The stock bushing resists and dampens caster change during acceleration, braking, and G-forces, the PSRS does not (and it increases tramline behavior), current poly bushings only resist caster change in the positive direction. The OE bushing is not long-lived, but the quality of life is good.
I still don't get it... it's the softest option out there, so by default it does the worst at resisting caster changes. If you have a good stiff coupling, why would one need to damp any caster changes. To get all techie, stiffer couplings will have a higher "Q" or natural frequency, a narrower ressonance peak and lower amplitude even if they have a longer decay constant. I also don't understand the tramlining as well. That seems to be much more coupled to tread pattern than anything else. Or are you saying that changes to caster increase or decrease the effect? Then it's the offest and alignement that does it, not the bushing materials per se. As an anecdotal point, the only track rats and racers I know that use the stockers do it because of rules, not because of performance. Those that want the performance ditch the suckers as fast as they can. Crap, solid heim joints (based on the dampening arguement) would be the worst option out there, yet it is the design choice for almost all serious race applications even though they have zero dampening. This isn't a best or worst as you present it. There are some compramises with all the designs. I now know exactly two people who really like the stockers, and tons that run away from them as fast as they can. The various compramizes in design and how each driver weighs them is what determins whats best for that person. That said, I still think the stock part is a piece of junk. A suspension bush that dies in ~30k of street driving just isn't meeting the design requirements of the part. I'm sure that there are cases of these bushes deviating significantly from ideal in less than a year! Anual changes of parts like this is totally inapropriate for street cars. Racers won't use them because of the "uncertain" handling characteristics under extreme braking. I think we'll just agree to disagree on this one. Matt
FWIW - I think they also significantly improved the stock bushings at some point - maybe the late 2006 build cars. My car is a 9/2006 build - and the stockers were pretty much like new after 58,000 miles of flogging when I had the Powerflex installed. Dan Z said that the newer bushings held up MUCH better than the older ones.
That's interesting.... REALOEM doesn't show any revision to the part number..... wonder if there's a lot of variation in the part from the manufacturer? matt
Also interesting... possibly variation from the mfg... or maybe they broke their own change management process and changed rubber compounds (but nothing else) without changing the part number... but if some folks have replaced multiple sets of the OEMs, I would have thought they would have gotten some "newer" ones by now if that was the case. Or maybe other mods I've done have extended the life of / reduced the stress on the bushings? In general we have smoother roads here than up north, and little or no salt. But otherwise I flog my car harder than 95% of MINI drivers... only the more frequent trackrats probably beat their cars harder....
I've got that last of the Powerflex bushings in the US, Powerflex is out of them. So I can tell you with confidence PF hasn't changed any molding or anything causing them to turn in the brackets. I've never had one turn in the brackets. So as an average person reading this I don't think that should be any concern. I can't explain why Keith's didn't work, and not gonna try. As for using stock bushings, Don't bother, but if you want a set I've got about 10 brand new ones lying around someone can have a heck of a deal on.
#1 for the powerflex bushings!! Turn in crisper, get on the gas sooner and stability under hard braking is so much better! The more power, better tires and better brakes you have exposes the OEM bushing weaknesses more and more.....
We have tried them all and Powerflex is hands down the best! TSW just signed up as a Powerflex dealer and will have our new stock of parts by the end of the week. Powerflex has 3 hardness ratings - you can get them in soft, medium or track. We use the medium hardness and have seen no NVH with them. Regards, [email protected]