Bilstein B16 PSS10 Setup

[ntg44]

Originally Posted by AlterZgo

Are you sure that's accurate? I thought these basic coilovers didn't have any preload adjustment. This is why when you raise or lower the spring perch by a certain amount, the car is raised or lowered by that same amount. This is when the car is on the ground w/ suspension loaded.

Another thing - I believe these bilstein coilovers have linear rate springs rather than progressive rate springs so even if the springs were being compressed, the spring rate is still constant. 500 lbs/in linear rate springs that have been compressed by 1 inch still requires the same 500 lbs to compress them another inch b/c they have a linear spring rate.

I truncated your quote to answer your questions.

The basic coils as you call them are called partially threaded. Which means they do not have independent height adjustment from preload. The adjustment you are provided on B16 is preload. It just happens to control the height since there is no other way to adjust the height. but the fact remains that the higher you set the height, the higher the preload as a result, since you are compressing the spring to make the entire body longer.

Spring rate has nothing to do with it, other than the rate of force increase with compression. Compressing the spring 1 inch is always going to require more force than compressing it 0.5 inch, whether linear or progressive. The point remains that the further the spring is compressed, the more force will be required to further compress the spring. That's why the springs require the least force to compress at full length. But this directly conflicts with the shock travel, so it's best to have independently adjustable height from preload was my point. And many of the lower end kits do not have this, including B16.

[JamesGames]

Originally Posted by AlterZgo

Are you sure that's accurate? I thought these basic coilovers didn't have any preload adjustment. This is why when you raise or lower the spring perch by a certain amount, the car is raised or lowered by that same amount. This is when the car is on the ground w/ suspension loaded.

Another thing - I believe these bilstein coilovers have linear rate springs rather than progressive rate springs so even if the springs were being compressed, the spring rate is still constant. 500 lbs/in linear rate springs that have been compressed by 1 inch still requires the same 500 lbs to compress them another inch b/c they have a linear spring rate.

From a seat of the pants perspective, with my basic PSS10s, currently raised to the highest front position possible, on small to moderate sized bumps, the ride quality feels about the same to me compared to when the spring perch was in the middle position. On larger or sharper bumps, the current highest setting feels the softest b/c the car doesn't bottom out as much, particularly on larger bumps and higher speed freeway road undulations.

As you indicated, it could just be due to the dampers as to why people with Damptronic suspensions feel their car doesn't ride that well. To me, there is a large difference in damping feel between 1-10 on the PSS10s. Setting the car at 1 is quite soft with more body roll as well as noticeably more nose lift and dive on acceleration and braking.

I drove around with front spring perches raised to max height and damping set to 1 to 2 at all 4 corners for at least several thousand miles. The car felt pretty soft with this set up.

A separate issue is tire pressure. I find that dealers and tire installers tend to overinflate the tires. Small bump ride quality was more noticeably affected when I reduced tire pressures from 36 psi to 32 psi than if I raised or lowered the spring perch. It's hard to tell what's causing the harsh ride quality without considering what people have their tire pressures set to.

PSS10 definitely are not linear rate springs. You can see they are progressive in this picture here;


The car raised to its highest ends up having more travel for the shock, so less bottoming out. If lowered down, shock stiffness needs to be increased to give the illusion of a better ride, but it's more so less oscillations / less impact to bump stops. Monotube shocks typically have less travel than twin tube, so the available drop amount for a monotube shock / coil is "usually" less. (Ohlins / Bilsteins)

[rborane]

What are the negatives of progressive springs? Is it better to spend a little more for a linear setup?

[Lt1camaro]

Increasing the height on the B16 ended up giving weight transfer in corners that didn't inspire confidence for me. This would be fixed by running the dial to 9F/9R which caused the ride to be overly harsh.

It was a pain adjusting these coilovers to get rid of that weight transfer/bodyroll(?) feeling. Right now i'm running on the 3rd thread from the bottom of the adjuster, the weight transfer in corner feeling is gone, however, ride is a bit bouncy.

I got a good deal on these coilovers, about 50% of what a KW V3 would have cost, so I'm not complaining.