I'm gathering info on a suspension upgrade and what I might do is buy the parts this year and either install them myself or have them installed next year. Looks more and more like I will do the modification.

However, the possible delay between my parts purchase and the install got me thinking about the fact that Bilstein shocks are gas filled. My question is whether these things are completely airtight or will they loose some of their pressure over time even if they are not used?

Which brings up the issue of how you know you're not buying shocks that have already been on some supplier's shelf for 2 years. Maybe it doesn't matter if the amount lost is miniscule. However, if these things loose say 10% over 5 years, you would already be down 4-6% if they are two years old.

Are there production dates stamped on the Bilstein HDs and is this something that should be discussed with the supplier?

 

I just had an interesting phone conversation with Bilstein's Sales and Engineering groups. Since I asked the question, I'll post what I found in case others are interested.

In summary, I was told shelf life for Bilstein Gas shocks is not an issue. The gas is actually behind seals which is under an oil blanket. The gas would have to leak past the seals and past the oil blanket then through the welded portion of the shock. They have run tests on Bilstein shocks with 500,000 miles that are still within factory specifications.

In addition, right now they have a fast turnover with their shocks. Typically, nothing stays on their shelf longer than 4-6 months.

There is production date information stamped on the bottom of their shocks, however, it is in factory coded letters and numbers and not immediately decipherable.

So my conclusion is that even if the shocks sit on the suppliers shelf for several years after being manufactured by Bilstein, there should be no issue with them losing any of their charge.

This gives me more confidence to proceed with purchasing the stocks without installing them immediately and eliminates any concern about buying shocks that have lost some of their charge due to age.

 

Interesting information - thanks for following up!

 

I'm not recommending currency speculation, but the dollar has been rallying against most currencies for a while now. On this basis, you might benefit from delaying your purchase until you need the parts.

Regards to all.

 

Guess they should last the average weekend driver ~200 years!

 

The Bilstein HDs on my 16-year old 930 with only 23k miles were shot and leaking all over themselves when I bought my car -- no telling how long they had been that way. My local dealer said they tend to lose their gas, then leak as they degrade over time.

Sixteen years is probably way longer than you were talking about, but I would say they definitely have a limited life, if not a shelf life.

The 500,000 miles mentioned was probably over a very short, unnatural (in the real world) time frame. Over my 16 years it would have been more than 31k miles per year, much higher than the average annual mileage. I think age probably takes its toll more than miles.