polyurethane bushes?

[pihlen]

hi,
im wondering if polyurethane (PU) bushes are raising handling noticably? i consider buying a full kit (20 pieces total) for the whole suspension and its a bit of money so i wanna see if anyone have experience of it and can tell me if its worth going for?

right now ive got the orig bushings which are shitty in shape and needs replacing. is PU a good option and worth the money?

it says it has hardness: 80ShA and i dont know what this means? is it very hard for road use? is it "too" hard for normal road use? (i like intense driving).

i have now orig susp but thinking of changing to new (not particulary fancy) susp with 40 mm lowering front and rear.


Here is the complete list:

2x 031319B Front anti roll bar mounting bush 18-23mm SPORT

2x 031320BRear anti roll bar mounting bush 15-24mm SPORT

Notes: Measure Anti Roll Bush diameter before placing order

2x 031321B Front lower inner bush SPORT

2x 031322B Front lower outer bush 39mm SPORT
or
2x 031446B Front Lower Outer Bush 42mm SPORT

4x 031314B Rear Trailing Arm Bush SPORT

4x 131126B Front Eye Bolt Mounting Bush SPORT

2x 031323B Rear diff mounting bush SPORT

2x 031466B Rear beam mounting bush SPORT


the price (in sweden) is approx $270/€245.

THANKS for any help!

[Jeroen]

In my opinion urethane bushes can only be the finishing touch if you're speaking of stiffening up your suspension. On the total package the influence of springs, dampers, sway bars etc is much, much bigger. So if that's all been uprated and you feel it should be sharper, go ahead. On a street car with the average suspension, no. Of course you will feel a difference (you will hear it too and feel it as vibrations are absorbed less) but it's not the world. Any other upgrade will have more effect.

Of course there are huge differences when you move from knackered 35 year old rubber to polyurethane, but that will already be the case with replacing the old stuff by fresh rubber.

Just my biased view

[petroscf]

I replaced almost all bushes by eurometric ones (I don't know what stiffness are they-but maybe Jesse Nemec couls answer that question, he's the manufacturer after all)
I saw big difference in sharpness of handling, so I would suggest them. However, the following facts, concerning my car, have to be taken into account, if one wants to holistically approach the matter:
A whole bunch of other things were changed-upgraded as well, so I can't be sure if this difference is due just to the bushes. Things replaced(which might also affect handling feeling):
Rear trailing arms (from 4cyl with drums to 6cyl with discs-I don't know if this has any difference at all though)
Steering rack (from factory to the new quick one-so this makes by itself a big difference on the whole car's feeling I guess)
Everything under the floor was re-inspected and tightened etc., as lots of things were replaced (engine-gearbox-exhaust-diff)
Soooo I guess Jeroen is right here: Maybe it's not the polyurethane by itself, but it's the new bushes (which means that if I still had the same bushes replaced, but by factory-rubber ones, I would still get the same exactly feeling)

However, I want to mention here something that I did not expect, in the whole experience:
-Sharpness yes, hardness or stiffness no! and,
-No noises or vibrations from the road
Although I expected to get a lot ao the above, as I was told-and had read before fitting the bushes. And think that an average Greek road is a lot worse than an average road anywhere in Europe.

[Jeroen]

On my road car I use rubber all around. One place where you might want to stiffen things up is where the front sway bar connects to the trailing arm, as an alternative I placed modified rings around the bushing to reduce free movement. Where I did fit polyurethane is for the large blocks holding the rear beam, but mainly because the OEM ones are bloody expensive. This has stiffened things up compared to my 35 year old stock ones, but has also slightly -only slightly- increased the driveline noise that is being transfered to the chassis. Back then I only did this upgrade and drove right before and right after the work was done so I could do a decent compare.

[petroscf]

...but has also slightly -only slightly- increased the driveline noise that is being transfered to the chassis...

Now I am thinking that maight be the bushes the reason I experiens some noise which I think might be coming from te diff?
I have some slight "humming" (not sure if this is the right description though) noise when I leave the accelerator pedal and the car goes by itself so the engine is just idling, windows up etc and I can hear other noises, for example during a downhill. I was thinking that it's the diff. It's like a noise coming from something "turning", as, when I push the brakes, the sound changes accordingly, if you can understand what I mean. If I leave the car speed up again (foot off the brake pedal) the noise "accelerates" again

[brockzila]

I'm looking at strongflex will be placing an order soon. Best value for money I can find. BMW are such a pain in the ass to deal with here. J have been told more than once that they can no longer get parts and then to order it on line before they even look at it.

[quote/]
Steering rack (from factory to the new quick one-so this makes by itself a big difference on the whole car's .[/quote]

Sorry for the Jack but where did you get the quick rack from??

[petroscf]

Hi, a group buy took place in the forum about 2 years ago (or was it 3?)
I got one but took me all these years to fit it lol

[Duracel79]

The supply of quick steering racks was from Kiley Clinton in the UK.
They need you to supply an original rack which they then convert with new internal components.
All manual racks LHD or RHD. But no power steering.

http://www.steering-racks.co.uk/bmw-e21 ... -rack-rhd/

Regards
Ben

[joe14]

What is the availability like for steering rack bushes? Are poly versions worth it?

[brockzila]

Thanks gents

[ruh]

I know this thread is not super fresh any more, but would like to add my 5 cents of wisdom

I agree with jeroen, the polyurethane upgrade should be done if all other things are top notch. Otherwise it will in one sense loose its meaning. However i have found that strongflex is perhaps the cheapest way to get new bushings for the entire car and that has to count for something too.

I noticed that the hardness of the polyurethane was a question. I found this chart online.



There are several "shores" that you use to measure the hardness of rubber and other materials. SHA means Shore A.

Your everyday normal bushes on the car would be around 70SHA in hardness. So 80SHa is a definate upgrade to a harder and more noisy and vibrating suspension, but you will also gain more control and feel for the dynamics of the car. I would never use the 90SHA ones on a road car, or aluminium ones for that matter. That is racecar stuff.

[Jeroen]

useful info!

[e21_lyf]

just get some PU bar and lathe it to seize with stainless internal sleeves & nylock nuts and bolts.

Must be cheaper than buying full kits. Looking under the car last weekend, there aren't too many points to bush either.

[Jeroen]

Just look at the supplier's websites like from Strongflex and you know what's there.