Re: Coilovers vs. Shocks/Springs/Struts

[Chuck Van Pelt <cvanpelt@aracnet.com>]

Good questions Khan. I wondered the same thing about coil overs so I checked one
out. This is what I came away with...

Basically, a coilover is just like an entire "stock" strut assembly with one
major difference: The lower spring perch can be raised or lowered by screwing it
up or down the strut body and tightening a lock ring against it. The coilover is
made to fit in on the same mounts as the strut assembly.

Since it is spring height that sets the actual ride height of the car, raising or
lowering the lower spring perch allows you to raise or lower the car. This is the
other difference between coilovers and regular struts: when you lower a car with
standard struts, you do so by either replacing the spring with a shorter one or
cutting the existing ones. On a coilover, you lower the car by compressing the
spring. A compressed spring is a stiffer spring, so a coilover is generally going
to give you a much stiffer ride.

To answer your question about upward and downward motion, the upward motion is
stopped by the upper and lower spring perches, just like a regular strut. I'm not
sure what stops the downward motion, but I would imaging that if you compressed
it enough, the coilover would bottom out by either compressing the spring until
the coils touched or until the shock hit the end of it's "throw". Standard struts
come with a rubber bumber that rides on the shock piston to absorb the blow from
the strut bottoming out...I don't know if coilovers have the same thing.

Hope this helps.

Chuck Van Pelt
'95 Jetta GLX "Rainy Northwest Edition"

Khan Klatt wrote:

> At 3:29 PM -0400 04/06/2000, Ng, Kevin (Bank of America Commercial Finance)
> >
> >Yup. "Shocks" is not really the proper terminology, since they're not really
> >doing any of the shock absorbing (that's what the springs are for). Call 'em
> >dampers or struts.
>
> So, what we're looking at (correct me if I stray from reality) is
> that struts are bolted to the wheel assembly and to the body of the
> car. The springs are somehow connected to both as well.
>
> When you hit a bump, the spring compresses, absorbing the energy from
> the impact. The struts, because they can compress or extend with the
> springs (filled with either fluids or gasses) provide a dampening
> force to make the spring less "bouncy"... in other words, damping the
> spring.
>
> The tighter your spring, the harsher the initial impact and the
> rebound from the spring. The stiffer (more heavy duty) the strut, the
> more force it exerts on the spring to normalize the spring.
>
> The looser your spring (think shock springs) the bouncier the ride.
> And, if the struts aren't very stiff, the ride will tend to float up
> and down and up and down for more oscillations than if there were
> stiffer struts.
>
> Is that correct?
>
> If so, what I'd like to know is how the mechanism actually works...
> the struts, it seems would simply be bolted between the wheel
> assembly and the body. The springs are connected... how? To the
> strut? Around the strut? What stops it's upward and downward motion?
>
> Thx for the info.
>
> -K
>
> Khan Klatt                                         khan@mediaaccess.com
>
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