donR

Hi Lucas, thanks for chiming in. Can a different PWM be set in the DSC? I have seen the Tractive controller but I think it is more suited for a dedicated track car.

I had the firmware updated in my DSC controller and the squeal noise now disappears after ~15s whilst parked but returns once moving so the background squeal is still bit irritating on quieter roads. Even my 11yo daughter noticed it and thought it was weird, particularly when it goes away when stopped at the lights.

As you say I can use the OEM controller and the noise goes away in all conditions but I'm not sure if the performance would be as good and I have been very satisfied with the handling on the Tractive coilovers.
There is definitely an advantage to not having to manually adjust valves particularly when driving on mountain style roads where the surface changes can be quite varied, unlike on the track where a fixed setting can work.

In the end I was told that it is the solid monoball top mounts on the rear that transfer the noise into the cabin and that some people are more sensitive to the noise than others.🤔
I was told that rubber top mounts would help but not sure if I want to try that.🙄

donR

My street/alpine map is 1.7 to 0.6 front and 1.7 to 0.7 rear with a sensitivity of 15.
I find if it is set too soft for the street with low sensitivity (higher value) it is a little under-damped/bouncy.

On a relatively smooth high speed track I load a different map with a narrower range, keeping in mind this is a low downforce cayman GTS.
1.0 to 0.4 front, 1.0 to 0.5 rear, sensitivity 15. So it is full firm at high G. This seems to work well for high speed sweepers although a little compromise on high G lower speed corners.
I also have a little bit of extra low, med, high rebound damping on the rear (10,15,5%) and less on the front (0,-10,-10)

I think given most people here are looking for a tack set up, it would be interesting to hear your thoughts on DDA valve settings for track setup?

edub

Hi @Lucase83 welcome to rennlist. I'm glad to see you here. Are you Lucas, sales engineer at Tractive?

I was told by Julian and JVO that the DDA operates between 600ma (closed) and 2000ma(open).

@donR You should try using the stock controller for a bit. The biggest difference is the stock controller operates at 1400ma in comfort and 800ma in sport mode. On the track, 800 will be softer than 600ma but the grip and balance of the car will largely be the same. It will just be a little stiffer with the DSC map you're using. It's bouncy because 1700ma is pretty soft =)

What tire are you running on the street Don? I dislike the Conti DSW I have for street driving, they are just too soft. They feel like they float everywhere when I'm driving quickly. The same strut settings, with a Cup2 or RT660 are great though. In other words, the tire is a really significant difference, and street driving there is much more undulations and chassis heaving that you don't find often on a race track.

For track your damping is pretty aggressive - evidenced by that you've got the damping reduced on the front for medium and high speed. You're probably crashing over bumps? Because you have the sensitivity high, and your mapping 1000ma - 400ma is closing the strut off at 60-65% of your g-force table. So by the time you're making your 3rd or 4th turn on the warmup lap you're already reaching gforces that are fully dampening the strut. At that point, the only thing you're really adjusting is the balance between the front and the rear struts. It's not a bad thing, but its likely whats compromising your low speed high g corners, the strut is fully closed before you've even got the car fully leaned into the corner. It's probably staying closed until you are well into the corner exit phase of the turn. That can make it harder to put power down at low speed.

I would try to find a setting valve setting that introduces the balance you want between the front and rear, but allows the fully range of damping to occur. It will make the strut softer when it can afford to be. The hard part of this is you have to edit the gforce table instead of the strut table, and thats pretty tedious in the DSC software.

@TRZ06 I'm glad you brought up the different settings through a button - I've been wondering how important this is to me as I've been going to the track a lot this year. Whenever I drive home I always regret not flashing my street map to the strut before I leave the track, I usually do it when I stop for gas a few miles down the road. I wish I could run multiple (4-5) profiles on the DSC, it bugs me thats not possible right now.

edub

@donR
A quick visual of how your street and track setups compare to each other.




The reality of that setup though is more like this chart though. Your valve is fully closed at 600mA so the relationship between front and rear dampers becomes equal at some point on your gforce table. I have not put the struts on dyno to see how they act when they are fully closed, they still work with the valve closed, but you're basically introducing a knee in the gforce table which you may be unaware of.

These charts also show you how much of the softer damper setting you're not using when you're on the track setting. Again, the car will drive and may be fine. But like you mentioned in the low speed sections, it may benefit you to use a more progressive damper response.

FWIW on street tires the car see's 1.2 lateral G, so in most steady state corners the damper valves are being fully closed anyway. That is where spring rate and sway bar, rake and ride height are balancing the car. As you enter and exit the corner is where having more of the damper range available may help you balance the car better.

edub

Ignore the yellow in the first chart - I meant to highlight the mA setting where the valve was closed but didn't update it for the new values (I can't get google sheet to do a vlookup conditional format!)

donR

Thanks for your thoughts on the tractive settings. I can see what you mean and I think you are correct. I have been thinking I should try the stock controller on the track just to see what it is like and how the car balance changes. Not sure if it will be faster though.

I am using GT4 spec Cup 2s on the street and have used Trofeo R in the past with excellent Alpine driving experience but of course it is always 8 or 9/10s unlike on the track.
On the track I am using a Yokohama A052 in medium compound. This has similar grip to a Dunlop Direzza 03G (M) and slightly more grip than an A051 or RE-71RS.

I need to experiment more with the DSC settings but very hard to get perfect. As a more novice driver having the firmer damping instills more confidence on high speed corners rather than having a car that moves around but from what you are saying I should try softening the damper limit to say 0.6 front and 0.7 rear?
My spring rates are 457(80) and 514(90) so firm but perhaps not frim enough for the track so extra damping can compensate. I am reasonably happy with the balance now as the main problem before was high speed over-steer which seemed to improve by reducing the rear rebound damping a little to values above and changing the G Comfort from 25 to 27.5.

I'm not sure what you can gain from it but this video is one of my better laps on my current Tractive track setup. You can see if I can get a bit more speed out of each lower speed corner with a softer damper setting then that is going to equate to a faster time all round.

edub

Sorry I can't really tell what speed you could gain from the video, I have not driven that track and quiet tires don't give much insight as to whats going on =)

You've got a much higher rate front spring on a 718 than I had (45/80). Did your dampers get valved for those rates?

donR

Yes, dampers have been valved for those spring rates (80/90) and seem to work quite nicely. The rates are very close to Tarrett 981/718 GT4 spring upgrade (78/98) and same as Ohlins R&T for 981 GT4 at 80/90, and close to the 718 kit which is a little softer at 70/80. These springs are all quite firm and not sure if I'd recommend them for daily driving but I notice the more track oriented rates are up to 100/120 for Ohlins TTX GT4, and Ohlins Dedicated Track 981/718 is higher at 110/130.

Four Ring Circus

Hi all- joining this thread a little late but since it seems that there are few different set ups being run by the commenters here I am hoping for some feedback. I am a White/Black driver (depends on track) with a 981 GT4 with some basically suspension mods for more camber, rear toe, etc. All of my OEM struts are either failing (fronts) or close (rears). I track the car for about 5-6 events per year and am not gentle (eg I send it over the curbs at the Glen bus stop, clip the grass over curbs at 1 at my home track NJMP Lightning, etc). My shop is recommending MCS 2 ways to replace all the OEM struts (which seem to be about $1500/corner for parts alone). Curious about Bilsteins or other set ups that can use DCS so that I can still comfortably drive on the street. The MCS are very expensive and not adjustable at the push of a button. Any suggestions? Thx!!!

donR

Sorry for the late reply. I assume you found your solution?
For anyone else these are my thoughts:
Ohlins R&T is adequate for most track work and receives excellent reviews, but needs softening for street work.
MCS 2 way - I don't know much about these but seem popular.
KW is another obvious choice.

To maintain PASM the only options appear to be Bilstein damptronic or Tractive.
I find the Tractive excellent and for mountain roads with variable road conditions you can't really go wrong, but I'm not sure if the benefits are there on the track when comparing with Ohlins, MCS or KW.
My only gripe with Tractive as I've mentioned above is the background squeal which seems unique to a minority of cars as not everyone reports it, but it can be irritating on a quiet road.

If had my time again I'd probably try the Bilstein damptronic with custom spring rates so that it would still work with the OEM PASM and DSC controller. They are excellent value and I wouldn't be surprised if the OEM are bilstein dampers anyway.

TRZ06

While I have not tried the Ohlins on my GT4, your comments DO echo my experience with them on my previous F80 M3. They do a great job at chassis control and giving the driver a boat load of confidence , but they are pretty harsh and unforgiving on poor pavement. I am in CA and our roads are horrible and I was constantly setting off the traction control with my Ohlins on the rebound stroke on larger bumps. In addition, the abruptness of them would often throw my head up into the headliner.

My MCS 2-way remotes on my GT4 are WORLDS better when it comes to smoothing/rounding out the harshness. They are still firm (as a motorsport damper should be) but they round out the harshness and the end of the rebound stroke is much less abrupt. They are worth the extra expense IMO.

If I had to do it all over again, my only change would be to spend a little extra and go with the MCS 3-ways.

Snowy999

Gathered this if of any interest. Spring rates FR in Nmm.

manthey supplied me a 80/100 set for my GT4 KWs. They were concerned about the balance between stiffness and the appalling road conditions in the UK non motorway systems.

the GT4RS runs comparable rates with the Ohlins Race set up and (despite being an amazing car) has had consistently poor reviews in UK roads vs amazing on smooth racetracks and European roads.

i went with Manthey’s suggestion and will report back later this season.

overall thing I would say is that coilivers have substantially improved the feel of my car (measurabky better performance in AutoX and hill climbs) and the stiffer front springs (as the first US guys who got the GT4 found) helps with braking/stability on track.

Manthey said that a hot slick or MSPC2R tyre is really needed to get the best from the higher spring rates!

i bow to their knowledge…

GT4 standard 45/80

GT4 RS 100/140

GT4 MR 60/80

GT4 RS MR 120/140

Swift springs 80/100

Ohlins 100/120

Ohlins Race 120/140

GT4 Clubsport IIRC are comparabke with the 4RS.

TRZ06

I think Manthey is pretty spot on with that recommendation for a well rounded car that will see more than glass smooth tracks.

Before I got my MCS's I did a lot of research and spoke with Dundon. I ended up with 80/100, as that is what Dundon used on their MCS 718 GT4 project car. They tested/tried higher spring rates and settled on 80/100 as it provided a good balance and some compliance.

Other race shops out there have suggested I should have went higher, but I think they are more track focused and my car is a street car. Once properly set-up 80/100 is a great balance for the standard GT4 that sees mixed duty. You can play with canister pressure a bit to fine tune, but I am glad I didn't go higher up in spring rates for my usage.

I find it interesting that Manthey used 60/80 for their GT4 MR kit. Since they specifically tune for "The Ring", that tells me that there is absolute value in lower spring rates when you have to deal with crappy road surfaces.

dnimi123

The 4RS stock requires those heavy spring rates to make up for the poor performance of the OEM PASM - as everyone knows full well, and is part of its downfall IMO (you cant put lipstick on a Pig). I went with 9/11 spring rates with my MCS 2ways which is what my race shop recommended (and I want to turn my GT4 into an actual "9/11"). The GT4 is amazing with coilovers as one would expect and if I got a 4RS I would immediately swap out the PASM for MCS 3ways..