TracTive active dampers

[Tremelune]

Anyone ever mess with these? They seem to be a slice of PASM for old cars...As someone who drives up smooth mountain roads as well as horrendous city potholes...any reduction in compromise between ride quality and motion control is welcome.

https://www.ttsuspension.co.uk/porschegseries

https://tractivesuspension.com/shop/automotive/porsche-automotive/911-g-modell-1974-1989-porsche-automotive/touring-line-torsion-bar-stand-alone-electronically-adjustable-shocks-for-oe-fitment/

At $6k plus electronics, they are not cheap. I wonder how they compare to a set of KW V3s...If I'm not mistaken the spindle heights are adjustable.

[2.7RS]

Never heard of them

They are shiny for sure!!!

[jsfried18]

I'd love to try them in an air cooled car. My friend has them in his gt3 with solid suspension bushings and arms. It rides better than a stock gt3 and handles like a cup car

[Steve W]

I think with the controller and software everything is around or over $10,000, at least with the software and tuning, depending on the source. The controller, software, and tuning(or lack of) can be completely different depending on where you source it from. Last I heard, Craig Watkins/Smart Racing on a couple of G body race cars, after removing the Smart Racing 31/27 sway bars - running no sway bars - at Laguna Seca, in a straight line the shocks absorb everything, and data showed the car was 1.5 to 3 seconds faster. The owners love them.

[winders]

Well, my chief competitor in PCA GT3 is running these and are working with Craig Watkins...so far they don't seem to be better than the MCS triple adjustable setup I am running.

We will be fighting it out at Sears Point this weekend....we'll see if they have found better settings.

[Tremelune]

I feel like the racetrack isn't where these would shine more than passive dampers, though, right? It often seems like race = super stiff whereas a lot of the "active" stuff shines on bumpy-ass roads in cars that already corner well and would suffer from simply stiffer springs...

[winders]

Well, with conventional dampers, you run a race car stiff to keep the radial tires where they need to be to generate the most traction. This means compromising mechanical grip in the process. Also, you need to control dive, squat, and aerodynamic compression.

These semi-active dampers should allow you to run much softer spring setups. possibly without anti-roll bars, and still control roll, dive, squat, and aero compression. I have not played with stuff so I am not sure what is all there yet. But, the gains could be quite significant for s race car.

[sgroer]

I have these in my garage. I got them from Inertia Lab in Texas. It’ll be quite a while before I can actually try them as my car is completely disassembled. I spoke with Leh Keen about them and he said they are amazing. The build quality in person is like art. I cannot wait to try them.

[winders]

Amazing for a street car or for a race car?

[Bill Douglas]

Originally Posted by winders

Amazing for a street car or for a race car?

I think amazing for a street car that wants to be a race car at times, then back to being a street car.

[sgroer]

Originally Posted by Steve W

I think with the controller and software everything is around or over $10,000, at least with the software and tuning, depending on the source. The controller, software, and tuning(or lack of) can be completely different depending on where you source it from. Last I heard, Craig Watkins/Smart Racing on a couple of G body race cars, after removing the Smart Racing 31/27 sway bars - running no sway bars - at Laguna Seca, in a straight line the shocks absorb everything, and data showed the car was 1.5 to 3 seconds faster. The owners love them.

I paid $7400 for the hardware, the ECU and the touchscreen controller.

[jpnovak]

I have been watching these since announcement a while back. Good reviews in a lot of places for modern cars. I have not seen ay installation on our air-cooled 911s. I wonder how steep the learning curve is for setup.

If only I had budget.

[Geneman]

best of luck at sears point Scott!

[Tremelune]

Originally Posted by jpnovak

If only I had budget.

Seriously. This is "well if I own it for the next 30 years" level of justification...

But then I realize the KWs are like $5k and a set of revalved Bilsteins are like $3k with spindles...and maybe I can get another year out of these bushings after all...

[Jonny042]

I've been trying to find out more about these but real world information seems pretty tough to come by - it's certainly an interesting setup. The hardware itself is pretty cool, with the ability to adjust spindle height.

When you get right down to it the control algorithm seems simple enough, and even though the DSC controller has a 3 axis accelerometer feeding it, it doesn't seem to have any programmable parameters for Z, only X and Y. So, pitch and roll, only. Calling them "Active" or somehow comparing them to the Williams F1 Active suspension (yes people are making this comparison!) is a bit of a stretch.

Unless I'm missing something, It's not as if the system is going to somehow sense a bump mid corner and allow the wheels to absorb it one after the other, or anything like that. There are no sensors for wheel position or shock travel so it's pretty simple.

You brake, it stiffens the front and softens the rear. Accelerate, and the rear stiffens and the front softens. Turn, and the outside shocks both stiffen and the inside soften. The tuning allows you to set a base position and how much damping is added for a given g-force.

I'm not trying to discount these at all, in fact quite the opposite, I find them pretty fascinating, but I like to understand things. Hopefully someone can chime in with some user feedback on using these standalone on a torsion bar car.

[Steve W]

Maybe it's not necessary? The first generation PASM shocks used on the 2005-2012 997s and 987 do not have suspension height sensors either but Bilstein and Porsche were able to make the active shocks work, and the Tractive shocks and aftermarket controllers such as the DSC takes the tuning and refinement to a higher level.

I don't think a suspension height sensor can function as a predictive input of the road surface ahead, it's not that smart as it cannot foresee an upcoming peak and dip in the road surface and send a signal that adjusts for what will happen. Even if you tried, I'd expect the latency, plus the valve response time could cause weird oscillations due to phase shift.

Instead, the second generation PASM systems such as on the 991s and 981s have suspension height sensors and use their signal to further refine the comfort of the shocks, such as for the rebound valving. In the DSC software, there is a table called Velocity that allows you to use the suspension height sensors to create a trim tables that trim the main valving table. These trim tables if you so choose can be used to create low/medium/and high speed compression and droop values, depending on where the suspension is in mm from the zero position. That's analogous to having a 6 way adjustable shock that is also active. So if you were to say the first generation PASM is like a two way adjustable shock, vs the second generation being a six way, does that take away from the effectiveness of the two way? If you had six way adjustable shocks, how complicated do you want to take the tuning? I think most people don't really have the know how to adjust shocks beyond two way adjustables.

But I suppose if one wanted to, you could fit the suspension height sensors from a 991 into a G body, and if the controller you used had a table that could use those input values, then you could program your own 6 way trim tables.

[Jonny042]

Originally Posted by Steve W

Maybe it's not necessary? The first generation PASM shocks used on the 2005-2012 997s and 987 do not have suspension height sensors either but Bilstein and Porsche were able to make the active shocks work, and the Tractive shocks and aftermarket controllers such as the DSC takes the tuning and refinement to a higher level.

I don't think a suspension height sensor can function as a predictive input of the road surface ahead, it's not that smart as it cannot foresee an upcoming peak and dip in the road surface and send a signal that adjusts for what will happen. Even if you tried, I'd expect the latency, plus the valve response time could cause weird oscillations due to phase shift.

Instead, the second generation PASM systems such as on the 991s and 981s have suspension height sensors and use their signal to further refine the comfort of the shocks, such as for the rebound valving. In the DSC software, there is a table called Velocity that allows you to use the suspension height sensors to create a trim tables that trim the main valving table. These trim tables if you so choose can be used to create low/medium/and high speed compression and droop values, depending on where the suspension is in mm from the zero position. That's analogous to having a 6 way adjustable shock that is also active. So if you were to say the first generation PASM is like a two way adjustable shock, vs the second generation being a six way, does that take away from the effectiveness of the two way? If you had six way adjustable shocks, how complicated do you want to take the tuning? I think most people don't really have the know how to adjust shocks beyond two way adjustables.

But I suppose if one wanted to, you could fit the suspension height sensors from a 991 into a G body, and if the controller you used had a table that could use those input values, then you could program your own 6 way trim tables.

Good points, Steve. Especially that the Tractive/DSC system performs well and is considered an upgrade to the early PASM cars. That would indicate there is value in implementing a similar (if somewhat dumbed down) system on our old cars.

I would say the Tractive is a one way adjustable shock. There is a single electric valve internal to the damper but not sure if it acts on compression, rebound, or both simultaneously?

I'm looking at these as an alternative to KW V3's (double adjustable) or possibly 2-way MCS dampers. Hence the curiosity.

I can't help but question (in that, I'd love to understand, not doubting these reports) how such an apparently simple system could improve lap times on a well-developed racecar by any amount (much less 3 seconds!) after removing the sway bars. Unless the system hydraulically locks out the dampers from corner entry to exit sooner or later body roll is going to occur, seeing as how dampers serve a completely different function to sway bars. Of course stiffening the shocks too much in the name of steady state body control would cause compliance issues if you were to hit a dip or bump mid-corner.

Like I said, not doubting, just curious. If they are that good I could see myself trying them on my AutoX car, which I'd like to make a little more of a driver, less of a racecar.

Perhaps I should email Craig Watkins...

[winders]

Originally Posted by Jonny042

I would say the Tractive is a one way adjustable shock. There is a single electric valve internal to the damper but not sure if it acts on compression, rebound, or both simultaneously?

For it to do what it claims, it would need to be effectively at least 4 way adjustable in that it could affect low and high speed rebound and low and high speed compression.

[Jonny042]

Originally Posted by winders

For it to do what it claims, it would need to be effectively at least 4 way adjustable in that it could affect low and high speed rebound and low and high speed compression.

How did your GT3 class compatriot make out with his this past weekend?

[Steve W]

Originally Posted by Jonny042

I would say the Tractive is a one way adjustable shock. There is a single electric valve internal to the damper but not sure if it acts on compression, rebound, or both simultaneously?

I think saying an active shock like the PASM or Tractive is a one way shock it too simplistic. You need multiway valves on passive shocks because it doesn't know anymore than what it's going through. You adjust the compression valving for when the shock is getting loaded, such as the outer shocks when cornering, and the rebound valving for the inner side.

But with active shocks, you cannot think of the operation in the same way. With an active shock, there's just one valve, but with the Tractives, the valve can change valving within 3-6 ms. So if under the same cornering scenario, the accelerometer senses the car is cornering the outer shocks go to a value that you optimized for compression, and the inner for optimized rebound. That is a very simplistic way of explaining it, but there are multiple trim tables that you can adjust for a multitude of conditions and input signals. For example on a car with a CAN bus, car velocity is used to increase rear shock valving after a certain speed to compensate for the additional downforce from a wing. Sensing the brake pressure increase can increase the front compression valving before even the brake pads have taken effect.

Basically the way an active shock such as the Tractive works is it is controlled between open and closed by an electrical signal between 300 and 2000mv. 300 mv the valve is basically locked, 2000 mv the valve is all open. With the main table you set an operation range for the shock, say 1600 mv for the soft end, and 600 mv for the max stiff range. Then all the auxiliary tables such as steering angle, wheel speed, G-force, suspension height if used, dynamically change the valving to what's needed depending on what the sensors tell the car is doing. DSC's engineers recently created a new table under the main map table called G-comfort Parameters, which allows you to further refine the comfort levels of the shocks, by softening all the valving to just a fraction of the main table, so that it can be as soft was you want such as on the street, below a certain g-force and sensitivity you set. This eliminates having a bunch of multiple maps, such as street, vs sport, vs track/autocross. Your track mode can practically have the comfort level as your street mode mapping. It's capabilities go beyond what most passive shocks can do, it's all up to the programming.