Question about coil over struts

Are coil over struts firmer than a new pair of complete McPherson struts?

I may be missing your point, but the 'firmness' is dependent on the spring rate and the damper rates.

Technically, all struts are 'coil over', whether McPherson, Chapman, or some other variant.

Some vehicles have the lower strut assembly as one thing - the stub axle, suspension nd steering points, and lower body of the damper and spring mount all as one part. Some vehicles have the stub axle, etc, as a separate part from the lower damper assembly which is clamped in the axle assembly. There is a third aftermarket version where the stub axle assembly has a threaded mount for the strut to screw into and is adjustable for height.

If I understand your main query, the biggest advantage of the "coil over" as available from the aftermarket is the standardisation and ready supply of different spring rates and dampers which can be built with desired rates and even up to 4 way adjustment.

If I were you, I would have a good think about what I'm going to use the car for, check out any relevant forums for my specific vehicle for their advice, and talk to the company/ies I was considering buying from - or at least their FAQ on their web sites. On that, what further information can you give for your application?

Thank you for your reply. I understand that the coil overs are for adjusting the ride height. I will be driving the car mostly for street, with occasion track days at the local road course.

Will the car have less body roll, and more control with a coil over suspension?

Again,while it is often used as a generic term for aftermarket dampers (what americans inaccurately call shock absorbers) with the springs (the actual 'shock absorbers') fixed to them, any strut can be described the same way.

You can buy them with fixed and adjustable spring seats - this is what you seem to be more interested in as it makes ride height changes quite easy, especially as a wide range of springs are available.

A second advantage is that while some cheaper, and premium, can only be purchased with fixed damper rates - this is what dampens, or reduces, the 'bounce' - they can be purchased with 1, 2, 3 even 4 way ajustment to damping - I don't think you need to worry about that.

Normally, the vehicle will have less body roll, and be much easier to control, with uprated parts, but if the spring and damper rates are messed up, it could even be worse. Body roll is also affected by the selection of anri-roll bars (ARBs), what Americans call 'sway' bars, and these can also be used to help limit under, or over, steer. Another factor may be the suspension bushes, where the suspension is attached to the vehicle chassis/body - some manufacturers use quite soft bushings which allow a bit of movement that will give some vaugeness to the stereing and over time any bushing will wear and break down, making things worse.

In your case, what I would suggest is you have a look at what's available for your vehicle from the bigger suppliers for suspension upgrades - they will usually have quite a range from 'fast road'right through to race only - I would suggest sticking closer to the 'fast road' end initially, as you can usually replace springs and adjust dampers (even have them re-valved) later. On that, exactly what is the vehicle - might be able to give some pointers?

While you're doing that, go over the current suspension with particular attention to the various steering and suspension joints and bushes.

Of course, all this isn't that helpful if the wheel/tyre package isn't up to the job! There are some very good tyres out there but check reviews as some can be rather harsh, especially if the roads in your area are in poor condition, and fast wearing on the street and you need to balance that out - personally, if you can afford it, I'm a big believer in having a second set of wheels fitted with track tyres that are just to be used there - that way you can have tyres with good all-weather performance and ride, and you won't be wearing out your grippier tyres when you don't need to. It can actually be cost effective.

Lastly, you're going to need to get the car set up by someone who knows what they're doing.

Oh, I should have led with this - next track day have a wander around and talk to people and see what they're using/avoiding and why - especially those with similar vehicles to you. Most track people are there for the fun and are very friendly and helpful.