Rolls-Royce and Bentley Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
62 Posts
Discussion Starter #1
The time has come for a new accumulate sphere on my 1976 SS (number #1 system). I purchased a beautifully rebuilt and charged unit from British Tool Works – it looks factory new (below).

I'm not a mechanic and this will be a first-time attempt at this repair. I’ve been reading the manual. However, it’s still not clear to me whether or not I have to remove the entire accumulator assembly, or can I just depressurize the system and remove the sphere from the value body while the valve body remains attached to the car? I understand removing the sphere can be tough and I have chain wrench on standby for that. The last time this sphere was replaced was 4-5 years ago by a RR shop, so I presume they did not over tighten.

To me, it looks like the Sphere simple unscrews by turning the nut under the charging-value cap.

Please share if you have knowledge of this procedure.
Thanks.

28418

28417


1594345450165.png
 

·
Registered
Joined
·
666 Posts
It's certainly worth a try. Just be very careful not to inadvertently unscrew the two hemi-spheres, as noted in the instructions you displayed. I personally would fully discharge the accumulators first to make them safe. I believe Kelly sells a tool to do this.

If they are too tight then removing the spheres and acvs as a unit will be the only option - just 3 pipes and 3 bolts and they are off. Sounds easy - the problem is accessing them. I used a variety of wrenches, sockets and wobble extension bars when I did the job, working from the side with the front wheel removed. Think keyhole surgery. If you have a lift then I suspect the job would be much easier.

If you do have to remove the acvs make sure you use two wrenches on the high pressure pipe from the pump, otherwise you might twist and split it.

BTW you are right, the sphere simply unscrews from the acv - the problem is it can be very very tight.

Geoff
 

·
Registered
Joined
·
62 Posts
Discussion Starter #3
Many thanks, Geoff! And thanks for the tip about using two wrenches on the high-pressure pipe coming from the pump in case I have to go that route.
 

·
Registered
Joined
·
666 Posts
Here's a bit more detail on having to use 2 wrenches. The red arrows in the first pic point to the two unions. The top union has to be undone whilst the lower one is held steady. If the lower one loosens the pipe stays clamped and it's easy to twist it. If you have to go this route, undo the pipe marked with the yellow arrow first - it can be moved out of the way to allow room to undo the other one.

Just in case you have not worked on the accumulators before, the red arrow in the second pic points to the lower support bracket. Just undo the five 7/16" bolts/nuts and remove it. You will need a deep socket to get onto the large sphere nut.

I'm interested how you get on and whether you are able to unscrew the sphere, so keep us all posted

Geoff
 

Attachments

·
Registered
Joined
·
2,176 Posts
Suggestion: I'll add a bit to D's wrench'g. I would add PB Blaster or similiar product and soak the union. I also use a micro butane pencil torch to expand the female flare nut. Wait until it cools and try to crack.
Be patient, you do not want to twist the the pipe. The adapter fitting may be hard to hold with a standard open end wrench. A very slim wrench is the key.
 

·
Registered
Joined
·
666 Posts
Hi Wraithman - I'd just like to tap into your expertise on these cars - have you ever removed the sphere only or do you always remove them with the acv?
 

·
Registered
Joined
·
2,176 Posts
Anything and everything. I completely take my cars apart and put them back together. You can have a 2 steop plan.
1. De-pressurize the sphere(s) for safety
2. Now you can try to twist the sphere off with a socket or strap/chain vise grip.
3. Worst case is to remove the entire assembly. A plus is you can send the regulator to Kelly for a superb re-build. They can also be tested as a system, knowing they meet factory specs. Peace of mind is priceless.
 

·
Moderator
Joined
·
565 Posts
We always remove the whole assembly and rebuild the valve too. It is false economy to just replace the sphere unless you have service history showing fairly recent overhaul of the valve. By the time a sphere diaphragm needs replacing, the seals inside the valve will need replacing too and it will need cleaning out and shimming the spring to the correct relief pressure. I can't think of a single instance where we've removed the accumulator valve assembly where it was not full of muck and corrosion unless the client had religiously flushed the brake fluid every two years. I'd say that 10 to 12 years would be an acceptable time between rebuilds if the fluid was flushed regularly but much, much shorter if not, especially if the car sat unused for long periods of time. The climate the car is used and stored in will affect that time somewhat but as a general rule I think one can count on that kind of time frame between accumulator valve rebuilds. That's my experience with the Shadows that come into my shop for brake work.
 

·
Registered
Joined
·
3,547 Posts
I'll be the contrarian here, at least to an extent.

Having now removed and rebuilt accumulators and accumulator control valves on multiple occasions, I offer the following observations:

1. You definitely need to depressurize the brake/hydraulic system first, which is easily done with repeated pumping of the brake pedal while the key is in the run position but the car is not running.

2. Unless something I have yet to ever see or hear of has occurred, the probability of accumulator halves ever coming apart when attempting to unscrew it from the ACV is so remote as to be not worth consideration. Draw a line across the retaining ring and on to the accumulator halves so that it would be easy to note if they go out of alignment with each other at any point in the removal process. Don't count on that happening, as the torque specs for that retaining ring are so high that the probability of it coming loose is virtually zero.

3. I have known of others to use the hex fitting on the bottom of the accumulator to get the whole thing started as far as removing it from the ACV. The torque for the accumulator to ACV is only 55-60 ft-lb (which isn't all that much more than the lug nuts are, at 45-50 ft-lb - See Chapter P in the Workshop Manual for torque tightening figures). Anyone who's ever removed or replaced the wheels on our cars knows that they have a much lower torque on the lug nuts than is typical for those with steel lug nuts. You should not have to exert much effort at all to break the accumulator free from the ACV if you wish to leave the ACV in place.

4. The ACVs are not nearly as difficult to rebuild as "myth" would have it. Been there, done that, got the T-shirt, and have posted about it multiple times in the past.

5. Be careful with torches around RR363 or YAK363, as it is flammable. Make sure you've soaked up every last bit that you can before using a torch, and don't be surprised if you get a quick burn off, with flame, if there is a small pool somewhere around what you're heating.

6. READ THE TORQUE TIGHTENING FIGURES BEFORE REASSEMBLING ANYTHING. There is a tendency to believe things should be much tighter than Crewe specified.

7. If you are putting an ACV back in place on the car, do not tighten down any of the connections completely until all the connections have been started for both the fluid pipes and the bolts that hold the ACV to the car. It's far easier to have freedom of movement until you have each and every connection started and then methodically tighten all of them down to the specified torque.
 

·
Registered
Joined
·
666 Posts
Hi Brian - good to see you posting again.

The thing I found when trying to split the acv/sphere (on the bench - I had removed both as a unit from the car) is that although the torque setting was only 55-60 ft lbs, the two had "welded" together over the years. I could not budge them with a wrench and the acv held loosely in a vice (to prevent rotation). Paul Yorke advised me to hold the sphere/acv in one hand, with the acv lowerwards, and tap it off with a copper mallet. Worked perfectly - the shocks from the mallet broke the seal.

I think it is worth Eatonmike trying to remove the sphere in-situ but if he has to resort to hitting the wrench to break the seal then things could get a little hazardous. I agree it's highly unlikely that the hemi-spheres would come apart, but the low risk/ high consequences equation comes in to force.

My last point is unless Eatonmike knows the condition of the acv, then he should take Jim's advice and rebuild the valve as well.

Geoff
 

·
Registered
Joined
·
3,547 Posts
Geoff,

I agree that if "all is of unknown condition" that removing the whole assembly is the way to go and rebuilding the valve is the way to go. It is also much, much easier to rebuild the valve than "legend has it," and I have yet to encounter one that needs anything beyond a good cleaning (if that) and replacing of the seals. I've never touched the fluon bits at all.

I guess I was trying to point out that if you've done this work yourself, and if you followed the torque specs (and, in my case, used the tiniest bit of anti-seize on the accumulator to ACV threads) when putting it all back together you should have zero difficulty in removing the accumulator using the underside hex for the foreseeable future.

But given my personal experiences with getting the accumulator halves apart, I believe it will be a very cold day in hell before anyone ever has even the slightest chance of "the ring being loose" and the halves not moving in perfect conjunction with one another. Even using anti-seize when I put these back together, when the amount of torque you apply involves putting your whole body weight into the effort and at the end of a pin wrench with a 3-foot or longer handle (I can't recall whether I attached an extension for the reassembly, definitely had to during the disassembly, and that only worked after having had the accumulators on a concrete floor and doing a "whack about" [relatively gently, mind you] with a hammer around the diameter of the ring to get it to release its slightly corrosion-welded death grip on the halves) I do not worry that there is any likelihood of the two halves ever moving independently of each other.

I believe at least some of the documentation with regard to the spheres in the SY cars was presented with a really extreme overabundance of caution because they were new to Crewe. Another example of that is the cautions that they give with regard to recharging the accumulators. I have friends who are aircraft mechanics who do this all the time, as well as knowing quite a few techs who work on SY cars, and absolutely not a one of them has an elaborate "charging safety cage" setup as is recommended in the Workshop Manual. If the two halves of the accumulator were truly loose, you'd have no success in charging. And if they are put together to spec, it would take way, way, way more pressure than the recommended charge to blow these things apart. They've got heavy duty walls compared to some of the accumulators used on aircraft, which have to be able to hold charges as high, and often much higher, at altitudes where the external pressure surrounding them is far less than "at or close to sea level."

You know quite well that I am not cavalier about safety in any way. But an abundance of caution is one thing, but an abundance of real overcaution can often trigger accidents that would never have occurred were reasonable, and only reasonable, precaution exercised.

I don't consider even fully charged accumulators to pose any real danger unless someone were to be so idiotic as to try to take them apart without having discharged the gas pressure first. They can be safely handled with a full charge for virtually any service one might need to be performing with them in that state. The later disposable ones are handled in that state by default.
 
1 - 12 of 12 Posts
Top