6.9

6.9 Strut rebuild research

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unpolire

12/15/2005 7:58 AM

While preparing to rebuild a set of 6.9 struts with an aerospace hydraulics engineer friend of mine, I stumbled upon this helpful procedure being performed on the rear struts of a BMW E32 (735il/750iL series), one of which I also own, that has a remarkably similar rear suspension to the 6.9, using the same style "bombs" or spheres. They all seem pretty much mystified by a self-leveling hydraulic suspension, something 6.9 owners were finding the benefits of and enjoying over a decade earlier! The sourcing of parts will be similar for the 6.9. Some creativity may be required but this is a start.

[http://shrubbery.student.utwente.nl/gavin/LAD_strut_rebuild.htm/url]

Phil OBrien

12/15/2005 6:44 PM

Does Neil Dubey rebuild the struts or does he sell a rebuild kit?

Phil

cth350

12/15/2005 10:14 PM

the url is bad. drop off the "/url" from the end. -cth

Ron B

12/17/2005 7:39 AM

The Citroen guys all rebuild their spheres("bomb" is a PC word these days....[:D][:D])so I cannot ,for the life of me see why thay cannot be refilled for use on a 6.9,same thing as Citroens,Rolls royce etc etc , origianly designed by the same people even!.As for the struts,the only worry is the valves on the pistons,if they are broken etc it is pointless repairing them.Although it's been possible to get 116 and 126 rear struts repaired in Brisbane here for years.I even did my own on my w123 300TD a while back.

...Can we fix it?? YES WE CAN!!!http://www.popartuk.com/g/l/lgmp0092.jpg

n/a

12/19/2005 1:07 PM

Ron, if the spheres go, its because the diaphragm blew out, mixing N2 with hydraulic oil. Time to replace. I have never heard of a 6.9 sphere going south by just losing pressure, its always a diaphragm failure.

Also, the strut seals can start leaking. They can be rebuilt if the seals and parts can be found. Its funny, rebuilding 6.9 struts is like seeing Bigfoot: a lot of people talk about it, lots of rumors, but no first hand experience of actually doing it. Seems odd that after 25 years somebody hasn't tried it??

Fred

JohnOlson

12/19/2005 2:09 PM

When this subject began I asked Neil Dubey (Star Motors) how his attempts to rebuild struts was coming. He replied that the 6.9 stut is similar [to the E32 BMW 5 Series] but the 6.9 teflon seals are not obtainable. He has the tools to take stuts apart but by the time they are finished with a new ball joint the cost is high. Ball joints cost $228 per strut, the new rubber mount is $150. After adding labor there's nothing gained over buying new.
.
The ball joint is removable so on "some" rebuilds the old ball joint may be saveable but we are talking about 25+ year onld cars. I have infact changed a few ball joints on original struts that are still behaving fine.

Ron B

12/19/2005 4:49 PM

I was going to mention those ball ends,on all the other self levelling struts it is sometinmes that ball end that wears out first.Mostly because the rubber is exposed to dirt( and oil from leaky engines and trannys) and holes are rubbed through the bellows part.Once dirt gets in there it acts like grinding paste to destroy the ball.a good idea is to get in there at least once a year and clean out the debris ,especially on high mileage cars in areas with rough roads.
To us outside of the USA the parts are horrendously expensive because of taxes and levies So the cost of repairs is negligable compared with the replacement with new parts.
...besides our government has just legislated slavery into law so wages will no longer be a factor..[}:)][}:)][}:)]

...Can we fix it?? YES WE CAN!!!http://www.popartuk.com/g/l/lgmp0092.jpg

n/a

12/19/2005 6:54 PM

The ball joints on the rear struts are easily replaceable, the fronts are not, you have to replace the whole strut. The ball joints can be cleaned up somewhat if rusty.

When you guys are talking about replacing the ball joints on the struts are you talking the fronts or rears? I am wondering if someone is saying there is a way to replace the ones on the front. It would be cool if there is a way, even if non-standard.

Fred

JohnOlson

12/21/2005 1:43 AM

The front lower ball joints on the hydrolic struts are replaceable.

n/a

12/23/2005 6:11 PM

John, you are right, now I remember, the front ball joints weren't available when I needed some.

psq

12/23/2005 7:10 PM

I've just replaced the front struts and have pics and notes for a LodeStar item I'll put together some time in the next 2 months.
Replacement was easiest for me - no time to take the car off the road for extended work. However, I know of a local (to Perth, W. Australia) firm which can supply replacement seals for the struts - some off the shelf, some they make up on a lathe. For a 560 they cost about $Aus80 per set. When I have time I intend to dismantle the old struts and take them in to get new seals made up to suit. I'll post something nearer to the time to see if anyone wants some too.
As for the spheres, Pleiades the Citroen specialists (UK and Australia, don't know about any other places) can regas them if the diaphragm is ok.

ctmaher

1/3/2007 3:38 PM

Did anyone ever figure out a source for the seals to rebuild the struts? I pulled one apart and it appears there are three o-rings and a couple of teflon rings that are needed. The o-rings shouldn't be too much of a problem, but the teflon items may need to be custom made.

I'll have to see if I can find a hyd. shop that can either make that pieces or has something close that will function as intended. Anyone have any leads on a manufacturer who can make small quantities of these? Somebody has to have rebuilt these before.

Chris

peterq

1/3/2007 5:39 PM

There is a company here in Perth that has made seals for the hydraulic struts from a 560SEL (please, let's not have the "126's didn't have hydraulic suspension" conversation again. They did, optionally, in some markets and this was a Hong Kong car). Their normal business is hydraulic rams. Some of the seals were off the shelf, the others they turned up on a lathe. At the time I spoke to the owner the seals had been in use for some 5 years with no problems.
I have my old front struts in the shed, and when I get time I intend to strip one and contact the company to see what they can do.

As for the spheres, some UK Citroen specialists have re-gassed MB spheres but you would need to get to them before the diaphragm fails. When I had a CX I was told that the main reason for diaphragm failure was prior gradual loss of pressure. So if there's a deterioration in ride quality but you haven't yet reached the point where that corner of the car has no suspension travel, try a re-gas and let us know how it goes.

peterq

1/3/2007 5:42 PM

Hmmm... just noticed that this is an old topic brought back to life, so what I just posted is a repeat of what I posted 13 months ago.

Phil OBrien

1/3/2007 7:08 PM

I'm kind of surprised that the struts only had a few seals on them.

Phil

peterq

1/4/2007 6:09 AM

That's about the same as the seal set I saw for the 560SEL.

Ron B

1/8/2007 8:13 AM

Grant,in SA ,had his rebuilt last year.

...There are old cars,and then there are Classics..(Mercedes Benz Ad. 1999)

Andreas

1/10/2007 6:16 PM

Hi Ron,

Grant in SA i assume is South Australia. If so I would like to get in contact with Grant to see of the result as I need to get on strut fixed up if it is possible. Under what name does Grant go so that I can contact him via PM.

Cheers
Andreas

Art Love

1/11/2007 12:29 AM

I believe Grant is in South Africa.
Art

Des

1/13/2007 12:38 AM

Try this bloke

Strut Re-Gas
0419 359 941
ph: (03) 6249 3652

He is in Tasmania however he is part of a larger national group of auto strut repair people, I spoke to him a few months ago and he has rebuilt struts for Mercedes, Rolls Royce and Citroen,

can also recharge the air cells/sphere's, I did query this as the 6.9 sphere's don't have a recharge point, which the ones in Rolls Royce do, he did comment that this was not a problem and they use a unique process to recharge them.

I never got mine done so can't comment on the work, simply bought new ones instead.

----

Ron B

1/13/2007 6:09 AM

The shperes can be recharged if a hole is drilled and a shraser valve fitted so the nitrogen can recharged.
Nitrogen leaks thorough anything so after 20 years it's not unusual for the spheres to fail.
If the diaphragm fails the shpere is shot.
Regarding the struts,regular self levelling struts are different to the 6.9 part and are actually a bit complicated in the seals and pistons so they ( the 6.9 parts) must be rebuildable.

...There are old cars,and then there are Classics..(Mercedes Benz Ad. 1999)

jdalis

4/15/2007 1:52 PM

As an aside, yes, 560sel's did have as an euro option a self leveling system and BEFORE laying out $1100.+US for a new pump or attemping a rebuild(I've tried that twice without success-started leaking worse at start up and second time lasted 30 days) junk yard dive for a 560 pump. It's the same. Also the 80's era TD wagon had the same self leveling system on the rear and same pump.

Ron B

4/15/2007 5:54 PM

The reason ,I have since found,that pumps leak after a rebuild is that you DO NOT remove the inner steel part of the pump unless you have access to the special O ring ( not available from Mercedes) and a former,to guide the inner part back into the alloy housing without damaging it.
I believe we have a member here (in Western Australia) who can do it.
Any little microscopic wear marks on the drive shaft will cause the rear seal to leakSo ingeneral either Spend the $1200 + for a new one or get a good used late model 560 pump.All pumps are the same actually except the very early ones fitted to W114's and that is a rare option on a compact.

...There are old cars,and then there are Classics..(Mercedes Benz Ad. 1999)

Des

4/15/2007 6:12 PM

quote:
Originally posted by Ron B
actually except the very early ones fitted to W114's and that is a rare option on a compact.

Was that a rear only option or could you have a full hydro suspension?

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oversize

6/8/2013 8:00 AM

Did anyone have any luck with these leads??

Mark

Last of the steel Mercedes

2001 Ford AU Fairmont Ghia 5L (Deep Blue)
1980 450SEL #101122 (Green Lantern)
1979 6.9 #6301 (Blue Flame)
1979 6.9 #5541 (Red Bull)
1979 6.9 #5318 (Silver Arrow)
1979 6.9 #5298 (Man o War)
1978 6.9 #4248 (Skye Blue)
1979 6.9 #3686 (Moby Dick)
1975 450SEL #28414 (Gold Nugget)
1957 Buick Roadmaster 73A (Titanic)

alabbasi

6/8/2013 9:45 AM

There's a guy on the 116 forum in the UK that recently had his rebuilt. Maybe worth a ping.

With best regards

Al

S class

6/8/2013 1:47 PM

Bill, who posts as "WGB" on this forum and the W116 forum, has successfully DIY rebuilt his struts. Here's a link to his thread with photos :

http://forum.w116.org/mechanicals/6-9-hydraulic-strut-overhaul-take-2/

116.036
116.036
116.024
116.028
116.028
107.044
202.018
202.026

oversize

6/9/2013 5:49 AM

Yes I have seen those threads and they are excellent reading. However the problem is that there's no seal kits available. Obviously someone went to the trouble of making at least a couple of sets at one point yet the source has disappeared. It seems rather odd as I'm sure they'd sell quite a few.

And now we're left having to strip another couple of struts and find someone else who's capable of matching up (or remanufacturing) the seals.

All I can say is it's extremely frustrating. [:(][V]

Mark

WGB

6/30/2013 5:29 AM

Pictures and measurements of all the seals were posted at this site, at W116.org and Topklasse about three years ago. I suggest you do a search.

If they are lost I still have the original photos of new seals with measurements.

It is probably not worth measuring worn old seals and it shouldn't be hard to have new teflon seals turned down from a billet.

Bill

1979 Euro 6.9 with AMG modifications #5554
1979 450SEL plus another 1979 for spares

etmerritt33

6/30/2013 11:28 AM

I suggest contacting Keith Bowers on any issues related to this system. He has all the factory manuals plus one really rare one and is a hydraulics engineer with a huge amount of knowledge. IMHO he now has a very good understanding of this system as well as some of the engineering thought that went into the original design.

I have offered the group two fantastic resources to assist with two frustrating 6.9 issues: the suspension and the fuel injection. Keith at B & B Suspension in Houston can handle anything suspension related and Larry Fletcher at CIS Flow Tech can rebuild, inspect, adjust, calibrate, etc. any CIS WUR and FD. I have been very pleased with everything Keith and Larry have done for me and am thankful I was able to locate them after literally years of searching. Both are really good guys that are willing to share their technical knowledge.

Hope this is helpful...

arcijack

6/30/2013 11:44 AM

I can vouch for Larry Fletcher. he lives 2 hrs from me so i had the opportunity to visit him, he has a nice set up and knows his stuff, he rebuilt my fuel dist and wur while i waited. and i have had no problems.
he is also a super nice character and will keep you entertain .

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