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Solid vs poly rear subframe bushing.


Lozer

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I'm about to order some rear bushing and I'm on the fence on which way to go.

 

The car is mainly street but is used for autox.

 

How noisy are the solid bushings?

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Solid will be really harsh on the street, shit poly is going to be pretty bad too. If the noise and vibration isn't a big deal I would still go poly over solid, save yourself some agony.

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I don't know why people still continue to use poly. Maybe the rubber ones are not available? This is another 'racing' innovation that does not translate well for the street. You will have to drive the car harder than what's allowed on the street to notice anything.

 

Rubber grips both moving parts, twists internally and has superior vibration/noise isolation. Poly is too stiff and one part slips leading to wear and noise.  Polly needs maintenance like regular replacement (racing) or lubrication.  

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Because they're readily available. It's easier to find the poly than it is to find rubber stateside for me. But I'm probably doing something wrong not wanting to wait on shipping from Thailand when I can have it brought up the i5 corridor so much cheaper and quicker.

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How much HP are we talking though? Rubber bushings are designed for a 97hp engine. I have poly and ball joints all through my street/auto-x toy 510 and I can tell you, it's damn noisy, but if it's about performance, who gives a damn about noisy? 

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How much HP are we talking though? Rubber bushings are designed for a 97hp engine. I have poly and ball joints all through my street/auto-x toy 510 and I can tell you, it's damn noisy, but if it's about performance, who gives a damn about noisy? 

 

Exactly! From a strictly purpose built car for racing (or equivalent) you don't need rubber, you could make them out of aluminum if you want, but for this, noise transmission and vibration are secondary to handling... probably closer to tertiary. In that venue, they are inspected and replaced regularly. If you choose to run them on the street, expect noise, vibration and early wear.  

 

I imagine the GTR uses rubber bushings. It has nothing to do with HP numbers. No one wants to spend that much money on a noisy squeaky ride with lots of vibration transmission..

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I'm running r1 carbs on a ka24de so noise is not so much a worry for me. I'm gonna snatch up those aluminum ones and run those. 

 

I will run rubber trailing arm bushings tho.

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The only reason I have poly in my 510 is because rubber replacements aren't available for most. I've got poly mustache bar bushing I just installed, and poly subframe bushings that aren't on yet. The rest are new rubber. If I find rubber I'll go with that, otherwise it's poly for me.

 

Have I not been looking long enough, or are there rubber bushings available for the subframe, mustache bar, and rear trailing arms?

 

I agree with Mike, rubber is preferred by me too. 

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Mike you're such an old guy, "it's too noisy," "the engineers designed it that way so why change it?". "It came with rubber stock that will be good enough"

 

 

This is true.

 

Why didn't they use solid or poly then?

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I don't care about noise either, it is my daily but max legal speed I see on the way to work is 40mph.  So it can't we that loud.  I'm so going to order some.  

 

I used a decibel meter phone app and it turns out my Sunny on the highway is louder than the plane ride I took to Hawaii.  haha.  

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Well, the "standard" 15% power loss in the drivetrain can be brought down to 5% with poly bushings, and -15% with solid mounts.

 

Kidding, nobody has that kind of proof.

 

Anyway, poly makes things rougher, so maybe people see that as a power adder?

 

Keep the pragmatism coming, Mike. I like it.

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