| Author | Message | ||
     Chris Miller Grand Master Username: cjm51213 Post Number: 335 Registered: 5-2013 |
After the exhilaration of learning that my ride height leveling system was working, the puddle forward of the rear wheel told me that brake fluid containment was not. I rebuilt each side as leaks appeared. I'm in the process of adjusting... First I need to be sure that "Showroom Standing Height" is correct. My front suspension "A" setting is 4" on the driver side and 4.25" on the passenger side. The manual says "3.525 +/- .125", so I'm out of spec. The '72 does not have the threaded adjustment of "early cars", so my option is spacers. The manual didn't go in to great detail about how to adjust these spacers, so who can tell me anything about how to do this? There are two questions: Is it worth the effort for a 1/4" side to side variance? Is it worth the effort for 3/8" standing height variance? The next step will be adjusting the hydraulics. I think I understand that pretty well, but I have a question about de-pressurizing. If the spheres are depressurized, does that mean the rams are fully retracted? Or do the rams have to be de-pressurized as well? | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1503 Registered: 6-2009 |
Chris, The accumulator spheres and the height control rams are, in the manner you're referring to, independent of each other. The rams aren't pressurized in the same way the accumulators are. If you want to make sure the rams are at their lowest position then do the necessary adjustment on the height control arm to trick the car and, for good measure, crack the bleed screw to see if you get anything coming out. If the height control valves are not feeding the rams and the rams have the car as low as it will go you shouldn't get anything from the bleed screws. If your height control were working you can do an experiment to prove this to yourself. You can trick the car into raising the rear height by manually adjusting the height control valves and leaving them in that position. Then do the brake pedal depressurization and you'll see that your height doesn't change because the fluid that's been pumped in to the rams will remain in the rams until the height control arm returns to a position where the HCV "thinks" the car is now too high and needs to release fluid back to the reservoir. All of the above presumes the car is immobile and in fast leveling mode. Brian, who recalls playing HCV arm games when working on LRK37110. See, Flush and Bleed Your Silver Shadow/Bentley T Hydraulics/Brakes the Easy Way, for the diagram from the workshop manual that shows the "safe" range of motion of the arm on the HCV. It's quite a bit wider than its actual travel when everything's hooked up. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 336 Registered: 5-2013 |
Hi Brian, That is exactly the answer I expected, meaning the ram positions are maintained by the ride height control valve, and I must do more than merely depressurize the accumulators to get to "zero". Thanks. One more detail. The manual says "Fast Leveling" happens in neutral. Does them mean "only" neural, or "also" neutral, with respect to "Park"? And will it work at all if the cut-out is removed from the fuse panel? If I can share my experience with the "safe" range of motion of the ride height control valve lever arm ... I learned that there is a range where the lever arm will permit the internal piston to advance and prevent engagement with the lever arm eccentric. I learned this after I had the unit installed and had not paid attention to the position of the lever arm, which, of course, had moved into this non-functioning position. I learned that I did not have to remove or disassemble the valve to correct this. There are four "cylinders" that comprise the valve and one is distinctive, because it has a snap ring, rather than a threaded cap. This can [probably] be remove in-situ, and then the piston can be easily repositioned, the lever arm eccentric re-engaged, and the snap-ring replaced. I say "probably" because I didn't learn this until after I did it the hard way... | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1505 Registered: 6-2009 |
Chris, I can't remember what fuse controls the fast-leveling solenoid valve, but I don't think a cut-out (and by that I mean the big, resettable Otter switch) does that. My experience is that fast leveling is on when the car is in park. I've never tried this in neutral, only park. The rams aren't pressurized in any conventional sense, the pressure is used to force the fluid in, and, of course, the weight of the vehicle creates pressure, and you will get maximum output from the bleed screw if the HCV is trying to allow fluid in to the ram at the same time as you're releasing it. You still get some just from the car lowering under its own weight, and when you bottom out you're as low as you go. This is the state the ram should be in when you're checking the standing height, though that is typically achieved by manipulating the HCV arm. The safe range of motion of the HCV arm is way more than is necessary to make the car raise and lower itself. Brian | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 280 Registered: 5-2015 |
Do not dismantle ride valve while fitted to car. One bit of dirt in the wrong place and you will kipper the valve. In the boot is the 2 rams each ram has 2 pipes. The pink one is bleed and the brown one is connected to the rear top of the ride valve. The bleed nipples are fitted to the rear inner sill. Also pink sleeve ID. Pump system down. Open nipples if car sags then probably the springs have sagged. I would be surprised if they haven't. The amount of sag is usually more than an inch. The maximum amount of shims total is about 1 inch. The correct way is to replace the springs. Or use the rams to level the car. Disadvantage of this that if a real heavy load is in the boot then the rams may run out of stroke to level the car. An advantage is that every time the the car is started the rams work which exercises the system. Plus the springs are not cheap. Used springs are pointless The fast solenoid has 2 wires. Connect test light to the wires. Open door etc to check power supply. The solenoid will be heard and felt to click. No click usually means no power. The fast bit is not really needed unless you need the car up quick because of the gold bars in the boot just stolen from fort knox. So if it doesn't work don't worry too much. If you want it fixed do a posting first because you will need a tech explaination which isn't in the manual. My car. The pink pipes from ram to nipples went rusty. I didn't have any new pipe so I screwed the nipples direct into the ram. I have never got round to doing it properly. (1990). I am a lazy git sometimes. A disadvantage is that there is a danger of spilling RR363 in the boot. An advantage is that to bleed the rams I lay in the boot which causes the rams to extend a bit more. Then open the nipples and the car drops. That way I am not underneath the car as its moving. 2300kg of car will kill you if it falls off the stands. This has happened to people Also if possible always have someone nearby. My wife keeps an eye on me via the CCTV. | ||
| Chris Miller Grand Master Username: cjm51213 Post Number: 339 Registered: 5-2013 |
Hi Bob, Thanks. So, specifically, will fast level work if the Otter cut out is removed? The current gear-state would be unknown to the the car. Is it worth the effort to adjust away a 1/4" side to side variance at the bow? Is it worth the effort to adjust away 3/8" standing height variance at the bow? My bow standing height is high, not low. I assume it is a substantial effort, and the manual doesn't go into much detail about how to do this, but maybe it is not. That would also be a good answer to have... How much hassle is it to adjust the bow "Showroom Standing Height"? Chris. | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 285 Registered: 5-2015 |
I don't know if removing gearbox cutout disables fast height as well. 1/4 difference is only slightly out of wack. Drive car 20 yards and check again. Because every time a car is jacked up it will need to roll to settle the ride height. The ride height adjustment will adjust out the 1/4" at the rear. Note the 4 corners of the car are joined together so a low right hand rear will effect the front a bit. So set rear at correct ride height then check the front. Once set the ride height will stay at that setting for years. Also remember that its the difference between 2 measurements taken at each corner. The 2 measurements are a pair and not relevant to another pair at another corner. | ||
| Alan Dibley Yet to post message Username: alsdibley Post Number: 1 Registered: 10-2009 |
The original post mentions a leak around the rear wheels. It MAY come from the seals on the spindles of the height-control valves. Do not assume that it must be faulty seals. There is a hose in the release pipe back to the reservoir which (like all the others) closes internally after umpteen years of age. It then does not allow the excess RR363 to vent to the reservoir, so the fluid takes the easiest way out - via the spindle seals of an HCV. The hose is (IIRC) the highest and rearmost of all. Regards from Alan D. |
