Can someone explain suspension to me?

Caporegime
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Hi all,

Can someone please explain suspension to me?

Like say If I wanted to improve handling and lower the car what is needed?

I'm not looking to do this but car mechanics has always interested me so if someone can clear things up for me I'd be very grateful :)

Tarly Muches.
 
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Many different components make up the suspension therefore it's hard to describe without going in to quite a lot of detail. If you're just after info on springs then tightening them will give the car increased handling/responsiveness but will result in a harsher ride, think of it as a rolling on metal as compared to something with give like rubber. Loosening the springs softens it up, giving increased ride comfort and thus less rolling but the car won't feel quite as responsive.

As has been said, howstuff works.com is amazing!
 
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How Stuff Works is good at describing the physical operation of things, but it won't tell you much about why a particular suspension design is good or bad, or design methodologies.

Springs and damper rates are just one part of suspension design, the actual geometry of the suspension, whilst much harder to change on most cars, also has a huge effect on the cars handling, and simply lowering a car can really mess this up.

A very useful book is Alan Staniforths "Competition Car Suspension: Design, Construction, Tuning" which has as much detail as most car modifiers could reasonably want.
 
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Now I'm no expert, but this is how I understand it.

Suspension is designed to keep the wheels on the road as the car moves over uneven surfaces and make the ride more comfortable for the occupants.

Springs absorb the bumps/dips.

Dampers stop the car from bouncing on the springs by dampening the springyness. As an example; if you push down on the wing of a car and let go the suspension should spring back up, then down and finally stop in a neutral position. Without the dampers it would continue bouncing up & down for a good while (think big old american car like a Cadillac etc)

Anit-roll bars stiffen the suspension laterally. They resist the suspension on one side moving in relation to the other side, thereby preventing the car from rolling too much from side to side.

Lowering a car is often done for aethetics but with a reduced ride height you have to reduce suspension travel. This is often done by using shorter and stiffer springs/dampers. The stiffening of the suspension reduces body roll when cornering and can improve handling and responsiveness. But as Dogbreath says, the suspension geometry is carefuly worked out by engineers and messing with it too much can muller the characteristics and ruin the handling & ride.
 
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Nelson said:
Now I'm no expert, but this is how I understand it.

Suspension is designed to keep the wheels on the road as the car moves over uneven surfaces and make the ride more comfortable for the occupants.

Not only has it got to keep the wheels on the road, it must try to keep them at the correct angle in relation ot the road to ensure the maximum amount of rubber is on the road, independant of the amount of body roll or compression of the suspension. For an excellent example of how not to design a suspension system to achieve this, look at the rear wheels of a lowered Beetle.

In the average road car it's a system of many compromises, with cost being right at the top which is why the majority of cars have McPherson struts fitted.
 
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Just to add on to your post Phate, if you don't mind.

If you notice that the ride has become a bit harsher recently, what part is most likely in need of being replaced?

In the MX-5 I've noticed that I can feels the bumps a fair bit more than before. I just can't tell if it's the suspension giving up or if the roads are just in rubbish condition (well they are, but even more so recently).
 
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MonkeyMan said:
Just to add on to your post Phate, if you don't mind.

If you notice that the ride has become a bit harsher recently, what part is most likely in need of being replaced?


Sure, I personally would check the tyre pressures first.

Why? because it's easily done and could be your problem,

When I first got the Saab all the tyres were flat where it had been sitting in the yard for awhile, so I filled all the tyres up but I put about 2psi to much in each tyre and the ride was horrid.

I let it out so it was at the recommended level and it sorted that problem out :)
 
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Phate said:
:p

I suppose If I wanted a convertible I would only need to by a chainsaw as well? ;)
You'll blunt an expensive tool doing that. Use an angle grinder :p

Don't lower it too far or you'll have a negative effect on the handling. Likewise don't go too hard on the springs or it'll be uncomfortable to drive.
 
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Jonny69 said:
You'll blunt an expensive tool doing that. Use an angle grinder :p

Don't lower it too far or you'll have a negative effect on the handling. Likewise don't go too hard on the springs or it'll be uncomfortable to drive.


I've heard of "progressive" suspension, does this mean the harder I drive it the better the handling and if I take it casually the ride is more comfortable but the handling isn't as good?
 
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Phate said:
I've heard of "progressive" suspension, does this mean the harder I drive it the better the handling and if I take it casually the ride is more comfortable but the handling isn't as good?

Pretty much.

What "progressive rate" means is that the spring gets stiffer the more it is compressed. This means that it is "softer" over light bumps or low speed cornering, but "stiffens up" as more compression is created, for example hard breaking or fast cornering.

It basically means that at low speeds the ride will be similar to "standard" springs, while under the more extreme stresses, they will become more like "sports" springs. A kind of "best of both worlds" for the road car.
 
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volospian said:
Pretty much.

What "progressive rate" means is that the spring gets stiffer the more it is compressed. This means that it is "softer" over light bumps or low speed cornering, but "stiffens up" as more compression is created, for example hard breaking or fast cornering.

It basically means that at low speeds the ride will be similar to "standard" springs, while under the more extreme stresses, they will become more like "sports" springs. A kind of "best of both worlds" for the road car.


Thank you :) - Progressive springs sound like the way to go then :)
 
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I think the spring is wound tighter at the ends so the first bit of travel is softer, then when the tight bit bottoms out it uses the main part of the spring. More expensive but soaks up the every day bumps a lot better. I'm guessing you can get progressive shocks now as well.
 
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