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Discussion Starter · #1 ·
Hi all

As the boxster I bought recently has a rear right strut bleeding from the PPI, and after a week of drive I find nothing else wrong with the car, I think it's time to have the structs changed. However, as I was calling the mechanics, they asked me the question, are you bringing your own parts or do you want us to order it. So I did a bit research and seems to find that Bilstein, which makes the OEM part also makes their own. I'm then starting to get confused. Online search seems to suggest that the B4 is exactly the same as the OEM (they also seems to be black as the OEM) but are at only about $250 on tire rack vs OEM at $450 at any reputable place. And B6 seems to be generally considered an upgrade for both handling and ride confort is only $30 more in front and $10 less on rear compare to B4.

So given that, would it be a no brainer to go for the B4 and a good idea to consider B6 as an upgrade? Would it be also true that if going for B4 then only the rear two since they are the same as OEM and if going for B6 all four needs to be replaced to keep the balance and all the other part of the suspension like spring don't need to be changed in both cases?

By the way my car doesn't have PASM, which seems to be making things much cheaper.

Also, I wonder would it be a good idea given the mileage (90,000) to change all four together? I seems to heard the general consensus is all strut are subject to very similar load through their life, so if one fails, rest should be dying pretty soon?

Finally, do you need to perform wheel alignment on the car after the replacement? As I am getting completely oppsite answer from two reputable indy shop that's both recommanded by PCA. One told me that it should always be performed after strut replacement and the other tells me as long as the "bicentric balance" of the car it should be fine.
 

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Definitely change all four. From my understanding B4 is OE equivalent and B6 is for if you have lowering springs. Someone correct me if I'm wrong.

If it's a street-only car I'd grab some H&R springs and the B6 struts and call it a day.
B4 and stock springs if you don't want to lower the car a bit.
 

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Keep in mind that "OEM" does not mean that the shock is the same "tune" as the Porsche shock. It just means that it is the same manufacturer, i.e. Original Equipment Manufacturer. Now are you ready to change the suspension tune that came from Porsche? That is the question. You can call Bilstein and ask if the shock they are selling is identical damping characteristics to the OE Porsche shock. If it is not proprietary info they may indeed be willing to answer. Also, I really don't think you want to put different tune OEM shocks on only the rears. This would upset the overall suspension setup. i.e. you may find yourself with a lot more over or understeer than you currently have. So if you are going to go the Bilstein route then do all corners. Good luck.
 

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Discussion Starter · #5 ·
Thanks for all the great suggestions. And it appears that I have not fully utilized the search in the forum.

Definitely change all four. From my understanding B4 is OE equivalent and B6 is for if you have lowering springs. Someone correct me if I'm wrong.

If it's a street-only car I'd grab some H&R springs and the B6 struts and call it a day.
B4 and stock springs if you don't want to lower the car a bit.
Umm, my understanding is that B6 and B4 have the same ride height and therefore could both use the stock spring that I currently have on the car. Only that B6 is a bit more aggressive. Are you sure it has a different height? Since that would have a big impact on my decision.

Keep in mind that "OEM" does not mean that the shock is the same "tune" as the Porsche shock. It just means that it is the same manufacturer, i.e. Original Equipment Manufacturer. Now are you ready to change the suspension tune that came from Porsche? That is the question. You can call Bilstein and ask if the shock they are selling is identical damping characteristics to the OE Porsche shock. If it is not proprietary info they may indeed be willing to answer. Also, I really don't think you want to put different tune OEM shocks on only the rears. This would upset the overall suspension setup. i.e. you may find yourself with a lot more over or understeer than you currently have. So if you are going to go the Bilstein route then do all corners. Good luck.
That's interesting, so the B4 could have a different tune? If so then perhaps OEM should be the way to go unless I want to alter the setup? In anycase, I feel I'm sliding toward the dangerous path of thinking I'm smarter then the Porsche Engineer who were paid to design this. :p
 

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Umm, my understanding is that B6 and B4 have the same ride height and therefore could both use the stock spring that I currently have on the car. Only that B6 is a bit more aggressive. Are you sure it has a different height? Since that would have a big impact on my decision.
No, not a different length shock body or perch height. Just that if you are at a lower ride height on a stiffer/shorter spring, the B4 is less than ideal. The B6 would be a better match. If you're staying on stock springs then I don't think the B6 will be an upgrade in comfort but it might be an upgrade in performance. Sorry if I sent you down a rabbit hole. From re-reading your first post it sounds like you want to maintain the stock ride height.
 

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Also, to expand on why I think you should replace all four struts - as others have said the damping characteristics may be quite different between the Bilsteins and the original struts, but also, if one is leaking the others are almost certainly not far behind. It would be a false economy to only do the rears and then six months from now have to put the car back in the shop to do the fronts.
 

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B4 = stock height & same as OEM (not sure if any difference 987.1 vs 987.2).
B6 = stock height & stiffer/sportier (more than a bit - read the linked thread above for my 0.02 on B4 vs B6)
B8 = sportier like B6 but used w lowered springs

IIRC, original porsche parts were much more expensive than aftermarket and were made by Bilstein.
Do budget for some additional related items such as the front mount bearings and mounting pads as some items may need replacement as well.
 
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