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      11-14-2012, 06:29 PM   #1
Shipkiller
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What constitues an Unusable OEM Damper (strut)?

This is an unusual question.

This last weekend, I replaced (planned) the stock OEM dampers on the Coupe' with something other than stock components.
When I had to rears off the car, I compress the damper down to it's full compression point which was quite easy, and it took almost 90 seconds for the piston rod to extend. One of the rear dampers would not completely extend...

The front struts were better. It only took them 45-55 seconds to fully extend.

I tested the new hardware and it only took them around 10 seconds to extend. These were much harder to compress.

Normally I would say that the stock OEM dampers were toast but I do not know what the return rates are on new OEM dampers.

Anyone have some data? The dampers only had 33k miles on them.

I also replaced the RTAB's with aftermarket hardware and installed the SSK.

I cannot tell you how they feel since my alignment is scheduled for Friday and I will not drive the car until that is accomplished. Toe and camber is all out of wack...
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      11-15-2012, 02:35 AM   #2
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off topic, but what shocks did you go with?
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      11-15-2012, 09:02 AM   #3
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Bilstein struts.
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      11-15-2012, 01:25 PM   #4
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Bump. Anyone have input on this one?
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      11-15-2012, 04:35 PM   #5
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I attended a TechFest West seminar hosted by Jay from Ground Control, and he has shock dyno charts that showed OEM Sachs dampers losing 50% of its effective damping by 30,000 miles, and by 50,000 miles they were down to 10%.

HAVING SAID THAT. Unless you're comparing shocks and struts of the same part number, it's hard to tell for sure what's going on between the old and new shocks. BMW has traditionally spec'ed shocks with higher rebound than necessarily for the rear. Again, I had some conversation with Steve Dinan at the same TechFest West back in 2004, and he said that on his stage I kits he actually DECREASES the rebound on the rears of most of his kits to make the car behave better in corners AND ride better. The fact that the new shocks returned to the full and upright position quicker may just mean it's tuned to provide LESS rebound control.

When I installed my Koni single adjustable tubes on the WRX, I purposely played around with the rebound setting before I installed it on the car, and surprisingly, at the "stiffest" rebound setting, the shocks took forever to return to fully extended, while at the "softest" setting the shocks returned to extended range with relative ease. So what you're seeing may be indicative of Bilstein choosing to reduce the rear rebound compared to factory setting, or at 30,000 miles, your shocks may be far less effective than they originally were.

Try this unscientific test. Once you compress the shock's piston fully, try and pull it back out rather than letting it slowly expand. If you can pull it up easily, then it's done for. If it still provides plenty of resistance to you pulling the piston back out to fully extended, it may just be designed to provide high rebound rate rather being busted.
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      11-15-2012, 04:55 PM   #6
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That makes a lot of sense.
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      11-22-2012, 09:55 PM   #7
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Strut mount?

I'm new to this forum. I just bought a 2003 z4 and spent every last penny buying it cash.
I just noticed that it looks like both of my front strut mounts are cracked almost completely around the center bolt.
My question is this. Is my car safe to drive, or can the struts come up and go into the hood or cause a wreck? The car drives/feels great, I just happened to notice the cracks all around the mounts. (It looks like its pretty much cracked all around on both strut mounts)
If I need to go into debt to insure safety or further damage, I definitely will, but I'd rather wait a couple of months to be able to save for it. (Not to mention it was a little bit if a hard sell to the wife and a big expense doesn't help the cause...). What should this repair cost?
Thanks in advance for your help and replies.
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      11-22-2012, 10:18 PM   #8
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If you are talking about something like this?




Then it is not as bad as you think, but you really should not be driving the car in this condition because as you already said, there is a possibility that the struts could poke through into the hood.

First you need a new 'Guide Support'. No. 1 in the following link:
http://www.realoem.com/bmw/showparts...48&hg=31&fg=10




When I replaced mine on the Roadster, they were about $45.00 each from BMW.
The stuts must come off of the car to replace these. No special tools required except for coil spring compressors (which you can rent from Autozone or Advance) and you can do it in your driveway or garage.

When I did this, it took 90min for the first one and 35min for the second one....

After re-installation, you will need to get the car realigned.

Looks bad but it is pretty simple repair. This is a common issue on older BMW's.


...
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