E46Fanatics - View Single Post - Differences Between Non-M and M3 Suspension
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Old 03-29-2013, 11:39 PM   #40
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Join Date: Jul 2011
Location: Southpark
Posts: 53
My Ride: E46 330
Non-M struts are partially compressed at rest position, fluid can be heard if shaken, and easier to compress, strongly suggesting a low-pressure twin-tube design. M3 struts are fully extended at rest, no fluid can be heard if shaken, and are harder to compress, strongly suggesting a high-pressure mono-tube design."
I know for a fact that non-M-shock-absorbers are twin-tube-design. However - the OEM-Sachs-shocks on my 330 (M-package) did fully extend in resting position (even after 5 years / 90.000km). Even the rear ones that were leaking oil did fully extend - indicating that there was still pressure inside.

Same goes for my brand new Bilstein B4 replacement shock absorbers which are listed as twin-tube-design - they fully extend - all by themselves. If your E46 Sachs/Bilstein shocks dont fully extend its likely they are worn out/shot/dead. I know - there are cases were brand new twin-tube-shocks dont fully extend but the twin-tube Sachs/Bilstein E46 shocks do!

Note: twin design shocks break down slowly. They even work (kind of) when they are in the process of failing. This is why a lot of people dont notice that their shocks are gone. It usually happens so slowly that they get used to feel. Mono-tubes usually last longer than twin-tubes but when they fail -> you know immediately

BTW - if you look up the E46 M3 shocks in the Bilstein catalog you will see that the B4 replacement shocks are listed as twin-tube-design as well. That of course does not prove that the OEM M3 shocks (I guess Sachs) are twin-tube-design but its an indication.

Last edited by silyb0y; 03-30-2013 at 12:04 AM.
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