What NON-coilover suspension do you prefer

[Icecream]

Bilstein B6 dampers make the car sit higher due to its high gas pressure.

Posting a simple statement and an accompanying picture of two different cars with two different specs and different wheels, tires options and then claiming the height change is due to the shocks fuels misinformation. The cars appear to maybe show hardly any difference in height and the wheel tires combination could attribute to that alone. The e46 m3 also came with different springs depending on year and equipment/weight will affect the height as well.
perhaps this cutaway will help clarify.

https://www.speednik.com/wp-content/...8_17-55-15.jpg

The gas pressure at the bottom pressurizes the entire chamber above, before and after the valve attached to the rod. The oil is under the same pressure everywhere when static and thus the net force on the piston (attached to the rod) is zero. It will have zero impact on spring rate and it is incorrect to think there is some spring force on the shock piston as a result.
I am open to hearing your or anyone’s reasoning for why it would be any other way.



edit; the cars are not even aligned the same way. The front appears higher in one and the rear looks higher in the other if you just look at the bricks alignment with the lines of the hood and trunk. The roof however looks to be at the same height.
to add more insult to injury, one Appears to have a sunroof, the other does not.

[SG/IRM3]

High-pressure monotube shocks absolutely have the potential to raise the ride height. I've experienced it twice on older Corvettes when using Bilstein shocks. And in both cases the springs were fresh and not sagging. The guy at Bilstein is wrong.

[Icecream]

High-pressure monotube shocks absolutely have the potential to raise the ride height. I've experienced it twice on older Corvettes when using Bilstein shocks. And in both cases the springs were fresh and not sagging. The guy at Bilstein is wrong.

Can you explain why that would be the case based on the actual design of the shock? Saying it is high pressure is about the most useless statement when describing the shock without considering where the pressure is and How it is interacting with the entire system. Generally speaking, the engineers and designers are not wrong about their products but I suppose exceptions are out there.

[heinzboehmer]

The gas pressure at the bottom pressurizes the entire chamber above, before and after the valve attached to the rod. The oil is under the same pressure everywhere when static and thus the net force on the piston (attached to the rod) is zero. It will have zero impact on spring rate and it is incorrect to think there is some spring force on the shock piston as a result.

Is the force actually zero when static (I'm actually not sure, not trying to be snarky or anything)? If it was zero, then the shaft wouldn't extend out after being compressed by hand, but I've never had that be the case.

On a related note, if the valves inside a shock let pressures equalize everywhere when static, then why are force vs position shock dyno curves not a flat line at 0? Does the dyno move the shock to a static position, wait for pressures to equalize, and then measure the force? Or does the force vs position graph come from the force vs velocity graph?

[Icecream]

Is the force actually zero when static (I'm actually not sure, not trying to be snarky or anything)? If it was zero, then the shaft wouldn't extend out after being compressed by hand, but I've never had that be the case.

On a related note, if the valves inside a shock let pressures equalize everywhere when static, then why are force vs position shock dyno curves not a flat line at 0? Does the dyno move the shock to a static position, wait for pressures to equalize, and then measure the force? Or does the force vs position graph come from the force vs velocity graph?

That’s a good point and I wondered the same thing, twin tube shocks do this as well. Perhaps I was being too general with my description. I do not know why they want the shock to extend or what specifically controls both types of shocks to extend when there is no load on them. There are probably a few more details and moving parts the cutaway does not address. My biggest point however was to illustrate that just because it is high pressure somewhere in the system, it does not necessarily mean that pressure is acting on the parts you may think it is in the way you think it is.

[maupineda]

^^ the answer is in the image you linked, assume for a second the position of the shaft in the image is at ride height with the car seating static on its wheels. the gas chamber at pressure is providing support to the strut tube insert, reduce the pressure, the assembly moves down, increase it, it will move up (and the shaft won't as you said).

In twin tube designs the nitrogen coexists within the same outer chamber with the shock's oil, in a monotube, they are separated, the gas chamber is at the bottom as shown in your referenced photo. though both have nitrogen at pressure, in the twin-tubes the nitrogen will flow up in the outer chamber, whereas on the monotube is a cushion at the bottom of the assembly inside the strut. so yes, it can raise the car, or better said, limit the drop.

[Icecream]

^^ the answer is in the image you linked, assume for a second the position of the shaft in the image is at ride height with the car seating static on its wheels. the gas chamber at pressure is providing support to the strut tube insert, reduce the pressure, the assembly moves down, increase it, it will move up (and the shaft won't as you said).

In twin tube designs the nitrogen coexists within the same outer chamber with the shock's oil, in a monotube, they are separated, the gas chamber is at the bottom as shown in your referenced photo. though both have nitrogen at pressure, in the twin-tubes the nitrogen will flow up in the outer chamber, whereas on the monotube is a cushion at the bottom of the assembly inside the strut. so yes, it can raise the car, or better said, limit the drop.

I don’t know if I can agree with that entirely. That is assuming all of the excess pressure is going into that one chamber and that none goes above to where the rod is, a simple pressure regulator would solve this problem if if it was an issue, I (and most people here probably) don’t know the internal design of the valves nor exactly what and where the pressure doing at a given time and condition. This may well be the case but im not convinced that is a complete statement.
it also begs the question, if that was the case, why wouldn’t Bilstein just design a properly lengthen shock to fix the height issue (if one existed).

[heinzboehmer]

I don’t know if I can agree with that entirely. That is assuming all of the excess pressure is going into that one chamber and that none goes above to where the rod is, a simple pressure regulator would solve this problem if if it was an issue

Looks like that's just how monotube dampers are designed (and is also why they spring back up when no load is on them).

I found this video that pretty clearly shows what maupineda is talking about: https://www.youtube.com/watch?v=E4T72sP2b6M

[maupineda]

I don’t know if I can agree with that entirely. That is assuming all of the excess pressure is going into that one chamber and that none goes above to where the rod is, a simple pressure regulator would solve this problem if if it was an issue, I (and most people here probably) don’t know the internal design of the valves nor exactly what and where the pressure doing at a given time and condition. This may well be the case but im not convinced that is a complete statement.
it also begs the question, if that was the case, why wouldn’t Bilstein just design a properly lengthen shock to fix the height issue (if one existed).

this may help you https://www.youtube.com/watch?v=hzC_TOHGQnE

Also, the B6 series are intended to be used with the OE suspension design.

if you look at their catalogue, they say (for normal E46 3 Series, not M)

B6 for standard ride height
B8 for M-Sport / M-Technique suspension

For the M, they only have B6, and that is because there was only one suspension design, not two as with the regular series production.

The B6 series is not really intended for lowered cars beyond what the OEM designed to. Coilovers on the other hand are a different affair as they take the base suspension, and design to lower from the standard setup (base, in this case, being the M)

The reason why there are no B8's for E46M and Z4M is because the B6 is designed to work with the stock M's suspension height.

If you look at their suspension travel, the M models are already compromised, being as low as it would be recommendable for a road car meeting OEM standards, lower the car passed that point and you really have a car with very little suspension travel without other measures in place.

So yes, the monotube gas chamber does provide cushion and if there is sufficient pressure, it will limit drop as opposed to a twin-tube design.

[r4dr]

How much of an improvement is there with running Bilstein B6 dampers with stock springs versus the OEM dampers (Sachs I assume?)?

[maupineda]

How much of an improvement is there with running Bilstein B6 dampers with stock springs versus the OEM dampers (Sachs I assume?)?

You may find this helpful. https://forums.m3cutters.co.uk/threa...review.125709/

[Arith2]

Watch this gem. It's Bilstein explaining the monotube system. It doesn't address the pressure pushing up on the car but it will answer a few questions.

https://youtu.be/W4ZZYqRVzLc

Here's two explanations by Fat Cat.

https://youtu.be/IIZNBRLFIKs

https://youtu.be/ODxU4ZC-0Zg

We were wrong about it not affecting ride height and here's why.

After some research I figured it out. Eibach's Pro kit I think the front is 158lbs/in(basically stock) according to someone on here. So when the spring is installed on the strut, the shock is not compressed at all. Once the vehicle is lowered, the spring is loaded. I read someone's corner balance for reference and they had 908lbs and 887lbs up front. When the vehicle is lowered, without any shock pressure, the compression would be 5.74" and 5.61". According to the video, the shock is counteracting the car is 45lbs. When not moving, the spring is pushing up 908lbs and 887lbs at those heights. Well what I did is add the 45lbs to the spring's total force and took a percentage.

(908+45) / 908 = 1.05
(887+45) / 887 = 1.05

1.05 more force is being applied so this will counteract the ride height considering the spring is pounds per inch. The counterforce is now 5% higher thus raising the height 5% basically.

1.05 * 5.74 = 6.02"
1.05 * 5.61 = 5.89"

So now the ride will be at 6.02" and 5.89" instead of 5.74" and 5.61" due to the little bit of extra force pushing up. Everything will stop moving and there will be equilibrium which makes this easy to figure out.

[Icecream]

Watch this gem. It's Bilstein explaining the monotube system. It doesn't address the pressure pushing up on the car but it will answer a few questions.

https://youtu.be/W4ZZYqRVzLc

Here's two explanations by Fat Cat.

https://youtu.be/IIZNBRLFIKs

https://youtu.be/ODxU4ZC-0Zg

We were wrong about it not affecting ride height and here's why.

After some research I figured it out. Eibach's Pro kit I think the front is 158lbs/in(basically stock) according to someone on here. So when the spring is installed on the strut, the shock is not compressed at all. Once the vehicle is lowered, the spring is loaded. I read someone's corner balance for reference and they had 908lbs and 887lbs up front. When the vehicle is lowered, without any shock pressure, the compression would be 5.74" and 5.61". According to the video, the shock is counteracting the car is 45lbs. When not moving, the spring is pushing up 908lbs and 887lbs at those heights. Well what I did is add the 45lbs to the spring's total force and took a percentage.

(908+45) / 908 = 1.05
(887+45) / 887 = 1.05

1.05 more force is being applied so this will counteract the ride height considering the spring is pounds per inch. The counterforce is now 5% higher thus raising the height 5% basically.

1.05 * 5.74 = 6.02"
1.05 * 5.61 = 5.89"

So now the ride will be at 6.02" and 5.89" instead of 5.74" and 5.61" due to the little bit of extra force pushing up. Everything will stop moving and there will be equilibrium which makes this easy to figure out.

If the difference in force to compress the mono tube vs the twin tube is indeed 44lbs, then I could agree. Remember too that even the stock twin tubes require some force to push down so the difference must be 45lbs and the actual force of the mono tube greater than 45lbs for this to make sense.
I’m just going to disconnect the rear shocks and see if the ride height changes. That should settle it. I’m not convinced that just because there is more pressure in a specific area that means there has to be more pressure where we are assuming it is pushing up the shock, that seems a poor design to have such significant spring rate inside the shock that would vary so much in extension/compression. Again, bilstein has not acknowledged this, they have told me directly this is not the case and if it was the case I feel they could design the shock in such a way as compensate for it and not alter ride height. If anyone has koni/eibach and can post their ride height, that would be great too.

[Arith2]

I’m just going to disconnect the rear shocks and see if the ride height changes. That should settle it.

Physics are pretty consistent. It's really just a quarter of an inch so it's probably not going to be visually seen.

That's why that picture of those two cars was irrelevant though it did make me laugh. If you can see a quarter of an inch that far away, on two object that far apart, then you aren't human.

[R60BBA]

Posting a simple statement and an accompanying picture of two different cars with two different specs and different wheels, tires options and then claiming the height change is due to the shocks fuels misinformation. The cars appear to maybe show hardly any difference in height and the wheel tires combination could attribute to that alone. The e46 m3 also came with different springs depending on year and equipment/weight will affect the height as well.
perhaps this cutaway will help clarify.

https://www.speednik.com/wp-content/...8_17-55-15.jpg

The gas pressure at the bottom pressurizes the entire chamber above, before and after the valve attached to the rod. The oil is under the same pressure everywhere when static and thus the net force on the piston (attached to the rod) is zero. It will have zero impact on spring rate and it is incorrect to think there is some spring force on the shock piston as a result.
I am open to hearing your or anyone’s reasoning for why it would be any other way.



edit; the cars are not even aligned the same way. The front appears higher in one and the rear looks higher in the other if you just look at the bricks alignment with the lines of the hood and trunk. The roof however looks to be at the same height.
to add more insult to injury, one Appears to have a sunroof, the other does not.

It’s the same car.