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Smoother riding coilovers - let's built it! Band together - then approach Bilstein/MotonSo

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So, the Model S has been out 5 years now and there are well over 100,000 on the road. Yet still there are no aftermarket coilover kits AFAIK from any of the typical players. Many of us feel the ride is rough with the coils - yet there are solutions in the aftermarket. I know it does not take air springs to have a magically smooth ride and also good handling - fond memories of the legendary E39 5 series BMW remind me of that frequently. And that car had not an air spring in sight.

To tame the rough ride over small, high frequency hits should simply require a combination of two things:

1 - A progressive rate spring which is softer in its first portion of travel than what we have now.
2 - A digressive valved shock absorber (available in kits for certain cars - such as the Bilstein PSS9). Digressive valving allows a shock to be softer over small, quick hits (expansion joints, pavement cracks, frost heaves, etc.) while retaining firmer damping for larger motions

Would this set-up give up some road feel and perhaps make steering turn-in slightly less crisp. Perhaps a bit more body roll in corners? Maybe - but for those of us using autopilot to travel long distances in comfort on bombed out freeways (California) - the trade-off could certainly be worth it. And a few thousand dollars for a coilover kit is a lot less money than trading in your higher mileage Tesla just to get one with air springs from the factory.

So I'm hoping to gather an interest list, then make contact with some major manufacturers like Bilstein or Moton and be able to say "TMC has this list of a zillion Model S owners who want to buy a coilover kit - please help us." Both of these companies make off-the-shelf kits for many mainstream cars. I keep hoping Tesla will show up on their list but it's been 5 years - no dice. Let's take matters into our own hands.

If you have any feedback please contribute. If you're interested in putting your name down please contribute or PM me. If you have contacts with a suspension designer let us know.

If I'm an idiot with this plan - let me know. :)
 
Interesting offerings from Bilstein:

B16 - PSS9/PSS10 Kit
The Bilstein B16 PSS9/10 kit is a race inspired system, providing the ultimate in high performance tuning. The manually adjustable monotube gas shock absorbers feature 9 or 10-stage precise compressiong and rebound settings, from comfort to competition. The threaded body allows accurate adjustablity of the front and rear progressive springs to achieve the vehicle ride height (30mm to 50mm), center of gravity and level of performance handling desired. Bilstein's patented Triple-C-Technology® coating ensures long-lasting resistance to corrosion.

B16 - Electronic ridecontrol® Kit
The Bilstein B16 Electronic ridecontrol® kit allows the driver to electronically select between a comfort oriented or a significantly firmer, aggressive performance damping mode with a push of the dash-mounted button. The integrated control unit switches the damping settings on all four shocks/struts in fractions of a second to deliver the handling characteristics you desire. The threaded body additionally allows for adjustable lowered vehicle ride height of 25mm to 50mm, depending on application. Bilstein's patented Triple-C-Technology® coating ensures long-lasting resistance to corrosion.

Understanding BILSTEIN's Product Line
 
And from Moton - these dampers look highly adjustable - Moton claims 4 way adjustability - independent adjustment of both high and low speed rebound and compression damping. And the site says they will custom build. This could be an ideal set-up - one universal set of shocks this adjustable could be used on many different Model S's. And then perhaps we could get Moton or someone else to design and build several different spring combinations - from soft to firm. And then perhaps get a few donor cars to a shop for testing - and then publish combinations of shock settings and springs that work best for different Model S's with different needs.

"The 4-Way adjustable Motorsport damper is available as a McPherson Strut in either Aluminum or Steel or as a Aluminum Coil-over damper. It can be custom built to your specifications. The Moton 4-Way damper features separate low- and high speed bump and rebound control. The 2 rebound adjusters are located on top of the piston rod and adjust completely independently from each other. Both low- and high speed rebound do have a adjustment range of 20 clicks each. The 2 bump adjusters are located on top of the reservoir, the low speed bump can be adjusted into 6 different settings by turning the small knob on top of the reservoir. The high speed bump can be adjusted into 15 different settings by turning the large knob on top of the reservoir.

The 4-Way damper is featuring a unique double piston design. The primary large main piston does have a double non preloaded valve stack on it for bump and rebound control and is designed for quick response during the smallest movement of the piston. The secondary piston is designed with the use of a unique blow off valve system for high speed rebound control. The low speed rebound is controlled by adjusting an internal needle valve."

MOTON 4-Way Motorsport Pro : Moton 4-Way Motorsport Pro
 
I had Koni FSD shocks on my BMW E92 that made an appreciable difference to ride comfort while maintaining handling -- that may be an option for us as well if lowering is not desired or needed. Does anyone know if those will fit a Tesla or how hard it would be for Koni to create one?
 
Tell us about the FSD's @hatman4731

Haha i'm terrible at explaining, but here goes:

In general there is a tradeoff in shock selection -- sportier handling and the need to "feel the road" tends to produce an uncomfortable ride, whereas softer damping will lead to a comfortable ride but boaty feel with lots of body roll. Koni FSD (Frequency Selective Damping) Dampers helps with this problem by using shocks that react differently to suspension loads based on the frequency of the impact -- high frequency loads (i.e. potholes or cracks in the road) are automatically softened whereas low frequency loads (undulations in road, rising or lowering crests) firms up the suspension so you stick to the road. The beauty is that all this functionality is designed mechanically inside the shock design using passive valves, which means no electronics or sensors and immediate response since it is just changing how the fluid flows inside the shock.

The end result is a ride that is firm when desired and compliant when cruising around town. It won't match the firmness of true sport dampers but for the large majority of us who drive it casually it's a great combination of sporty handling and luxury comfort.

Here's a link to see more:
https://www.tirerack.com/suspension/tests/koni_fsd.jsp
 
  • Informative
Reactions: calisnow
I like where this thread is heading. I would stay with a Bilstein monotube shock. 1. Because already OE supplier 2. Imho I doubt the motion shocks would come close in valving performance.



Whilst I'm not a fan of progressive rate springs, they do have their place in some applications.

I would also lean towards revalving the current stock shocks and possibly converting to coild over

I think first job is too find out the spring rate of the stock coils. Going to need some photos and measuring. There are several online calculators for this.
 
My suggestion would be a poll to gauge how many MS/MX owners have coil springs. You will need this as a market analysis before you can persuade a company (Bilstein, etc.) to make an aftermarket solution. Their interest will depend on the number of potential customers. A concern I have is that most people buying MS/MX have ordered the air suspension (from what I have seen posted about this). To make a product for a small customer base is to make something that will be quite expensive... that might be OK, I know, but stilll
 
Although we do not have a coilover set up for a D, we do have lowering springs for a two-wheel drive Model S.

Model_S_lowering_springs_1.jpg
 
My suggestion would be a poll to gauge how many MS/MX owners have coil springs. You will need this as a market analysis before you can persuade a company (Bilstein, etc.) to make an aftermarket solution. Their interest will depend on the number of potential customers. A concern I have is that most people buying MS/MX have ordered the air suspension (from what I have seen posted about this). To make a product for a small customer base is to make something that will be quite expensive... that might be OK, I know, but stilll

For what it's worth, the vast majority of inventory cars Tesla sells have coils.
 
@calisnow have you already reached out to the manufacturers with an inquiry? It would be nice to know what their threshold count is to make the R&D worthwhile -- I'm sure it's different per car based on the difficulty, I wonder if the excess weight of our Tesla causes additional complications.
No not yet - and you may be right. There are both AWD/RWD weight differences - and of course the battery differences - to take into account. I'll make some calls next week and report back here.