So what is a coilover??

[Red Bicycle]

Dear all

Now that I've paid my deposit on bilstein coilovers and impatiently waiting for them to be air freighted in I've had time to ask what it is I'm actually buying and why is the design regarded so highly??

Wikipedia says that although similar to mcpherson struts in that they are coil over springs they are not to be considered the same but then doesn't really say what they are in the context of suspension design.

Can members provide any clarity please?

Best

Michael

[kaanage]

TECHNICALLY, a coilover is a suspension unit where the coil spring surrounds the damper (which includes MacPherson struts and also many double wishbone front ends) but this is not what you are after.

The conventional usage of the term "coilover" kit (coilies) is a set of MacPherson struts where there is a threaded adjuster for altering the base height and a set of rear suspension springs and dampers where the springs sit on perches with a threaded adjuster for altering the perch height, all so that the ride height can be changed. The rear units do not necessarily (and usually don't) have the dampers surrounded by the springs, since if the original suspension is not mounted this way, then major modifications would be needed.

The design is regarded highly as the ride height adjustment allows corner weighting and also it means the vehicle can easily be lowered. On this forum, the second reason is vastly more important than the first. In real performance terms, just replacing the dampers with higher quality units will often improve suspension behaviour as much as installing a coilover kit (but then the vehicle can't be slammed which buggers the behaviour anyway)

[Sunny43.5]

Geez Kaanage I thought I was the resident grumpy old fart , so many members have indicated that to me after my rants etc . But hey if you want it it's yours , nice write up by the way I have coil overs in our van and they make a big difference over stock . The van feels better on the road and as you said height adjustable to boot .

[Red Bicycle]

Thanks Kaanage

"...(but then the vehicle can't be slammed which buggers the behaviour anyway)..."

So it is basically the ability to dial in lowering but then I don't understand your last sentence. Do you imply that lowering somehow upsets the performance of the system?

Cheers

Michael

[Sunny43.5]

I think what he means is that if you lower it to the max then handling will be very different , you only have to watch how cars which have been "slammed " behave on the road . They rock like a boat in a storm and shake like hell as they have no ability left to absorb normal road undulations and rough surfaces. I could be wrong .

[Racemag]

most Bilstein coil-over units are not adjustable for spring seat. The adjustability does not equate to lowering only.

[Red Bicycle]

Sunny Is there a general agreement as to how far to lower the T5 with B14's on stock 16" rims?

Michael

[kaanage]

most Bilstein coil-over units are not adjustable for spring seat. The adjustability does not equate to lowering only.

So what is their basis for being a 'coilover'?

Both of the below have spring seat adjustment for height and corner weight adjustement
BILSTEIN B14 - PSS
BILSTEIN B16 - PSS9/PSS10

[brad]

Thanks Kaanage

"...(but then the vehicle can't be slammed which buggers the behaviour anyway)..."

So it is basically the ability to dial in lowering but then I don't understand your last sentence. Do you imply that lowering somehow upsets the performance of the system?

disregarding the affect on roll centres, bump steer, etc:

Reducing the ride height on a coilover equipped vehicle reduces the available suspension travel & also reduces the amount of preload on the spring.

When you hit a bump the spring reacts immediatly (if it was preloaded it would require a certain amount of force before it started moving). Moving immediately wouldn't be an issue if you had plenty of suspension travel available but you haven't - so the spring compresses quickly & eventually hits the bump stop & runs out of travel so the chassis behaves like a billy kart.

many coil overs have crazy high spring rates to try & counteract this "problem" & it works to a certain degree but is still a compromise.

You've bought a good quality kit which should work well providing you don't try & drop the thing into the weeds.

Some of the best handling cars I've owned were the ones that I raised rather than lowered.

[Red Bicycle]

Thanks Brad

I suppose I have two questions:

1. Is the 'no drop' ride height of the Bilsteins the same as stock?

2. What is a good compromise in terms of the benefits to handling from reducing the height above the road surface of the vehicle's centre of mass and available spring travel for our crappy roads?