. (If only
one warning light comes on after 70 pumps, you probably have
a bad pressure sensor for the system that hasn't lit. If neither
light up *both* are probably bad.) You definitely need to pump at
least 30-50 times *after* the pressure lights illuminate to completely
depressurize the system.

2. Slowly turn and remove the bleed screw on the accumulator you are
testing and screw in a proper pressure gauge.

3. Start the car. In a PERFECT system:

- The gauge should quickly go right up to 1000 PSI. THis is
called the "flick up pressure" and directly relates to the
amount of nitrogen charge in the lower half of your accumulator.

- After the initial flick up the gauge should start rising higher
and higher until it reaches 2500 PSI and stops. This is called
the "cut out pressure".

- The gauge should then drop by about 100 to 150 PSI and then stay
steady between 2350 and 2400 PSI. This is called the "fall back
pressure."

4. Turn the car off. The pressure should now stay steady. If the pressure
drops at this point you have a leak somewhere in the system that could
be internal (some internal valve not closing when it should) or external
(a leaking o-ring in a valve somewhere. You may see dripping or, more
often, a "crust" has formed over time where there is a tiny, slow leak.)
If you've got a leak, find it and get it fixed before starting this whole
process again.

5. Start the car again and pump the brakes or activate the height control to begin using accumulated pressure. The gauge should drop slightly each time. When the decreasing pressure drops to between 1750 and 1850 PSI the accumulator valve will open to begin pressurizing the system again. The pressure at which the valve opens again is called the "cut in pressure."

6. The gauge will then begin rising, going back up to the cut out pressure of 2500 PSI then drop back down to somewhere between 2350 and 2400 PSI, the fall back pressure. *ANY* loss of pressure if there has been no activation of the brakes or height control indicates a leak *somewhere* in the system.

7. If there is a leak, you need to keep isolating the different components until you find the problem.


Some examples of possible problems:

A) System is depressurized to 0 PSI, you start the car and the gauge rises slowly and steadily to 2500 PSI, then falls back to 2350 and holds steady. You turn the engine off and the pressure continues to hold steady:
YOUR ACCUMULATOR LACKS ITS NITROGEN CHARGE.
YOU KNOW THIS BECAUSE THE FLICK UP IS ABSENT.

B) System is depressurized to 0 PSI. Engine started and gauge goes quickly to 600 PSI [flick up present, but low] then rises slowly to 1900 PSI and stays there. Turn off the engine and the gauge slowly falls back.
YOU HAVE AN INSUFFICIENTLY CHARGED ACCUMULATOR AND
A PROBLEM WITH THE ACCUMULATOR PRESSURE VALVE.

C) System is depressurized to 0 PSI. Start engine and a quick rise on the gauge to 1000 PSI [correct flick up] then steadily rises to 2500 PSI at which point it settles bak to 2350 PSI [correct fall back]. When driving the car you feel a clunking sensation that seems like a misfire (but you know the engine isn't misfiring).
YOU ARE FEELING THE BRAKES ACTIVATE WHEN THEY SHOULDN'T. ONE
POSSIBLE CAUSE IS THAT THE SOLENOID VALVE THAT CONTROLS THE SPEED
OF HEIGHT CONTROL IS ENERGIZED AT THE WRONG TIME (CAUSING FAST
LEVELING BEHAVIOR WHEN IT SHOULD BE SLOW). MORE LIKELY, THOUGH,
IS THAT YOU HAVE A PLUGGED UP RESTRICTOR VALVE THAT'S CAUSING
FLUID BACK PRESSURE.
-----------------------------------------
 

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there may be trouble ahead

Just one thing to add to previous reply. when pumping down the brake pedal remove the caps of the brake fluid tanks or cover over with rag. If you leave caps on brake fliuid can come out of the 2 little holes in caps and damage paintwork!
 

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Discussion Starter · #7 ·
Update today.

Removed the lid on the resevoirs and the baffle plate and had a poke around with my finger. Didn't seem to be any lumps but did stir up a bit of cloud in the fluid.

Anyhow....replaced the battery and fired her up. Red light stayed on as per usual but went out after a few minutes. Not sure why but seems ok for now.

Heater motor doesn't work now.......but I guess it might tomorrow. :lol:
 

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there may be trouble ahead

If the light is staying on for several minutes it sounds as though the pressures has gone from the accumulators. Whilst with the engine running the pumps on the engine provide the pressure for the braking system the accumulators give the reserve pressure ie if the engine stalls the brake will work until the accumulator is exhausted then you will have no brakes!!
easiest way to check take off caps from reservoir after running engine for 5 minutes or so switch off engine and pump pedal till light comes on. Good pressure would be approximately 40 pumps if only a few really need to have pressure checked with gauge by someone who knows what they are doing.
 

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Brake-problem

If your brakefluid lookes cloudy, i would have it changed in a decent workshop and let them inform you about the brakelights too.
The fluid may be mixed with water after some time; it should be changed at least every 2 years, but even better every year.

It cannot be that expensive for a start and will feel a lot better wright ... :shock:





:arrow:
 

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If you're having the brake fluid changed (which you should) you should definitely have the brake/hydraulic system flushed as part of that process as well.

The fluid in my 1978 Shadow II was cloudy (very cloudy) two years after I'd had it changed out while other issues were attended to. Much of that was crud that remains circulating throughout the system unless you flush it.

Full step-by-step directions: here.
 

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I suggest you check when the last big service was undertaken. In this service all flexible brake pipes are changed. Because of low mileage most cars need this change each (say) 7 years rather than 75,000 miles (if I remember the RR service interval correctly).
These pipes do deteriate leaving debris in the fluid, and can become blocked or at least restricting the flow.
I have changed the pipies myself and included changing the brake piston seals as well. It was not too expensive, but because of the labour content it significantly hurts the pocket if done professionally.
If in doubt do not leave it. At best deteriorating pipes will quickly re-contaminate the brake fluid, at worst brakes will fail.

All the best

Phil
 

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There may be trouble ahead

THe recommended interval for hydraulic services are 96000 miles or 8 years
and it is important that all hoses and caliper seals are changed if hoses aren't changed hoses collapse which inturn causes brakes to bind and in serious cases all the grease in rear hubs to melt major work and cost. If you allow I hour per hose to change you can see that costs in a garage will soon mount up (10 hoses on brakes + 5 on height control) You need to ensure that RR 363 Fliud is used when you change brake fluid and probably need about 8 pints to refill and bleed system . not meaning to scare you
 

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The "official" change interval is, I believe, six years though I know of very few people who follow it.

I will second your sentiments but add this: unless you're a stickler for authenticity or intend to enter the car for judging I would strongly suggest you look into having braided stainless with teflon "core" hoses made. These can be made for not much more than the original rubber hoses but, unlike those, their service life is "virtually perpetual". The only thing you must be more careful about with these hoses is that you don't kink them, since this makes them not fit for use.

After having replaced virtually all (haven't yet done the high-pressure hoses - those will happen when I rebuild the accumulators) the hoses in the system I can honestly say you shouldn't have any problem with kinking unless you stupidly do it yourself. The hoses to the wheels do flex, but not to the extent that they should kink.

If you want to use rubber hoses, I put together a full chart of substitutes (with the same SAE Specs) that can be obtained for far less money in the Rolls-Royce & Bentley Parts, Repair, Restoration & Other Resources Compilation. One shop in the U.S.A. that makes the teflon hoses is in there as well, though there are many shops that do brake lines that can do this. Just be certain that any teflon hoses you order will be street-legal, as there are varieties for racing that are not.
 

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It's not literally 1 hour per hose, but some of the things are such a pain in the %$&*^% to get to and remove that I wouldn't be surprised that this is the average.

You also must remember the job isn't just "pop 'em out and pop 'em in." Most of the fittings are coated in undercoating, which must be removed completely before starting, and you must be really, really assiduously clean around all of the connections and use blanking plugs (if you've got them) or some other barrier (I used Glad Press-N-Seal) to keep any trace of free floating dirt out.

Replacing the hydraulic hoses is not, overall, difficult but it is a long and tedious process. Also, some of the spaces you have to get into are very, very tight, so a set of stubby wrenches (possibly ground down to make the heads thinner) are a must.
 

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I think Brian has provided some excellent advice, but I'm a bit more skeptical about the benefits of stainless braided hoses. They're great on a race car where they're swapped out every few years (and where you need the increased pedal feel). But they have some issues on passenger cars, and the brake feel won't improve on a RR (or Citroen) because its a pump-driven system.

On an uncovered stainless hose, dust and grit gets in under the stainless braid and then the braid moving back and forth over the abrasive erodes the hose underneath. You can overcome this by wrapping it (yet again) in shrink-wrap tubing or something, but at some point it becomes more trouble (and expensive) than swapping out rubber hoses every 8 years. (You can also get hoses that come with the outer sheath from the start, but they're not as popular because they don't have the stainless "look".)

But for me the main issue is seduction. I'd rather be "forced" to go over the brake system every 8 years, then be seduced into thinking I can let it go a bit longer because all the hoses are probably fine....

Jeff.
 
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