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The main issue with the standard bushes isnt the material they are made from but that they are void bushes which allow too much movement so with the alignment set correctly or even to a revised setting as soon as the wheel is under braking or acceleration load it moves rearwards and gives a lot more toe out.
This has been discussed many times and although oe is correct in his theory that is assuming that the design and development of these bushes was without error, and we all know that many other parts of the cars had design faults so it is fair to assume that so the bushes may not be correct.
Its a simple case of the poly or plastic whatever you want to call them bushes do improve on a bad design and without any reported downsides.
To reiterate an observation I made when this issue came up a long while ago, I would not use polys where there was any direct connection with Alloy transmission assemblies.

But there is a complete disconnect with the Q4 rear trailing arms and there is very little travel to exacerbate squeeks, in my experience.

The rear drive system becomes incredibly more precise, which with the four wheel drive system, leads to a much more predictable steering geometry. That was not the case hitherto. Accepted, one was leaking oil.

However, I did replace that arm with a new one at over four hundred quid. And while Powerflex developed the bushes I was continuing to "Play" with my 159".

I had them fitted within a few days of Powerflex contacting me, despite the back end being "up to spec", with the original arms. And the difference was immediately tangible. No squirming when I floored it and braking was also that much more precise. One could concentrate on setting the car up better for a bend, knowing the back end was precisely planted and no counter - adjustments were needed on the steering.

As for squeek, I just don't recognise what is being suggested. The travel is far too small to generate it - IMHO - less than 15 deg. The bushes are very large and any noise there may be would be muted. Assuming they were fitted correctly - tightened up with the car on the ground.

Nope - I remain unconvinced as to the argument about these bushes and they will work equally well on front wheel drive versions. Probably better as they are not subject to the same load as those fitted to the Q4. After all, they are substantially for location and they are much more precise than the standard ones.
 

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Voids are what make the rubber bushes special. They allow the joint to have different characteristics under different loads. The joints move entirely as designed.
 

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Voids are what make the rubber bushes special. They allow the joint to have different characteristics under different loads. The joints move entirely as designed.
Very precise. You will get no argument from me. Oh that you didn't go into engine design where things need to be much more precise - a lesson Alfa have long forgotten!

But, we are not talking about original equipment manufacturer supplied parts. It is aftermarket parts. And individuals can make their own decision, based on information from various sources. In the strictest sense, you provide a definitive opinion. But, as with all things, people can choose to ignore it - experts are out of fashion. Nonetheless, I value your input.
 

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Back in the real world:
OE rubber = tyres last 8,000km
Powerflex/poly = tyres last 20,000km with no ill effects after 50,000km
 

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Lol...8000km???....that less than 5000miles! Even as a supporter of poly I think that's a little pessimistic....some of my originals were still on and passing MOTs at well over 100,000 miles!! The rears (with the small amount of movement) more than the fronts but even they are usually good for 50,000miles plus.
 

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To reiterate an observation I made when this issue came up a long while ago, I would not use polys where there was any direct connection with Alloy transmission assemblies.

But there is a complete disconnect with the Q4 rear trailing arms and there is very little travel to exacerbate squeeks, in my experience.

The rear drive system becomes incredibly more precise, which with the four wheel drive system, leads to a much more predictable steering geometry. That was not the case hitherto. Accepted, one was leaking oil.

However, I did replace that arm with a new one at over four hundred quid. And while Powerflex developed the bushes I was continuing to "Play" with my 159".

I had them fitted within a few days of Powerflex contacting me, despite the back end being "up to spec", with the original arms. And the difference was immediately tangible. No squirming when I floored it and braking was also that much more precise. One could concentrate on setting the car up better for a bend, knowing the back end was precisely planted and no counter - adjustments were needed on the steering.

As for squeek, I just don't recognise what is being suggested. The travel is far too small to generate it - IMHO - less than 15 deg. The bushes are very large and any noise there may be would be muted. Assuming they were fitted correctly - tightened up with the car on the ground.

Nope - I remain unconvinced as to the argument about these bushes and they will work equally well on front wheel drive versions. Probably better as they are not subject to the same load as those fitted to the Q4. After all, they are substantially for location and they are much more precise than the standard ones.
tightening up with car in the ground is not required as the bush is a 2 part design that allows inner (bit connected to arm) to rotate within the outer part. It was at least the case with my front lower bushes anyway.
Despite the lack of movement you mention they made an awful racket after being fitted for a while.
Admittedly steering sharpness was better than standard rubber but it’s a trade off between handling improvement and the god awful noise emitted going over bumps.
 

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tightening up with car in the ground is not required as the bush is a 2 part design that allows inner (bit connected to arm) to rotate within the outer part. It was at least the case with my front lower bushes anyway.
Despite the lack of movement you mention they made an awful racket after being fitted for a while.
Admittedly steering sharpness was better than standard rubber but it’s a trade off between handling improvement and the god awful noise emitted going over bumps.
Story becoming convoluted - yet again.

Point taken on the inner sleeve/bush. But to repeat - we are still talking about the rear trailing arms here - not the fronts.

So, with direct regard to the rears, there has never, ever been a squeak out of these Power flex bushes, fitted to my car.

As for the fronts, I would never fit them. Not because they squeak and not because they don’t improve handling - because clearly they do.

Simply because I would not like them transferring impact to light alloy castings. Be that the GTA’s, GTV’s or 159’s.
 

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The OP asked about poly bushes generally and which would you fit first not specifically about the rears. Regarding fitting poly's to the lower fronts and any additional stress goes, the components like the lower and upper wishbone alloy castings are substantial and probably stronger than any steel equivalent so I don't think poly's would transfer a dangerous additional level of vibration or impact. In my experience with them the ride is not excessively harsh (I bought the standard purple powerflex bushes - they also had denser black versions and perhaps those might be a bit too harsh)
For me fitting poly's on the lower front control arms, and the alignment, were the fix for the excessive tyre wear I was getting, simple as that.
I've not needed to fit poly's throughout, perhaps that would make the ride harsh for our rough rural roads.
 

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The OP asked about poly bushes generally and which would you fit first not specifically about the rears. Regarding fitting poly's to the lower fronts and any additional stress goes, the components like the lower and upper wishbone alloy castings are substantial and probably stronger than any steel equivalent so I don't think poly's would transfer a dangerous additional level of vibration or impact. In my experience with them the ride is not excessively harsh (I bought the standard purple powerflex bushes - they also had denser black versions and perhaps those might be a bit too harsh)
For me fitting poly's on the lower front control arms, and the alignment, were the fix for the excessive tyre wear I was getting, simple as that.
I've not needed to fit poly's throughout, perhaps that would make the ride harsh for our rough rural roads.
That’s fine. It’s your car and you are happy with what these bushes bring.

For me, I’ll just stick with the ones I’ve got. And they don’t squeak!
 

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Back in the real world:
OE rubber = tyres last 8,000km
Powerflex/poly = tyres last 20,000km with no ill effects after 50,000km
To be clear.; Original rubber joints but steering set to my figures in the stickies will give you 20,000 miles. Together with a softer front spring and original stiff rear end will give neutral handling. If you drive at 100MPH then setting the steering to Alfa settings will give you very high speed stability.
 

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Yeah, we did not rush into poly but first tried all sorts of alignment settings and it still ate the tyres with rubber lower front control arm rear bushes, as I said earlier, perhaps the later wider bushes give slightly less flex so hold the alignment settings better than the narrower bushes that we have on our car. I don't think most people would need to drive at 100mph these days, perhaps if they go to track with a real long straight but the 159 is probably not the best choice for a track day either and I would think that the poly bushes would be fine for 100mph anyway. I can understand people defending the holy grail of Alfa engineering, but in this case the swap to those poly bushes that we did on our car really improved it.
 

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Yeah, we did not rush into poly but first tried all sorts of alignment settings and it still ate the tyres with rubber lower front control arm rear bushes, as I said earlier, perhaps the later wider bushes give slightly less flex so hold the alignment settings better than the narrower bushes that we have on our car. I don't think most people would need to drive at 100mph these days, perhaps if they go to track with a real long straight but the 159 is probably not the best choice for a track day either and I would think that the poly bushes would be fine for 100mph anyway. I can understand people defending the holy grail of Alfa engineering, but in this case the swap to those poly bushes that we did on our car really improved it.
You won’t catch me defending the holy grail of Alfa Engineering. That was lost decades ago.

Sorry I’ll rephrase that. Fiat Buried it decades ago!
 
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