| Author | Message | |||
     Chris Miller Prolific User Username: cjm51213 Post Number: 230 Registered: 5-2013 |
Hi Folks, So, here's a picture of a diaphragm rupture, not that you wouldn't have recognized it had you encountered it in your travels. I've opened four and three had intact diaphragms. When they fail, they make it obvious... So, I'm interested to hear stories. Is this typical in your experience, or do the ruptures happen in a variety of ways?  Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.91 |
This is the first sphere diaphragm I have seen split. It is an obvious place for a diaphragm to split. Chris don't run away with the idea that splitting of diaphragms is common. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 232 Registered: 5-2013 |
Hi Folks, This ruptured diaphragm turns out to be a blessing. I have four ACVs that I need to calibrate. This means applying pressure until they cut-out and measuring that pressure. If it is too low, then add arbor shims to increase the force necessary to compress the spring of the regulator valve. I have three sets of arbor shims in thicknesses of X, 4X and 8X, where 8x = 0.047", so I can approach an ideal value by half measures. Why is this a blessing? Because without the diaphragm, there is no compressed nitrogen, and I am doing nothing more dangerous than hydro-testing. Hydraulic pressure in not explosive in a containment rupture, but gas pressure is. I can keep this sphere, which is an old style from the '66 cadaver car, rebuilt and filled with brake fluid for quick and easy ACV calibration, and I can keep the other one correctly rebuilt and charged for more comprehensive unit tests. Chris. | |||
| Geoff Wootton Grand Master Username: dounraey Post Number: 465 Registered: 5-2012 |
Chris Did you manage to remove the ball bearing from one of your other spheres. Geoff (who is currently sitting out an absolute humdinger of an electrical storm) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 233 Registered: 5-2013 |
Hi Geoff, Yes. Both spheres from the '66 cadaver car had steel "crush balls" in the nitrogen check valve. And both were "recalcitrant". I've opened four of these things, each more difficult than the last. The first two were from the '72 and the second two were from the '66 cadaver car. The first one I opened with a 3' handle. The second one required a 5' handle. The third required a 5' handle and a winch. The fourth bent the 5' handle and required an 11' 2"x2"x(1/4"), 60 pound handle. I hope there is a limit here... Of the two with steel "crush balls", one was clearly discharged and I was able to crack him with the 5 foot black pipe handle on my pin wrench and the come-along winch. I tried the "pound the ring on an anvil with a heavy hammer" trick and as nearly as I know, it did not do anything except knock the ball bearing loose! This is the one with the ruptured diaphragm pictured above. The other was not known to be discharged because I could see the diaphragm through the "salt and pepper shaker" ports in the sphere, although I suspected that it was. Turns out that I was right; it was discharged. I tried the "pound the ring on an anvil with a heavy hammer" trick as well, but this time I couldn't say it did anything, not even knock the ball bearing loose, and I whacked it pretty forcefully. This one bent the 1" black pipe handle into a hockey stick, so I had to go even bigger... I had an 11' section, misreported as 9', of 2"x2"x(1/4") square steel tube. This section was pretty heavy, at about 60 pounds. Add most of my weight, 120 pounds, to it and I think I had to apply 150 lb @ 11' = 1,650 ft.lb. of torque to open it, but open it I did. Then I punched the ball baring out. So, the answer to your question is, "Yep. Got 'em." Was there really ever any question? (-: So, now it is on to ACV calibration for all four ACVs. I have two completely unknown units and I have two with known cut-out points of 2,100 PSI and 2,350 PSI. I think I want to try to get these guys closer to 2,500 PSI. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.91 |
Chris, The acv cannot be tested without a sphere at a 1000 psi. Because as soon as the bleed nipple is opened the pressure will drop to nothing. And the reading for cut in pressure will be unknown. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 234 Registered: 5-2013 |
Hi Bob, I'm not testing an ACV; I am calibrating the "Cut-Out" pressure to 2,500 PSI. Chris. | |||
| Bob UK Unregistered guest Posted From: 94.197.122.81 |
The cut in pressure is just as important to check. It may be that setting to 2500 will automatically set the 1850 to 1900 cut in or maybe not. If it doesn't then when you test on car you have to do the job again (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 236 Registered: 5-2013 |
Hi Bob, I don't think you understand how the ACV works or you'd understand that you can't set "Cut-In". "Cut-In" pressure is determined by the calibrated "Cut-Out" pressure, the geometry of the piston, and the friction of the "sealing ring" between the piston and the cylinder. If "Cut-In" is out of spec, then it must be the result of the sealing ring not producing enough friction with the cylinder and the only option is to replace the sealing ring. You get what you get. I can show you the math, if you like. It will make your dog laugh. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.77 |
I understand perfectly how it works. Providing nothing is wrong with the big spring then the cut in and cut out pressures will be ok. Assuming the 2500 psi is set ok. Without doing a proper RR approved test then it cannot be known if the cut in pressure is correct. The approved RR way means 1000 psi sphere connected. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 237 Registered: 5-2013 |
Hi Bob, O.K., so you know how it works. Then maybe I don't. Please explain how you fix "Cut-In" if after your "proper RR approved test" the "Cut-In" value is out of spec? Let's say I have added arbor shims and calibrated my "Cut-Out" to 2,500 PSI. I test my ACV and I learn that "Cut-In" is 2,400 PSI. Now what? I test my ACV and I learn that "Cut-In" is 1,500 PSI. Now What? Thanks for the help. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.71 |
The big spring is a high hysteresis spring. K Your springs are 40 years old. They may have lost a bit of their ability to absorb energy. If this has happened then the cut in maybe to high causing the pump to do more work. Low hysteresis springs have linear load and unload lines that are close together and parallel. High hysterious springs have a non linear load that steepens. The unload has a flater unload. The area between them on the graph is the hysteresis. When springs get tired the extra shiming may put the helix angles of the coils to far away from the ideal and upset the hysteresis. The spring will be working in the wrong part of the graph. That's the theory. In practice most springs which have been looked after well such as relief springs running in oil will last years. As I said maybe by just checking cut out the cut in will be ok or maybe it won't. The acv in will need to be checked so use a charged sphere connect a tube from bleed valve to pump reservoir and then if a valve is not correct change the spring and try again. Make sure the spring shims still leave a good location in the top hat. Obviously take normal safety precautions such as safety goggles and soapy water. My main concern is the sphere that cuts out at 2100 ps. That's 19% less rate assuming that the acv was correct when last overhauled. This could mean a tired spring. The tolerance on cut out is I would suggest is 50 psi 2475 to 2525psi. (Message approved by david_gore) | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1024 Registered: 6-2009 |
Bob, According to the check sequence chart for the hydraulic system in the SY1 Workshop Manual there's even more "slop" in the system than you account for. What's even more interesting is that the figures that are permissible in the check sequence chart (CSC) are different than what's in the text of the section on Hydraulic Accumulators - To Test (HT). Just for the record I'm going to repeat the figures cited for a correctly functioning system here from each source (TSD4200 - Series Two Workshop Manual): Flick-Up: 900-1000 PSI immediately or after 2 or 3 flicks of the pump (CSC) 1000 PSI (HT) 1000 PSI (TSD4200) Cut-Out: 2200-2500 PSI (CSC) 2500 (HT) 2400-2600 PSI (TSD4200) Fall-Back: 1800 - 2000 PSI (CSC) 2400 (HT) No more than 150 PSI below Cut-Out, can take up to one minute to settle (TSD4200) [Note: What I've observed on SY1 series cars as far as fall-back pressure goes is far more in line with what's described in the SY2 manual than the CSC. I've never seen a 400-500 PSI drop and I have the feeling that was an error in the documentation. This would mean fall-back pressure in the 2050-2350 PSI range, depending on the actual cut-out pressure.] Cut-In: 1850-1900 PSI (HT) [not mentioned in CSC] 1850-1900 PSI (TSD4200) At least I'll now have something to refer to that pulls this all together. But, back to the spring and hysteresis. It seems to me that, unless your ACV came from Crewe with no adjusting washers on the seating washer for the big spring, that the only way one can adjust both the cut-in and cut-out pressures is higher. While the relationship between the two may not be linear, if you compress this spring via the use of adjusting washers it should create situation where: 1) It's more difficult for the piston to push the regulator valve disc open, increasing the cut-out pressure. 2) Having the spring exert more force on the regulator valve disc, which would cause it to be pushed closed a bit earlier than it would have been, which means the cut-in pressure is slightly raised as well. Is this thinking correct, or am I missing something? Brian | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1025 Registered: 6-2009 |
And the tidy, downloadable tabular format of the figures quoted above for anyone who might want them:
Brian | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 238 Registered: 5-2013 |
Hi Bob, > ... will automatically set the 1850 to 1900 cut in > or maybe not. If it doesn't then ... Despite all you have said, you haven't explained how to adjust cut-in. I don't think it can by done. I think you calibrate cut-out and cut-in is nonadjustable and determined by regulator valve geometry and friction. One of us doesn't understand how this thing works. > The big spring is a high hysteresis spring. The regulator valve spring, the big spring, is a ground end, coiled, cylindrical steel spring, which is about a linear as you can get, especially given that our deflection is about 1/8". How does hysteresis in the regulator valve spring have any bearing on cut-in threshold? Thanks for the help, Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.84 |
Chris if the cut in pressure is wrong and the cut put pressure correct then the spring is faulty. To repair the fault fit a new or good spring. If the spring didn't have hysteresis then the relief valve would hunt and chatter. Eg ball lifts at 2500 psi and closes at 2499.99 psi. Which is impossible. In this case the ball should lift at 2500 and close at 1900. The 600 psi gap is the hysteresis. You can just set the cut out pressure and not check the rest If I were doing the job it would get the whole test because it's an accumulator control valve that should be tested with an accumulator that is charged. A bit like dizzy points set the dwell.And then check the rest (Message approved by david_gore) | |||
| Bob uk Unregistered guest Posted From: 94.197.122.88 |
The figures I use are 2500 cut out, 2350 to 2400 fall back and 1850 to 1900 cut in. 1900 fall back is definitely wrong. When the pressure gets to 2350 to 2400 the relief cracks and then goes full flow at 2500 and then falls back to 2350 to 2400. I am guessing here because RR don't give a crack pressure or full flow pressure. Full flow is always higher than crack. The reason for shims is manufacturers tolerances. No two springs are exactly the same and no two bobbins are exactly the same. And so on. I think running the system at incorrect pressures will upset the brake balance. Probably after 11 years of service (SY2 introduction) experience RR found that 2400 to 2600 as cut out pressure made little difference. So to get the 1850 to 1900 cut in right, it may be ok to adjust the cut out to suit between 2400 and 2600. Fortunately mine have given no trouble and I can only know what I read and look at the pictures. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 239 Registered: 5-2013 |
Hi Bob, > if the cut in pressure is wrong and the cut out > pressure correct then the spring is faulty. I'm sorry Bob, this is just not true. That is not how it works. You're assuming that the spring produces less force, under compression than it took to compress it, which is true, but you don't loose 25%! (2,400 PSI to compress at "Cut-Out", compared to 1,800 PSI returned from expansion at "Cut-In"). For a steel coil spring, with ground ends, the difference is negligibly small. The hysteresis of the ACV is from the geometry of the regulator valve piston and friction between the piston and the enclosing cylinder. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.83 |
Coil springs are not linear over the whole range only the middle 60 % which can be stretched to 80 %. Which why spring rates are tested by loading to compress one inch then loading to 3 inches and halving the sum of the two loads. An 1" above design loaded length and an 1" below design loaded length. Or fractions of the above for small springs. The geometry of the bits and the friction do contribute to the hysteresis. So does the spring. I was told many years ago that over shiming tired springs to get the correct load will cause problems in hydraulic valves. Because the load is right but the spring rate is wrong. Another way of looking at it is I could put stronger springs on a car and set the ride height at the same height and the ride handling will be different even though the load (the car) is unchanged. It is not possible to alter friction or geometry but it is possible for a spring to be weak. Which is why a proper test of the acv is carried out. Which is why RR say do it this way. As I said I don't know for sure as to the condition of the springs maybe the pressures will be correct maybe they won't. Incidentally as the spring compresses it turns the top hat a bit which is some of the friction. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 240 Registered: 5-2013 |
Hi Bob, The regulator valve spring is 3/2" unloaded, and compressed to 1" in the valve, so it is clearly in the linear range by your definition. Furthermore, it is compressing 1/8" to open the regulator valve, and over such a small traversal, any purported hysteresis is negligible by almost any standard. I think we can put to bed this nonsense of the spring hysteresis having anything to do with design of the ACV. > The geometry of the bits and the friction do contribute to the hysteresis. Yes. They contribute 100% > So does the spring. No, it doesn't. > Because the load is right but the spring rate is wrong. There is no doubt that this can happen. The force at 1", meaning with the regulator valve closed may be correct, but the force at 7/8", meaning with the regulator valve open is not correct. The spring rate never increases, so if the spring rate changes, meaning decreases, and shimming gets the correct force at 1", then the force at 7/8" will be slightly less then spec, which makes it easier to hold the regulator valve open, which will decrease "Cut-In" pressure. I could calculate this for a given loss of spring rate, but it won't matter because it is going to be a small value and you can't adjust this; you can't change the spring rate. So, we are back to "Cut-in" being a nonadjustable artifact of design and a function of "Cut-Out". So, I stand by my original observation that "Cut-in" is not adjustable. If "Cut-In" is too high, it is the result of a loss of friction at the "sealing ring", which means the sealing ring must be replaced. If the regulator spring weakens, this will lower both "Cut-Out" and "Cut-In". Chris. | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 241 Registered: 5-2013 |
Hi Bob, The original discussion was adjustments to the ACV what would effect "Cut-In", because I claimed that "Cut-In" wasn't modifiable. The discussion migrated and the topic became, "Causes and sources of ACV hysteresis" where you claimed that the regulator spring was part of this and I flatly refuted that. I was wrong. There is no question that the rate of the regulator spring has a profound effect on the hysteresis of the ACV. In my defense, the hysteresis of the spring is meaningless in the design, and the rate of the spring can't be adjusted. Even though these statements are true, and were clearly pertinent earlier in the conversation, they do not address the topic as evolved. My statement should be modified to: The hysteresis of the ACV is from the geometry of the bobbin, friction between the piston and the enclosing cylinder, and the rate of the regulator valve spring. Please accept my apology. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.78 |
When the piston moves it increases the volume behind it. If there is no gas spring then the piston cannot move back. This will also maybe upset the cutout pressure. The valve controls the accumulator charging it is not possible to test the function of the valve without a accumulator. If you want to do it your way then do so, it is your car. (Message approved by david_gore) | |||
| Bob UK Unregistered guest Posted From: 94.197.122.76 |
Chris don't worry about offending me by arguing your theory. You made me revisit stuff I learned at tech school and second time round I understand more. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 242 Registered: 5-2013 |
Hi Bob, I have completed my model of the ACV, and I was mistaken when I agreed that the spring rate had an effect on the ACV hysteresis. It doesn't. The regulator valve "snaps" open and compresses the spring by an additional 1/8", as a consequence of the internal "bonus" pressure, which is a function of the "dumped" external hydraulic pressure on the piston almost instantly reducing the external force on the piston to the force of the spring alone, hence internal "bonus" pressure. The spring rate determines the force necessary to keep the regulator valve open to the full extent, which is a compression or 1/8". However as internal pressure subsides, the regulator valve gate ("spring top hat") approaches the aperture gradually and only "closes" in the last infinitesimal part of the expansion, which means that the operational range of the valve gate is actually only the minuscule part of the 1/8" closest to the aperture in the bobbin, which is effectively constant. When the regulator valve gate opens, it dumps the external pressure to by-pass, which creates a "bonus" internal pressure which "snaps" the regulator valve open. However, as internal pressure diminishes, the gate proportionally approaches the closed position. This means that the spring traversal of 1/8" does not enter into the calculations at all anywhere, meaning there is only one point where the strength of the spring has any effect and that is exactly at the point where the gate contacts the aperture. Since the spring force is only necessary at one point, the rate has no effect on the operation of the ACV. This also means that there is no such failure as a "weak" spring and shimming to calibrate has no side effects whatsoever. Therefore, I reverse my previously reversed position. The rate of the spring is irrelevant. The only pertinent value is the force applied by the spring over the infinitesimal range in the neighborhood of the "closed" position, which is effectively constant. Sorry for the confusion. Chris. | |||
| Bob uk Unregistered guest Posted From: 94.197.122.84 |
Coil springs that are heat treated a certain way and contain between 1.2 and 2.2 silicon exhibit enhanced hysteresis loop areas when stressed. The loop area is banana shaped so the correct stress will put the spring in the right place in the area. Get to close to the ends of the banana and the switching hysteresis might be wrong. In the middle it is parallel. Which allows leeway. This sort of spring has been tried on suspension because of the damping effect but it was found that under shock loads with faded or weak dampers the springs would fail starting with micro cracking. 1950s. Since then French cars use similar springs which are heavily loaded for the wire gauge, and are preloaded to half the original length. There are three springs in the acv the third spring is the the accumulator which is also a gas spring. Meaning that the piston has springs both sides. Without the accumulator the third spring will have been replaced with a solid wall of liquid. The piston therefore cannot return. In normal ball relief valves the relief flow usually flows in the same direction as the lift this one goes the other way. Regardless of switching hysteresis and all the other academic banter. The fact remains that the RR fault flow chart says check accumulators first and fix as needed then check other stuff. This strongly implies that a charged accumulator must be connected to the valve. The assembly is the acv not just the valve. Shims are often fitted to engineering stuff and are attractive to repairers as a way of compensation for wear. But often the shims are to compensate for manufacturing tolerances. And should the shims need upping then something has worn. A good example is a taper roller bearing. If it is set right when New then adjusting tighter because of rock at the rim 100000 miles later. Will not fix it because unless the nut has got shorter or stub axle longer then the brgs must be worn. Same applies to the piston end, the ball, the bobbin seat, the spring and the two top hats. By the way the approved RR method doesn't need inverted commas around it like it was something to sneer at. Incidentally it is not because RR is a British car that I get shall we say reserved. I also think that the Americans are very good at engineering and when GM manuals say do it this way I do. Because they have worked out the cheapest effective way of repairing their products so that their customers get their GM cars fixed properly at a reasonable cost thus enhancing the GM products. RR think the same. It took me 2 hours to fit New spheres to my car 18 years ago and since then it's been rusty brake pipes and dodgy hoses. That's how reliable the system is. Which compares well with servo master type brakes. I had to do the job with no manual just a brief explanation from my local RR guy. (Message approved by david_gore) | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 243 Registered: 5-2013 |
Hi Bob, It looks like we are in agreement that the only variables in the ACV are "Cut-Out", which is adjusted with shims, and friction between the regulator valve piston and the containing cylinder in the bobbin, which is discretely addressable by replacing the sealing ring. So far, so good. Hysteresis of the regulator valve spring is negligible. Examine your hysteresis curve and measure the area when the traversal, the X-axis variable, is nearly zero, and you will see that the hysteresis measurement is negligible. The range of operation of the spring is nearly zero being only effective within the infinitesimal region of the bobbin aperture. The gate can only "open" so far, and the distance of the gate from the aperture will not open it any farther then it already is. So, neither negligible spring hysteresis nor any spring rate has any effect on behavior. Now, we are back to my procedure for calibrating "Cut-Out" with out nitrogen pressure in the sphere. If there is no "nitrogen spring" internally, then, until "Cut-Out", internal pressure is equal to external pressure minus the pressure drop across the check valve. When "Cut-Out" is reached, the regulator gate opens, but does not "snap" open; it is no longer a discrete response device. The reason is, as you have observed, the piston extends and increases internal volume, which drops internal pressure to nearly zero, and the gate immediately closes, where external pressure will build internal pressure, the gate opens, pressure drops, the gate closes, and so on. This sounds like an osculation, but there is no osculation, because without a "nitrogen spring" the ACV is no longer a discrete response device; it has become a proportional response device. At "Cut-Out" pressure, the regulator valve will open sufficiently that the friction loss across the regulator valve gate will exactly equal "Cut-Out" pressure, and I suspect that if you put a stethoscope on the ACV, you'd hear the external pressure escaping through the regulator valve gate under pressure. The internal pressure is enough to open the regulator valve gate to allow the external pressure to escape, but not enough to remove the friction. So, from my bench, with a charged sphere, I have to provide nearly 20 cu.in. of fluid to reach "Cut-Out" and that takes a lot of work. Then, I have to release the fluid pressure before I can disassemble everything to add or remove arbor shims. This fluid has to be returned to the pump reservoir before the cycle can start again. This means that it takes 15 minutes or more for each measurement/adjustment cycle. With my technique, volume of fluid necessary to reach "Cut-Out" is about 1 cu.in. I can reach "Cut-Out" in a few strokes, rather than one or two hundred. And I don't have a charged sphere that I have to remember to discharge for each cycle. And my "Cut-Out" is external pressure without the complication of "fallback", since "fallback" is a consequence of the state transition from "Charging" to "Full" and the associated volume changes and fluid losses; I have none. Chris. Responses to your post: > The piston therefore cannot return. With no gas pressure, the internal pressure is external pressure minus friction across the check valve. The regulator valve gate reaches equilibrium where the friction loss across the gate is exactly equal to internal pressure. If friction increases (gate approaches the aperture) the internal pressure will rise to open the regulator valve gate farther, reducing friction; if friction decreases, external pressure and therefore internal pressure drops to closing the regulator valve gate farther, thereby increasing friction. Equilibrium. > The fact remains that the RR fault flow chart says check > accumulators first and fix as needed then check other stuff. And that is precisely what I am doing... I need an ACV that will hold 2,500 PSI, before I can charge and load the spheres to 2,500 PSI. > By the way the approved RR method doesn't need inverted commas > around it like it was something to sneer at. I wasn't sneering at anything; I was quoting you. The "inverted commas" are called quotation marks and indicate text that did not originate with me. > Incidentally it is not because RR is a British car that I > get shall we say reserved. I also think that the Americans > are very good at engineering and when GM manuals say do it > this way I do. Because they have worked out the cheapest > effective way of repairing their products so that their > customers get their GM cars fixed properly at a reasonable > cost thus enhancing the GM products. As it turns out, I'm pretty good at engineering, myself. I have demonstrated a profound understanding of the brilliance and simplicity of the ACV which I have figured out over the course of the last few weeks, and I would be enormously surprised if there is anybody that understands it better than I do at this point. There may be peers -- Brian Vogel, but I believe my understanding is complete. > I had to do the job with no manual just a brief > explanation from my local RR guy. So, it turns out that you're pretty good at engineering yourself. Go out to your lathe and make me an ACV plug and send it to me. Make one for yourself, and one for Jim Walters. It is 9/8" diameter with 16 TPI. Be sure that it has the flange and channel for the o-ring, which I think is AS586A-218. Right now I have a bung in the 1/2" bore at the top of the sphere, but it is messy. Chris. | |||
| Bob Reynolds Prolific User Username: bobreynolds Post Number: 151 Registered: 8-2012 |
"This sounds like an osculation, but there is no osculation" I think you mean oscillation. Osculation means something else entirely!!  | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 244 Registered: 5-2013 |
Hi Bob, Oops... You know that red warning light on my computer has been shinning for a very long time indicating that I need more nitrogen in my spellchecker. Chris. | |||
| Ernest Carty Experienced User Username: edcarty Post Number: 43 Registered: 12-2012 |
Forget about adjusting any pressures just replace the faulty units with new or reconditioned ones ,after all we are not dealing with GM stuff.DO IT PROPERLY OR NOT AT ALL.This thread has become boring with too much theory and not enough practice,so let us all get on with enjoying our cars as they should be. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1030 Registered: 6-2009 |
I don't find advice to "replace faulty units with new or reconditioned ones" particularly useful. We all know you can do that. If the things can be reconditioned, then a discussion of what that process would be is infinitely more useful. Part of that would involve checking the behavior of the ACV with regard to cut-out and cut-in pressure and knowing how to adjust same. That's a part of doing it properly. It's also far more useful to discuss than saying, "buy them already done." Some of us would like to know how to do an overhaul from start to finish. Brian | |||
| David Gore Moderator Username: david_gore Post Number: 1462 Registered: 4-2003 |
Taking on "mission impossible" when restoring old vehicles and their components is fine if you have the expertise, time and, most importantly, the facilities needed to do the job properly. The satisfaction when the job is successfully completed is immense. If you do not have these prerequisites then the best advice is to replace suspect components with a new or reconditioned item from a professional reputable outlet who guarantee their work; this usually saves time, reduces frustration and gets the car back on the road faster than would be the case with "100% in own garage/workshop" restoration. Where my concerns arise is where DIY owners try to modify components from standard specification and/or conditions of operation especially where these are critical safety items; they may not have the relevant expertise and/or knowledge to fully comprehend the engineering and performance inter-relationships that caused the item to be designed and manufactured for use on the vehicle and may not realise the extent and outcomes of the testing and on-car evaluations undertaken by the manufacturer before the part was approved for use on the vehicle. This is before the implications of the car being involved in an incident after unapproved modifications to standard components or operating system by an unqualified unlicensed person; here in NSW, modified cars require a report from a registered licensed professional vehicle engineer before they can be registered for road use. Vehicle insurance policies exclude the insurer's liability when vehicles have been found to be modified outside the limits of our vehicle compliance legislation without the requisite engineer's report and approval for registration from the relevant authority. Other countries may have less-restrictive requirements however insurance companies around the world are careful to restrict their liability wherever possible. Overhaul and recondition - yes; modify critical suspension and braking system components and/or settings without professional assessment, inspection and written approval - no. IMHO, changing the operating parameters of the Shadow hydraulic system comes into the second category. | |||
| Chris Miller Prolific User Username: cjm51213 Post Number: 245 Registered: 5-2013 |
Hi David, > changing the operating parameters of the Shadow hydraulic system... Who is talking about changing anything? This entire thread is about calibrating the ACV to 2,500 PSI Crewe specified "Cut-Out", and the proof that "Cut-Out" is the only variable. When you issue warnings for non-existent conditions, I have to ask if you believe such conditions do exist, which makes me wonder if you understand any of this. Chris. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1032 Registered: 6-2009 |
David, Well, that brings me back to my original point: saying "replace it with a new or reconditioned part" doesn't achieve much of anything other than to state the obvious. There is not a soul here, or on any other automotive forum I've participated in, that doesn't know that buying new (or correctly reconditioned) and installing same is the easiest of all legitimate options. I believe most adults are capable of making a determination of whether a given "mechanic's mission" is over their heads either before starting or when working. I also don't think detailed discussions regarding how one can change the operating parameters of the Shadow hydraulic system to bring an incorrectly functioning or non-functioning part back to correct function is dangerous or inappropriate in any way. The vast majority of people don't relish the idea of having no brakes nor becoming a winner of the Darwin Award. All of these things are utterly separate from the legal requirements of any given jurisdiction. Brian, who believes that discussing why something is incorrect, and how it might become that way, is generally a part of any discussion of how to actually do something correctly | |||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1262 Registered: 6-2006 |
The vast majority of people don't relish the idea of having no brakes nor becoming a winner of the Darwin Award. . . . . WHICH IS WHY THE VAST MAJORITY BUY CORRECTLY REPAIRED UNITS AND FIT THEM! "I believe most adults are capable of making a determination of whether a given "mechanic's mission" is over their heads either before starting or when working." Believing something will never make it a fact! Because when people have inflated opinions of their knowledge or deflated opinions of how dangerous a vehicle can be when not repaired safely they will (wrongly) feel that they are within their depth. "As it turns out, I'm pretty good at engineering, myself. I have demonstrated a profound understanding of the brilliance and simplicity of the ACV which I have figured out over the course of the last few weeks, and I would be enormously surprised if there is anybody that understands it better than I do at this point. There may be peers -- Brian Vogel, but I believe my understanding is complete." Once again - believing will never make something a fact. Buy some correctly overhauled parts from somebody who knows what they are doing. Tighten the valve and the accumulator together TIGHTLY - because they will not need to be separated for the next ten years or so - and fit them to the car. Move onto something else. MODERATOR'S COMMENT: Quotations from earlier posts by other members have been formatted as such to avoid possible confusion with Paul Yorke's opinion/advice. In this instance, I agree with the opinions expressed by Paul Yorke | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1033 Registered: 6-2009 |
Paul, You are tilting at windmills and being very insulting while doing so. There is nothing wrong with in-depth discussions regarding the workings of the Shadow hydraulic system or any other system for that matter. You seem very confident that your personal beliefs are, indeed, facts. They're no more (or less) valid than my assertions that most people I know who participate in forums such as this one are not idiots who are incapable of making some reasoned decisions about their own talents and limitations. I'm sick to death of being condescended to for no reason whatsoever. It's rude and utterly uncalled for. Brian | |||
| David Gore Moderator Username: david_gore Post Number: 1463 Registered: 4-2003 |
This thread is now degenerating into inappropriate and unnecessary personal abuse where the rights of members to have alternative points of view is not recognised let alone accepted by certain members. This thread is now closed and I advise anyone contemplating work on a Shadow hydraulic system to seek professional advice before proceeding rather than relying on potentially inappropriate opinions. |
ACV Testing Pressures