I put power flex lower rear bushes in mine it made ride better and steering more precise along with the 4 wheel alignment. However they were noisy as hell once the silicone grease dried out

 

I had that same problem with the fronts. Sounded like a tramps mattress


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There is only four, the two large ones and the smaller locating arm bushes. Do them in one hit, it is worth it, IMHO!

 

I had front lowers fitted recently by Autolusso. I queried the squeaking after reading about it on here and was told only the uppers had that issue. No problems as yet...

 

Stick to rubber like all original auto designs. If the cheaper plastic worked all manufacturers would use them.

 

You know that's not true.....if it was just a case of getting better geometry or handling all the manufacturers would all fit poly....but they have to consider lots of other things...cost, comfort, manufacturing ease...and most important NVH....but lots of us will put up with a little more of that to get a sharper handing car. I doubt plastic (poly) bushes are much if any cheaper to make than rubber ones.

 

As a suspension designer I can confirm that your thoughts are rubbish. I have contributed many posts on plastic bushes. The first thing you ought to note is that plastic is much cheaper than rubber so if it worked you know it would be used. The complex bushes in today's cars are designed with many attributes. Sticking in a lump of plastic destroys carefully tested compliance and movement. You destroy self steering, you destroy anti dive, you destroy alignment etc etc. The plastic bush is just something that fits the hole and often not even this is achieved. Squeaking comes from incorrect sizing of the hole which either allows too much movement or too little (it's forced in). Fitting non compliant plastic does not improve handling; it just fools you by making the steering tighter while washing the car out wide because the wheels are not in optimum contact with the tarmac.
Finally, there is not a single manufacturer that fits plastic. And some of those are producing cars that are aimed at track use. If it improved handling they would use them.

 

I had the poly aka plastic bushes in the lower rear arms on both my 159 for 30k plus and in my Brera for around 20k with no noise or negatives.
Steering felt more precise and the tyres wore evenly, its the upper arm bushes that have the squeaking issue.

 

That really does sound like a load of theoretical nonsense written by someone who had thought about it a lot...but never actually felt the chalk and cheese difference of the same two cars...one stock and the other polyed. Sharper, faster turn in due to more accurate geometry that stays where it should be. I don't know why you keep saying they are cheaper...polyurethane is about 10 times the cost of rubber and more difficult to shape. It will be noisier and possibly stiffer feeling but a price worth paying for many. Like rubber there are different compounds with some offering a softer compound for street use that, although not holding everything as tight as the harder ones is still better than rubber. Most rally or race cars don't use rubber bushes they use poly...some even use solid metal...the excessive NVH not being much of an issue there!

This is from a poly bush supplier...I know you will say they are bound to be biased but it gets the point across and there are lots of independent features online that day much the same. I realise they are not for you...but they will be on my car (as I've done on cars in the past with absolutely no negative effects) when mine wear out.

Why don't manufacturers fit them from new?

Cost, availability and marketing. Polyurethane, as a raw material is about ten times the cost of rubber plus it is more expensive and slower to process. Car manufacturers buy a lot of components. If Ford decided to use polyurethane bushes in their range of cars they would need to find a supplier capable of making literally millions of bushes a year. There is no company in the world (even EPTG Ltd) who could make those sort of quantities. Cars are all about marketing. As long as the standard rubber bushes work without serious failure for two or three years then the manufacturer is happy. Would fitting of polyurethane bushes make you buy one car in preference to another make? Probably not.

 

I bought a 159 2.4jtdm 2007 4 years ago with 105k km and it was eating the tyres, lasting about 7-8k km with heavy wear on the inside edge even with rotating them. Got Powerflex front lower rear bushes done by my local indie (about 500nzd/250 gbp all in) and toe adjusted with a touch to positive and they last about 18-20k km now and the steering is better, no squeaks and not too harsh. Done 160k km now.
Ps. great car, power, economy, style, comfort.

 

To be fair and pre-empt OEs reply!.....most of that the wear reduction will be losing the toe when they did the geometry..the bushes will help of course but the the 159s had way too much toe out from new and many members have similar results on stock bushes...just by changing the alignment.

 

Yeah, I tried mucking about with alignment but the flex in the original rubber bushes pushed the toe out anyway. It wasn't until I got my guy to put in the poly that the tyre wear improved. I would mention that I have the earlier narrower bushes, so the later wider ones may be slightly better.

 

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.

 

Just on a point of accuracy...under acceleration you gain toe in ...not toe out...that why most front drivers have toe out as stock...so that it straightens out under acceleration (the driven wheels trying to pull forward).....opposite is true of rear drive cars which are typically set up toe in as the front wheels get pushed back under throttle..

 

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.

 

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.

 

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.

 

I meant the tyres!

 

Lol...well that makes rather more sense!

 

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!

 

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!