Rebuilt E34 EDC from Nagengast - Issues - BMW M5 Forum and M6 Forums
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post #1 of 5 Old 28th May 2019, 11:06 PM Thread Starter
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Rebuilt E34 EDC from Nagengast - Issues

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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post #2 of 5 Old 31st May 2019, 07:32 AM Thread Starter
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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?
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, 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.

Last edited by m6bigdog; 31st May 2019 at 08:31 AM.
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post #3 of 5 Old 2nd June 2019, 04:44 PM
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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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post #4 of 5 Old 14th June 2019, 05:11 PM
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Any progress with this issue ?

Have you fitted the refurbished EDC dampers ?

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post #5 of 5 Old 15th June 2019, 03:52 AM Thread Starter
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Originally Posted by davidoli View Post
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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