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Discussion Starter #1
Just got a set of rebuilt front & rear EDC back from Nagengast.
Physically they are everything you want, well packaged, new labels, wiring, paint...

They did not come with dyno test sheets. That is disappointing.

Also, I just hand pushed and pulled the front and they have very different resistance.
Without powering the EDC solenoids they will be on firm setting and should provide a lot of resistance to the shock rod motion.

One of the fronts is good but the other is much much weaker and I'm not installing these until I get them tested.

Anyone had their Front EDC shocks tested upon return from a Nagengast rebuild and know where I should send them in the USA to be tested.
I will contact Nagengast to find out what they want me to do.
Another 10 week round trip back to Poland will be a pain.
 

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Discussion Starter #2 (Edited)
Help needed, please!!

So my question in the OP is; did anyone that received rebuilt shocks from Nagengast and get a copy of the final test shock dyno runs as shown in their video?
https://www.youtube.com/watch?v=p4QPEZnaKpY
Video shows the testing of a late model E31 rear EDC shock. Resolution of the video makes it difficult to read and it is in Metric units

Got a reply from Nagengast today:
"The final test should be in the memory of our computers. Im currently on holiday but will be back on Monday when I will check it and let you know.
We sugest that you install the shocks and have a test ride and diagnostic test. The shocks will start to work properly once they have been installed in the car and when the oil and gas will start to flow properly through the main valves and EDC."

I don't know about you, but I'm not going to install shocks on my M5 that are symptomatically dysfunctional, align the suspension, etc. just to see what happens!!

Did some basic testing of the front shock compression rate (shock rod traveling in). Rear shocks require an oil supply (no SLS pressure required) and I may try to test at some point.
The compression rate is much less (controls vehicles 125-150 lbs of unsprung weight) than the rebound rate (controls approximately 900-1150 lbs of spring tension from the vehicle sprung weight) but since I don't have a shock dyno to dynamically measure the shocks lbs-in./sec. rate, I have to make due with a simple test.
To do this, I use my digital MasterCool scale that can measure up to 243 lbs (this scale is designed to measure Air Conditioning Freon cylinders and constantly measures the real time weight on the scale).

So I place the shock on the scale (22 lbs set tare to put the scale to zero) and with the shock rod fully extended I use a 12 inch piece of 2x4 to force the shock rod down with all my strength/weight.
The left shock will read 212 lbs (my body weight) long before the shock rod reaches the end of travel.
The right shock reads only 90-100 lbs and no matter how hard I try it is just to weak to measure my body weight.
Just happen to have another set of high mileage used EDCs on the shelf and even though the shock sounds like it is sucking air, the used shock easily went over 170 lbs
The rebound measurement would require a spring scale capable of 300 lbs. and I don't have one in my tools. Ebay time.
Basically, there is really little reason to pursue the rebound rate because whatever is wrong also affects the rebound rate and that is easily felt between the shocks just by pulling up on the shock rod by hand.

Oh no..no, I just measured the shock rod length, (lowest point of the bottom spring perch spiral to the shoulder of the shock rod taper for the upper spring perch) and the Nagengast replacement shock rods are 3/4 inch longer than the stock EDC shock rods, I have.
Did a quick setup with the H&R Sport 29579 spring and they will be loose with the added 3/4" shock rod length.
This is not going well.

Has anyone else used H&R 29579 springs with the Nagengast rebuilt EDC's? What was your experience?
Anyone have specification and/or measurements for the stock EDC shocks and/or Nagengast rebuilt units?
I assumed Nagengast would rebuilt to BMW specifications and not some other spec of conveniences, like adding 3/4" to the shock rod!!
I would like to confirm what i'm seeing if anyone could help.

The issue with NLA EDC shocks is making life more difficult than I ever anticipated.
 

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i ran H&R front springs on my old 6 speed, the the shocks were not rebuilt units but OEM bmw replacement EDCs and it rode the same as stock just a touch lower
 

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Discussion Starter #5
Any progress with this issue ?

Have you fitted the refurbished EDC dampers ?
Nagengast replied; "we don't have test results for the shocks we rebuild."
That is very disappointing given the cost for the rebuild and shipping to California, USA.
Next time I will make the dyno test results part of the work-order!

I don't like doing the work twice so I will not install a shock that is obviously dysfunctional.
I have located an authorized shock rebuilder locally with a shock dyno and I will try to get the set if shocks dyno'ed next week.
I have set up a tester to check the EDC valve stages and I will see if my oil reservoir setup will allow testing of the rear shocks
I will have the test results to share.
 

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Discussion Starter #6 (Edited)
Shock Dyno results attached

Been awhile but, I had the Nagengast rebuilt shocks dynoed at PSI a local performance suspension and authorized shock rebuilder.

The attached shock absorber dyno graphs shows the #1 front strut has only 25% (25 lbs vs 115 lbs) of the compression rate and 50% (200 lbs vs 380 lbs) of the rebound rate of the #2 strut, hence the #1 strut is no good. Also, while testing I noticed the #2 front strut kumfort solenoid coil has an open circuit, so it is no good also. This is no fun!!
The rears were more difficult to dyno, but I anticipate the dyno results we got indicate they are both good, although the lower mounting rubber bushings were not replaced and show sign of age and wear.
The only conclusion I can come to is the front struts were not tested after final assemble before they were shipped to California!!

Also, in my earlier post, I commented the replacement shock rod was 3/4" longer when it is more like 1/4" longer after I was able to study the strut dimensions in more detail.

Also, in the last email reply from Nagengast, they commented "The fact that a second hand shocks has a higher compression strenght doesnt mean anything. The valves through which the oil flows may be damaged and this can be the reason."
I assumed form the Nagenast website they rebuilt shocks to as close to OE specifications as possible, so why would they say my second hand shocks would still be damaged after they were rebuilt?
I must say this shakes my confidence in the quality of Nagengast's shock rebuilds. Physically they look great but functionally they are unusable.

I just sent the dyno results to Nagengast, request that they authorize the return, pay for return shipping and I'm awaiting their reply.
Stay tuned and I will post when I get their reply
 

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Discussion Starter #8
Update: Both front shocks arrived at Nagengast today.

When I contacted Nagengast with the PSI dyno results they said if the shocks I received were bad they would reimburse all shipping if they concluded the shocks have the problems I describe.
I assumed that is shipping US-Poland-US. So far I paid PSI $310 for testing and $379USD to ship them to Nagengast.
I will update my post as soon as I hear from them and/or receive the shocks.
I requested verification of performance with shock dyno results, so I shall see if they fulfill my testing request.

Return Shipping to Poland surprise:
USPS has a 44 Lb limit for Priority Mail International - to Poland.
Each front shocks weighed just over 19.5 lbs alone after they were rebuilt by Nagengast (more oil in shocks plus machined collier nut).
The BMW specification for a front E34 EDC shocks is 18.1 lbs.
When I first sent the shocks from California to Nagengast be rebuilt, I was able to ship both front shocks in a single box with plenty of packaging for $270USD @ 43.lbs 2 oz but no matter how I tried I could not package the refurbished shocks in a single box and keep the weight under 44 lbs, so I had to ship each front shock in a single box @ 25 lbs each for a total USPS shipping cost of $379USD.

FWIW: Priority Mail International California to Poland - the weight matters more than the size of the box as I shipped each shock in a 10" x 17" x 29" box and reducing the size of the box would have had no effect on the $179USD cost to ship 25 lb.
 

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I have been dealing with Nagengast for many years now and , whilst there has been the occasional issue , their service and workmanship has been top quality .

They have also provided an excellent after sales service .

That is my experience having sent them over 20 sets of E34 M5 shocks for refurbishment .

D
 

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Discussion Starter #11
I have been dealing with Nagengast for many years now and , whilst there has been the occasional issue , their service and workmanship has been top quality .

They have also provided an excellent after sales service .

That is my experience having sent them over 20 sets of E34 M5 shocks for refurbishment .

D
That is good to hear, however my recent experience with my first set is disappointing to say the least.
At this point, I can only hope their performance improves as I've spent the money!!
Also, I will always requested they provide documentation of the dyno testing after regeneration.

My disappointments:
1) Nagengast advised/insisted I install an obviously bad front strut to see what happened, test drive, instead of accepting my observations and providing return shipping when I first received the bad shocks in May, 4 months ago!
2) Nagengast then advised me they have no record for performance testing the refurbished shocks.
I paid $450USD for UPSP shipping to Poland and wire transferred $1935USD for their refurbishment and return shipping to the US. Total: $2365USD and they have no test results for performance?
3) After numerous emails with Nagengast I get replies like this, "we are 100% convinced everything is ok" and "fact that a second hand shocks has a higher compression strenght doesn't mean anything", "The valves through which the oil flows may be damaged and this can be the reason". These are all avoidance and nonsense answers!!
So, I am forced to schedule dyno testing with a local certified ZF/Sachs repair/custom shock valving facility.
4) Also, while waiting for an opening to test the shocks, I discovered the other front strut (good one) had an open solenoid coil, (i.e. infinite ohms between pins A & C) at the EDC 3-pin connector.
5) Now with the Dyno testing confirmation at the cost of $310USD for the 2 front & 2 rear shocks, Nagengast will accept the return on both front shocks as long as I pay the USPS shipping cost of $379USD to get them to Poland for inspection.
6) Nagengast did provided a email stating if they can confirm their regeneration is bad they will reimburse the shipping cost. However, I assume, I'm out for the $310USD for dyno testing and I'm left trusting Nagenast won't just fix the shocks and say, they found nothing wrong and then I'm stuck paying the round trip shipping US to Poland!!

Now, waiting to hear back from Nagenast, they have had the struts since Monday, Sept 2.
 

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Most pertinently for folks in the US, but for everyone as well if people start to have issues with the Poland option: we're planning to get a handle on rebuilding EDC ourselves. We'll plan to dyno shocks and get our hands dirty this winter.

Wishing for a good outcome for the OP, especially for the significant outlay! We understand your frustration 100%.
 

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Discussion Starter #13
update: Sept 12, 2019,
Please reply or PM with suggestions
for the regeneration issue I encountered.

Essentially Nagengast is unwilling or unable to repair the right EDC strut and they are DONE with their regeneration.

Reference: Nagengast web page:
Regeneration Shock Absorber;
-Verification of damage
-Replacement of all worn components with new ones
-Assembly
-Tests in the diagnostics station

I just received the Dyno performance results for both front struts, still at Nagengast , and the right strut still has a bad compression rate @ -27daN (-60Lbs) force compared to the left strut @ -75daN (-166 lbs) force. The V3 velocity at 150 rpm at 30 mm shock rod stroke is a peak rate of 235 mm/sec (9.27 in/sec.)
See attached shock dyno results from Nagengast:

I also received a reply from Nagengast after I requested they repair the compression valving on the right strut.
Quote:
[Dear Sir,
V1,V2,V3 are test speeds, not EDC.
The only important parameter is the tension force. They are correct. The compressive force has no meaning and is also in the norm.
Nothing more we can do with your shock absorbers.
I'm afraid only new shock absorbers can satisfy your needs. We can pay you back for the repair, but then we'll keep your shock absorbers.
Regards,]

I know I have enough performance knowledge about Ground Vehicle Suspension Dynamics and suspension performance requirements that Nagengast is just plain wrong in stating: “The compressive force has no meaning and is also in the norm”.

Letting Nagesgast keep the struts is absurd:
I paid $500USD for the spare set of E34, EDC’s, $270USD to ship them the Nagengast, $300 to have the Nagengast regenerated struts dyno’ed at PSI, because Nagenest doesn’t listen to a customer’s legitimate concerns, $379USD to ship the struts back to Nagengast and $950USD for regeneration of 2 front struts and shipping to California.
Total EDC investment of $2400USD for EDC’s and one with a bad compression valving.

Be aware:
Nagengast does not check/energize the EDC solenoids valves so the comfort and medium valve rates are never performance tested before they ship after regeneration.
That is how I received the left strut with an open solenoid coil (now repaired). I’m also convinced they may not always dyno performance test the shocks in firm rate after regeneration and that is how I received the right strut with only 200 lbs rebound force (now repaired to 405 lbs) and -25 lbs compression force (unrepaired) @ a shock rod rate of 9.27 in/sec.
 

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Discussion Starter #14 (Edited)
To clarify the regeneration issue remaining:
The Nagengast Dyno graph attached is the data from the Front Right strut after initial regeneration (May 2019) and return to Nagengast for rework (July 2019) with the defective compression rates highlighted in red.
Also, these dyno results are performed in firm mode and would decrease substantially with comfort and medium rate solenoids energized.
The compression values in this dyno graph can be compared to the Front Left strut dyno results in the attachment in reply #13 above.

It is my experience the defective compression rate on the Front Right strut would cause wheel hop and chassis/suspension waddling over bumps..
I have conformed the compression rate problem with a local shock rebuilding professional and they confirm the Front Right strut is defective and requires additional repair.
 

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Discussion Starter #15
More - Shock Dyno results attached:

On Sept. 26, 2019, received another email from Nagengast with more shock Dyno results:
Email quote: "The result of the work on your shock absorbers is attached. The damping on both shock absorbers is correct"
This is the 4-5th time the email from Nagengast stated: "the shock absorbers are correct"; however this time the Dyno results looks like the right Front compression valving has been repaired.

I must say this has been as frustrating as it can get because even with their own obviously poor Dyno result, Nagengast would insist the shocks are correct or that "The compressive force has no meaning and is also in the norm”. Post#13 above is the full story to include the Nagengast refund offer:, "I'm afraid only new shock absorbers can satisfy your needs. We can pay you back for the repair, but then we'll keep your shock absorbers."
Of course my reply to the Nagengast obsurd offer was, not acceptable, the regeneration workorder agreement is:
“Verification of damage”
“Replacement of all worn components with new ones”


Yesterday Oct. 2, I received the tracking number for the UPS shipment so it should be another week before they arrive.

On Sept. 26, 2019, I sent Nagengast the receipt for USPS Priority Mail International shipping cost $379USD, they said: “If it turns out that the regeneration was wrongly carried out, the transport cost will be refunded to you.” I have yet to get a reply.
 

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