Why do expensive supercars still use bushings?

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Caito
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Why do expensive supercars still use bushings?

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Why do expensive supercars still use bushings as opposed to ball joints?

I'm guessing ride comfort, but I must admit that I can't really quantify how much performance is to be gained with solutions less compliant than rubber bushings.

This is a Lambo Aventador, it even seems that the whole crank for the pushrod is on rubber, can't see clearly
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This is LaFerrari, uses balljoint for the ARB, seems not for the A-arms
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This is a Zonda R, I don't know what they're using in the A-arms, looks quite covered.
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flynfrog
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Re: Why do expensive supercars still use bushings?

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they could be rubber seals you are seeing

Jolle
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Re: Why do expensive supercars still use bushings?

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Pure speculation, but next to be a bit more comfortable, rubber bushings give the tolerance to cope with a bit more normal service intervals and reduce wear.

Greg Locock
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Re: Why do expensive supercars still use bushings?

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Less stiction. Don't rattle when worn. Last longer. Can be stiffer . Better NVH. Don't fail due to water intrusion.

Ball joints are smaller for the same load capacity, and tend to have better off-axis articulation. It is probably easier to design a smaller lighter mechanism with ball joints.

Bear in mind that what you are calling supercars are mainly rich kid toys, there is less engineering optimisation in them than in your average family car. I've worked on two supercar projects, frankly the lack of constraints was a bit boring and encouraged laziness in design. The basic architecture could just be rejigged around whatever the chief engineer's current pet peeve was.

GSBellew
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Re: Why do expensive supercars still use bushings?

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I'd be inclined to think they are rose joints with rubber boots

Greg Locock
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Re: Why do expensive supercars still use bushings?

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Another advantage of bushes is that you can tune your lateral toe and camber compliance, and your tractive force toe characteristic. As you may remember our German friends b/sed journalists everywhere over the virtues of the Weissach axle, leading chassis designers everywhere to think, hmm, they caught on?

krisfx
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Re: Why do expensive supercars still use bushings?

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Greg Locock wrote:I've worked on two supercar projects, frankly the lack of constraints was a bit boring and encouraged laziness in design. The basic architecture could just be rejigged around whatever the chief engineer's current pet peeve was.
I work on supercar projects and I've been in mass production, too and I'm inclined to agree

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godlameroso
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Re: Why do expensive supercars still use bushings?

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Full spherical bushings are kind of harsh if used in the wrong place, for example the lower wishbones, particularly the front compliance bushing. On upper wishbones, and multi-link setups it's fine, for road cars.

http://www.astbearings.com/spherical-pl ... rings.html
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Greg Locock
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Re: Why do expensive supercars still use bushings?

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Agreed but there are several solutions. One is to use SBJs in your suspension to frame joints, but to compliantly mount the subframe. This allows that whole axle to react as one, and your compliant mounts will be spaced well apart so will introduce smaller angular errors. I'm not a fan of subframes though. Another option would be to design a compliant body-side abutment, ie flex the steel. That can work but it's a gutsy move. It is nice because steel has very little damping compared with rubber so the high frequency attenuation is better for a given stiffness. But for impact harshness and precession control, yeah you want a nice big hydrobush at that NVH location.

gambler
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Re: Why do expensive supercars still use bushings?

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Snow , salt, sand, rain. They are a wearing part that requires lube and probably would not make it for the 100,000 mile warranty. Major mfgs have to produce a car that is unfortunatly idiot proof. Most tracks now are laser smoothed, unlike cobblestone streets acting as jackhammers on every single moving part.

Greg Locock
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Re: Why do expensive supercars still use bushings?

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Oh do tell me which supercars have a 100000 mile warranty.

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godlameroso
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Re: Why do expensive supercars still use bushings?

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gambler wrote:
Thu Mar 09, 2017 2:56 pm
Snow , salt, sand, rain. They are a wearing part that requires lube and probably would not make it for the 100,000 mile warranty. Major mfgs have to produce a car that is unfortunatly idiot proof. Most tracks now are laser smoothed, unlike cobblestone streets acting as jackhammers on every single moving part.
You know what they say, if you make something idiot proof they'll just build a better idiot.
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wrcsti
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Re: Why do expensive supercars still use bushings?

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after driving a mosler mt900 i have to say that car is too uncomfortable for how expensive it is. Simple as that. Manufacturers need to be able to sell something with a hint of comfort

torsen
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Re: Why do expensive supercars still use bushings?

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I can write something about dampers. Aventador use bushings on both sides of dampers. LaFerrari (and most of other Ferrari models) use ball joint on lower mounting ring of a damper. Upper top mount is still with rubber.