Thanks.
I've added more and hopefulyl once we get the details/information together we can make a usefule/education article from this.
NOTE: If anyone feels I've left out or "messed anything up" in my copy/paste (slight edit for spelling, etc) please email me through the addy in my profile.
BluntSmoker wrote:I recharged all 9 accumulators for $140.00 this was 60,000 miles ago and three years.
The guy who did it said he felt bad because all he did his drill holes install Schrader valves with aircraft approved valves caps (good to 5000psi if valve fails) Cost $2-3 Each.
If you search accumulator repair you will find many kits to recharge accumulators using nitrogen tank from a local welding shop.
All the kit is this an adapter from the nitrogen tank to a locking Schrader valve adapter, open up the tank fill to proper PSI 450-650. (It may seem like it is very high pressure but these pressures are what the canisters are designed to operate under)
This Is Not a Very Difficult Operation, Accumulators on Aircraft Landing Gears Are Recharged As Often As You Might Put Air in the Tires of you car, and just as simple.
Do it yourself and Save big bucks or go to a local small aircraft repair station where they will have all the necessary equipment and know how to recharge your active system.
BluntSmoker wrote:The reason I had my accumulators recharged at an aircraft shop is there familiarity with nitrogen charged accumulators plus its right next to my hanger.
The operation is very simple I watch the guy do it first; he drilled and tapped the accumulator. Next, he installed the Schrader valves. Then connected to nitrogen tank to the Schrader valve recharged the accumulators.
My recommendation is to purchase Schrader valves and caps that are FAA approved.
MS20813-1B Caps which are used for Schrader valves, tire valves, accumulators and other high-pressure applications. These Caps have a special rubber sealing washer and are rated for high pressure units up to 5000 PSI. So if the valve does fail the cap is a failsafe for maintaining the proper pressure.
Further, Scott Jackson another member of this board has had his accumulators recharged (DIY) at his local John Deere Center and has posted the pictures. He states:
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“The accums were charged at the local John Deere dealership. They have nitrogen accumulators on tractors and combines and some of those charged to 1300+psi.
I only went with 600psi on mine. They have a simple gauge with fittings that have a hand operated valve on the nitrogen tank (like what you'd get from a welding supply place) and the other end threads onto the schrader valve.”
BluntSmoker wrote:Accumulators have been used and are currently used in many applications which include farming and aviation. Accumulators use incompressible fluid and a compressed gas, spring or raised mass to store potential energy. Accumulators are used in fluid power systems to store energy, absorb shock, and maintain system pressure
The accumulator’s on the Infiniti’s active suspension system are piston type accumulators (See pic)
Unfortunately, in the final design infiniti never included a gas valve/Schrader valve for recharging.
Thus, in order to recharge the accumulator you must drill a hole and install a Schrader valve.
Recharged to OEM specifications (psi): may be precisely calculated at http://www.wilkesandmclean.com/formulas/index.html please note the actual formulas used by the calculators. These calculators use the size and dimensions of the accumulator to mathematically determined the proper PSI.
Hydraulic repair facilities are also very familiar with accumulators and do this type of work every day. They have the expertise and facilities to drill tap and filled with nitrogen to the precise PSI.
Jeff Williams wrote:I feel pretty safe, landing in commercial and private aircraft, so letting some aircraft repairman charge the accumulators in my Q would not scare me. I doubt I would go to the nearest welding supply place for schrader valves. Heck, I am in the air conditioning business, we use schrader valves and Nitrogen daily. We just don't get much over 600 PSI with it. I too, thought they were charged "Well over 2000 PSI".
Now, to get an "a" Q without upsetting the misses......
texasoil wrote:... I do wish I could do my recharging process with less time and cost--but 5 years of development do not show how. Simply "drilling and taping and screwing in" is far from what's required for a warrantable and safe recharge.*What about the metal chips that fall inside? Can't remove them through a 1/4" hole.*What about the sludged up oil I usually find inside them?*What about the broken piston ring lands or worn piston rings I sometimes find?*How are they inspected--boroscope? or look see from arms length?
My actual time averages around 12 hours per set of 9 accumulators, and 8 hours per set of 4 strut units only. Measured many times. Parts & supplies cost is a little over $26 per accumulator. I am the largest single non-aircraft supply purchaser of the aircraft service valves I use. Right now there is a 8 week back-order on the normal valves and I am having to use valves costing over $50/accumulator. Nitrogen--its the only really cheap supply--about $1.00 per strut accumulator and $5 per main accumulator average--depending on mix of strut units to mains--but the special high pressure regulator and charging hoses are far from cheap. Low cost welding regulators simply will not achieve the much higher pressures needed for the Infiniti system. (the OEM presures are quite different than those mentioned in this thread) I guess one could use a simple needle valve and pressure gauge and fill to a pressure and close off the valve--but that sure doesn't achieve uniformity in charge pressure-side to side and elsewhere its highly desirable.
Ever seen what happens when a high pressure hose on a very high pressure gas supply bursts? It can easily take off an arm or take your life. A "blow-out" of a valve when charging or "in service"--where pressures can exceed 5 times the charging pressure-- would launch a high velocity projectile-just don't get in the way. Have the simple tap and screw in valves been hydrotested to determine the actual blow-out failure pressure? One has to remember that John Deere (BTW I grew up on JD tractors) and aircraft hydraulics do not experience the potential/probable very high overpressure that rough road bumps can cause in the Infiniti system. A 5000# rated aircraft valve won't fail, but it will blow-out of the steel shell of the Infiniti accumulator (which is much thinner than the aircraft component for which it was intended). So, one CAN do it at lower cost than I charge. If you can find someone to donate their time,expertise,and equipment and no inspection, cleaning, testing, etc.. However, I do advise extreme caution when working with compressible gas (nitrogen) at these pressures. It is many times more dangerous than hydraulic oil one has to work with in swapping out the accumulators. Be safe--work smartly.
ScottJackson wrote:The accumulators are quite thick and if you get the right tap, there's a lot of threads to hold in the schrader valve. But the steel of the accumulators is thick, and hard so it is not a walk in thyne park to drill them. At least it wasn't for me. It does take some effort and Keith's service is only mildly over-priced for the labor involved around this area. I live in a very rural and POOR area so I would say that anywhere else in the country his prices are very fair. The only reason I would recommend doing the job yourself is if you are somewhat mechanically inclined and know how to sharpen drill bits and have the common sense to drain the oil from the accumulator, THOROUGHLY clean it out (I used aerosol brake parts cleaner) and check it for leaks before installing. For most folks, I would suggest using Keith for your recharge. He is very knowledgeable. I'm sure my 600psi was a low charge but I too am concerned with safety and my accums were completely empty so even a half charge feels much better than before. If you are mechanically inclined and will see to it that you do things carefully and get the proper size and taper tap for the STAINLESS STEEL schrader valves, you can save some $$$ if you have a lot of time on your hands. I think these cars are old enough and have dropped in value enough that it's obvious there are people like me who own them that don't have the $ to perform luxury car professional maintenance all the time. So, instead of seeing people convert to standard suspension, who may have the time and ability to do their own but not the cash to have Keith do them, it is important to show that it can be done on the cheap. A boroscope would be handy. I don't have one, yet, and I hope none of my other accumulators turn out to be leakers. Basically, it is a somewhat involved job and does have safety concerns attached, but it can be done if $1200 isn't feasible to some poor active Q owners like myself.
ScottJackson wrote:Yes, the accumulators probably need quite a bit more than 600psi. I would suspect around 800-1000. Page FA-112 of the service manual tests the active by going from 256 to 1422psi. The pressure on the schrader valve isn't some incredible amount. Even if it hits 3000psi inside the accumulator when hitting a large bump, that's not 3000lbs of force against the actual valve as it is far less than a square inch. The thread contact between the valve and threaded hole in accumulator is PLENTY and I would never worry about one blowing out if the correct tap was used to cut the threads and the valve was tightened with loctite. Even though I only put 600psi in mine to start with, doesn't mean I wasted my efforts. The ride is greatly improved and once the valve is in, it's easy to recharge for next to nothing as I wish. Keith does have more knowledge and I have little doubt he does more thorough work when charging an accumulator but it should be buyer's discression where they buy recharged accumulators. I'm a poor farmer hick with no class or culture but I do like my active Q and I liked my non active Q also. I like my 635CSi bmw a bit more and 540i even more than that. I can't afford any of them but I do enjoy them and try to do my best to keep them running and make the best decisions I can as far as maintenance and how best to go about that. Fact is, luxury car or not, the Q is an inexpensive car and FEW people who have large amounts of cash will buy one that's over 10 years old. Like Donnie in "The Big Lebowski", due to poor resale and depreciation they are now out of their element and we must do the best we can with what we have for resources and what is needed to keep the car functional. To be honest, when I bought my active Q, I didn't have a clue what the little "a" meant on the trunk lid. I soon did figure it out and I love it, OEM spec accumulators or not.
