[wookieecantina]

Hello,
I recently purchased an extremely well cared for 1976 Silver Shadow, simply beautiful vehicle, but the brake 1 light is coming on while stopping and when brakes are applied slightly harder, the brake 2 light will blink but then stop. The brakes seem to be working fairly well, no noise, but the pedal is tad bit hard, not like a standard Shadow's brakes.
There is also a loud ticking coming form the engine near the distributor, so I'm thinking it could be a hydaulic pump.
Can't see any visual leaks, but perhaps a broken return spring is preventing adequate pressure from being built.
Any help would be dearly appreciated! I have a 1959 Cloud I and she's such a simple vehicle. This Shadow is very much a completely different vehicle but a true pleasure to drive.
Thank you for any assistance!

 

[guyslp]

Do you have the service records for the car?

The first thing that comes to mind based upon your description is that your accumulators are shot and need to be rebuilt. The fact that the lights both go out quickly suggests, at least, that the pumps are doing their job.

Here's the way to do a fairly exhaustive check of your hydraulic system and to isolate (in most cases) the source of problems:

-------------------------------------------------------------------------------------
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 switch for the system that hasn't lit. If neither
light up *both* are probably bad. That, or the lights themselves are
burned out, and you should know whether this is the case or not when
you try to start the car and the warning panel does its "light all the
lights to show you they're working" bit.)

This step is also a "quick test" of how your accumulators are doing
in terms of accumulating pressure. If the indicator light for either
system comes on in less than 30 pumps you can be almost certain
that the nitrogen charge in that system's accumulator is less than
1000 PSI and that the accumulator should be rebuilt. If the indicator
light comes on after less than 10 pumps, you may very well have
a ruptured diaphragm [which basically means that were the engine
to stall you have no brakes for that system almost immediately. NOT
GOOD.]

[To complete the "Quick Test",
AFTER BOTH LIGHTS HAVE ILLUMINATED:
1. Start your engine.

2. Observe your warning lights. They should go out after
10-15 seconds.

a. If a light goes out in just a second or two, it's
almost certain that you have a ruptured diaphragm
and the accumulator is being brought up to pressure
by being filled with fluid. If this is the case, YOU HAVE
NO BRAKING IN THAT SYSTEM IN THE EVENT OF AN
ENGINE STALL!!.

b. If they go out after longer than about 15-20 seconds
you probably have a depleted nitrogen charge.

IF EITHER a OR b is the case you need to have your
accumulators serviced. Circumstance 'b' is suboptimal
and circumstance 'a' is downright dangerous.

END QUICK TEST]


2. After you are certain the system is completely depressurized, slowly
turn and remove the bleed screw on the accumulator you are
testing and screw in a proper pressure gauge. Make sure that this
gauge has been used ONLY on RR363 based systems. Mixing even
the smallest amounts of RR363 and the later mineral oil hydraulic
fluid can create a BIG mess.

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.

-------------------------------------------------------------------------------------

Good luck.

Brian

 

[wookieecantina]

Thank You Truly!

Dear Brian,
I truly cannot thank you enough! You spent a great deal of time researching this topic and I'm so grateful for your assistance!
The widow we purchased this Shadow from could not locate any records, although she promised to mail them to us should they appear. She had a fellow who ran a limo business assist her in the care of the Rolls after her husband passed away and while he honestly seemed to care for her, he had his own mechanic complete much of the maintenance.
Judging by what you have stated, it does sound as though the accumulators are bad. The car levels and rides wonderfully, which sounds as though the accumulator 2 is probably not quite as bad as #1, but should be rebuilt also.
Wow, you have truly saved me a great deal of time, I can't thank you enough.
I'll try to pick up some gauges and diagnose a bit further. We have a shop nearby who comes very highly recommended but finances are a bit tight and being able to repair myself would be terrific.
Thank you again Brian, have a wonderful weekend!
Dale

 

[guyslp]

Reposted below with a few updates needed after several years have passed and more information has become available.

 

[wookieecantina]

ALL FIXED!

Well, it took some time and a little money, but the tools to repair the accumulators arrived from the UK and after a very tiring weekend, both accumulators, both brake pressure switches and both accumulator valve body assemblies are now rebuild!
Thanks to Brian for his wonderful advice!

 

[mattjdduncan]

Blimey Brian, I could not have put it better myself.

And well done for overhauling the spheres they are a pain. I always had to wack the hell out of them before I could split them, even with the proper tool.

For the next time you can buy reconditioned spheres and valve bodys on an exchange basis.

Matt.

 

[mattjdduncan]

Blimey Brian, I could not have put it better myself.

And well done for overhauling the spheres they are a pain. I always had to wack the hell out of them before I could split them, even with the proper tool.

For the next time you can buy reconditioned spheres and valve bodys on an exchange basis.

Matt.

 

[wookieecantina]

Wonderful Support From The Forum

This forum has been so exceptionally helpful during my Shadow education, thank you to all.
One thing I did notice on the accumulators, was the amount of torque required to split them. I purchased a 3/4 air impact, as in the Curzon video, but even at 100 PSI it was not enough. Then I realized my airline was only a 1/4 diameter, and it should have been a 1/2. Using a cheater pipe on a 3/4 drive breaker bar, the rings finally broke free. I'm actually 6'7, 290 pounds and it wasn't easy. This led me to believe that the last mechanic who assembled the accumulators probably used a 400 ft lb impact gun and tightened them purely with the impact gun, not a 3/4 torque wrench set to the specific required torque.
Just my impression and perhaps something to think about for those soon to take on this job.
I purchased a used 3/4 drive torque wrench on ebay for approx. $140.00 which was tremendously helpful.
Thank you again for your help and patience!

 

[mattjdduncan]

When ever I used to overhaul the accumulators I used to remove the caps, depress the valve to ensure no gas left in, thenI would lay the sphere in its side on an anvil and hit the ring with a 4.5 lb hammer. I would have to hit it very hard several times before I was able to split them.

When doing them back up I would put the valve together in the top, fit the new diaphram, then I put the two halves together and spin on the ring, As the torques are about 400 lb ft we would use a 2 meter scaffolding bar and hang on it. They have to be tight as they hold such high pressure.

Any way well done for doing them

Matt

 

[guyslp]

FYI, to anyone following this thread, rebuilding accumulator spheres requires a special set of tools and is not, generally, a DIY job. If you can get access to the tools to disassemble the accumulator spheres and a nitrogen tank and the connection to charge them it is possible, but not an easy job.

You definitely need a very, very solid workbench to attach one part of the accumulator-splitting tool to and, often, will need two people to get sufficient torque to open the accumulator. When reassembling it, be sure to use some anti-seize compound on the threads to make it easier for the next person who has to rebuild them.

The accumulator rebuild kits (a diaphragm and a few other assorted bits) are to my knowledge available available exclusively from Crewe original parts suppliers. These days that means an authorized Bentley dealer.

There are several people in the U.S. who rebuild these accumulators. If you want an extensive list of resources for parts, repair, restoration, etc., then click on RR & Bentley Parts, Repair, Restoration & Other Resources Compilation on Google Docs to download the file.

If you are doing this job you should also plan on flushing and bleeding your entire hydraulic system. This is easier to do than one might expect. Take a look at SY Hydraulic System Flush & Bleeding Instructions for specific step-by-step instructions.

 

[Challenged]

Hi. Thanks for your posts. I now feel less overwhelmed but still intimidated. I just got a beautiful one owner 1975 Silver Shadow with only 19,000 miles. It's 17,000 mile service was done in 1997. However, it is suffering from lack of use. On my first drive the brakes failed. With the exception of the not stopping part the drive was still a blast. The pedal went to the floor leaving me with slight braking capability and the warning lights read "1-Low Pressure" and "Master Cylinder". I noticed that some smoke came from the left rear wheel arch area and the rim was warmer that the others. I took the wheel off and noticed that the caliper releases a little slowly but does seem to fully release. I believe I have most of the records and a lot of maintenance work has been done to this car over the years. Unfortunately, I see that the system was filled with DOT4 in 2006. I plan on keepng this car and I want to drive it. Any ideas about where to begin?
All the best.
Raymond

 

[guyslp]

Congratulations on your purchase! Not to make you feel more overwhelmed or intimidated, but do expect to be taking some significant time and effort to make this car truly roadworthy again. You are one of those people who have a car that is dying from both disuse and deferred maintenance (both very common with cars from Crewe). I mean, 19K miles on a 36-year-old car works out to less than 600 miles a year driving. Cars need to be driven to work well and keep working well. The good news is that the more you drive your car, once things are put right, of course, the better it will get and stay.

From everything you've described it's obvious that you are going to need to do a complete overhaul of the hydraulic and braking system. Your first focus should be replacing every flex hose on your system. The problem you describe on the rear is a classic sign of hose collapse from the inside. As these hoses age and react with the RR363 hydraulic fluid they "get spongy" from the inside out and eventually lose the ability to remain open when the hydraulic pressure is withdrawn on braking, which keeps the brake at least partially activated for a very long time once your foot is off the brake pedal. This, of course, generates a ton of heat in the wheel in question. In a worst case scenario it can get so hot as to melt the grease out of the wheel bearings and cause failure.

Were I redoing my hoses again I would strongly consider having a set made up that are PTFE (Teflon) core hoses with a stainless braided sheath with a plastic coating over that. This style of hose has the advantage of being plenty strong enough (provided you get ones rated at over 3000 PSI burst strength, and most are) and the Teflon is completely non-reactive, so the service life is greatly extended compared to conventional rubber hoses. There's a full chart of all the hoses in the system in the resources compilation referred to in earlier posts.

Your system should not be running on straight DOT3 or DOT4. The only officially recommended brake/hydraulic fluid for these cars is Castrol RR363. This is a DOT3 fluid that has additional lubricating additives for the brake pumps in these cars, which are machined to insanely close tolerances and use no seals internally. The only lubrication for the piston is from the brake fluid itself. There are some who are using either DOT3 or DOT4 mixed 85% to 15% castor oil. Should you choose to do this it is an "at your own risk" proposition, but it's better than straight DOT3/DOT4 as far as the pumps are concerned.

Your accumulators are almost certainly shot by now as well. The testing technique for this has already been outlined in a previous post.

Good luck in getting things sorted out. With sufficient time, effort, and patience you will be rewarded with a wonderful, and actually pretty reliable, car (provided that you keep using it and maintaining it to "keep the juices flowing").

 

[Challenged]

Brian,
I believe you are right about a complete overhaul. I think i will try and make this a rolling repair constantly refurbishing as I go. I plan to flush the system with DOT3 and replace it with RR363. Then, replace all the hoses, overhaul the master cylinder and replace the accumulators. I hope that will see me mobile. Then, in short order I will begin replacing/repairing all the hydraulic brake components and then, all things being equal, move on the rest of the hydraulics.
I have sourced the hoses, fluid and master cylinder kit and I am now sourcing the accumulators. The more I investigate this system the more I realise how simple the concept is and how ingeniously convoluted the paractise is! Thanks for the great information.
Sally forth!
Raymond

 

[jeyjey]

Raymond,

I think you just need to do the accumulators, rubber hoses, and flush/refill to get you going. The master cylinder is only used on 1/2 of the rear braking system so isn't as critical (in fact, it was dropped entirely on later cars).

Jeff.

 

[guyslp]

Brian,
I believe you are right about a complete overhaul. I think i will try and make this a rolling repair constantly refurbishing as I go. I plan to flush the system with DOT3 and replace it with RR363. Then, replace all the hoses, overhaul the master cylinder and replace the accumulators. I hope that will see me mobile. Then, in short order I will begin replacing/repairing all the hydraulic brake components and then, all things being equal, move on the rest of the hydraulics.

Raymond,

Several points:

1. Given the condition of your system, I would not plan on a "constantly refurbishing as I go" with the exception of the height control valves, solenoid valve, and height control rams. Your system is clearly in need of overhaul and you will end up having the "neverending project" if you don't do most of it in one fell swoop. It actually sounds like that's your actual plan, but I want to re-emphasize that this is the way to go in your situation.

2. Given the current price of RR363 I would not do a flush and fill and then go back and lose all that RR363 to replace all your hoses, etc. I say this because the way you wrote this makes it appear that you are planning to do a system flush and fill then "hope for the best" and replace afterward. Believe me when I tell you that you do not want to do this. Once the system is drained replace all your hoses, rebuild the accumulators and accumulator control valves, then do a system flush with DOT3 until everything coming out of the various bleed screws looks fresh and clear. Let the DOT3 drain out then, as the final step, fill with RR363 and bleed the system. In my "How to Bleed & Flush" documentation I mention that you really want to open your reservoir and check things out first, too. What is found in there is often shocking.

3. My experience so far is that for most of the valves that are not exposed to extreme heat (read, anything except the accumulator valves) the only seals that break down are those that have exposure to air. On the height contol valve this was a single seal. I've not touched my rams or the solenoid valve, either. These valves go without trouble for several decades, at least, from new or after a rebuild. Unless they're leaking, or you just feel like doing them for the sake of it, I wouldn't touch them unless something shows signs of a leak. There are many parts of this system that definitely fall into the "if it ain't broke, don't fix it" category.

4. Know that the brake distribution valve in the "rat trap" is designed to leak, though very slightly. It is absolutely normal for there to be a drop of fluid hanging from this valve and a "splash area" on the bottom of its cover where previous drops have fallen and dried. This is documented in the workshop manual. Many people panic when they see this drip and presume something needs to be fixed when it doesn't.

5. I'm kinda with jeyjey with regard to the master cylinder. When you're doing the DOT3 fill and bleed before doing the full purge of the DOT3 fluid see what happens with that warning light. Things might be just fine. I'm guessing this all spins off of the accumulators being shot.

 

[Challenged]

All,
I think we are on the same page. I have a reservoir kit and hoses enroute. I plan to drain the entire system, clear lines, replace the hoses and then flush it with DOT3. I have an exchange arranged for both accumulators and will fit them when they arrive. At that time, Ill drain the system again, refill with RR363 and bleed. Your description of the distributor is perfect. I'll see where I am then...hopefully mobile! If mobile, I will start replacing the seals on the rest of the valves one at a time or in groups to include the brake calipers, brake pump kit, height contol solenoid etc. Basically, anywhere sludge or deteriorated seals may start from or settle. I hope to have it all completed in just a couple of months or less.
I wonder if Robert Burns had a premonition about Rolls Royce when he wrote his poetry!
Thanks to all and I will keep you posted.
Raymond

 

[lordphi]

Raymond, you state "I have sourced the hoses, fluid and master cylinder kit".
I hope this does not mean you have purchased them, because your car (as per your earlier posting = 1975 SS) does not have a master cylinder.

I have changed all the flexible brake hoses on my 1976 SS. It is time consuming but not difficult. Apply plenty of penetrating oil to the fittings before starting and use good quality spanners to avoid damage to the fixed brake pipes. Some are very difficult to replace.
I would recommend changing the brake caliper seals (or, if rusted, complete pistons) whilst the system is empty of expensive RR363 brake fluid.

Phil

 

[rollmech]

Raymond,

I think you just need to do the accumulators, rubber hoses, and flush/refill to get you going. The master cylinder is only used on 1/2 of the rear braking system so isn't as critical (in fact, it was dropped entirely on later cars).

Jeff.

While agreeing with all the comments already said , the master cylinder does in fact give the brake pedal 'feel' so if the brakes feel ok leave alone if ever while driving the pedal goes to the floor you will need to sort out the master cylinder. On late cars a rubber cone was used to give the brake pedal feel

 

[guyslp]

Two small additions to this thread for the historical record.

The master cylinder was deleted beginning in June 1975 at chassis number 22073 for the Shadow LWB and at chassis number 22118 for the standard wheelbase Shadow. It's entirely possible to have a 1975 Shadow produced before these chassis numbers that has a master cylinder.

Also, although the master cylinder's job is to give some semblance of brake pedal feel, it is not the primary mechanism for returning the brake pedal back to its neutral raised position. That's done by a spring. See figure G56 on PDF page 82 of Chapter G - Hydraulic Systems of the Workshop Manual (TSD2476).

Brian

 

[Pillow]

This will hopefully add to the discussion on the "alternatives" to the RR 363. From a Citreon discussion about the issues they have in finding hydraulic fluid, yes RR is mentioned.

The author seems to recommend Texaco Biostar 32 as a suitable replacement for the Citreon system, which should apply to the RR 363 as well since they are similar systems designed by Citreon.

http://citroen.cappyfabrics.com/tony.html

Not to put words in Brian's mouth, but I believe this Texaco Biostar 32 is what he referred to as the substitute he was thinking about trying.

YMMV...