Rubber vs. Urethane Bushings - help

[Legacy_Otaku]

Hey All,

 

Apologies if this has been answered elsewhere (my Advanced Search through 5 pages of threads didn't show up any answer):

 

* Are Rubber Bushings supposed to be better than Urethane Bushings, specifically for the Front Lower Control Arm?

 

 

My Alignment Mechanic mentioned to me about the advantages of Rubber Bushings, because any "indentations" caused by various movements of the LCA would be "reset" due to the Rubber material.

 

But on Urethane, any "indentations" made wouldn't be "reset" because of the hard material nature of Urethane, and thus, over time (and/or numerous indentations from driving), the Urethane Bushing would have so many various indentations that it becomes useless (and it's time for replacement).

 

I didn't understand all of what he had to say, but that was a rough paraphrasing of it. So to my fellow LGT'ers that know about this,

 

Is it true? Is it better to have Rubber Material Bushing vs. a Urethane for the Front Lower Control Arm?

 

Thanks~

[LittleBlueGT]

I for one think your alignment mechanic is wrong, at least from all the research I have done, and from the few bits of urethane I have had on my modded cars.

 

Can't say for sure though, so listening out for someone that knows better.

[ebpda9]

i had urethane bushings on my hondas before, and i loved them. they do not rot like the rubber ones do, but if torqued improperly they will deform. i had to change the radius rod bushings on the accord because of that. it all depends on the durometry of the material. the softer it is, the more elastic is. Yeah, in other words your mechanic is right about the poly bushings, but you will need to worry about them after 60-90k miles after install. The other bushings were still in perfect shape after 70k miles of abuse.

[Boostjunkie]

Ken, I know Merv already PM'ed you about this, but YOUR BUSHINGS ARE FINE! I know they are cracked... EVERYONE'S lower control arm bushings are cracked... While I don't like the looks of them either, SOA has said that cracks are normal and not a problem. If it makes you feel better then go ahead and get them changed, but it is not a safety issue.

 

As for urethane versus rubber, I like urethane for a performance oriented application. Urethane is also more durable than rubber. On the downside, if the urethane used is much stiffer than stock you will have more NVH. As with all things, it's a compromise.

[PGT]

I for one think your alignment mechanic is wrong, at least from all the research I have done, and from the few bits of urethane I have had on my modded cars.

 

Can't say for sure though, so listening out for someone that knows better.

 

oh wise one, please share the fruits of your laborious work. What was your tested methodology?

[LittleBlueGT]

oh wise one, please share the fruits of your laborious work. What was your tested methodology?

 

I didn't claim to know for sure, but here goes.

 

1995 Civic: I autoXed it for 2 years and had urethane bushings for the "wishbones" and sways (including end-links). Drove car for 3.5 years (100,000 kms) over rough roads at times and just before I sold it I was underneath it with a mechanic and we noticed that all the poly looked brand new, nice and tight. The person I sold the car to drove it for another 3 years and he had no problems at all what-so-ever.

 

2000 Maxima: Urethane for RSB bushings. Drove car for 170,000 kms. Took bar off just before I sold it and everything looked brand new!

 

1980 YJ (my cousins) vehicle: Pevious owner had urethane everywhere, I mean everywhere. Body attached to frame via urethane, no rubber at all in suspension. I took a real close look at his YJ (think it is a YJ, maybe CJ, I forget) three weeks ago and everything he has is 100%

 

 

 

Didn't claim to have a tesing methodology.

[PGT]

anecdotal evidence != 'research'

[Underdog]

"sarcastic responses to cut someone down" != benefit to anyone here

 

Wow, I could be a mod too...

 

:

 

This is the second time that I have seen lbGT getting cut down by a mod when he is contributing to conversation. Are you guys all good friends and I just can't tell thru the inter-ether? I would really like to know so I don't get angry when I see it. (I hate getting angry at computers, they don't bleed!)

[PGT]

no, you couldn't. You'd need to see the point, which is apparently lost on you. We have a few too many 'experts' on this board who seem to have all the answers and are all to eager to share it. Forgive me for reigning them in a bit, but it's not a benefit to anybody here. It's all too easy to throw 'research' out there with no documentation. Please read the forum rules - opinions are like, well, you know...

[rc0032]

"sarcastic responses to cut someone down" != benefit to anyone here

 

Wow, I could be a mod too...

 

:

 

This is the second time that I have seen lbGT getting cut down by a mod when he is contributing to conversation. Are you guys all good friends and I just can't tell thru the inter-ether? I would really like to know so I don't get angry when I see it. (I hate getting angry at computers, they don't bleed!)

Im here for the insults :lol:

[godwhomismike]

I don't know shit about anything to do with the technical side of Subarus or Leasing Financing stuff. But, I can pretend to be an expert too like many people on LGT

[jazzymt]

You'd need to see the point, which is apparently lost on you. We have a few too many 'experts' on this board who seem to have all the answers and are all to eager to share it.

I think you're getting a bit caught up in the semantics on this one. While clearly not laboratory research, LBGT obviuosly has significant personal experience with poly bushings he felt compelled to share. If you have any laboratory test results to share with us, please get to the point. If (as I suspect) you do not, as none of us probably do since there is little marketable purpose for such research, spare us the sarcasm for now since personal experience is about all we're likely to get on the subject.

 

Clearly you have some personal experience of your own to share based on similar comments in the other swaybar thread - how about you enlighten us already instead of playing devils advocate. I can tell you you're not the only one with no patience on the forums today, but take a deep breath and try to show some anyway.

[Guest]

[PGT]

semantics maybe, but if you want my 'experience' vs. 'research', I'll share.

 

Urethane/PU allows more precise control and casting techniques. It's performance is directly related to it's durometer, or hardness. Rubber has much the same characteristics, but for our purposes, has one significant benefit. It's generally more pliable on the surface, which means it doesn't need grease to be quiet.

 

PU is no super material - it's as prone to degradation physically as rubber, though it won't dry rot like rubber can (the main benefit, besides more precise durometer). Anybody who doubts this need only look at the bushings on first MSI endlinks used with a narrow Cobb bar....the extreme deflection will chew up PU bushings just as quick as rubber.

 

None of this is relevant to this thread. PU is generally harder durometer than rubber when it comes to aftermarket applications, but that's specific to the specs the manufacturer requests, not the material itself. For proof, look at an STI pitch stop or transmission mount vs. standard ones. Same mold, harder rubber.

[LittleBlueGT]

Can't say for sure though, so listening out for someone that knows better.

 

My original post.

 

Makes sense to me what I wrote.

 

 

 

 

BTW my research has been countless hours on the internet researching things like this for this car and others that I have had.

 

Did I say I know all, NO. Hence my original disclaimer.

[godwhomismike]

http://img224.imageshack.us/img224/4800/bkscare0cz0ec.gif

[Underdog]

I'm sure the real experts will be here in no time to give us the durometer of the stock and various aftermarket bushings in a technical document following ASTM test method #D2240-05. Then we can measure the SPL's and run a harmonic finite element analysis.

 

My point is that "experts" usually have information that the laymen won't be able to use. Anecdotal evidence is the best "bang for the buck" especially when the OP clearly is asking a vague question like "which is better: rubber or poly?"

 

My annoyance comes from the fact that you are most likely an expert in this matter but choose to nitpick lbGT's choice of words instead of just offer your advice. (Which I notice you did in the time I was typing.)

[PGT]

wow....how much googling did you have to do to use those buzzwords

 

seriously though....forgive me for poking fun at our resident 'expert'. anybody that's on here daily knows LBGT has too much time on his hands no harm intended

[jazzymt]

Interesting notes PGT - to add on to that a bit: I have almost no experience with PU, but a fair amount with rubber since the company I work for molds LOTS of rubber. Some cliff notes:

 

1) Yes, rubber durometer is hard to control accurately. Part of this is due to material variability and part due to mold preheat, cure time, etc...there's a lot of things to control and because of vulcanizing, the exact same rubber can come out very differently from batch to batch if you're not careful. I don't think PU has those problems because of its chemical composition.

2) Yes, rubber durometer can be varied greatly, from very soft to very hard.

3) Yes, natural rubber oxidizes quickly. After 2 or 3 years, our parts are not terribly useful and need replacement, but that's because the oxydization hardens them...generally I don't think that would be a problem on bushings.

 

One thing I don't know though is if they're actually using natural rubber in any/many bushings. There are endless blends and synthetic rubbers out there that in many ways outperform natural rubber, especially in longevity. We use several of them in our parts too such as EPDM, Silicone, and Nitrile.

[PGT]

one other important point that anybody with summer tires currently on their car can attest to.....natural rubber changes durometer with temperature. PU is not as affected, giving a good consistent hardness to work with.

[Underdog]

wow....how much googling did you have to do to use those buzzwords

 

<--- Mechanical engineer in the medical device industry (although I did look up the ASTM# )

 

seriously though....forgive me for poking fun at our resident 'expert'. anybody that's on here daily knows LBGT has too much time on his hands no harm intended

 

Yeah, that's why I hate the internet, you can't tell when someone is laughing with or laughing at. I still think there should be a universal sarcastic font.

[Legacy_Otaku]

Hey Paul,

 

But... I gotta be like Merv... JDM, yo! (j/p)

 

Seriously, yah, I feel better about them now. I just posted this thread to ask everyone about what type of material is better, for my eventual replacement . (just curious, cause it seems like the *only* Rubber material Bushing replacement for our Legacy LCA is... OEM Stock, right?)

 

Peace~

[PGT]

the aluminum Spec B control arms have rubber inserts, reportedly stiffer than the squishy LGT ones. I'd say leave it alone, or, if you must do something, just get the Spec B control arms and leave the firmer rubber bushings. You can sell your steel arms for a core for those wanting the PU bushings pressed in (easier to do it this way than leave your car on stands while you get the work done).

[GTsleeper2]

wow....how much googling did you have to do to use those buzzwords

 

seriously though....forgive me for poking fun at our resident 'expert'. anybody that's on here daily knows LBGT has too much time on his hands no harm intended

 

agree

[LRegvall]

Thanks LBGT, Underdog and others for helping to clarify the rubber vs. polyurethane issue. Is it possible to get a durometer for christmas?