| Author | Message | ||
     Peter Dixon Frequent User Username: petenlinid Post Number: 98 Registered: 8-2003 |
Some time ago I found and read a detailed article on a DIY procedure for removing and replacing accumulator spheres with reconditioned exchange units. I thought it was in this forum but have not been able to relocate it. If it is, or for that matter if there is one elsewhere, could someone kindly point me in its direction. Thanks Peter | ||
| David Gore Moderator Username: david_gore Post Number: 1728 Registered: 4-2003 |
Peter, The article[s] were probably in Tee One Topics - try Issue 54, page 788 has details on removal Shadow 2 accumulator and there may be others in the Index to Issues 1 to 92 which can be downloaded from the Technical Library - unfortunately the index is not alphabetical but is by issue so you will have to go through the lot and then go through the individual issues from 93 to 97 to try and find references to the accumulators. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1607 Registered: 6-2009 |
Peter, Also see the thread Separating the Accumulator from the ACV . . .. Depending on how long your current ones have been attached to the ACV, how much torque was originally applied, and whether or not anti-seize was used on the threads you may be able to simply attach a 15/16" socket on the bottom hex fitting on the sphere and use that to loosen it. Given the amount of torque applied to the ring that holds the halves of the sphere together I find it close to impossible to believe that there's ever been an instance where using that technique resulted in the lower half beginning to unscrew from the ring. Using the pencil marks technique that allows you to see if that were happening is, even according to "the official documentation," precaution enough. Brian | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 438 Registered: 5-2015 |
If the ring moves relative to the sphere then it would explain why the sphere is discharged. | ||
| Peter Dixon Frequent User Username: petenlinid Post Number: 99 Registered: 8-2003 |
Thank you for your responses. I have located a number of articles based on your information. If I may impose further; my reason for changing the spheres is that the accumulator valves and spheres were completely professionally overhauled about 12 years ago. Apart from the pumps being replaced 8 years ago and the fluid changed etc., no further brake work has been undertaken on the brake hydraulics. The vehicle has, due to circumstances beyond my control travelled only 18,000 easy highway and country kilometres in the 12 year period. The purpose of the later pump work was to address low speed activity brake failure subsequent to the work on the spheres. It did not succeed. I still have the problem. Basically under normal driving conditions the brakes are excellent and in emergency style stop test conditions incredibly good. A foot pedal depressurisation test this morning resulted in the pump lights coming on at #1-34 pumps and #2-26 pumps. However any attempt at using the vehicle in conditions such as a street parade requiring very slow speed and possible frequent gentle braking eventually causes the lights to come on. Even a few minutes shunting to park the car can have the same result. I am located about 1300 round trip kilometres from the capitol city engineer I used to use and he was the closest to me. I would be most reluctant to drive in a big city environment anyway. Any suggestions on further testing I could do myself to try and identify the cause of and rectify this problem would be greatly appreciated. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 919 Registered: 5-2012 |
Peter Since your car is not generating enough hydraulic pressure at low revs, I would look first at the pumps and then the acvs. I realize you had your pumps replaced 8 years ago, but are you sure they were set up properly, with the correct number of adjustment shims. It just seems the pumps are still not generating enough pressure at low revs. Worn cam lobes can also prevent the pumps from working properly. The other thing I would be looking at are the ACVs. If they are worn or faulty they may not be allowing the hydraulic system to fully pressurize. Are you intending to repair the system yourself? Geoff | ||
| Jim Walters Experienced User Username: jim_walters Post Number: 37 Registered: 1-2014 |
Check that the filters in the fluid reservoir are not collapsed or clogged preventing full fluid flow to the pumps. SRE22493 NAC-05370 www.bristolmotors.com | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1611 Registered: 6-2009 |
That's a good catch from Jim. You could very easily find the inside of your reservoir looking like this: After 5 years sitting after full hydraulic service:  or this one year after having a complete system flush and fill on a system that had been neglected for some time:  If you haven't already done so, download, Flush and Bleed Your Silver Shadow/Bentley T Hydraulics/Brakes the Easy Way, even if you don't intend to DIY. Brian | ||
| Peter Dixon Frequent User Username: petenlinid Post Number: 100 Registered: 8-2003 |
Gentlemen, thanks for your responses. I offer the following to possibly give a little insight into the matter. The relative work carried out by the mechanical engineer, quoted from the accounts, to rectify the problem was as follows: July 2003 @ 202656 kilometres • “Overhaul both accumulator valves and spheres. • Replace all supply and return hoses. • Clean out brake fluid res. flush through and fill with new fluid”. September 2004 @ 206683 • “Fit pressure gauges and test both systems (found both very slow to recover pressure) holding pressure OK. • Remove and inspect front pump (found to be partially blocked with sludge) rebuilt cleaned out supply pipe, refitted and tested (found now to recover correctly)”. • “Remove rear pump and inspect (not blocked) cleaned and rebuilt, refitted and tested (still very slow to recover). Remove pump return valve, machine surfaces and re-seat, refit and test (found to be recovering correctly). • Remove reservoir top cover clean out and refill with new fluid”. September 2007 odometer not recorded. • “Connect gauge to car and test system. Found pressure recovery too slow. • Dismantled pumps and inspected, found no visible faults, rebuild pumps with new seal kits and second hand pump pistons and barrels. • Bleed system and tested pressure (drove car for several days tested OK • Removed gauge and tested further”. I am embarrassed to say that until I read Geoff’s response I had never considered undertaking the blatantly obvious, a stationary brake pumping test at idle speed to see what would happen. My understanding was that the engineer undertook substantial road testing with gauges attached etc, I have no idea if he actually engaged in the slow moving low revs activities which appear to cause failure. Yesterday I undertook the following: Completely depressurised brakes so both lights came on, turned ignition off and let vehicle stand for 6 hours and then restarted the engine. Light #1 went off immediately #2 took 16 seconds. Left engine to idle until full working temperature was achieved. Stopped engine, turned ignition on conducted brake pedal pumping depressurisation test resulting in light #1 coming on at 37 pumps and #2 at 23 pumps. Restarted the engine and allowed to idle for 3 minutes then raised and held the revs at approximately 10,000rpm and began a pumping test. Light #1 came on at 55 pumps and #2 at 46. I repeated the test with the same results. Subsequently raising the revs to about 15,000rpm the lights could not be pumped to come on at all. Please note I did not use a tachometer and the revs are only a guesstimate. Brian and Jim, thank you for your contributions. A fluid inspection and service will have a high priority. As far as possible I have to do all necessary work myself. I have a reasonable tool selection and am blessed to have my own hoist. The probability is however the majority of more advanced testing will necessitate the use of change over parts to see what does and does not work. Unfortunately I do not have access to a gas supplier or associated equipment for recharging the system if necessary. Brian, the cleaning and bleeding document is fantastic. Can I ask its origin and are there any other similar documents available? Even I can understand the one you have supplied. Sorry for this extended tome folks, I will be indebted and appreciative for all and any guidance and advice forthcoming. Regards Peter | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 445 Registered: 5-2015 |
Don't worry about the extensive tome you are welcome. I reckon that your ACVs and spheres are safe. But still do a flick up test with a gauge connected. The Shadow ONE manual gives the quantity that the pump should output. This is done by attaching a pipe to the ACV bleed nipple and running the engine at a set rpm and measuring the amount fluid pumped out in a given time. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1612 Registered: 6-2009 |
Peter Dixon wrote:
The origin of that document is me, with a great deal of credit going to Richard Treacy for sending me what constituted the skeleton upon which I hung "flesh" as I learned things. I find that I really like step-by-step instructions to have what I call nauseating detail. You can always skip over what you may already know but I want these to be useful to the complete beginner. A few other bits you might find handy for this project: 1. SY Accumulator Recharging Unit & Recharging Steps 2. Building a Hydraulic Pressure Test Gauge (B.Vogel) 3. Building Your Own Hydraulic Pressure Gauge (W. Hunter) 4. If you're unfamiliar with the "flick-up" test that Bob refers to, have a look at this post (or the whole thread, actually) on rollsroyceforums.com: my post on testing the hydraulic system and what various results might mean For other projects: a) Thermostat Issues and Selection b) The SU Fuel Pump: How It Operates c) The SU Fuel Pump: How to Test It d) UD19427 Rolls-Royce/Bentley Coolant Level Amplifier Repair e) The Most Dangerous Job (Containing the front springs & replacing the front shocks) Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 922 Registered: 5-2012 |
Hi Peter I think Brian and Bob are on the money. Here are two very simple tests you can carry out. 1) Remove the reservoir lid and take a look inside. Just undo the 14 setscrews and lift off the lid. Note the holes the setscrews came from so they can be replaced the same. From the above, it appears your brake fluid has not been changed in 6 years, so it is quite possible your reservoir is similar to the ones in the photos that Brian has put up earlier in this thread. This will give you a good indication as to whether a blockage is causing the problem. 2) Carry out the very simple test that Bob alluded to. It is documented in section G6-3 (Hydraulic pumps-To test (on the car))of the series 2 manual. This will give you a very good indication of whether the pumps are causing the problem. The tests you carried out at 10,000 and 15,000 rpm are telling me the pumps are the problem. Here's why. The brake pedal test is meant to give an indication of how much nitrogen pressure is in the accumulator sphere. It is carried out with the engine off. If the lights come on when the brake pedal is pumped with the engine running, then that's telling me there is insufficient pressure being created by the pumps. BTW, I know you gave the engine revs as a guesstimate - you probably mean 3000 and 5000 revs. 10 - 15 is formula 1 race car territory - lol. It would be really interesting if you could carry out the test documented in the workshop manual and report back the results. Geoff | ||
| Peter Dixon Prolific User Username: petenlinid Post Number: 101 Registered: 8-2003 |
Thanks everyone, you have certainly given me plenty to think about and work on. Geoff, the pumps have only done a few thousand kilometres since they were worked on. I have no reason to doubt the quality of the work undertaken by the engineer, he is highly regarded by the RR community here. The revs referred to are a consequence of too much cabernet sauvignon and attempting to one finger type at the same time  . I should have said (I think) the car normally idles at about 700rpm, I slightly raised it to 1,000 and then to 1,500. Hope that makes more sense and maybe reflects on the condition of the pumps. Cheers Peter | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 925 Registered: 5-2012 |
Peter Re: However any attempt at using the vehicle in conditions such as a street parade requiring very slow speed and possible frequent gentle braking eventually causes the lights to come on. Even a few minutes shunting to park the car can have the same result. What happens when the lights come on. Do you lose the brakes? If not and the brakes are working even though the lights are on, then maybe the fault is as simple as the acv pressure switches having springs that are too stiff. Maybe your ACV pressure switches require so much force to turn the lights off, they are only switched off on very high pressure. i.e. when the engine revs are higher. Whatever happens, could you keep us informed with developments. Given the history of your car (well maintained) , this is a curious fault. Geoff | ||
| Jim Walters Experienced User Username: jim_walters Post Number: 38 Registered: 1-2014 |
Peter, the fact that the front pump was partially blocked with sludge in 2004 tells me it is likely the filter to that pump was damaged allowing sludge to enter the pump. Did your mechanic replace the filters at that time? Based on my experience I suspect the filters are the cause of your current problems. I suggest the first thing you do is to remove the lid and baffle from the reservoir and clean it out and inspect the filters carefully. I bet you will find them collapsed. The brake fluid must be changed and flushed every two years to ensure optimal functioning of the brake system. Eleven years is guaranteed trouble. SRE22493 NAC-05370 www.bristolmotors.com | ||
| shane alward Experienced User Username: the_gambler Post Number: 32 Registered: 5-2015 |
hi peter. if you do decide to change your accumulator spheres. there is a guy in QLD ken balmforth that you can do the exchange with he is a really nice chap and his prices are reasonable with fast service. just google him | ||
| Peter Dixon Prolific User Username: petenlinid Post Number: 102 Registered: 8-2003 |
Thanks for that Shane. Took a look at his website. Interesting chap and operation. Can't have too many parts suppliers so he is now noted in my little blue book. Cheers Peter | ||
| Peter Dixon Prolific User Username: petenlinid Post Number: 103 Registered: 8-2003 |
Jim, based on the comments so far and armed with Brian's article a Working Guide on RR Brake Hydraulics for Dummies (an absolute godsend for me) the whole fluid system inspection, cleaning, and flushing process will be my first priority. I had wrongly assumed that because the vehicle had completed so few road miles and that as the fluid system is sealed the fluid and system would be OK. Geoff, when I ran the stationary foot pump test, at the same time the first light came on there was a decided loss of pressure felt on the pedal. The first time I became aware of the problem was shortly after I acquired the car when I was edging into and out of a car parking space. The only thing that stopped me was when I gently reversed into a brand new Ford passing behind. No damage was caused and the other driver was most impressed that the incident involved a Rolls Royce (as he should have been of course). I have been driving for 56years and have never been quite so honoured. I can't begin to start working on the brakes for a little while, I can not afford to have the car completely immobile, it has to have a little panel shop work done (insurance job not my fault  ) so it has to be available on demand. This will also allow me time to source any parts I need, probably from Flying Spares. Salutations Peter | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 447 Registered: 5-2015 |
The definitive test is with a pressure gauge 0 to 3000 psi. Gauges cost 7.5 quid. This will also show at what pressure your pressure switches are set at. Basically without a gauge you will be pissing in the wind. There are little tests that one can do without a gauge but for the sake of 10 bucks all is revealed. When the engine is started the gauge should flick or jump to 1000 psi. This is the pressure of nitrogen in the sphere. As the engine idles the gauge will pulse up to approx 2500 psi and stop at that pressure. This is the relief valve opening pressure. If the brakes are pumped then the pressure will drop when the pressure gets down to 1900 psi the pressure relief inside the ACV will close and the pump will pump the pressure back to 2500 psi. These tests combined with quantity of fluid or rate or capacity of the pump are the quickest and most accurate way and once the gauge is acquired the cheapest. |
