964C4

When my car was new, I felt the understeer, so I installed a MANTHEY stock suspension kit to get more negative camber at the front and rear

Car much better now, it turns in nicely!

But after some track days (once a month, 2-3 hours) I feel the stock suspension is weak point... Should I only upgrade the springs on the 4 shocks ( https://tarett.com/collections/coil-...ade-kit-gt4suk ) or better get a set of coilovers?

Please comment, thank you!

Larry Cable

I think you need to be more specific about what aspect of your current setup is weak ...

TRZ06

I think he meant in general, and while being technical is helpful, in the case of the GT4, I totally get where he is coming from without needing specifics, as I get exactly where he is coming from.


OP: There are a few of us on here on a full coil-over transformation. I myself have the MCS 2-way remote dampers and swift 80/100 springs and it a night and day difference. It is VERY intensely debated here on what the GT4 needs to feel competent, and a lot of it depends on the roads conditions.

For me personally and for the types of roads that I drive on, it was absolutely transformative and no doubt on track would be welcomed as well.

Feel free to share more info. and ask any questions you would like. I don't mind sharing any of the knowledge I have learned over the last year on my journey. You can also search as there are several threads on the subject as well. I am not one of those "GO SEARCH" Aholes who will withhold info. just to come off as superior, so if there is something that you want to ask here, even if it is buried in another thread, I don't mind sharing my thoughts.

964C4

I feel shocks are not stiff enough, so I wonder:
- enough to change only the springs and keep OEM shocks with OEM height?
- better upgrade to MANTHEY coilovers and lower the height of the car as per MANTHEY's specs

My goal is to improve my lap time by around 1.5-2.0 seconds per lap in my local track (other GT4's are with same timing as I am now and with simmilar upgrade as my car)

Larry Cable

ok, so shocks are not the primary source of "stiffness", that is provided by the springs; shocks, or dampers, are intended to "damp" the resulting oscillations of a sprung system (such as a car) and are adjustable to modify the behavior of the resulting system:
- compression high/low speed
- reboundmhigh/low speed

watch this for explaination...


changing your spring rates *may* be enough, but you may also want to go to a spring + shock setup, if you do that:
1) get experts (like Manthey) to spec a packaged combination of springs (rates) and dampers (valving)
2) learn, or find someone with the experience, to adjust the damper adjustments

failure to do either of the above - you might as well donate or burn the $$$'s you spend on this.

you *might* look at a "tractive" https://tractivesuspension.com/automotive/ solution which improves on the OEM dynamic damper adjustment of PASM

TRZ06

I think what you are referring to is underdamped, specifically on the rebound stroke, however the compression stroke still plays a role. While you can increase the spring rates some on the stock dampers, with that you are really just giving the dampers more work to do, as their job is to control the spring energy and you will have more of it with stiffer springs on rebound. A DCS controller can help some and add in some rebound force, but you are still limited to the stock internals.

For chassis control, rebound is the most important factor, which is why on single adjustable coil-overs, its is the rebound control that you can alter. Compression is for support and secondary for chassis control

Tay101

At 600 miles on my 2021 GT4, I installed pretty much every part Tarett had to offer which gave me all solid bushings plus TPC offset rear toe links and immocars rear camber plates. This was great on the stcok Sport Cup 2s and even better when I went with 19" Nankang AR-1s. At 1800 miles, I installed a set of Ohlins TTX coilovers and it transformed the car and brought it to a whole other level. I have zero understeer and turn-in for days. I don't have any data, but everything everyone said who has installed a quality set of coilovers is true. I highly recommend it.

Its good that you did the Manthey kit first. I don't think you would get the full potential of the coilovers without the other stuff. I am running Tarett front camber plates by the way and not using any shims.

TRZ06

Oh man, I didn't know the TTX's were available for the 718 GT4, otherwise I might have gone with those instead of MCS, not that MCS isn't great, but Ohlin's TTX line is one of the best out there, right up there with Penske from what I know.

Tay101

The TTX have been amazing so far. I really like the inverted front strut design as well: https://www.ohlinsusa.com/parts/2016...an-gt4-981-982

But obviously the MCS you have are no slouch.

donR

I do notice stock GT4s rolling quite a bit when I'm following them on the track.
I don't think you can go with the Manthey KW kit, MCS or any of the Ohlins kits, amongst others, as people have recommended. They will all have uprated springs to around the 450 to 550 lbs mark or more if you wish, give or take, but you will comprimise your street comfort, unless you open up the dampers for street driving, which then isn't so good if your are still taking corners.

I like the idea of the Tarret spring upgrade such that you can retain your PASM, and combined with a DSC controller you can fine tune the dampers to a point as well as having a soft setting, as those uprated springs are going to be mighty uncomfortable on the street at their track damper setting. I'd be interested to hear from anyone who has gone this route.

I have the Tractive RT dampers on my GTS, once again you can choose spring rates for your application and the Tractive dampers are effectively a 6 way damper and retain your PASM system via the DSC controller, with a much faster (100xs) and dynamic response rate. I went with 457lbs (80NM) front and 514lbs (90NM) rear and this seems perfect for the track and mountain roads with no body role and stock sway bars. I load a sperate DSC map for the track, mountain driving, and the street and of course have a soft setting and appreciate the additional comfort when driving home on rough roads, and/or bumpy moutain roads where you need the compliance in the damper. I have quite a few vidoes chasing GT4s and 3/4RSs, as well as some mountain style hill climbs, if you are wanting to see how the suspension performs and the potential Gs.

My only gripe with the tractive dampers is they have a very faint high pitched electronic squeal which is audible in the cabin from the rear dampers at low speeds on smooth roads but this may be unique to my install.

TRZ06

I can't speak to KW or Ohlins, but MCS does just fine with 80/100 spring rates and there is still compliance. We have horrible roads here in CA and there is definitely a setting on the MCS that accomplishes both ride quality AND support.

The Tractive stuff I am sure is great as well, and I did look into it briefly before deciding on MCS, but there just wasn't enough support or info. out there about them for me to feel comfortable taking that plunge. Hardly any race shops have experience with them.

donR

Tom at https://www.tpcracing.com/ is the contact for Tractive coil overs if anyone is interested. I believe their products are very good and he offers a lot of support, even on email.

However, I don't see much advantage with the Tractive dynamic damper system on the track but I believe the Tractives really comes in to play on the street, and Tarmac rally/mountain road style driving or hill climbs where the surface condtions, suspension heights, road gradients, and corner speeds are rapidly changing such that those inputs into the DSC alter the damper behaviour accordingly, and then back to a softer setting on the highway cruise home. On the track you don't really have this happening such that fixed damper settings are usually adequate, but then Porsche bult your car with PASM for a reason so some people might want to retain that function so Tractives is a good option, particularly if you are looking for an improvement in dampers as well as springs.

edub

I don't notice any noise in my struts - have you tried to see if its a specific damper thats making the noise?

donR

The tractive dampers are electronic and by design they make a constant faint high pitched noise/squeal which normally isn't audible in the cabin due to fire wall, insulation, etc. However, in the Cayman the rear dampers are very close behind so I can hear the damper squeal, particularly when parked. Un-plugging the damper/PASM cable eliminates the noise, although this could be unique to my damper set, as I haven't been able to confirm otherwise with other Cayman/Tractive owners. Interestingly, if I put in the OEM PASM controller the noise also goes away but then of course the dampers do not work properly. So could be just some unique issue relating to my setup or some module in the damper that needs replacing. I'm sure if I was in the US or Netherlands it could be sorted.

colnagoG60

FWIW, I bought the 450/570'ish Swift kit for my 981, but haven't installed, but also set DSC damper settings to 100mv (mVA?...whatever the unit is), for the entire damping range (ie - 100 - 100 vs. 1,650 - 100), so effectively almost full stiff throughout the range, and it was fine for most situations in my pot-holed/road imperfection area.