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Pre-emptive active suspension is a very difficult thing to achieve, especially as a retrofit package so there is an inevitability that such a system will be reactive. If using the CAN signals and bus then the system will still be reactive. Tractive has designed a system to minimise lag when acting on inputs that can be fitted relatively easily to many vehicles.

As you’re probably aware, CAN signals are used by some OEMs to control their active dampers, and Tractive sell their aftermarket controllers as an upgrade for some of these vehicles (cars and motorbikes). Using CAN was considered and discussed with RaceShock.uk at the start of the project but as Simon has explained above, discounted because the bus is too slow to effectively control the dampers valving. We also discussed fitting individual accelerometers on each suspension leg, and this is something that Tractive may introduce later though it will push up costs, so perhaps more appropriate for a GT class racing team rather than me! I’m wondering if using two of the existing accelerometers might be the way forward (one at the front and one rear, rather than a single unit near the centre of gravity) to allow signals to be measured at he ends of the car.

Il post some installation details later to provide an idea of what’s involved
I’m not talking about predicting the road, but reacting/prepare to driver inputs before car has had time to really do much. Then further adjustments can be done progressively when car has had time to act, and accelerometer can pick up changes.

I think noticeable improvements can be made by simply looking at brake on/off and steering wheel angle, then prepare differently depending on if you are in comfort or race. This could even be hardwired to controller, eliminating delay in bus.

Edit: what’s the benefit of fitting individual accelerometers? If a gyro type accelerometer is used, I do not really see the use? Gyros are used for whole ships to calculate how different points are moving compared to bottom. You do not need one sensor for each point. Easier for programmer, but more expensive and more parts to fail...
 

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I’m not talking about predicting the road, but reacting/prepare to driver inputs before car has had time to really do much. Then further adjustments can be done progressively when car has had time to act, and accelerometer can pick up changes.

I think noticeable improvements can be made by simply looking at brake on/off and steering wheel angle, then prepare differently depending on if you are in comfort or race. This could even be hardwired to controller, eliminating delay in bus.

Edit: what’s the benefit of fitting individual accelerometers? If a gyro type accelerometer is used, I do not really see the use? Gyros are used for whole ships to calculate how different points are moving compared to bottom. You do not need one sensor for each point. Easier for programmer, but more expensive and more parts to fail...
I guess the individual accelerometers are the velocity sensors mesuring each shocks movment. This methold is used in higher end OEM system.

I am with you that there are ways this system can be done better (I have experience with drone racing), like linking up wheel speed, steering angle etc. But seriously, how many of us is willing to spend more than 10% of the viechle cost on a set of suspension? They are lucky if they can sell 10 set within the first year... (7 more to go lol)

You can search DSC motorsport. They are doing what you were mentioning about, tunning the software side of Tractive and OEM adaptive suspension.
 

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With CANbus signals, I'd be worried about the logic understanding what's really going on. That's like an electronic automatic transmission, which gets the signals right SOME of the time. Not good enough on the track, where predictable is better. So, besides being delayed, it might set the car up for a "zig" when you intend to "zag". Being reactive, with millisecond response times, is in my mind the better alternative. Although I agree that an accelerometer at each end, or better still at each corner, would lead to even faster reactions.

Great thread!
 

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I would not bother too much with this.
On the race track you set the suspension on maximum stiffness so I don't know if the car will do anything more from that point on - not much left to do anyway
On the street you set the suspension on comfort and You don't extract the last drop of performance anyway.

Racing on the streets may use this system more (like targa tasmania) but 99% of us don't participate to such events.

So, the fact that this suspension reacts in 6ms to the car behavior and can be set to be comfortable or stiff on demand, it's good enough IMHO.
This car have some issues anyway and it's not a porsche. I'm not even sure that I would like a suspension that deals with the road imperfections like a porsche does.

Imho, it may already be too good for what this car is meant to be.
 

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I know that this boat has sailed, but fwiw
As promised, stock non-race suspension...

Front Left 354mm. Right 357mm
Rear Left 360mm Right 360mm

Keep in mind, the body panels are quite adjustable, which may account for some variability.
 

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Discussion Starter #106
My car is progressing towards more compliance on road and with firm control when on track but now the car’s been on Tractives for a few weeks I may have lost my original internal calibration of how the standard suspension felt (particularly due to my goldfish like attention span and Rioja-affected memory).
Driving over the less than perfect local backroads I know well, it’s possibly a good idea to remind myself of the ride on a standard car so I’m looking for a volunteer to meet me locally with their 4C somewhere between Cardiff and Swansea to try both cars over some world-class driving mountain roads. I’ll post similarly in the UK section here.

Any volunteers?
 

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Discussion Starter #107
A fascinating fact has emerged from this project which I wasn’t aware of before. Raceshocks.UK sent my standard non-race damper units to Tractive Suspension for dyno testing and it turns out that the dyno plots and spring rates are identical to Alfa’s 4C ‘Race’ versions. That’s £1500 for a rear anti roll bar and upgraded ARR tyres.
 

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A fascinating fact has emerged from this project which I wasn’t aware of before. Raceshocks.UK sent my standard non-race damper units to Tractive Suspension for dyno testing and it turns out that the dyno plots and spring rates are identical to Alfa’s 4C ‘Race’ versions. That’s £1500 for a rear anti roll bar and upgraded ARR tyres.
Is not really a surprise for me, the same stupid deal like the HIFI option
 

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A fascinating fact has emerged from this project which I wasn’t aware of before. Raceshocks.UK sent my standard non-race damper units to Tractive Suspension for dyno testing and it turns out that the dyno plots and spring rates are identical to Alfa’s 4C ‘Race’ versions. That’s £1500 for a rear anti roll bar and upgraded ARR tyres.
Wow. Considering there are different part numbers for the two styles of shocks, that’s amazing (and weird).
 

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Discussion Starter #113 (Edited)
As part of the development process I recently attended a track day at Thruxton race circuit to test the suspension at high speeds. The event was organised by the Institute of Advanced Motorists, and provided an opportunity for plenty of lappery on a largely deserted track with just a dozen cars on track at a time. Thruxton is a very fast circuit with the unofficial lap record being set in 1993 when Damon Hill demonstrated his Williams FW15C F1 car with an average lap speed of 147mph, reaching 186mph at Brooklands corner, the fastest section of the track, and more of a long curving ‘straight’. The Alfa could probably reach around 130 there, but two temporary chicanes had been added for the trackday to reduce speeds and leaving three other 90mph corners to test both my new suspension and me.

The usual plan was utilised to first get an idea of where the track went, whilst keeping within the organisers announced speed limit of 110mph which suited as my purpose was to get used to the suspension. The plan was to adjust the suspension for each session, starting on soft (setting 1) and working up to setting 5, the firmest. It’s possible to use the touchscreen to adjust the settings on the move, but I wanted to use each track session to get a feel for what the car was doing.

On the road, I currently feel an imbalance front/rear on the softer settings because the rear is much harder than the front. On firmer settings all round, the balance improves as the front is firmed up to match the rear. The firmest setting is very firm with little resilience on the road, and certainly this doesn’t achieve what I want on setting 5, but I was looking forward to trying it on track.

For the first non-sighting session the front and rear firmness was set at 1, and slightly firmer 2 used for pitch and roll. Thruxton has low kerbs on the inside of a few slower corners and on this soft setting the front rode them beautifully - they almost weren’t noticeable. At the 50mph Club chicane the car was balanced and superbly controllable, and different to the standard setup which I found could spear me off the track when the limit of adhesion was breached at the rear, because of too little rear rebound damping. At Allard, a 90mph corner with a slight bump in the middle there was a slight front/rear diagonal motion, but that’s understandable as I was using the softest suspension settings.

During the next session the suspension was set to 2, with 3 selected for both roll and pitch. Turn in at slow speeds was more precise though I couldn’t feel a change at higher speeds (after all, it was a change of only 1 setting), and low kerbs were still being dealt with without deflection. The diagonal pitching continued during the fast corner with a bump, though I’m confident that would be sorted at stiffer settings. What was particularly noticeable was how controllable the car had become. When standard, I’d always found that driving passed the limit of adhesion a bit too ‘exciting’ and inconsistent. With the Tractives it was possible to choose driving neutrally, induce understeer, or oversteer on demand, and drive round 90mph corners beyond the level of grip whilst being able to move the front or rear as required, with the car moving smoothly beneath me.

For the next session, suspension was set to 3 and pitch and roll set to 4 but I didn’t notice any difference out on the track compared with the previous setting. Whilst driving, setting 5 was chosen but no difference felt. From the road I know this is very firm so it was clear that something was wrong. I drove the remaining sessions stuck on 2/3 which from a testing perspective was a shame but the car was so drivable on this setting I simply enjoyed driving it, thinking there was nothing I could fix at the track.

The touchscreen controller currently has 3 screens from which to select suspension settings. Screen 1 allows adjustment of the front/rear/pitch/ roll parameters and save the settings, whilst Screens 2 and 3 provide larger icons to allow easier selection between the stored settings. When I returned home, I found that screens 2 and 3 weren’t working which explains why I was stuck on one setting. If I’d continued to use screen 1 at the track I would have had all settings at my disposal. I informed Tractive who very quickly corrected the firmware and emailed me the corrected files for uploading to the screen. All screens now work properly.
 

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Discussion Starter #115
Raceshocks UK and Tractive suspension worked instantly to fix the touchscreen issue and reacted quickly to my feedback following the track session, and I’m again grateful and impressed by both their excellent customer service.

Within a fortnight, new damper curves have been created which will reduce bump settings (especially at the rear to lessen the current front/rear imbalance) and increase rebound which will add a little control particularly at the softest settings.

My car will be left with Raceshocks UK who, I understand, will make the necessary changes at their premises in the UK rather than returning the units to the Netherlands.

There’s still the issue of the elongated holes in the front upper suspension chassis mounts to be dealt with, and this is proving tricky because it doesn’t make sense nor a reason found why Alfa chose to elongate them during production.
 

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Great write up!

So you mean Tractive and Simon can send you file to change the curve on top of you adjustment through the screen?

我從使用 Tapatalk 的 SM-G9650 發送
 

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Discussion Starter #118
Great write up!

So you mean Tractive and Simon can send you file to change the curve on top of you adjustment through the screen?

我從使用 Tapatalk 的 SM-G9650 發送
Yes they can for the intermediate settings of 1 to 4 but because of my particular requirement for a fuller range of adjustment from quite soft to firmer than standard the physical damper setup needs to be changed. The upper limit of firmness is the default (ie 0V) setting for the dampers and this together with the force velocity curve is established conventionally by altering valving, shim stack, gas pressure - so these will be altered by Simon.
 

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Late to the party, but I also will not buy Eibach springs ever again. Lifetime warranty, until you try to get them to honor it.
eibach_LOL.jpg


6 years, ~80k miles. Both rear springs in my cheap commuter car.
 

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Well I just measured my '15 US coupe that has been sitting for a week, race tuned susp, just over 1/2 fuel, no driver, only flat kit in trunk. 16k miles, 18/19 wheel set up, 215/245. Measured from center of center cap to edge of inner fender lip.
LF 358mm
RF 360mm
LR 358mm
RR 360mm

I am pretty sure the US cars sit slightly higher from the factory....not exactly how much. Thought it was about 10mm
 
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