Negative. It depends on the design and application.The 'problem' with urethane bushes is that they need regular greasing in order not to knock.
what design? the trailing link bushings are pretty much identical between prothane and energy suspension. whiteline only really makes the caster bush for the front control arms, but prothane and ES make a normal replacement for those as well. however i fail to see how an outer metal jacket on the whiteline bush will keep the inner metal sleeve from binding on the polyurethane once the lube wears away, which it WILL do on any poly bushing that actually has to move (deflect like the stock rubber).Negative. It depends on the design and application.
Whiteline's urethane ones will more than likely last the life of your ownership of a car, and then some.. As it's metal jacketed.
the prothane trailing link bushings are a 2 piece design. 2 poly shells that slip in on either side with a inner metal sleeve that still needs to be slipped/pushed/pressed in. due to the size of those bushings i wouldn't be surprised if the ES was designed the same way, but i haven't seen a pic of one of those so i can't say for certain.Many of the two piece bushings, would squeak without proper maintenance every year or three.
The trailing arm bushings from prothane are a one piece design.. I dont think those will have issues for at least 5+ years.
well let me clarify. all of my previous experience with poly bushings has been on another car make/chassis. because of said experience i will never install poly bushings in suspension arms again.Fraktal et al, does the same apply for all urethane bushes used in ARBs and drop links, not only in trailing arms?
All I know is I had a clunk after installing whiteline ARBs and droplinks with urethane bushes in my previous WRX that I don't know what was caused by (at the same time I had Prodrive springs that had the plastic sleeves on the bottom of the coils at the rear to prevent touching but the noise was coming from the front - unsure whether the noise was coming from the coil springs touching or ARB/drop link bushings)
I noticed that most of the grease on the bushings had either dried or disappeared after 7 months as said so I am hesitant to fit 'upgraded' urethane bushes again. I want to fit something and forget not create extra jobs.
You have PMI have them and they are exactly the same as stock sans color and bushings. I am sure they made some difference but not $375 worth of a difference (i did not pay anywhere near that much)