- No matter how much money you've got invested in your racecar, ultimately it
comes down to the contact patch between your four tyres and the racetrack that's
going to define how your car will handle and how fast it will be.
A key component of optimising that contact patch of course is the dampers and the
suspension system.
Now conventionally we have dampers with adjustable bump and rebound however this
is a adjustment that we make in the pits and that could be a compromise for
a certain part of the track.
We're here with Tom from DSC Sport to talk about tunable suspension,
in particular DSC is the U.S. distributor and importer of Tractive Suspension.
So Tom, before we get into your electronic controls, can we just talk a little bit about
what Tractive's coil over suspension or dampers are, where is the advantage with
that Tractive suspension?
- Tractive makes a great coil over system.
They have their patented DDA valve which is the fastest electronic valve in the world
at six milliseconds, so using our controlling algorithm it can change the damping curve
166 times per second.
- Alright so what you're talking about there, instead of a conventional manual
adjuster for bump and rebound or maybe you've got multiple adjustments for high
speed and low speed bump and rebound, this is all done internally within a shock,
within the damper electronically?
- Yes absolutely, with our software we're using G force as the primary load.
It's always looking for a certain G force signature.
So regardless if you have changing conditions or a different driver that
delivers the car to a corner a little bit differently, it will show a different G
force signature and that's how we set the damping and on top of that,
we're offsetting the actual driving situation with high speed, low speed,
medium speed compression and rebound based on the signal from the ride height
sensor as well as vehicle speed.
Just like you would tune a ECU for the engine, you have your main table and then
you have other offset tables.
- Alright you've just dumped a huge amount of information there so I want
to just go back and unpack a little bit of that bit by bit.
So first of all, you've just talked about low speed, medium speed, and high speed
for compression and rebound dampening so just for our enthusiasts watching this,
maybe they're not completely familiar with how that's going to affect the way the car
handles, can you just talk to us either with a manual or your automatic electronic
control, what those three areas, medium, low speed, high speed
damping actually affect?
- Yes absolutely, so we're actually not talking about vehicle speed,
we're talking about suspension travel speed.
- So rate of change of the suspension movement?
- Yeah as far as low speed is concerned, we consider zero to two inches per second
low speed.
So two to six is medium speed and six to 20, six to 20 plus is high speed.
So if you were to hit bump, that would be high speed and loading the car up in a
long sweeper, that's low speed.
- So essentially in real simplistic terms, the low speed is the sort of stuff where
the driver's actually moving the wheel, turning the car into a corner and it's
pitching or moving around and rolling so that control of that aspect of the
suspension.
At the other end high speed maybe where we run a curb and the suspension is forced
into bump travel very very quickly, is that a reasonable way of breaking it down?
- Yeah you're 100% correct.
- Alright so again we talked about the conventional manual bump and rebound
adjustor and at some point we're making compromises, maybe it'll work really well
on a section of corners but there's another set of corners that maybe aren't quite
ideally suited.
So you've got the ability to change the bump and rebound dampening as the car's
going around the track and this is where your DSC control module comes in.
So before we get into the logic behind that control, what sensors are required
in order to use this system?
- We have two lines a system, plug and play, hence the name for cars that come from
the factory with electronic suspension.
So these cars already have enough sensors on a CAN bus.
But what we do is we read the factory CAN bus and the CAN bus rates 500 hz, 500 times
per second so we can get a lot of information from brake pressure, vehicle speed,
to accurately get the damping commands that we want for the situation.
- Just with those systems where you plug and play, I'm right in saying you're still
swapping out the factory dampers with the Tractive but you're just saving money
and simplicity by reutilising all of those factory sensors, that's what you're saying?
- Yes that's correct because the sensors are already there so why not use it?
And they're pretty quality sensors for these newer cars.
And our controller will actually work with the OE electronic shocks too.
But nowhere as good as a Tractive of course.
- Alright so you've got the sensors, whether that's a plug and play system or you're
reading your new sensors in that you've added in with a standalone system.
So you mentioned there a little bit like tuning a standalone aftermarket ECU
for engine control, that's what you've likened it to.
What sort of control do we have, maybe talk us through a little bit about
that logic of the control system and how that's really going to benefit a car out on
the racetrack.
- OK yeah we have a load dependent system just like an engine ECU has and our primary
load is the G force.
So we're always looking for a G force signature, so that table is pre written by us.
In fact every controller that we sell is already mapped very well.
We spend a lot of time on it.
Now the other sensor that comes into play is brake line pressure because in the braking
event the brake line pressure rises before the G force.
You're talking about a split second but nonetheless it's advanced.
So we're using the brake line pressure to pre-empt the damping force before the
G force actually occurs.
So that's one way to tune it, as far as other sensors that are used are the
velocity sensors.
We talked about that briefly before.
So if you were braking and you happen to be braking on a bumpy patch the sensors
will pick up the patch and then we will subtract x amount of damping force to make the car
a lot more compliant.
So the car is not uncomfortable and it remains stable in a braking zone.
- Alright so again just breaking that down into something, in real simple terms,
you're talking about, you're coming into a braking zone, you've got your suspension
with bump and rebound damping that's relatively compliant so that it's not
skipping over bumps.
When you hit the brakes you're going to end up essentially with weight transfer towards
the front of the car so you are stiffening the front suspension in a result of that to try
and optimise the braking force.
But if you were by chance on a very bumpy section then you would actually soften it
slightly to remain compliant over that bump, is that sort of how I'm reading that?
- Yes that's correct, we're offsetting in other words.
- OK so basically you've got some base tables in there you can tune but the
system is smart enough to be active as you're going around the racetrack?
- Yes it's active all the time.
- Now one thing that concerns me here is I know that most track day enthusiasts
and maybe the system's a little bit beyond the track day enthusiast, it's a very high
end professional system but they struggle with just setting a single bump and
rebound adjuster manually.
So when we're throwing this much adjustability and control my guess
is if you didn't know what you're doing it would be possible to actually go backwards
and end up with a worse result?
How do you guide a person through making calibration adjustments and getting a better
result with this active suspension system?
- What you just said is completely true, I've been doing this for 24 years and you
definitely could go down a wrong path in manual adjustment.
So with the electronic, we mostly eliminated this possible error by providing a very good
base map.
Now with our plug and play controller, instead of tuning for what you expect a
peak load to be, we are tuning for the driver so instead of tuning from the tyre up,
we're actually tuning from the steering wheel down.
So it's using the driver's reaction, braking, steering, in order to trigger the next set
of commands.
So in that way it simplifies the tuning process because it's already pre written in
an algorithm.
- So essentially you could put this in the car, you could expect a really good improvement
over a passive system anyway and if you really want to dive in deep you've got
the data to back it up and the knowledge to back it up.
There's potential to make improvements for a particular track, a particular driver
preference and how car's set up?
- That is true and we've proven this by doing a number of track demos.
Jeremy and I have gone to different tracks and obviously the driver has to be familiar
with the car and that track.
After they do a couple of warm up sessions we would swap it out and 99% it will show
an improvement in the lap times.
- It's actually probably a good time to ask, if we're going from a conventional passive
suspension system, one that's already well dialled into a particular chassis,
a driver and a given track, swapping from that passive system across to your active
system with Tractive, coil over suspension dampers and setting that up properly,
can you give us an indication of what sort of lap time should you expect to be able
to drop?
Well the lap time's going to depend on the length of the track and the driver and
the conditions of course.
I have also worked in a pro race team, we won 24 hour races and championships
but in such an environment if you have top engineers with great drivers, with great
feedback, you're looking at the data and that passive suspension is fully set up
for that condition for that day, the improvement is going to be very
little but most people don't have the resources to do this.
So with our electronic it could take their car without the engineer,
without the pro driver feedback to that level.
Now even in a pro race level with this level of resources, our system will
show a significant advantage during the race if there's a change in condition.
If it's not raining in a race, we don't have to come in and change to a rain setup,
it will automatically detect a change in the G force signature.
Because in the rain naturally we're running less G force.
So you automatically have a rain setup for changing the conditions.
Or do you have to take it offline somewhere, to get a different line, it will change
the G force profile and our system will remap it instantly.
- Now another thing you mentioned off camera before we started recording here
was that you can essentially instigate an electronic bump rubber or bump stop
which is something that really interested me.
So a lot of people, the bump rubber there is kind of the last line of defence before
the shock bottoms out, preventing tyre contact with the chassis.
A lot of cars now though that are running a lot of high aero down load,
this becomes a bit of a compromise and some of them are actually now relying
on the bump rubbers so that at very high speed where they've got potentially
2000 kg or more of downforce, the car isn't physically running onto the ground.
Now how does this electronic bump stop work and how controllable is that?
- It is very controllable.
Well first, this is a very advanced feature that we use, we don't expect every user
to use it but for those who actually need it, want to use it, in the velocity table that we
have, once the ride height is zero then we can fill in a numeric value.
So once it gets to a certain travel point, the electronic bump rubber will begin
which we would command the shocks to increase the damping force.
And we can also have a ramp angle to ramp up the force so it's not so abrupt.
- That's a really important aspect with tuning the bump stops as well.
If you're going to be running onto them, a lot of people run a very very hard
bump rubber and essentially as soon as the corner of the car runs onto that bump
rubber your spring rate essentially goes to infinity, overloads that particular corner
of the car, so what you're talking about there is tuning the damper position where the
bump rubber will start to contact or the electronic bump rubber starts to
contact but then you can also control essentially electronically the stiffness
of that bump rubber?
- Yes that's correct.
We have, well all of these dampers are amperage based, so current based.
We can control the peak stiffness of the electronic bump stop, you can change the
ramp angle of it.
- Awesome product, really really innovative and sort of almost hails back to some of
the F1 active suspension technology starting to trickle down into road user cars and
enthusiast track day cars.
Could you give us, obviously it's going to be very application dependent but just
so our viewers sort of have some idea of the ballpark, can you tell us what a kit would
be worth?
- Well we actually have two lines of products, we have our plug and play controller,
they range anywhere from $1000 USD to $1300 USD.
It will plug and play to a newer car with electronic suspension.
- So that's where you're controlling the existing shocks.
- That's correct.
And the Tractive coil over package is what we consider a stage two package with our
controller and it's very vehicle dependent but they will range anywhere from
$5000 USD to $7000 USD.
They will all have monoball top plates, applicable springs and some of the
MacPherson strut design's going to be on the higher end versus the eyelet
to eyelet traditional shock design.
- At the end of the day though when you're developing a racecar, $5000-7000 USD,
if it's going to give you a significant improvement in lap times, that could be considered really
well worth it, good value for money.
Look Tom thanks for the chat there, if people want to find out more about
your products, the DSC controllers and the Tractive suspensions, where can they head to?
- Our website is www.dscsport.com.
- That's great, thanks a lot Tom.
- Thank you very much for the opportunity.
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