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E85 Rubber Bush Replacement Program

2003 - 2009, roadster, coupe, facelift
Peterboroughdave
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E85 Rubber Bush Replacement Program

Post by Peterboroughdave » Mon Jul 17, 2017 9:21 pm

Mike

Yes that's the correct video

Dave

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GuidoK
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E85 Rubber Bush Replacement Program

Post by GuidoK » Mon Jul 17, 2017 9:43 pm

Peterboroughdave wrote: Mon Jul 17, 2017 9:01 pm Hi Neville,

There is a really good youtube video entitled "Polyurethane Suspension Bushes - The Good & Bad" , 27 minutes long but well worth watching. It shows some of the problems with using powerflex bushes and the advantages in using a properly engineered product, "super-pro bushes..
Actually, let me nuance this a bit because if you apply this video on the z4 its just a bunch of 'fear mongering'
I'm probably one of the only people here who has personally polybushed a z4 for all bushings and has a few years of experience (5-7 years) driving it.
That video is about an MX5. All problems with bushings, or ANY part on a car are always part specific (so brand/model specific)
The problems highlighted in that video are probably real (although there is no real comparison there as we dont see a proper mounted powerflex bushign), but they only apply for that specific bushing for that specific car. If that specific bushing isnt applied in the z4, it wont have that specific problem.
That doenst mean that certain important design features are worth looking at. For instance that knurling which is talked about. For the z4, most powerflex and strongflex bushings also have that knurling. So thats absolutly not a superpro feature, powerflex has that too on most bushings. (and there are also superpro bushings without that knurling) That means that (in your words) powerflex makes a properly engineerd product. Also in that video we see an old bushing that how long god knows may have been in there. Both powerflex and superpro (and strongflex for that matter) continiously redevelop their products and you can see that in that their products for specific applications change over the years. As a matter of fact, if you'd now look up that very same bushing at powerflex that's talked about in that video, you'd see that their current product has a different design. For all we know the bushing in that video is a design sold back in the 90's. (looking back at everything in hindsight is always very easy but not representative)
I'm not trying to talk down superpro because I think they too make a very good product, but basing opinions on that video and transposing it on z4 products makes absolutely no sense at all from an engineering pov.
Usually the first product on the market is the worst one designwise.
Last edited by GuidoK on Mon Jul 17, 2017 9:50 pm, edited 1 time in total.
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | fully polybushed | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs Race Engineering clutch

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E85 Rubber Bush Replacement Program

Post by Ducklakeview » Mon Jul 17, 2017 9:50 pm

GuidoK wrote: Mon Jul 17, 2017 9:43 pm
Peterboroughdave wrote: Mon Jul 17, 2017 9:01 pm Hi Neville,

There is a really good youtube video entitled "Polyurethane Suspension Bushes - The Good & Bad" , 27 minutes long but well worth watching. It shows some of the problems with using powerflex bushes and the advantages in using a properly engineered product, "super-pro bushes..
Actually, let me nuance this a bit because if you apply this video on the z4 its just a bunch of 'fear mongering'
I'm probably one of the only people here who has personally polybushed a z4 for all bushings and has a few years of experience (5-7 years) driving it.
That video is about an MX5. All problems with bushings, or ANY part on a car are always part specific (so brand/model specific)
The problems highlighted in that video are probably real (although there is no real comparison there as we dont see a proper mounted powerflex bushign), but they only apply for that specific bushing for that specific car. If that specific bushing isnt applied in the z4, it wont have that specific problem.
That doenst mean that certain important design features are worth looking at. For instance that knurling which is talked about. For the z4, most powerflex and strongflex bushings also have that knurling. So thats absolutly not a superpro feature, powerflex has that too on most bushings. (and there are also superpro bushings without that knurling) That means that (in your words) powerflex makes a properly engineerd product.
I'm not trying to talk down superpro because I think they too make a very good product, but basing opinions on that video and transposing it on z4 products makes absolutely no sense at all from an engineering pov.

http://www.suspension.com/blog/rubber-v ... -bushings/ :fuelfire: :fuelfire:

:D

Mike

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E85 Rubber Bush Replacement Program

Post by GuidoK » Mon Jul 17, 2017 10:00 pm

^sure most polyurethane will give more nvh but thats because they're mostly stiffer because they're a performance product.
A KW coilover kit is also stiffer than OEM but will also give more performance.
I have quite a few performance products on my car and seriously I cant name a single one that gave less NVH. But that comes with having a faster/better handling car, there's always a tradeoff. But the car in itself is also already a tradeoff. If you want a cumfy car, buy a mercedes S class (not suitable for enthousiastic driving on back roads or mountain roads though.....)

As for your article about the re-grease (4-5 years) I've inspected my fcab (powerflex) after 7 years (they have been the longest on my car) and they were still properly greased, so thats not a set rule (the bushing looked like new also). However what has been a fact is that the factory bushings in that spot DIDN'T last 7 years on my car, so in this instance the re-greasing period was longer than the lifespan of the OEM bushings. And thats quite a testimony to quality I think. (usually performance products dont have OEM lifespan because their main goal is performance gain, not lifespan)

Also indeed fitting them is easier, but If you can remove the old bushing it usually means you can also install an OEM bushing (because thats always easier). But it saves some time (although there are multiple poly bushings that also have to be pressed in; most bushings that have a orient critical mounting).

BTW OEM bushings can also squeak once they start to wear a bit. And not all OEM bushings are bonded. The OEM arb bushings for example. They have the same risc of squeaking (maybe even more) than polyurethane ones.
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | fully polybushed | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs Race Engineering clutch

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E85 Rubber Bush Replacement Program

Post by Boris » Tue Jul 18, 2017 11:17 am

Dave/Mike,

Much appreciate the trouble you have gone to digging out that vid; a picture or vid in this case speaks a thousand words as they say.

I must admit I thought the poly bush was an interference fit on the crush tube and the crush tube rotated around the bolt, but now you see it in action it can't its crushed between the two flanges, simples.

:thumbsup:

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