Polybushes (again)

The "I" part of "we" is not against them but decided that "our" suspension was hard enough already so went for OEM bushes.

David

I'm for them - just for the ease of changing them next time.

David

Ditto

I changed the ones on my 90 for the red polybushes. Wish I had put genuine rubber ones on as its made the ride very hard. But a positive side of it is that it handles great on the road now! Richard

It doesn´t get harder, just more precise in handling things. I use them in my IIa 109 (together with parabolics and Konis) and in my RR Classic.

The 109 has to take me through the sahara and it does it to my great pleasure. Perfect axle articulation over the dunes and very low body roll.

Raoul

Definately still very against - fitting is easier which is a bonus because the minute you give them any stickj they die and need changing.... The big ( also most overlooked ) problem is that they knacker everything else around them - elongating holes in axle casings, wearing the holes they fit in and all sorts of stuff

All in all a great marketing exercise but a crap product!!!

David LLAMA 4x4

I'm against them. I just can't see that the difference is that much for the price they cost. Fitting Parabolics will make a significant difference to the vehicle, polybushes won't.

Why change what ain't broken?

Alex

Do they really damage their housings? It would seem almost self defeating, as if this could be proven, the company producing them would be liable for any damage caused by using them instead of the OEM kit.( wouldn't they ? )

`Agrippa

Don't think so. You'd fit them at your own risk.

However they would be "not fit for the purpose sold" as they are explicity sold as replacement bushes, and I believe various claims are made about their being better than OEM parts. I don't think there's a court in the country would agree that causing damage to the vehicle is being fit for purpose.

P.

You have any proof for this? I use them for some miles now and have no problems in this way. Polyurethane bushes are very common on many types of cars in the aftermarket or sports segment. I am not willing to believe that they just kill Landrovers. They are widely used in motorsports and there you won´t use bushes which let your suspension deteriorate in an unknown manner. Sorry, but to me this sounds a little bit rivet counting.

Raoul

So if they are easier to fit and change and improve performance why are they not fitted as standard?

And if the forces that are absorbed by the hopelessly mushy rubber bushes are no longer absorbed there, where do they go? Certainly not to anywhere that was designed to take them.

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

Thinking about this, purely from a theoretical point of view, the polybushes are more likely to absorb the force gently as they compress more slowly. The standard bushes will hit their elastic limit much faster and at that point transmit the full force directly to the part they are fitted in.

On the other point of them wearing the housings, I did read somewhere that it is strongly recommended not to use any lubricant when fitting the bushes and to ensure that the housing is not worn. The polybushes aren't supposed to turn in the housing and will wear the housing if they do.

I haven't used them on my Land Rovers but used them to great effect on my Mini's with no wear to the housings in well over 100000 miles of use.

I don't really follow. The force is applied at a rate determined by what the wheel hits and at what speed. This will be mostly low amplitude, high frequency. A polybush will deform at the same speed as a rubber one, but to a lesser degree.

You can't absorb a fast impact slowly. A high-stiffness material will transmit more of the force to the chassis, a low-stiffness material will absorb more and transmit less.

When the amplitude of the impact is greater than the size of the bush you cannot help but transmit the force to the chassis. What you can do is mitigate the first part of the impact. When the bush is fully deformed the whole movement transfers to the chassis, plus the rebound of the bush. The net result is a similar amplitude of movement, but at a lower frequency and with a more gentle curve. Too hard or too soft a material will not do this effectively and more shock loads will be transferred to the chassis components.

It's been a long time since I did proper engineering, but this seems to make sense to me?

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

You are completely right, but do you think, that the primary job of the suspension bushes is absorbing bumps and thus preventing the chassis from getting "hurt"?

The whole car has to take everything the road gives, polybushes are just a bit harder than originals. And the original crappy rubber ones do not preserve the chassis from being pushed by road obstacles.

Raoul

Hi David

Does that go for red, blue and orange?

Aubrey

Same reason LR don't fit proper gas shocks ....comes down to cost compromise.

In the real world, if you're changing bushes yourself and you lack a fully kitted out workshop with large press and mandrels of appropriate sizes, then you use polybushes.

Otherwise, there's nothing at all wrong with sticking with new genuine bushes.

Regards

William MacLeod

In my experience ( including the wider experiences of the rest of my crowd of friends - 2 of whom work on LRs on a daily basis ) this applies all the 'poly' bushes... Fit good quality rubber ones and don't even think of the poly ones - long term you will thank me!

David LLAMA 4x4