Genuine Bushes Vs Powerflex Bushes?

[Jim320i]

Which are better and why?


Obviously the powerflex ones may have the advantage, but in comparison to price, which would make sense to buy?


I'm rebuilding my 320i and looking at bushes... Do I just buy genuine or the pf ones?


Any help or opinion is helpful!

[daimlerman]

I have polybushes most places,now,on both cars.Mounts that still have rubber,I have poly one's in stock to fit when the rubber gives way.

I have kept to stock rubber,however,for the rear beam mounting bushes,as I understand that the rubber bush allows the beam to move as BMW intended.

Elsewhere,poly bushes 'tighten' the feel of the cars on the road and preserve the 'new bush' feel forever.But they do transmit a little more noise into the cabin,you can hear the suspension working.

[Jim320i]

Whats the sort of price difference for them? I had a look at the powerflex ones on Ebay, and you can buy the whole rear end set up for about £180... I felt a bit sick. lol... But at the same time, you can buy them indivually so I dont mind as I can get them as I go along.

The car is going to be rebuild all over and taken back to 'new', so it won't be raced around, or driven stupidly, and only out on nice days. So thats why I think just go for genuine ones as it would be much cheaper and with the use it will have,they should last quite long anyway.

[penton08]

when i first re built my car i poly bushed the complete car, i changed the front tca bushes to genuine m3 items with in a week!! the diff bush got eaten within a month and i changed the rear beam bushes back to bmw rubber soon after. all that remains poly bushed is the trailing arms, and it drives so much better for it

[Jim320i]

I'm assuming 'Polybush' is another leading brand at this point, but doesnt sound like you had a good experience with them Penton08.

I like the idea of genuine bmw ones, but I just want something that will last that bit longer as I won't be using the car as much as I have done... It its wet outside it wont be out, it will only be out through the summer months too and insured for no more than 1000 miles a year, so with the limited use, i'm worried they may just deteriate.

[daimlerman]

Ah,now there's the difference,my cars are in daily use!

Polybushes are a 'fit and forget',I will not need to change them for years,if at all.

Rubber degrades slowly over time,you do not notice it until you change a bush or drive a similar car with new bushes.

The noise transmision thing is only really noticable with TCA bushes,I had a polybush on the diff mount on one car,swapped the diff and the replacement diff had a sound Z3M rubber bush already fitted,I cannot tell the difference.

Same with ARB bushes,one car has rubber,other poly,I cannot tell the difference,I suspect that the rubber bushed car will start to 'feel' different as the bushes de-grade and become due for replacement.

One big advantage of poly over rubber is that poly is very easy to fit,TCA bushes,for example,come in two bits,the lolly pop bit pushes in with ease and the pin bit just slides on,and off,when the TCA's balljoints fail you can transfer the poly pin to your new TCA,very much more difficult to do with a rubber bush.

Trailing arm poly's come in three bits,two 'top hats' that just slide into the housing,and a stainless steel pin/bush thingy that goes in the middle for the retaining bolt to sit in,dead easy to fit!

[kam325itouring]

i was going to poly bush the front end of mine. whats the difference with eccentric and concentric ones i wanted to order the right ones. Also what size antiroll bar ones would i need for my 2.5 touring?

kam

[daimlerman]

i was going to poly bush the front end of mine. whats the difference with eccentric and concentric ones i wanted to order the right ones. Also what size antiroll bar ones would i need for my 2.5 touring?

kam

Concentric is standard fit.

Eccentric is M3 pattern,and is a vast improvement.Gives more steering 'feel',to the point that when I had one car with concentric and one with eccentric,even my wife noticed a difference!

ARB could be one of several different sizes,best get underneath and measure it.Use either a vernier caliper gauge or a tape measure(wrap the tape measure around the bar and divide the result by 3.14,remember pi from school maths lessons?)

[DanThe]

IMO the only places worth fitting poly on a road going E30 is the trailing arms and ARB bushes. Fit M3 eccentrics on the front wishbones, for the rear beam fit OEM quality bushes with bush supports, and on the diff id rather fit a soft rubber bush than a hard poly bush, if the bush is soaking up movement and vibration its less likely to do this to your floorpan



This is a Z3, but with reasonable power it can happen to an E30 also. Id rather replace a fcked rear beam than have to weld the floor up...

Superflex are a better quality bush than Powerflex

[eltel]

wow..

[leeparkes]

Did a mighty M42/44 cause this?

[DanThe]

Im guessing it was an S50 or S54 donk Lee

[Kos]

One big advantage of poly over rubber is that poly is very easy to fit,TCA bushes,for example,come in two bits,the lolly pop bit pushes in with ease and the pin bit just slides on,and off,when the TCA's balljoints fail you can transfer the poly pin to your new TCA,very much more difficult to do with a rubber bush.

and i've seen them fail with scary results

i've seen the damage, as show by dan what polly diff mounts can lead to

admittedly the Z3's damage is extreme but it is possible on car where you fit bushes with little on give

on a road car i'd fit OEM rubber bushes. you often hear people say " wow i fitted polly bushes and the cars amazing, drives like new" etc, but in reality new OE bushes will have the same effect.

final, powerflex are rubbish in compassion to superflex.

[daimlerman]

Thing is though,Kos,when or if a TCA bush fails,the TCA is trapped within the bush mounting,so although the car will feel 'different' or 'wrong',it can still be brought to a halt without drama.

A polythene bush is no more or less likely to fail than a rubber one,the poly bush is easier to fit for the DiY guy,and will retain that 'new bush' feel for far longer.

The area highlighted by Dan does refer to very high powered versions of a car known to be not as solid or well built as an E30,and there are also well documented failures of boot floors in higher power versions of E46,but I cannot recall any reports of failure in this area regarding standard versions of E30.
Perhaps you know better?

[DanThe]

Some zoners have posted pictures of their E30 diff hangers ripped off the floorpan, most of the time they pull the tophat reinforcing section with them. Mainly turbo conversions.
The Z3 does have a harder rubber mount, so will transmit more vibration into the chassis which helps it fall apart

The main bit about most Powerflex bushes that I dont like is that they come in two halves, if anything this makes them softer.

[daimlerman]

Some zoners have posted pictures of their E30 diff hangers ripped off the floorpan, most of the time they pull the tophat reinforcing section with them. Mainly turbo conversions.

My point exactly!

When carrying out upgrades,every part of the car needs consideration.

I get the distinct impression that the OP is intending to keep his 320i standard.

[Kos]

when i say the TCA bush failed, its the polly bushes that have failed and the consequences were quite shocking. there were plenty of dramas.

i've said it before, the 2 piece design is rubbish, the OE bmw eccentric bushes are prefect and work perfectly. i put my faith in bmw parts in this instance. they need more effort to go in, but they do a job and are less likely to fail than the powerflex ones. how they wear is differently.

in regards to the ZM coupe issue, it a well documented subject as are the e46 problems. i have seen similar in e30's but they were higher powered ones with over 250bhp. its no just matter of build qualty its down to the high out put of power and driving style.

so, if you start using polly bushes which have very poor vibration absorbing qualities on the diff, they transmit stress to other points. there is lot of torque pulling in this area and its a constant on off force. imagine a paper clip, wiggle it a few times and it breaks. this principle applies to the car. so, for this reason unless you start reinforcing the back end of the car, i'd stay away from polly diff bushes. i've seen broken diff covers, diff mount hangers and boot floor issues all from road cars with power outputs varying from 200-700bhp

want an upgraded diff bush, buy a ZM one, it fits on to all e30 diffs be it a small or medium case

so, in short, yes i do know better on this subject

[Kos]

Some zoners have posted pictures of their E30 diff hangers ripped off the floorpan, most of the time they pull the tophat reinforcing section with them. Mainly turbo conversions.

My point exactly!

When carrying out upgrades,every part of the car needs consideration.

I get the distinct impression that the OP is intending to keep his 320i standard.

so, why lean in the direction of recommending a polly diff bush ?

the ZM one is a perfect OEM upgrade and will not be detrimental like a 2 piece pooflex one

[nathyb]

poly bushes every time especialy when running alot of power they help keep the car handling as it should i have even had solid rear subframe mounts on a 400bhp pulsar they where a little noisey tho

[Kos]

poly bushes every time especialy when running alot of power they help keep the car handling as it should i have even had solid rear subframe mounts on a 400bhp pulsar they where a little noisey tho

not on an e30

[daimlerman]

Some zoners have posted pictures of their E30 diff hangers ripped off the floorpan, most of the time they pull the tophat reinforcing section with them. Mainly turbo conversions.

My point exactly!

When carrying out upgrades,every part of the car needs consideration.

I get the distinct impression that the OP is intending to keep his 320i standard.

so, why lean in the direction of recommending a polly diff bush ?

the ZM one is a perfect OEM upgrade and will not be detrimental like a 2 piece pooflex one

Poly diff bush that I have used came in five parts.....

Two poly bits that fit into the bracket,one from each side,
Two stainless backing plates,
One stainless centre bush.....

For STANDARD cars,polyurathene bushes are fine,read my post above regarding modified,high power cars,where I am more than happy to bow to your experiance in this area.

But do read again the OP's original post....

[nathyb]

[/quote]



not on an e30[/quote]
why not on a e30 ??

[daimlerman]

I have kept to stock rubber,however,for the rear beam mounting bushes,as I understand that the rubber bush allows the beam to move as BMW intended.
.

[Kos]

Poly diff bush that I have used came in five parts.....

Two poly bits that fit into the bracket,one from each side,
Two stainless backing plates,
One stainless centre bush.....

For STANDARD cars,polyurathene bushes are fine,read my post above regarding modified,high power cars,where I am more than happy to bow to your experiance in this area.

But do read again the OP's original post....

i did, but what wrong with the OE one piece bush ? nothing. what's wrong with the poweflex one ?

well, its made up of 5 pieces as you said, the 2 main ones and 3 other bits to hold it together and in place. how is that an engineering improvement?

and even if the car is standard, these will give more vibrations into the car/chassis/floor pan so in time it will be detrimental.

high powered e30 will need more than a diff bush upgrade. anything over 300bhp will need reinforcing

nathyb

read my posts above and do some research

on standard car fit a OE one or a ZM item, there is no benefit to be had from polly, even if they are "easy" to fit, the OE ones dont exactly take more too long. i've done it with 90 and that jacking the car up, draining diff, dropping back cover, pressing out old bush, pressing in new one and re fitting it all and having a ciggie in between

the man who uses dulux paint on a car should not be giving advise

[daimlerman]

Thanks,Kos,I am pleased that you agree that you were wrong to say the poly diff bush came in only two pieces!

I am not offering' advise',or even advice,just passing on years of practical car maintainance experience,it is up to my readers to decide just what they fit to their property.

[skipunda]

Leave any personal insults out please.

[Jim320i]

Wow. Debate. Aha


As for the 'powerflex bushes', I only said them as they are the only ones I know of to be honest, I now know there are a few brands out there, but i'm assuming the oem ones will be dirt cheap in compairson to 'upgraded' ones. And like Dailmer said, I am keeping it all standard and won't be racing it around, and if I do, its in a straight line...


I am still debating on whether to upgrade it to a 2.5 lump, but even if I did go that direction,for the use it will get, I think the oem bushes might be my best bet as I dont see the point in paying all that cash out for something that seems like its designed for something more 'fruity' under the engine.

Does anyone know of the top of their head how much bushes are from bmw on average? I might try and get a price from cotswold on here but always do that and never buys.


Still got so much I need to buy from them just never get round to it.


Please keep debating though as I like to see the pros and cons of both, but like Skipunda said, keep it cool.

[DanThe]

The only ones to get from the dealer are the M3 front eccentrics, (about half the price of powerflex)
For rear beam mounts and diff use Febi or Lemforder from eBay, ECP or GSF etc. Superflex for the trailing arms as they are better and a lot cheaper than Powerflex and BMW.
Your diff bush will probably be fine anyway.
This is the best combination for a road car, you dont want them too hard because of the pi55 poor state of our roads

[penton08]

The only ones to get from the dealer are the M3 front eccentrics, (about half the price of powerflex)
For rear beam mounts and diff use Febi or Lemforder from eBay, ECP or GSF etc. Superflex for the trailing arms as they are better and a lot cheaper than Powerflex and BMW.

this is now exactly what i have except all the rubber bits came from bmw, i have fitted the same set up to a customers car recently and it came in at around £200 for all the bits.

[leeparkes]

I had a quote from Cotswold the other day for rear beam bushes and ARB bushes

Rear beam £60.77

Rear ARB bushes £12.74

[Jim320i]

Sweet jesus thats more than I thought for the rear beam. Gonna have to buy them gradually.


Just need to figure out whether I rebuild the 2 litre engine and keep it nice and original as not many people actually do that, or to just stick a 2.5 and rebuild that before it gets put in.

If I do that then I'm assuming all the bushes I need will be different anyway?

[DanThe]

No, the above list is for an E30 road car in general.

If your rebuilding an M20 it would be daft not to stick a 2.8 crank in

[Jim320i]

That was a future question actually, I have read about it in the past on here. To my understanding it can only be done with the 2.5? Or am I wrong and it can be done on a 2ltr? And in doing so, what does it actually do? Sorry for the daft question, new to it all so jumping into the deep end, but should be fun!

[DanThe]

It will give about an extra 100hp over the 2 litre

Best to build the engine with M20 2.5 parts while the car is still in use

[Jim320i]

Cars off the road mate as got another one for the winter, but in no real rush to get it back on the road yet so dont mind if its off for a year or more while I gradually do the work. Want to try and rebuild everything so its like new again so gonna take me ages anyway.


I was thinking of getting a donor 325 and going from there, that way I have everything I need to convert it all over, plus neither car will be needed.


Any links to projects like this that have been done would be helpful as need to learn a bit more about it. And a extra 100hp does sound appealing.