Urethane or rubber?

[spannercrab]

Hi all,
Just in the process of doing some of the front end bits (tie rod ends, radius arm bushes) etc. that are a bit worn and figured while I'm at it, I might as well replace the rest of the bushes since they are such a PITA to get to.

The question is, which is the better way to go?

Invariably in the manufacturers blurb for either rubber or urethane, each states that their product gives superior off road ability and lasts for longer - which is quite confusing from a customer point of view!

Any opinions on the subject?

Thanks in advance!

[Gwagensteve]

Spannercrab,

you haven't really given us enough information - what kind of car? What do you do with it? How is it set up?

Generally, I am a big fan of rubber bushes, mostly because urethane generally restrict a bit of travel, can be noisy, and can also increase the war on bolts/brackets.

However, in some applications they are OK - where the bushing only suffers very slight misalignment - like the wishbones on IFS vehicles.

IMHO the WORST place for a urethane bush is in the diff end of radius arms (like the front of a GQ/80series/LandRover. The misalignment these bushes are required to do is in two planes, and uretheane bushes WILL increase your roll stiffness and reduce travel in this location, especially when combined with caster correction which places less meat around one side of the bolt so there is less material to squish up.

Generally, Rubber bushes last about 12 months- and that is their downside.

I have a collection of worn bolts and scarily cracked/worn shackles from people running urethane bushes on Suzukis.

Steve.

As an aside, there are lots of urethane bushes on the market mostly because A) they do have a place in road cars and B)they are cheap and easy to set up to manufacture.

A heavily and frequently greased urethane bush is fine, but in some cases they are hard to grease, and in any case if the bush materal is too stiff no amount of grease will help.

[zooki]

Urethane all the way, last longer, doesnt grow and bind to the pins and bolts to restrict travel, self lubricating.

of course there is Urethane and there is urethane, most of the bushes available are cheap quality material made with too high a Duro (hardness) bushes made from Quality Material and a similar Duro to most rubber bushes are a million times better than anything else you will try

[Gwagensteve]

I agree that there is a big range in quality with urethane bushes, but I think you might be overstating the strengths of urethane.

I have some very old urethane bushes at home which are very very hard and poorly designed. I agree that newer designs are much better.

I have not found them to be "self lubricating" In my experience as they wear then tend to trap grit and scale which is very abrasive and accelerates pin wear.

Rubber bushes will only "grow" if they are greased with a hydrocarbon based grease. When this happens they also get softer so they don't hinder travel, but they flog out very quickly.

(PS don't want to sound like an a$$hat but if rubber "grew" over time we wouldn't be buying many tyres!)

Urethane bushes must be greased to be effective. In my experience of leaf spring bushes, regularly greasing them requires a strip down and clean about once a year because of crud built up in and around the bushes.

For my money, if I have to pull the suspension apart once a year to clean all the sand grit etc out of the grease and re pack them, then I might as well just run rubber and change them once a year, and run no grease.

Just my 2c.

I will add that my principle experience is with leaf spring bushes, but I have seen and heard enough people have trouble with urethane in radius arms to know it isn't a good idea. It is quick fix for caster and that is all.

PS my Gwagen still has all its original rubber bushes at 300,000km and 25 years, including 7 years with far more travel than merc designed for, so rubber can last just fine.

Steve.

[me3@neuralfibre.com]

So apart from drilling and welding new holes on the Live Axle cruisers (I'l get there eventually), is there a rubber equivavlent of the offset bushes? OME is dropping them in with their 2" kits, and whislt I agree they increae likyhood of cracking mounts, figure that the occurance must be low. Perhaps with swaybar connected it takes enough travel away to stop the problem? (and limits flex).

Paul

[Gwagensteve]

I am not aware of any offset rubbers.

I think they might not work anyway as the flexibility of the rubber would mean they woudl fail quickly with the small amount of material between the bolt and the arm.

I have redrilled radius arm holes in coil suzukis and it is an excellent modification. IMHO. Unfortunately in the case of suzukis, there ar eno rubber replacement bushes only urethane and they ultimately crack their mounts.

Steve.

[Highway-Star]

Rubber bushes will only "grow" if they are greased with a hydrocarbon based grease. When this happens they also get softer so they don't hinder travel, but they flog out very quickly.

(PS don't want to sound like an a$$hat but if rubber "grew" over time we wouldn't be buying many tyres!)

You shouldn't grease rubber bushes at all, should you? Don't they just end up like soe abrassive rubbing block if you do?


Mate, if rubber really grow (I don't meen on trees either), then we could start off with standard size, and end up with 10% bigger in a couple of years . Tyre shops would sell you new tyres to fix your gearing and stop scrubbing, and you could sell your oldies to someone who wants sme cheap biggies.

[zooki]

no overstating at all, there are far more grades than you think would ever be needed, the trick is knowing somebody with the experience to spec the correct stuff based on performence and not price

http://www.auszookers.com/index.php?nam ... &profile=6
that guy is in the business and has no probs doing jobs that are different to achieve a specific result and knows his stuff

[chimpboy]

I am pretty sure Gwagensteve hit it on the head with the first reply, if the application is one where the bush really just acts kind of like a bearing and allows full movement without needing to deform much, then a harder material is fine, but if the bush is one that is designed to flex a lot to allow proper suspension travel, then a hard material like urethane is a really lousy solution that reduces travel and increase wear on non-replaceable parts.

Just my thoughts.

[Gwagensteve]

no overstating at all, there are far more grades than you think would ever be needed, the trick is knowing somebody with the experience to spec the correct stuff based on performence and not price

I know there are very many grades of urethane. However, the issue you miss there is percieved value. It I spend $12 on a urethane bush rather than $4 for a rubber one, I expect 3 times the life. I f you mke a grade that flexes just like rubber in a axial joint like a leaf spring bush, it will not achieve three times the life of rubber. It might do twice the life, but what kills it will be the environment its in, not the properties of the urethane.

In a rotational joint like those on an IFS front end, urethane is the business because duro is what's important, but duro is a measure of "hardness" which is not really what we are after in a high misalignment joint.

PS you can grease rubber bushes with rubber grease. I use it to aid installation. It washes out pretty easily, but it does make everything go together smoothly.

PPS - for my money, if I was going to go with urethane (which requires greasing) then bushes machined from brass/bronze would be far superior IMHO.

Steve.

[zooki]

I am pretty sure Gwagensteve hit it on the head with the first reply, if the application is one where the bush really just acts kind of like a bearing and allows full movement without needing to deform much, then a harder material is fine, but if the bush is one that is designed to flex a lot to allow proper suspension travel, then a hard material like urethane is a really lousy solution that reduces travel and increase wear on non-replaceable parts.

Just my thoughts.

I have had bushes made that you could deform in your hand, Urethane is not always a hard material

[zooki]

I know there are very many grades of urethane. However, the issue you miss there is percieved value. It I spend $12 on a urethane bush rather than $4 for a rubber one, I expect 3 times the life. I f you mke a grade that flexes just like rubber in a axial joint like a leaf spring bush, it will not achieve three times the life of rubber. It might do twice the life, but what kills it will be the environment its in, not the properties of the urethane.

who said anything about $12? I would gladly resell them to you for that and keep the nice profit

In a rotational joint like those on an IFS front end, urethane is the business because duro is what's important, but duro is a measure of "hardness" which is not really what we are after in a high misalignment joint.

your confusing the material and applications that require a stiff bush, Urethane can be harder than some metals or soft as foam so its a mute point

[Gwagensteve]

I know, I have seen some incredibly soft urethane. At that point though, why is it better than rubber for a bush? It is certainly dearer, and I do not believe that for the same duro it will be more durable.

The major selling point for urethane is durability. (which means increased stiffness and reduced flex)

Energy suspension (from memory.... might have been daystar) in the US sold some urethane they claimed increased travel over worn rubber.

Petersens tested them, and they did.

They were a pretty specialised part though - the spring hangers had to be spread because the flanges were super thick.

The compared these with old worn out rubber with very tight hanger/spering clearances. I'm not saying it was a trick, but they weren't really comparing apples with apples.

Steve.

[me3@neuralfibre.com]

I know on my rally car we (and most) people ran rubber everywhere. It significantly reduced stress cracking all over the car. Group A guys ran poly, as it gave more precise predictable handling, but they weren't running cars where fatigue cracking was such a problem.

There is more to it than stiffness. I expect there would be differing hysteresis affecting how they heat up when worked. More important on high speed stuff.

Paul

[badger]

what about in the instance of patrol rear arm bushes?
genuine nissan are the only rubber bushes that last (lucky to get a year if you fave good flex) and they sell for about $30 each plus pressing in n out
where as the urethane bushes are less than $60 for a whole set and way out last nissan bushes. they also have no effect what so ever on the articulation of the car.

admittedly they do fill up with grit but since i have changed to urethane i just pull out my bushes to clean and regrease occasionally. if i had rubber i would be pulling them out to replace them wich means i have to find someone with a press and cough up 2 times asmuch to buy the lesser lasting bush.

ps has anyone got any idea where to buy poly flex bushes as i beleive these are the go but cant fitd them now ORI is closed down

[Gwagensteve]

Badger, this is an interesting case. To my mind, GQ patrols have inadequate rear roll stiffness anyway, so even though you're technically tightening things up with urethane, the car will be fine because GQ's ned a bit more stiffness in the rear anyway.

In that case, it sounds like you could have found a good application for urethane. I guess the advantage of GQ's is that their bracketry is heavy enough that they don't crack it due to the urethane. Suzuki's do.

I never bagged out urethane, I just said it wasn't for every application.

I have seen and played with some very soft "foam" urethane. I can't see how it would be any more durable of rubber of the same duro, or else we would be driving around on urethane tyres, which would be about the best test for durability of a rubber like compound, duro for duro.

Steve.

[nastytroll]

got 6 weeks out of urathane in rear trail arms n split them right through, 2 weeks from front panhard n chassis end bush came out, panhard was still bolted in, 5 months out of front radius arm bushes n they had 2mm clearence on steel sleave. on a gq coil cab. urethane has its place in press tools, not suspension.
80 series are bad for cracking diff end radius arm brakets off also.

[Mick.]

I only ever run genuine Nissan rubber bushes on my patrol everywhere. I wont touch Urathane. Mine gets flogged pretty hard off road and I always get a couple of years out of my bushes.

Cheers Mick.

[Shadow]

got 13 years out of the origonal rubber bushes on the 60 LOL

[daveb]

pedders make a 2deg offset rubber radius arm bush for less than nayone sells urathane for. They wotk very well and help absorb shock and noise from front end when on rough roads. suit toyota and nissan and have a void in the mould to help with articulation. As with all pedders products come with a no-bull warranty if they crack, split etc. Have fit many sets and not had any dramas at all. Anyone can also make a rubber bush for just about anything on your vehicle if they have the mould for it. Queensland rollers do pretty much all that sort of stuff for a very good price.

[rockcrawler31]

I would have to differ with gwagonsteve here. I beleived the hype about rubber bushes having better travel, but here is my findings

I had urethane bushes in my leaf troopy for 2 years they were only ever greased when first put in.

After 2 years they finally bit the dust and were completely worn through. so i replaced with rubber bushes.

The rubber bushes lasted 1 trip before completely falling to bits.

I have gone back to urethane and found no less travel as a result.

Here is what happens - Firstly i get pretty good travel in the front springs and there is at least 15-20degrees of angular twist between shackle pins and the spring eyes.

first the angular twist chops off the flanges of the bushes that stops the spring from sliding laterally along the pins. Then chews out the meat internally above and below the pins. as this happens the shackles are then allowed to parrellelogram as the meat of the bushes helps to support the weight at the edges. This is particularly noticable on side slopes, turning and when the shackle strikes and object laterally

Both types did this but the difference was the time it took. I am still running the original rear urethane bushes and now that the spring packs have been lightened they don't limit flex at all.

go poly's i say but try to find a medium soft compound brand. At least for leaf springs.

[Gwagensteve]

But troopy's don't flex anyway

no seriously, on a car as heavy as a troopy, urethane might be OK. On a sierra, they wreak havoc.

for load bearing, I know that urethane are fine in leaves.

Ps you didn't grease them did you? one trip sounds pretty short life - in stock toyotas (i.e from the factory) they last better than that.

Steve.

[spannercrab]

Thanks for the replies all - the general consensus would seem to be in favour of the rubber bushes.

The vehicle is actually a GQ and the bushes being replaced are the radius to chassis, radius arm to diff, swaybar pivot, swaybar link pins, and panhard bushes. I think that's pretty covers the lot!

I had no real choice but to do the radius diff bushes in poly to correct the caster, but I'll probably stick to rubber for the rest ... I might throw in a couple of polys in strategic locations depending on the application (e.g. link pin bushes, panhard etc.) where misalignment and flex is not an issue.

[KiwiBacon]

Generally, I am a big fan of rubber bushes, mostly because urethane generally restrict a bit of travel, can be noisy, and can also increase the war on bolts/brackets.

But when you say "travel", you really mean "articulation".

I run polys in the front of my rangie (panhard and radius arms). The radius arm poly's do increase the roll stiffness significantly, but with the heavy diesel in the front it eats rubber bushes too damn quickly.
It's a compromise I'm happy to live with and without that extra rollstiffness in the front, it's disgustingly tail happy.