Understanding Bilstein shock range

[WP0ZZZ]

I'm planning to do a suspension refresh on my SC and would like to get the big picture before starting to buy parts. At the moment I'm trying to understand Bilstein's shock range for classic 911s and would really appreciate your input.

I can buy 4 levels of shocks (not sure if US folks use the same names):

- Turbo
- Sport street
- Club Sport
- 1000 Lakes

Would love to hear opinions on the options and also what torsion bar stiffness are best suited to each shock.

Example of the rear options. "Parameter" refers to compression/rebound forces at a given shock speed:

[Bill Verburg]

Originally Posted by WP0ZZZ

I'm planning to do a suspension refresh on my SC and would like to get the big picture before starting to buy parts. At the moment I'm trying to understand Bilstein's shock range for classic 911s and would really appreciate your input.

I can buy 4 levels of shocks (not sure if US folks use the same names):

- Turbo
- Sport street
- Club Sport
- 1000 Lakes

Would love to hear opinions on the options and also what torsion bar stiffness are best suited to each shock.

Example of the rear options. "Parameter" refers to compression/rebound forces at a given shock speed:

all the shocks listed are for the rear, hopefully they have matching fronts available too

the difference between them is the rebound/compression valving #s which correspond to the damping force generated(in most cases) in N/10 at a piston Velocity of .52m/s (factory method) otherwise all are differently valved versions of Bilstein b6 aka hd shocks.
The #s is the chart are similar to but do vary some from the #s I have from Bilstein so someone else may have generated them or the valving may also have changed




here are the factory specs

HD's Rebound/Compression, as used on oe 911, 930 & Carrera applications
Front 130/76
Rear 195/151

Bilstein Club Sport
Rebound/Compression
Front 160/161
Rear 220/180

Sport(rally) Rebound/Compression
Front 194/150
Rear 311/160


The different valving is supposed o be matched to different spring rates, chassi wt and applications.

The best thing that you can do w/ any of these is sends them in for a digressive rebound w/ rates that match you use. Barring that most peoples will be best off in most apps w/ stock hd, a slightly sportier setup if hd front/sport rear especially if uprated tbars are also used.


There are also versions w/ fully threaded bodys, usually called RSR that are useful mostly to those w/ coil over conversions

[WP0ZZZ]

Thanks for your input, Bill.

Originally Posted by Bill Verburg

all the shocks listed are for the rear, hopefully they have matching fronts available too

Yes, I chose just to show the rear ones because because for the front there are more references depending on the kind of strut and I thought it would make my point about the 4 kinds of valvings less clear.

I took the snapshot from the catalog that can be found at bilstein.com

Originally Posted by Bill Verburg

The different valving is supposed o be matched to different spring rates, chassi wt and applications.

That's exactly what interests me: how to match torsion bars with shocks for a given application.

For instance, Elephant Racing has several stages of suspension tuning. I believe that Street Performance 1 uses stock torsion bars and updated shocks. And comparing the Bilstein catalog with Elephant Racing naming, I think that:

HD = Turbo
Sport = Sportlich Strasse

[WP0ZZZ]

I'm looking at the Von Shocks website now and they offer 5 levels of damping

level 0 - 18.8/25mm - stock
level 1 - 21/28mm
level 2 - 22/29mm
level 3 - 23/31mm
level 4 - 24/33mm

http://www.vonshocks.com/product/911/porsche911shocks.htm

If I'm interpreting correctly the equivalence to Bilstein would be

level 1: Turbo
level 2: Sportlich strasse
level >2: Club Sport?

[Driven97]

Linear rates are real old tech. The world has moved on. Not sure if the options you've listed are linear or not, but not knowing isn't good. I know the Bilstein rate listing is for one specific shaft speed. There was a day when if you gave me the torsion bars you wanted, and the corner weights of your car, I could calculate the Bilstein numbers you wanted. Doubt I could find the spreadsheet anymore.

The important thing is that damping is a bit of a dark art. Real wrong can make a car ride and handle real bad. However, the "acceptable" window is pretty big, aka it's hard to really screw it up.

If you plan on using the car for competition, and have at least a light grasp on vehicle dynamics, find a good shock shop that will help you reach your goals.

If you've got a street car and you're upping torsion bar rates more than just a little, calling Elephant isn't the worst idea. A little pricey for canned tunes but they'll be modern valving and good enough for most people.

If you're sticking close to OEM rates, most of the off the shelf options should be fine.

Ymmv, one person's opinion, and all that jazz.

[Trackrash]

Or Koni sports and have adjustability. Old school, I know, but an option....

[WP0ZZZ]

Originally Posted by Driven97

Linear rates are real old tech. The world has moved on. Not sure if the options you've listed are linear or not, but not knowing isn't good.

Does anyone have force/velocity plots for the Bilstein range?

Originally Posted by Driven97

If you're sticking close to OEM rates, most of the off the shelf options should be fine.

I'm not sticking to OEM rates. I'm looking at the hard options in the Bilstein range for a rally/track usage.

[Bill Verburg]

Originally Posted by WP0ZZZ

Does anyone have force/velocity plots for the Bilstein range?




I'm not sticking to OEM rates. I'm looking at the hard options in the Bilstein range for a rally/track usage.

You are going to need the guidance of a shop familiar w/ different custom setups

when I did mine I was working w/ Dan Jacobs they took the brand new shocks and shipped them to Bilstein SD for a digressive revalve to their spec. W/o a shop you'll need to rely on whomever does the work, also turnaround is likely to be much longer w/o some sort of preferential treatment. If you don't have a local shop then Elephant is another good choice for advice. At a minimum they will want to know the suspension specs, chassis weight and intended use. It's no really rocket science just knowing what works w/ what


I've got the Bilstein manuals w/ 40 or so different digressive stacks but couldn't tell you the difference.




Just so you can see what a shock dyno readout looks like. Here are the curves for a 2008 RSR

[Driven97]

I'll try to laymans's terms those charts.

- Those are F-v charts, so shock force vs piston speed.
- Bottom is labeled bump, or compression, top is rebound, or resisting the spring extending.
- The multiple lines are different settings on the adjuster on the shock - these have knobs.
- Towards the left is low piston speed. That means body control, or transition.
- Towards the right is high piston speed, or bumps / holes.

The curves are mostly digressive. This means the shocks build force quickly at low speeds for body control, then "knee off" to a different, more gentle slope at high speeds for correct damping over bumps.

With linear valving you have your choice of either good bump control and insufficient body control, or good body control and being overdamped over bumps. Digressive valving kinda lets you goldilocks between the two needs.

Ideal forces are a product of unsprung weight, spring rate, and motion ratio. Basically, the stiffer and heavier the car, the more damping you need. Tweaking both compression and rebound can change how the car reacts in different phases of a corner, but NOT the steady state balance.

tl;dr it's complicated, find an expert. And since it's complicated, you'll have to take an expert's word for it that they know what they are doing.

[WP0ZZZ]

Thanks guys. I happened to write my master's thesis on car vertical dynamics at a rally team and was close to the guy running the shock dynamometer so on the theory front I'm pretty much sorted. But, as Bill says, the important thing is to know what works with what and adapt it to the particular use case. And this requires experience!

The "canned" setups offered by Elephant have been very useful for me to get an idea of different suspension setups depending on how track-biased a car is. But I'm not US-based and buying from Elephant is not practical so I don't want to bother them with a call if I'm not going to buy anything. Moreover, I'm very interested in the car behaving well during hard driving on very twisty mountain roads with potentially bad surface and I'm not sure who can help me for this particular usage.

This is the kind of road I'm referring to so that you get an idea:

[Bill Verburg]

I'm not at all familiar w/ rally car setup but it seems to me that it's close to the opposite of what we do for track and aggressive street use.

track will have little travel, low ride height, relatively high rates lots of damping, wide low profile tires

rally will have longer travel, higher ride height, relatively softer and more progressive springs, lots of damping but w/ heat a bigger concern, narrower hiher profile tires

I'd look at what the factory/teams did on the SC/RS rally cars. Like this

[mikedsilva]

Originally Posted by WP0ZZZ

I'm planning to do a suspension refresh on my SC and would like to get the big picture before starting to buy parts. At the moment I'm trying to understand Bilstein's shock range for classic 911s and would really appreciate your input.

I can buy 4 levels of shocks (not sure if US folks use the same names):

- Turbo
- Sport street
- Club Sport
- 1000 Lakes

Would love to hear opinions on the options and also what torsion bar stiffness are best suited to each shock.

Example of the rear options. "Parameter" refers to compression/rebound forces at a given shock speed:

What did you end up with?