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This is a bit of a narrative, and includes a tldr section at the end if you just want the details.
I bought the 718 GT4 to replace my last drivers car, a 1994 Miata r package. The expectation was the GT4 would be relatively lightweight, have a well balanced chassis with its mid-engine, and provide strong driver feedback signals like steering, braking, shifting, and weight transfer (gas pedal and steering wheel). The flat 6 and design were just extra icing on the cake. I’ve been really happy with the GT4 except for the suspension. Driving on twisty and bumpy back roads, it often felt like the car was bouncing, or hopping, or heaving. Whichever way you’d like to describe it, to me it felt unsettled, and I lacked confidence pushing the rear of the car when driving quickly.
I learned after purchase the geometry of the GT4’s rear suspension causes toe out when it extends (or rebounds), and toe in when it compresses. As you can imagine, under braking where the chassis pitches forward and the rear strut extends, additional toe out could feel unnerving if you were not prepared for it. The more +/- vertical movement in the GT4 suspension, the greater the toe and camber changes become. These are inherent traits in MacPherson suspension, and not unique to the GT4 and many Porsche models utilize these struts in their design.
To address the frustrating rear suspension I started with the basics - alignment and corner weighing.
If you read anything about PCA or SCCA series involving the GT4 you’ll see tons of talk about alignment limitations on the car which I wanted to avoid myself. In addition to the alignment and corner weight I added the following:
Corner weight, ride height, alignment (This resulted in an alignment of -2.5 front, caster 8.7, zero front toe,, -2 camber rear with .07” of rear toe per side or .14” total.
Result
The rear of the car felt less unsettled while braking, and the factory alignment and cross weights were fixed.
No preload on the swaybars thanks to the endlinks and the camber plates give me lots of room to move camber while keeping caster in an agreeable range.
The rear end uneasiness was still present. Crossing dividing lines or crowned roads when passing slower traffic still felt like the rear of the car was pulling away from the front.
The strong feedback in the steering wheel when the car heaves, especially at speed on back roads was present
Overall there were improvements, but not a dramatic difference, and it still felt like I was leaving a lot on the table.
Next Iteration
I tried out the DSC Controller.
Starting off with the provided GT4 config file, I was able to make some changes primarily in the low speed damper settings, and a change in damper ramping which resulted in higher corner speeds and increased confidence in the rear. I also appreciated being able to make a larger distinction between street and sport PASM profiles, which really improved the daily driver experience in the GT4. Less crashing over bumps and on uneven road surfaces. The downside was the ‘street’ setting was unsuitable for back road driving, and the ‘sport’ setting was a little harsh for daily driven roads. Really, it proved the considerable effort spent tuning chassis dynamics at the manufacture before releasing it to the public. Many of us may not like the default PASM settings, but they are there for a reason and they are quite accommodating to whatever driving you do, with no coffin corners that I'd noticed (a place where if you venture, disaster is imminent).
I also like to consider that everything you love or hate in a car’s behavior was the result of a specific decision some engineer made - either it was too expensive to implement, too complicated to maintain, or perhaps too competitive with other model lines, or maybe there was a manufacturing line already producing parts... but little is left to unconsidered, and the default PASM settings demonstrates this thinking well. Anyway...
While I enjoy the configurability of the DSC, the software and interface have limitations which make it annoying to tune with and I felt like I was overly reliant on stiffening up the front of the car to make improvements to the rear. (Basically, if you let the rear suspension move less, you have less toe and camber changes occurring). I wouldn’t say I was done tuning with the DSC, but I did make improvements for me and I appreciate the flexibility it provides without having to get under the car.
Suspension tuning is considerably difficult without a race track or data logger. Some of the performance envelope you want to test in a given DSC configuration requires specific conditions, like a certain speed and lateral g load before the suspension will be changed. Recreating these conditions on the street is usually unreliable, or unsafe. Not to mention it is difficult to consider what is low, medium or high speed strut movement resulting from a given street corner or bump in the road. For this you need a data logger at minimum, and ideally a race track and some professional help to perform the log analysis.
Final Changes
The last change I’ve made is the addition of the Tractive Touring struts. These struts use the OEM springs, and though I’d already switched to the Tarett 'race' front camber plates, the struts have the physical profile of the OEM struts and are compatible with the Tarett camber plate.
Tractive Touring struts
Free toe links I didn't know where included with the struts. Neat, and thoughtful.
Everything installed, Tarett plates and Tractive strut are compatible with the OEM spring.
I decided on the Tractive struts because I’d learned the OEM Bilstein were described having a 20-100ms latency to change the strut valving on demand of the PASM computer. Apparently the valve design locks until the strut unloads the value, after which the valve can be adjusted. When I did the math on how much ground the car could cover before a valving change could be realized in the strut, it was clear there would be many situations where the PASM desires a suspension change and you’ve literally driven past the pavement before the strut can be adjusted.
Tractive sells 3 strut variants, ranging from street to motorsport use . All the dampers use their DDA valve which is responsive to within 6ms, the more track oriented struts include a mono-bearing top plate and up to 4 way adjustment which is handy, but costs some noise vibration harness (NVH) (many monoball top plates click-click as the suspension loads). I’ve used both styles of strut, and since this is a street car, I was happy I could utilize the quiet Tarett top plates with a strut using the DDA valve on their Touring line strut.
With these struts, I've stopped using the DSC controller for the time being. The 'good' OEM strut profile I previously used works horribly with the Tractive struts. This is expected, their operating ranges are very different and I imagine the damper velocities are also different.
Old struts. Little was said at their funeral
Current Status
The suspension is sufficiently solved now for fun street driving. Improvements I’ve noted using the 'sport' PASM setting:
Rear has markedly less hop, heave, and/or bump steer.
Braking stability is improved
Vehicle dynamics over undulating roads is remarkably composed
Steering wheel feedback over bumper roads is present, but it doesn’t feel like you could lose control if your hand slipped of the wheel (as it used to).
Anecdotally I find myself often flat on the gas out of corners or mid corner holding a line that I know will hit a bump or broken pavement - simply to see what will happen now. So far its been unflappable. Most bumps feel like their top has been flattened off, if that makes sense.
The front tucks into corners very well, but after running 8000 miles on the Cup2’s it’s evident I could use more camber up front without consequence, so increased camber to -3 degrees. Caster remained the same and the rear camber was left at -2
If the car had been this way from the factory, I wouldn’t have changed a thing. It drives more like I recall the Miata felt, being able to throw it into a corner faster than seems reasonable and it holding the line as asked.
Future Plans
I have a couple more goals and desires for this project
Get a new data logger (I used to data log when I tracked the Miata)
Data log the wheel velocity (please help me)
Build a suspension profile in the DSC similar to the PASM sport profile, then iterate on it. (will be easier to do with a data logger and racetrack)
Build a wet and daily driver profile for the DSC
Add functionality to the DSC (I want to be able to load many profiles without using the DSC software or laptop)
And the last thing that bothers me - is that this entire post is without quantitative data. Apologies. I also haven't been to the race track yet, so I have still have no idea the limits of the car or if it oversteers or understeers as it's setup now. I'll get there one day though.
Too Long Didn't Read section
Superlative 718 GT4 Street settings:
Rear toe links (anyone's, or the included ones from a Tractive strut kit)
Rear toe lockout bolts (probably optional but I hate eccentric bolts)
Tractive Touring struts (deal includes rear toe links)
Tarett Race Camber plates front
Corner weight and alignment
Front -3 camber, 9 caster, .03” total toe
Rear -2 camber, .07” total toe
50.3% cross weight
55.6% / 44.4% Rear/Front
I have ride height however, I don't have the reference point for the measurement so its no use to anyone. It is slightly raked and a touch lower in the front than factory.
Swaybars are mid/mid
Cup2’s 32psi front and rear 'hot' (I need to double check pressures manually, as they are probably higher than the TPMS reports)
Costs
All told parts were ~$6,800 plus around $1,500 in labor.
You might be able to get away for less, using shims instead of camber plates, no lockout bolts, and knock off another $650 from this total because the Tractive struts come with toe links and I'd already purchased Tarett's.
I could not have gotten here without the help from my shop who did the work, provided their council, and their professional experience (unnamed I have no idea if they want mention), Smart Racing Products who sold me the struts and provided advice,
...With these struts, I've stopped using the DSC controller for the time being. The 'good' OEM strut profile I previously used works horribly with the Tractive struts. This is expected, their operating ranges are very different and I imagine the damper velocities are also different....If the car had been this way from the factory, I wouldn’t have changed a thing. It drives more like I recall the Miata felt, being able to throw it into a corner faster than seems reasonable and it holding the line as asked.
...Add functionality to the DSC (I want to be able to load many profiles without using the DSC software or laptop)Acquisition
Congrats, and good luck to getting it dialed in. I spent (2) years "tweaking" my DSC settings, to get it to the point where I was happy, and there was still room for improvement. Getting rid of that rear end "hop" was the last hurdle (no pun intended), but getting aftermarket dampers was probably the ultimate solution, as you have accomplished...didn't know thaty had a "Touring" package. Have you tried DSC's "Tractive Calibration File"? If not, that may save you some time by giving you a better starting point.
Also, for the multiple profiles, will you be adding a **** setup, like in this Paul Stephens build? (starts at 24:07):
Nice outline. You chose to reuse the OEM springs, can you give a little more color as to why?
Good stuff.
I’ve seen a lot of folks choose to change their spring rates. Increasing spring rates decreases chassis roll and pitch which reduces suspension movement (so less toe and camber changes) which would be something I'm interested in achieving. But firmer springs also increase ride frequency which is a generic expression for how a car will likely handle. https://www.ijera.com/papers/vol9no3...3036064%20.pdf (page 62 marked in the doc) explains ride frequency and the relationship between front and rear wheel frequency. After reading that I concluded I shouldn't be messing around with spring rates since I don't know what I'm doing, and I lack data to tell me otherwise.
I also don't want stiff ride on the street, just a responsive one. I can make the car more responsive by switching to ball joints in the suspension arms, or just firming the dampeners up through the PASM button or the DSC. Lowering the car would also improve responsiveness but I drive it on the street and it's low enough already, why give myself heartburn?
My escape plan if I need to get a higher rate spring is I can still add them to the existing strut, and then change the damper profile with the DSC. Stiffer springs need less compression and more rebound, and the DSC primarily modifies the strut rebound profile.
Congrats, and good luck to getting it dialed in. I spent (2) years "tweaking" my DSC settings, to get it to the point where I was happy, and there was still room for improvement. Getting rid of that rear end "hop" was the last hurdle (no pun intended), but getting aftermarket dampers was probably the ultimate solution, as you have accomplished...didn't know thaty had a "Touring" package. Have you tried DSC's "Tractive Calibration File"? If not, that may save you some time by giving you a better starting point.
Also, for the multiple profiles, will you be adding a **** setup, like in this Paul Stephens build? (starts at 24:07): https://youtu.be/usNGTuNJ934?t=1446
Thanks for that link. Yeah something like that I think. I'm aware that Tractive sells a controller which lets you select 5 profiles using a button or ****, it is often used for older cars to retro-fit a PASM capability into the car. Their controller also lets you just change settings similar to the new GT3 RS (but not as cool with the ***** on the steering wheel)
I suspect the DSC controller can actually support more profiles than 2, but that they've not included them because there is only a on/off button in the car and customers would get confused which profile they are in. The DSC microcontroller also supports wifi, it just isn't enabled. My guess is support issues, but since the car includes a hotspot already it would be pretty cool if you could just be on your laptop and push a new profile to the DSC while the car was running.
Thanks for that link. Yeah something like that I think. I'm aware that Tractive sells a controller which lets you select 5 profiles using a button or ****, it is often used for older cars to retro-fit a PASM capability into the car. Their controller also lets you just change settings similar to the new GT3 RS (but not as cool with the ***** on the steering wheel)
I suspect the DSC controller can actually support more profiles than 2, but that they've not included them because there is only a on/off button in the car and customers would get confused which profile they are in. The DSC microcontroller also supports wifi, it just isn't enabled. My guess is support issues, but since the car includes a hotspot already it would be pretty cool if you could just be on your laptop and push a new profile to the DSC while the car was running.
Sounds good. However given that the car has to be off, in order to make profile changes, OTA updates may not be possible. I'd hit up Tom at TPC/DSC (he frequents these boards as well), if you haven't already, to see what's possible. Otherwise, you'd be doing like "The Buster":
I feel your pain brother. I had the same complaints as you (all documented on here if you want to check it out) and went down the same rabbit hole as you, although I took a slightly different path.
I looked into the Tractive system, but there was not enough info. out there or local race shop support for me to feel confident in spending that much coin. I ended up with a passive MCS 2-way remote dampers and upgraded springs. (plus all the other misc. stuff).
I also went about it in steps, first just an alignmernt and rear toe links, then my bump-steer was horrible from the caster so out of whack, so I added thrust arm bushings to correct the caster and at the same time did the MCS coil-overs and springs. Then I spent months tuning compression, rebound, and canister pressures to get a good dialed in feel.
I still had a lot of front bump-steer, so I then added the bump steer kit and the adjustable toe links. Finally got the bump-steer resolved, although the steering wheel is still more "lively" than any other sports car I have had, at least it doesn't jerk over every bump now.
I now have the car as dialed in as it has ever been, and it does hook well and is pretty composed in most situations. It is not perfect though, larger bumps at speed can still upset the rear of the car a bit. The chassis as a whole still moves around laterally more than I would like near the limit. I am going to try a stiffer sidewall tire (Goodyear SC3) next and see if that will keep the chassis from moving around laterally when loaded up.
Unfortunately, (some will obviously disagree with me) I think the Cayman and specifically the GT4 is the worst offering that Porsche offers. All other Porsche products I have driven have been spot on, including the Macan. The GT4 is just so unsettled and not confident inspiring when pushing it hard on anything other than smooth roads. What really baffled me was all the rave reviews I watched on Youtube praising the GT4's handling and composure. I swear it was a cult somehow and they all got together and said, lets give this thing rave reviews. It is all that on smooth roads, but when the roads because broken, undulated, bumps, dips, that car falls apart FAST.
I knew nothing about the disadvantages is of a strut design before getting my GT4, but now it is very obvious. I am still triggered that Porsche had the audacity to put a six figure price tag on a car that has such outdated suspension, especially since it is a coveted GT car. This car should have AT LEAST a multilink rear. Even the Macan is a double wishbone front and a multilink rear.
My plan for the car was for it to be my "forever" car (or at least drive the sh*t out of it for 100K miles car), but it only took me 6 mths of ownership and a lot of disappointing drives to put my deposit on the C8 Z06. It just isn't what I was expecting at all.
I know my C8 Z06 wait will be 2-3 years, so now I am trying to decide if I want to hold on to the GT4 until then, or move to the Macan GTS and have a better daily. Financially, it makes more sense to hold onto the GT4, but some days the car feels "on" and other days if feels "off" depending on the roads I am traveling on. I know I would get more pleasure from having a more composed drive on a regular basis, and the Macan GTS would fit that bill well. Just not sure I want to take the financial hit.
Sounds good. However given that the car has to be off, in order to make profile changes, OTA updates may not be possible. I'd hit up Tom at TPC/DSC (he frequents these boards as well), if you haven't already, to see what's possible. Otherwise, you'd be doing like "The Buster":
Maybe Tom knows - the DSC docs state the controller can be either USB powered by the analysis computer, or powered by the car. But that the state of power supply should not change while the DSC is on.
ie. don't turn the car on if the DSC is already powered by a computer.
Since the car has been turned on and I've flashed the profile on the DSC, I'm going to guess it doesn't matter if the car is rolling or not at the time. BUT, I haven't checked.
I think the addition of other profiles may exist anyway, and there just lacks an interface currently to switch to them. The profiles are very tiny, and memory is abundant.
I feel your pain brother. I had the same complaints as you (all documented on here if you want to check it out) and went down the same rabbit hole as you, although I took a slightly different path.
I looked into the Tractive system, but there was not enough info. out there or local race shop support for me to feel confident in spending that much coin. I ended up with a passive MCS 2-way remote dampers and upgraded springs. (plus all the other misc. stuff).
I also went about it in steps, first just an alignmernt and rear toe links, then my bump-steer was horrible from the caster so out of whack, so I added thrust arm bushings to correct the caster and at the same time did the MCS coil-overs and springs. Then I spent months tuning compression, rebound, and canister pressures to get a good dialed in feel.
I still had a lot of front bump-steer, so I then added the bump steer kit and the adjustable toe links. Finally got the bump-steer resolved, although the steering wheel is still more "lively" than any other sports car I have had, at least it doesn't jerk over every bump now.
I now have the car as dialed in as it has ever been, and it does hook well and is pretty composed in most situations. It is not perfect though, larger bumps at speed can still upset the rear of the car a bit. The chassis as a whole still moves around laterally more than I would like near the limit. I am going to try a stiffer sidewall tire (Goodyear SC3) next and see if that will keep the chassis from moving around laterally when loaded up.
Unfortunately, (some will obviously disagree with me) I think the Cayman and specifically the GT4 is the worst offering that Porsche offers. All other Porsche products I have driven have been spot on, including the Macan. The GT4 is just so unsettled and not confident inspiring when pushing it hard on anything other than smooth roads. What really baffled me was all the rave reviews I watched on Youtube praising the GT4's handling and composure. I swear it was a cult somehow and they all got together and said, lets give this thing rave reviews. It is all that on smooth roads, but when the roads because broken, undulated, bumps, dips, that car falls apart FAST.
I knew nothing about the disadvantages is of a strut design before getting my GT4, but now it is very obvious. I am still triggered that Porsche had the audacity to put a six figure price tag on a car that has such outdated suspension, especially since it is a coveted GT car. This car should have AT LEAST a multilink rear. Even the Macan is a double wishbone front and a multilink rear.
My plan for the car was for it to be my "forever" car (or at least drive the sh*t out of it for 100K miles car), but it only took me 6 mths of ownership and a lot of disappointing drives to put my deposit on the C8 Z06. It just isn't what I was expecting at all.
I know my C8 Z06 wait will be 2-3 years, so now I am trying to decide if I want to hold on to the GT4 until then, or move to the Macan GTS and have a better daily. Financially, it makes more sense to hold onto the GT4, but some days the car feels "on" and other days if feels "off" depending on the roads I am traveling on. I know I would get more pleasure from having a more composed drive on a regular basis, and the Macan GTS would fit that bill well. Just not sure I want to take the financial hit.
We've spoken briefly in a post on the tractive vs. mcs decision. You're price estimates for Tractive didn't match mine but we didn't compare a BOM either. I'm annoyed as well about the limitations in the 718 platform, it does feel like a protection racket for the more expensive 911 chassis. I'm not upset, a tiger doesn't change its stripes as they say. Porsche can make money however they like, and I can buy a different car if I like. It's harder since driving a car at the limit isn't possible on a test drive, never mind a high demand model that requires years of preorder.
the Z06 could end up being just as bad haha, we'll never know until its too late
I'm going to DM you about driving each others cars. Would be nice to compare if it becomes possible.
LOL, yeah, not sure why you'd want to upload new damper maps "while driving"...could possibly lead to some danger to your manifold. But setting up a method of switching between 2+ maps would be cool. May be possible with the existing wiring to the PASM button and maybe a keypad, if you're not down with the ****.
LOL, yeah, not sure why you'd want to upload new damper maps "while driving"...could possibly lead to some danger to your manifold. But setting up a method of switching between 2+ maps would be cool. May be possible with the existing wiring to the PASM button and maybe a keypad, if you're not down with the ****.
Ideally something tactile, with distinct indicator for what profile you are on. The pasm button is almost tactile enough for daily driving, but not on a race track.
Stubbing out a little plate like those phone holders, with some backlit buttons would probably be my solution. I want something I can turn a couple laps on, press a button while I'm on the front straight to change my profile and compare those laps data for throttle, braking and other relative performance. It would make testing much faster and accurate than coming in/out of the pits and loading the current method.
If you've got the DSC on wifi, well then you could even do it over cellular if you wanted.
This is a bit of a narrative, and includes a tldr section at the end if you just want the details.
I bought the 718 GT4 to replace my last drivers car, a 1994 Miata r package. The expectation was the GT4 would be relatively lightweight, have a well balanced chassis with its mid-engine, and provide strong driver feedback signals like steering, braking, shifting, and weight transfer (gas pedal and steering wheel). The flat 6 and design were just extra icing on the cake. I’ve been really happy with the GT4 except for the suspension. Driving on twisty and bumpy back roads, it often felt like the car was bouncing, or hopping, or heaving. Whichever way you’d like to describe it, to me it felt unsettled, and I lacked confidence pushing the rear of the car when driving quickly.
I learned after purchase the geometry of the GT4’s rear suspension causes toe out when it extends (or rebounds), and toe in when it compresses. As you can imagine, under braking where the chassis pitches forward and the rear strut extends, additional toe out could feel unnerving if you were not prepared for it. The more +/- vertical movement in the GT4 suspension, the greater the toe and camber changes become. These are inherent traits in MacPherson suspension, and not unique to the GT4 and many Porsche models utilize these struts in their design.
To address the frustrating rear suspension I started with the basics - alignment and corner weighing.
If you read anything about PCA or SCCA series involving the GT4 you’ll see tons of talk about alignment limitations on the car which I wanted to avoid myself. In addition to the alignment and corner weight I added the following:
Corner weight, ride height, alignment (This resulted in an alignment of -2.5 front, caster 8.7, zero front toe,, -2 camber rear with .07” of rear toe per side or .14” total.
Result
The rear of the car felt less unsettled while braking, and the factory alignment and cross weights were fixed.
No preload on the swaybars thanks to the endlinks and the camber plates give me lots of room to move camber while keeping caster in an agreeable range.
The rear end uneasiness was still present. Crossing dividing lines or crowned roads when passing slower traffic still felt like the rear of the car was pulling away from the front.
The strong feedback in the steering wheel when the car heaves, especially at speed on back roads was present
Overall there were improvements, but not a dramatic difference, and it still felt like I was leaving a lot on the table.
Next Iteration
I tried out the DSC Controller.
Starting off with the provided GT4 config file, I was able to make some changes primarily in the low speed damper settings, and a change in damper ramping which resulted in higher corner speeds and increased confidence in the rear. I also appreciated being able to make a larger distinction between street and sport PASM profiles, which really improved the daily driver experience in the GT4. Less crashing over bumps and on uneven road surfaces. The downside was the ‘street’ setting was unsuitable for back road driving, and the ‘sport’ setting was a little harsh for daily driven roads. Really, it proved the considerable effort spent tuning chassis dynamics at the manufacture before releasing it to the public. Many of us may not like the default PASM settings, but they are there for a reason and they are quite accommodating to whatever driving you do, with no coffin corners that I'd noticed (a place where if you venture, disaster is imminent).
I also like to consider that everything you love or hate in a car’s behavior was the result of a specific decision some engineer made - either it was too expensive to implement, too complicated to maintain, or perhaps too competitive with other model lines, or maybe there was a manufacturing line already producing parts... but little is left to unconsidered, and the default PASM settings demonstrates this thinking well. Anyway...
While I enjoy the configurability of the DSC, the software and interface have limitations which make it annoying to tune with and I felt like I was overly reliant on stiffening up the front of the car to make improvements to the rear. (Basically, if you let the rear suspension move less, you have less toe and camber changes occurring). I wouldn’t say I was done tuning with the DSC, but I did make improvements for me and I appreciate the flexibility it provides without having to get under the car.
Suspension tuning is considerably difficult without a race track or data logger. Some of the performance envelope you want to test in a given DSC configuration requires specific conditions, like a certain speed and lateral g load before the suspension will be changed. Recreating these conditions on the street is usually unreliable, or unsafe. Not to mention it is difficult to consider what is low, medium or high speed strut movement resulting from a given street corner or bump in the road. For this you need a data logger at minimum, and ideally a race track and some professional help to perform the log analysis.
Final Changes
The last change I’ve made is the addition of the Tractive Touring struts. These struts use the OEM springs, and though I’d already switched to the Tarett 'race' front camber plates, the struts have the physical profile of the OEM struts and are compatible with the Tarett camber plate.
Tractive Touring struts
Free toe links I didn't know where included with the struts. Neat, and thoughtful.
Everything installed, Tarett plates and Tractive strut are compatible with the OEM spring.
I decided on the Tractive struts because I’d learned the OEM Bilstein were described having a 20-100ms latency to change the strut valving on demand of the PASM computer. Apparently the valve design locks until the strut unloads the value, after which the valve can be adjusted. When I did the math on how much ground the car could cover before a valving change could be realized in the strut, it was clear there would be many situations where the PASM desires a suspension change and you’ve literally driven past the pavement before the strut can be adjusted.
Tractive sells 3 strut variants, ranging from street to motorsport use . All the dampers use their DDA valve which is responsive to within 6ms, the more track oriented struts include a mono-bearing top plate and up to 4 way adjustment which is handy, but costs some noise vibration harness (NVH) (many monoball top plates click-click as the suspension loads). I’ve used both styles of strut, and since this is a street car, I was happy I could utilize the quiet Tarett top plates with a strut using the DDA valve on their Touring line strut.
With these struts, I've stopped using the DSC controller for the time being. The 'good' OEM strut profile I previously used works horribly with the Tractive struts. This is expected, their operating ranges are very different and I imagine the damper velocities are also different.
Old struts. Little was said at their funeral
Current Status
The suspension is sufficiently solved now for fun street driving. Improvements I’ve noted using the 'sport' PASM setting:
Rear has markedly less hop, heave, and/or bump steer.
Braking stability is improved
Vehicle dynamics over undulating roads is remarkably composed
Steering wheel feedback over bumper roads is present, but it doesn’t feel like you could lose control if your hand slipped of the wheel (as it used to).
Anecdotally I find myself often flat on the gas out of corners or mid corner holding a line that I know will hit a bump or broken pavement - simply to see what will happen now. So far its been unflappable. Most bumps feel like their top has been flattened off, if that makes sense.
The front tucks into corners very well, but after running 8000 miles on the Cup2’s it’s evident I could use more camber up front without consequence, so increased camber to -3 degrees. Caster remained the same and the rear camber was left at -2
If the car had been this way from the factory, I wouldn’t have changed a thing. It drives more like I recall the Miata felt, being able to throw it into a corner faster than seems reasonable and it holding the line as asked.
Future Plans
I have a couple more goals and desires for this project
Get a new data logger (I used to data log when I tracked the Miata)
Data log the wheel velocity (please help me)
Build a suspension profile in the DSC similar to the PASM sport profile, then iterate on it. (will be easier to do with a data logger and racetrack)
Build a wet and daily driver profile for the DSC
Add functionality to the DSC (I want to be able to load many profiles without using the DSC software or laptop)
And the last thing that bothers me - is that this entire post is without quantitative data. Apologies. I also haven't been to the race track yet, so I have still have no idea the limits of the car or if it oversteers or understeers as it's setup now. I'll get there one day though.
Too Long Didn't Read section
Superlative 718 GT4 Street settings:
Rear toe links (anyone's, or the included ones from a Tractive strut kit)
Rear toe lockout bolts (probably optional but I hate eccentric bolts)
Tractive Touring struts (deal includes rear toe links)
Tarett Race Camber plates front
Corner weight and alignment
Front -3 camber, 9 caster, .03” total toe
Rear -2 camber, .07” total toe
50.3% cross weight
55.6% / 44.4% Rear/Front
I have ride height however, I don't have the reference point for the measurement so its no use to anyone. It is slightly raked and a touch lower in the front than factory.
Swaybars are mid/mid
Cup2’s 32psi front and rear 'hot' (I need to double check pressures manually, as they are probably higher than the TPMS reports)
Costs
All told parts were ~$6,800 plus around $1,500 in labor.
You might be able to get away for less, using shims instead of camber plates, no lockout bolts, and knock off another $650 from this total because the Tractive struts come with toe links and I'd already purchased Tarett's.
I could not have gotten here without the help from my shop who did the work, provided their council, and their professional experience (unnamed I have no idea if they want mention), Smart Racing Products who sold me the struts and provided advice, RCVD and Analysis Techniques for Racecar Data Acquisition
What made you choose the standard Tractive kit over the DSC version?
What made you choose the standard Tractive kit over the DSC version?
Yeah good question
The DSC version is just the Road and Track model from Tractive's line of struts, but Tractive sells 3 models: Touring, Road and Track, and Motorsports.
They all use the faster-than-stock semi-active valve, but the shim stack and construction of the struts is more motorsport oriented as you move up in price. The RT and Motorsport versions also come with a monoball tophat which I already had.
This is primarily a street car, with street car maintenance intervals and NVH requirements, so those criteria combined with the advice* I got, I went with the Touring line.
*The longer answer is I spoke to 3 motorsport professionals about Tractive (a chassis engineer, an engineer that brought a new coilover to the market with Tractive, and a race car/development driver) I took at face value the advice those folks gave me and applied it. Going with the Touring line, the struts are compatible with any aftermarket spring if I need to change springs later.
08-30-2022, 02:41 AM
Suspension Journey & review of Tractive Struts
