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Discussion Starter #1
I understand that there is an internal memo stating that some seepage of fluid from EDC dampers is perfectly normal (!?!).

Does anyone have a copy they can post here or email to me?

Many thanks in advance.

R
 

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Rob Plummer said:
I understand that there is an internal memo stating that some seepage of fluid from EDC dampers is perfectly normal (!?!).

Does anyone have a copy they can post here or email to me?

Many thanks in advance.

R
Hi Rob
EDC dampers again :D
I would love to see a copy of a document like this !
Come M.O.T test time, I can just imagine all those M5 owners waving a bulletin letter under the nose of a vehicle tester stating
"My car is not like all the others on the road, leaking dampers is perfectly normal & although you would fail most other cars on this safety critical item,
BMW says it is OK....! " :D

I cant see many M.O.T Testers going for it myself.

On a serious note though Rob, I guess the difference is between sweat & leak. When my dampers have gone, the evidence of P.A.S fluid covering the damper all way down to the bottom spring pan & spatters on the wheel arch liner are very evident. I will be honest & say that this inspection usally follows a noticeable reduction in handling & an increase in ABS Patter when applying the brakes.

Sorry its a little off your main aim for this thread but if a document does exist I would like to see it too.

Regards
Farrell
 

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a light 'sweat' (not leak) from the rear-dampers is a result of the construction
of the dampers when the car is lifted up n down, f.ex. during a wheel-change
for winter-tyres, I believe there is no such 'memo', what there is however (and I do have it at home somewhere in 'german') seems to be a print-out from a TIS CD (TIS=technical information service system) supplying 'internal' service-information to the BMW-authorized dealer-workshops - :typing:
 

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M5touring reg said:
a light 'sweat' (not leak) from the rear-dampers is a result of the construction
of the dampers when the car is lifted up n down, f.ex. during a wheel-change
for winter-tyres, I believe there is no such 'memo', what there is however (and I do have it at home somewhere in 'german') seems to be a print-out from a TIS CD (TIS=technical information service system) supplying 'internal' service-information to the BMW-authorized dealer-workshops - :typing:
It's SI 37 02 88 (1713) Oil Leakage from Rear Shock Absorbers



MODELS: All (equipped with self-leveling suspension)

Situation: The high system pressure inherent in the self-levelling suspension system can cause oil to seep past the piston rod seal of the shock absorber, and this film becomes even more apprent as it tends to collect dust.

This seepage is normal and is not to be considered a defect Excessive oil leakage will be evidenced by distinct drops forming on the shock absorber body.

Also, when the vehicle is raised on a lift with the wheels hanging free, it is possible that there will be an overflow from the reservior, due to the unusual amount of oil being returned to the reservior. This is also considered normal"
 

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To All,

As a 17 year Hydraulic technician on mutliple US Air Force aircraft I can attest to the fact that the M5 dampers are like hydraulic actuators on airplanes and helicopters (actually they're the most basic type of actuators)
With their dynamic setup (sliding piston inside an actuator housing) fluid will
on rare occasions seep past the o-ring/packing during movement of the piston or changes in temperatures. Aircraft hydraulic systems are notorious for leakage during temperature changes. Plus, overtime seals lose their elasticity and become very hard, this also leads to leaking actuators. The best fix for leaking dampers (actuators) is to replace the old brittle internal O-rings, instead of replacing the entire component (the tough part is locating the right part number for the O-ring seals, I'm sure they're probably standard aircraft type O-rings.) After spending numerous years returning leaking dampers/actuators to like new condition with a simple internal seal replacement, it truly amazing that those companies charges thousand of dollars for replacement when a $2 to $5 seal/packing will return the component to like new/serviceable condition. Should you decide to replace those dampers for leakage problem please send the old dampers, I'll replace the internal seals and use them on my car. Just trying to help :cheers:


Garcia
 

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London Mike said:
Garcia, do you fancy trying to rebuild some of these units for members?
Hello Mike,

Before I say yes, I'd have to secure/locate one of the dampers, completely disassemble it, inspect the internal components, procure the correct seals, reassemble it and test for serviceability, only after completing the above could I say yes, it definitely would be an interesting task and yes I would enjoy helping a fellow enthusiast restore the dampers on their M5 to serviceable (non leaking) condition. The tough part will be locating the part number for the internal seals and securing these seals.

Garcia
 

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Garcia

I think you'll find a big demand for this if you could achieve it. So far the only option seems to be sending them to Brazil.
I for one have a '95 with 4 knackered shocks, and I know there are a quite a few more floating around too. Don't think there would be any trouble getting you a front and a back to experiment on.... :)
 

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London Mike said:
Garcia

I think you'll find a big demand for this if you could achieve it. So far the only option seems to be sending them to Brazil.
I for one have a '95 with 4 knackered shocks, and I know there are a quite a few more floating around too. Don't think there would be any trouble getting you a front and a back to experiment on.... :)
Mike,

One area I didn't cover regarding the dampers is they have to be pressure tested after overhaul/seal replacement, hydraulic actuators on aircraft are proof pressure tested to 6000 pounds of pressure per square inch (PSI), which is double the normal operating pressure, I'd have to also secure the "after repair testing procedures" for the dampers, if the pressure/proof test is impossible to locate, then the only way to test them is too reinstall on a test car and check out the car's handling. If anyone is willing to donate 1 damper for a trial run, I'll gladly give it try (I'll even take pictures of the internals and post on the web), should someone decide to donate a damper make sure it's one that has excessive leakage.

Garcia
 

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London Mike said:
Do the front dampers work in the same way as the rears? Are they repairable in the same way?
Mike,

Both are basically unbalance actuators connected to a hydraulic systems that's controlled by some type of servovalve (which is controlled by a computer.) The next time you're flying on a large commercial aircraft/jet,
sit next to the wing, when the aircraft is performing some type of manuever (i.e. roll, bank, pitch). Stare the aft portion of the aircraft wing and you'll see large surface movements on the wing (flaps, spoilers, or ailerons), under those movable surfaces you'll see components somewhat similiar to the dampers, they're called roll actuators, spoiler actuators, or ailerons, the same type of components. One great thing about aircraft technology, they always seem to find a way use the same components/systems on cars (fuel injection, overhead cams, horizontally opposed engines, antilock brakes, multiple valve engines, superchargers, turbochargers), most were developed for aircraft use but found their way to the good ole hotrod. Guess that's why I have a passion for planes and cars (especially fighter aircraft and sport cars)

Garcia
 

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Garcia, I don't know if this is any help, but I attached some info on the EDCIII system and how it works in the thread entitled EDC III - Where are the G-sensors? . Unfortunately, it doesn't go into the internal parts of the dampers (I suspect only Boge has that detail), but you might find it useful nonetheless.

Cheers

Garcia said:
Mike,

Both are basically unbalance actuators connected to a hydraulic systems that's controlled by some type of servovalve (which is controlled by a computer.) The next time you're flying on a large commercial aircraft/jet,
sit next to the wing, when the aircraft is performing some type of manuever (i.e. roll, bank, pitch). Stare the aft portion of the aircraft wing and you'll see large surface movements on the wing (flaps, spoilers, or ailerons), under those movable surfaces you'll see components somewhat similiar to the dampers, they're called roll actuators, spoiler actuators, or ailerons, the same type of components. One great thing about aircraft technology, they always seem to find a way use the same components/systems on cars (fuel injection, overhead cams, horizontally opposed engines, antilock brakes, multiple valve engines, superchargers, turbochargers), most were developed for aircraft use but found their way to the good ole hotrod. Guess that's why I have a passion for planes and cars (especially fighter aircraft and sport cars)

Garcia
 

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Discussion Starter #13
Garcia - many thanks for your input onto this thread.

As far as I understand it, the dampers are sealed units and when the guy in Brasil had his rebuilt, they basically cut them in half, replaced the seals and welded them back together.

Is this what you anticipate doing?

I've got a "seeping" rear, so although BMW claim this is OK, I'd rather it didn't seep at all! But having said that, I certainly don't want to be rushing out spending £1500 on a pair of dampers.

Before I even discovered my "leak" I was thinking that there MUST be someone in the UK who can rebuild these damned things, rather than being kicked in the knackers by BMW.
 

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Rob Plummer said:
Garcia - many thanks for your input onto this thread.

As far as I understand it, the dampers are sealed units and when the guy in Brasil had his rebuilt, they basically cut them in half, replaced the seals and welded them back together.

Is this what you anticipate doing?

I've got a "seeping" rear, so although BMW claim this is OK, I'd rather it didn't seep at all! But having said that, I certainly don't want to be rushing out spending £1500 on a pair of dampers.

Before I even discovered my "leak" I was thinking that there MUST be someone in the UK who can rebuild these damned things, rather than being kicked in the knackers by BMW.
"cut them in half, replaced the seals and welded them back together", WOW, that's scary considering the cylinder and piston are machined parts with polished external and internal surfaces (for smooth seal movement during retraction and extension.) In the book "BMW M-Series" on page 28, it's a black and white picture of the Boge Damper and it's internal components.
I'm sure you'll need a special tool for damper disassembly (instead of cutting in half and welding together, sounds horrific) and reassembly, I just can't imagine cutting and rewelding somethings as sensitive as dampers. Another question, what effect does the cutting and welding on the integrity of the metal, especially considering the loads the dampers are subject to during cornering and high speed manuevers over uneven surfaces, could you imagine losing control of your M5 because of a suspension failure ("cutting and welding back together" really sounds dangerous and unbelievable).

Garcia
 

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David,

Thanks for the damper information, I'm sure they'll (BMW and Boge) will continue to keep a tight lip on the internal workings/parts breakdown of the Dampers as it directly supports the high prices they're charging for damper replacement (gotta guard the company secrets.) I'm currently in the process of converting my 1995 M5 to US spec, I'd love to remove one of the dampers and disassemble for an experimental repair, but why remove a perfectly serviceable damper (especially during while I'm in the middle of EPA/DOT conversion process), when I return to the states I'll try to secure a unserviceable damper from some where, disassemble it and check out the internals.

Garcia
 

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I've done jobs in the past, whereby I've had to gouge out a weld on a hydraulic piston/cylinder and then re-weld and it proved to be a nightmare, trying to make sure it is again properly aligned.

Any misalignment would almost certainly result in premature wearing of the internal seals again.

I would think that they way these units are assembled, would be that there is a machined shoulder which when fitted in place is welded, this would then allow for the weld to be removed and when the repair is complete, then the machined shoulder simply fits snug back into place and is re-welded.


Having said all that, I had mine replaced by BMW, not all at once though £££££'s :thumbsup:

I should probably have asked for the old units back and played around with them a little :confused3
 

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Hi Garcia

I´m the guy from Brazil. The dampers weren´t literally "cut in half", they opened the top part of the damper which probably rendered it useless once it was open. Because of this, they had to create a new "lid" in order to put it back together (as far as I know, I´m pretty ignorant when it comes to damper internals so what I am saying might be completely off...).

This was done about 10 months ago and my two rear dampers work perfectly in S and P mode. After reading this thread, I checked my rebuilt dampers yesterday and I noticed that there was a tiny little bit of sweat on them, like you had described earlier. But I guess it´s normal.

I think that you should take on the challenge of using your expertise in order to rebuild these, as there are many people in the US and Europe that would rather have them rebuilt ($$$).

Luckily, I have taken pictures of the shocks after they were rebuilt. Go to this website´s search engine and type in "EDC dampers rebuilt" and you´ll find my thread with the pics.

VBR,
Pedro
 

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Hi All,

LondonMike just called me to let me know about this thread. I have two rear EDC units which 'Garcia' can be used for experimental purposes. One was leaking really badly. Let me know how we want to proceed, postal address etc.
 

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yewcorner said:
Hi All,

LondonMike just called me to let me know about this thread. I have two rear EDC units which 'Garcia' can be used for experimental purposes. One was leaking really badly. Let me know how we want to proceed, postal address etc.
Pedro, thanks for the information/photos, based on the pictures I'd say there's a least two different ways to separate the cylinder end cap from the forward body section for access to the internals ( and it will not required welding or cutting.) London Mike and all, I'd gladly accept the unserviceable dampers for an experimental, but please understand I'm in the middle of preparing my 1995 M5 for shipment to the US, plus I'm also preparing myself and family for the move to the North Carolina. Send the unserviceable dampers (only need 1 for the experimental repair) to: Mr. Brown, 50 Sycamore Drive, Beck Row, Mildenhall, Bury St Edmund, Suffolk IP288ST.
Remember it's a first time trial run for this experimental repair, but after 17 years of repairing hydraulic components on SR-71s, F-15s, U-2s, C-141, and MH-53 Helicopters I should be able to handle this tasking.

G
 
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