Swift spring swap install

[Samo6556]

Just thought I’d share my install with swapping to swift springs. I recently purchased this M4 GTS from the original
owner and coming from an e92 and e46 track car with motons/mcs. They both had higher spring rates than the stock gts set up. Looking at pictures and videos the gts looks “unathletic” on track. Lots of pitching, weight transfer, high etc. So I decided to wing it and up the rates to see how it goes.

Eventually I’ll do a different set up like ohlins ttx but not yet. So for now I upped the rates based on daveishi post of what he did. I reached out to kw on my own and they said to contact bmw m about what rates I can move up to? So I got impatient again and did the swift 110 front and 160 rear which is about 200lbs higher than stock. I purchased swifts in the front 6 inches length because I added the swift assist springs. Rear is an 8 inches like stock. Also I put the swift thrust sheets on the front strut.

I wanted the car to be lower than the race track height (race is about 27 inches rear and 26.5inches front). I went about another .5inches lower than race height. Doing this required me to cut off the lock collars from the factory. Front left I’m about 26 1/8 inch (I left it slightly higher for driver weight). Front right 26 inches. Rear left 26 5/8 inches and rear right 26 1/2 inches. I wanted to keep a similar rake between the front and rear height like it was before which was .5 of an inch as well.

Install on the front I started with the removal of the stock spring and cutting off the lock collar. I had originally planned to use the assist spring on the top of the main spring, but I found out when swapping the springs the kw bottom perch is slightly bigger than the 60mm spring so the main spring wouldn’t fit without modification. Same with the trust sheets as well. After a little googling I saw that there was a company that would machine the lower perches on kw suspension to fit the 60mm swift springs. I really didn’t want to deal with that so luckily the swift assist spring fit around the bottom perch and the main spring went on top. None of the stock rubber isolators or plastic caps I re-used on the swift set up. They couldn’t be reused if I wanted as they are a different design. The swift thrust sheets I used on the bottom and top of the main spring. During the disassembly I found the ground control camber plates had shifted on the previous owner on the passenger side. The top strut nut was jammed into the brace and digging into the aluminum. I corrected that and matched placement to where the driver side is until I do an alignment. Maybe controversial, but I cut the top portion of the bump stop off. It seemed like there was little to no travel before it would hit them at static height. I kept the part I cut off in case I want to try and put it back I can just put it back on top.

On the rear I dropped the lower control arm from the subframe to remove the spring, along with the bolt to the rear shock. Per the gts manual the shock bolt/nut needs to be replaced each time it’s removed. So I replaced that along with the control arm to subframe bolt/nut. The height adjuster I removed to cut off the lock collar from the height adjuster. As a starting point I took the spacers used for street height to track height and put it above the spring perch and between the top. This is the 7mm spacer. It ended up being exactly what I wanted height wise so I left them in there. I also re used the lower rubber rear spring isolator. Seemed to fit good with the swift spring still

I haven’t been able to take the car out yet besides a quick drive around my neighborhood. Everything feels good right now and better, but maybe because the passenger front right doesn’t have -2 more camber than the left. Also as a starting point I used the recommended race compression/rebound settings and will go from there.

As much as performance matters I also care about looks. I think it sits much more athletic looking now. Which to me means more sporty. With going lower I can get into my driveway without scraping. In my e92 I’d sometimes scrape. So it’s nice to have clearance still while having the car lower.

Swift part used.
Front: 2.36" ID x 6" - 616lbs
Rear: 2.36" ID x 8" - 896lb
Swift assist: Swift 60mm x 72mm - 4kg (2.25" ID x 2.8" - 223lb)
Thrust sheets: 60mm thrust sheets.

[M3SQRD]

Nice upgrade to the stock KW 3-ways.

To keep the damped ride similar to the stock F/R 400/700 lbf/in damped ride, you’d want to increase the front damping by ~24% and the rear by ~13%. Probably 2 clicks front and 1 click rear on rebound and low-speed compression. However, the change in your unsprung weight at each corner is negligible so you can leave the high-speed compression setting where it’s currently set.

Note: for a damped single degree of freedom spring-mass-damper system with a negligible change in sprung mass, critical damping is proportional to the square root of the spring rate so the change in damping coefficient is equal to the square root of Knew/Kold. For example, the front change in damping coefficient is sqrt(616/400) = 1.24.

[Samo6556]

Originally Posted by M3SQRD

Nice upgrade to the stock KW 3-ways.

To keep the damped ride similar to the stock F/R 400/700 lbf/in damped ride, you’d want to increase the front damping by ~24% and the rear by ~13%. Probably 2 clicks front and 1 click rear on rebound and low-speed compression. However, the change in your unsprung weight at each corner is negligible so you can leave the high-speed compression setting where it’s currently set.

Note: for a damped single degree of freedom spring-mass-damper system with a negligible change in sprung mass, critical damping is proportional to the square root of the spring rate so the change in damping coefficient is equal to the square root of Knew/Kold. For example, the front change in damping coefficient is sqrt(616/400) = 1.24.

Thanks for the explanation. I’ll try that out as well. I am by no means a numbers person. More of use my logic and trail&error but things like this could help save me time on set up it seems.

[M3SQRD]

Originally Posted by Samo6556

Thanks for the explanation. I’ll try that out as well. I am by no means a numbers person. More of use my logic and trail&error but things like this could help save me time on set up it seems.

Absolutely. The seat-of-the-pants feel trumps theoretical calculations but they can give you a good starting point to work from. Look at F1, they spend countless hours in the sim and chassis rig to come up with the optimal theoretical setup but then they spend three practice sessions, with continued sim runs, to find the actual best practical setup for both qualifying and race. Even with all of that, teams still don’t find the best setup. I’m not a fan of sprint race weekends but I do like the single practice session before qualifying. It does a decent job of mixing up the field.

[jfritz27]

Originally Posted by M3SQRD

Nice upgrade to the stock KW 3-ways.

To keep the damped ride similar to the stock F/R 400/700 lbf/in damped ride, you’d want to increase the front damping by ~24% and the rear by ~13%. Probably 2 clicks front and 1 click rear on rebound and low-speed compression. However, the change in your unsprung weight at each corner is negligible so you can leave the high-speed compression setting where it’s currently set.

Note: for a damped single degree of freedom spring-mass-damper system with a negligible change in sprung mass, critical damping is proportional to the square root of the spring rate so the change in damping coefficient is equal to the square root of Knew/Kold. For example, the front change in damping coefficient is sqrt(616/400) = 1.24.

Cool example of applying theory to practice.... I'm curious though, how do you quantitatively (or semi-quantitatively) translate the required 24% increase in damping for the front into about 2 clicks of adjustment (in absence of dyno curve data)? Is that just knowing the total # of clicks available on the damper in question and then equating the calculated relative rate increase required to the same relative increase in clicks as a fraction of the total available?

[M3SQRD]

Originally Posted by jfritz27

Cool example of applying theory to practice.... I'm curious though, how do you quantitatively (or semi-quantitatively) translate the required 24% increase in damping for the front into about 2 clicks of adjustment (in absence of dyno curve data)? Is that just knowing the total # of clicks available on the damper in question and then equating the calculated relative rate increase required to the same relative increase in clicks as a fraction of the total available?

It was a guess based on previous experience with KW, Moton, JRZ, Ohlins, MCS…setups. You’ll see around roughly a 5-10% change between clicks, some higher & some lower. The real number may be > 2 clicks but 2 will help you get close as a starting point for the increased spring rate. I have no experience with KW 3-ways. However, a 200 lbf/in spring rate increase could put the damper near/at its max rate that it can handle and, therefore, you’d need to add additional clicks to properly control the spring. The original Moton CS remote-reservoir dampers had only six clicks so it was a huge change for each click! One thing that’s useful, is to start with C and R set fully open and then adjust R in 2-4 clicks (15%-20% of total clicks) increments to see how the damping changes and when the damper packs down (i.e., becomes overdamped, no need to increase further). Then repeat but this time adjust C is 2-4 click increments (R can be set at what felt good when varying R settings) and note the change in response/handling at each increment. This combined info/notes will help you setup the suspension for future changing conditions (hot, rain, green track, etc.) and/or spring rate changes.

[SYT_Shadow]

Interestingly, the 'track' setting recommendation in the GTS manual only has 1 click available for the rear, and 2 for the front if I remember correctly. So it sounds like you can run these springs, maxing out the damper settings

[M3SQRD]

Originally Posted by SYT_Shadow

Interestingly, the 'track' setting recommendation in the GTS manual only has 1 click available for the rear, and 2 for the front if I remember correctly. So it sounds like you can run these springs, maxing out the damper settings

Interesting. That sounds like settings you’d use on F1 smooth tracks, not the Nurburgring full course. You’d shatter teeth with that much damping!

On your GTS with stock 3-ways, did you find it needing almost fully closed damper settings? If you did then perhaps a 200 lbf/in increase is too much for the stock 3-ways? Most dampers can handle a ~30% increase in spring rate with headroom but I guess the front is a ~50% increase over the stock rate (rear is ~29% increase). 200 lbf/in doesn’t sound like much when you’re running 800 lbf/in rates but wrt a 400 lbf/in spring it is a large change.

[SYT_Shadow]

Originally Posted by M3SQRD

Interesting. That sounds like settings you’d use on F1 smooth tracks, not the Nurburgring full course. You’d shatter teeth with that much damping!

On your GTS with stock 3-ways, did you find it needing almost fully closed damper settings? If you did then perhaps a 200 lbf/in increase is too much for the stock 3-ways? Most dampers can handle a ~30% increase in spring rate with headroom but I guess the front is a ~50% increase over the stock rate (rear is ~29% increase). 200 lbf/in doesn’t sound like much when you’re running 800 lbf/in rates but wrt a 400 lbf/in spring it is a large change.

Although the GTS stock suspension had much softer spring rates than we are used to, the recommended damper settings for 'track' use worked quite well out of the box.
We did not experiment with different settings, we have done that in the past and end up driving around the limitations and still manage to go fast.

The biggest downside of the stock GTS suspension is definitely braking. We brake very aggressively and routinely use it to catch other cars. The difference between braking performance between GTS1 (MCS 3WR, GTMore spec, 1000 front and rear, full coilover rear) and GTS2 (stock) is staggering.

Track settings for oem GTS suspension, starting from fully closed position:
FRONT
Rebound: -4
Low Comp: -2
High Comp: -6
REAR
Rebound: -4
Low Comp: -1
High Comp: -9

[Samo6556]

Based on the first drive on the street and highway. I think increasing high speed dampening is what I’m going to attempt first. It didn’t feel drastically different compared to stock but the rebound settings previously on the rear where high. Obviously noticing after I changed settings for my base point.

There was a spot on the highway that I made sure to visit, where my e92 would scrape the splitter on compression. It didn’t happen in the gts but for sure the kw’s were not absorbing the bumps as friendly as the motons I had on the e92.

When I eventually track road America is my go to. I haven’t been on the track since they re paved it. But based on what I see cars are almost 2-3 seconds a lap quicker compared to before the re pave. With the grippier smoother service. So maybe the track settings would apply there. But autobahn country club where it’s bumpy would need the additional rebound

[M3SQRD]

This sounds more like you’re encountering a large smooth dip in the road that’s causing the entire car to pitch/move relative to the road rather than an individual wheel(s) moving/oscillating up/down relative to the car. The primary job of high-speed compression (C) damping is to control/damp the motion of unsprung mass (wheels/tires, brakes, hub/knuckle, suspension arms, etc.) such as when hitting an expansion joint or a curb on track or a series of small bumps midcorner whereas low-speed damping is used to control/damp chassis/car pitch and roll motion (i.e., how quickly weight is transferred) under braking or rotation at turn-in or powering out of a corner. A good example is in a smooth braking zone with forward pitch motion occurring too fast and then suddenly you start to encounter a series of bumps that are causing the wheels to bounce/oscillate too much. In this example you’d increase low-speed C to slow down the rate of the pitch motion to allow the front tires to be loaded gradually AND you’d increase high-speed C to better control the bouncing of an individual wheel(s).

In your case, with the bump causing the car/splitter to almost bottom out, is it: (1) a smooth long-ish bump that causes the entire car to move downward relative to the road or (2) a large sharp bump that causes a wheel(s) to move upward relative to the car?

Another thing you may be feeling is the reduction in peak displacement due to the recent large increase in F and R spring rates compared to the motion of the original softer spring setup. Even if the new setup is less damped than the original setup, the peak displacement of the new 50% stiffer setup should be lower than the more damped original softer setup. Theoretically, the largest possible dynamic displacement is twice the static displacement for a pure square wave input which is something you likely won’t encounter in real life However, a 50% increase in stiffness is a large change and perhaps it’s too much for the damper and, therefore, it’s having trouble controlling both low and high damper piston speeds. Being near or at the max spring rates the dampers are valved to handle means you’ll have to dial in much larger increments of both low and high speed C damping.

Also, cutting off the more compliant part of the bump stop may have made things worse by either having previous motion that engaged the bump stop but with the shortened bump stop you’re no longer engaging the bump stop or you’re getting a sharper “impact” now due to an abrupt large increase in stiffness from the shorter stiffer bump stop. Additionally, the sprung mass may have more momentum now at the time of engagement with the shorter bump stop (i.e., the sprung mass has more time to accelerate upward, thus achieving a higher velocity and higher momentum). You really want a bump stop with a nice progressive ramp up in initial stiffness, not an abrupt massive increase in initial bump stop stiffness. The bump stop length and progressive stiffness are selected to insure there’s no abrupt stiffness increase (i.e., sudden loss of grip) and no contact between damper internal components.

I’ve linked below an animation that shows the relationship of peak displacement and oscillatory motion vs. %, of critical, damping (zeta = 1.0 is critically damped). This SDOF mass-spring-damper model represents the motion of the unsprung mass at a single corner of a car.

https://www.purdue.edu/freeform/ervi...ed-single-dof/

[Samo6556]

I don’t think I did a good job of explaining that the dip in the highway was just something I wanted to see if I would bottom out putting the car lower. Not that high speed compression would make that smoother next time. I do understand high speed compression is more for the sharp bumps where the strut/shock is hit quickly with compression.

The car being bumpy feels identical to the way the car felt before. I’m also thinking this because rebound was set so high in the rear previously but I didn’t know till setting the suspension to a baseline with the spring install. So as of right now I don’t think I can make a judgement on if the springs are causing the damper to be at the limit or not. Definitely need to spend more time playing with settings

You could be right about the bump stop which is why I saved the top portion in case I’d want to try putting it back on.

Worst case if things don’t seem right I can always revert back to the stock springs. But I feel this is the right move for now. I was able to find some random comments on post about others who upped their rates and the car went faster. Of course subjective to the people driving them and their skill or natural progression of getting faster.

Thanks again for the great explanations on things too.

[M3SQRD]

Originally Posted by Samo6556

I don’t think I did a good job of explaining that the dip in the highway was just something I wanted to see if I would bottom out putting the car lower. Not that high speed compression would make that smoother next time. I do understand high speed compression is more for the sharp bumps where the strut/shock is hit quickly with compression.

The car being bumpy feels identical to the way the car felt before. I’m also thinking this because rebound was set so high in the rear previously but I didn’t know till setting the suspension to a baseline with the spring install. So as of right now I don’t think I can make a judgement on if the springs are causing the damper to be at the limit or not. Definitely need to spend more time playing with settings

You could be right about the bump stop which is why I saved the top portion in case I’d want to try putting it back on.

Worst case if things don’t seem right I can always revert back to the stock springs. But I feel this is the right move for now. I was able to find some random comments on post about others who upped their rates and the car went faster. Of course subjective to the people driving them and their skill or natural progression of getting faster.

Thanks again for the great explanations on things too.

I believe you and I’m a believer that the f8x needs higher spring rates to squeeze the most performance out of it. TC Kline’s soft spring suspension tuning approach was struggling to work well on the e9x but it’s of no use on the f8x. Although I’m using a MCS 2WR (100 psi res pressure) F/R 500/800 lbf/in (divorced rear) setup on my wife’s f22 240ix and it’s a phenomenal performance yet compliant street setup. It’s her DD and she absolutely loves it! She loves it so much that she wants our (her’s) e92 M3 with JRZ RS1s and G20 330ix with stock suspension both replaced with MCS 2WR setups TCK’s recommended f8x track setup is F/R 400/700 lbf/in which is also the max rates his Koni DA setups can properly handle (he’ll go to 500/800 if you complain enough but it’ll be so lightly damped). I’d be surprised if the KW GTS 3-ways can’t control F/R ~600/900 lbf/in spring rates. Once your GTS is on track this year, you’ll know quickly whether the 600/900 rates are the right rates for them.

[Samo6556]

Originally Posted by M3SQRD

I believe you and I’m a believer that the f8x needs higher spring rates to squeeze the most performance out of it. TC Kline’s soft spring suspension tuning approach was struggling to work well on the e9x but it’s of no use on the f8x. Although I’m using a MCS 2WR (100 psi res pressure) F/R 500/800 lbf/in (divorced rear) setup on my wife’s f22 240ix and it’s a phenomenal performance yet compliant street setup. It’s her DD and she absolutely loves it! She loves it so much that she wants our (her’s) e92 M3 with JRZ RS1s and G20 330ix with stock suspension both replaced with MCS 2WR setups TCK’s recommended f8x track setup is F/R 400/700 lbf/in which is also the max rates his Koni DA setups can properly handle (he’ll go to 500/800 if you complain enough but it’ll be so lightly damped). I’d be surprised if the KW GTS 3-ways can’t control F/R ~600/900 lbf/in spring rates. Once your GTS is on track this year, you’ll know quickly whether the 600/900 rates are the right rates for them.

That’s awesome your wife is about the nice suspension too and appreciates the upgarde in driving dynamics.

Possible another thought was the spring rates are lower on the gts is that the car was developed for the the Nurburgring and dual duty use. So to be more compliant on the bumpy roads/tracks.

I took it for a little ride today and messed with the settings before the drive. I had them at the below


4 clicks low speed front
8 clicks high speed front
Rebound 4

3 clicks low speed rear
9 clicks high speed rear
Rebound 4

At these settings I think it felt pretty good on the street. It took the bumps pretty good and didn’t upset the car. Not that you can push on the roads but the on ramp to the highway felt nice too. I’d be happy cruising around the streets with this set up.

[M3SQRD]

Originally Posted by Samo6556

That’s awesome your wife is about the nice suspension too and appreciates the upgarde in driving dynamics.

Possible another thought was the spring rates are lower on the gts is that the car was developed for the the Nurburgring and dual duty use. So to be more compliant on the bumpy roads/tracks.

I took it for a little ride today and messed with the settings before the drive. I had them at the below


4 clicks low speed front
8 clicks high speed front
Rebound 4

3 clicks low speed rear
9 clicks high speed rear
Rebound 4

At these settings I think it felt pretty good on the street. It took the bumps pretty good and didn’t upset the car. Not that you can push on the roads but the on ramp to the highway felt nice too. I’d be happy cruising around the streets with this set up.

I tried getting her interested in motorsports but the few times I was able to get her to go to IndyCar races in the ‘90s all she cared about was which drivers were the cutest lol We camped outside of Villeneuve’s trailer for three hours just to get his autograph! To this day, she only follows F1 because of the drivers. She tends to drive a bit more aggressively since installing the MCS suspension on the f22! It didn’t happen when the JRZs were installed on the e92. Perhaps she just fells more confident with the AWD, although the f22 is probably faster than the e92 on the street due to the AWD, turbo torque and more useable power. I think I’ve created a monster but I have no one to blame but myself

How many clicks does the GTS 3-ways have for LSC, HSC and R? Yeah, a few clicks should make a noticeable difference even on the street. Higher spring rates make a car feel more stable and confidence inspiring vs. a car that’s moving around a lot. KW uses similar rates to what you’re now using on the GTS 3-ways that they use on their own CS 3-ways. Makes you wonder why BMW would use softer spring rates on their ultimate track-focused limited-edition GTS? Even more surprising is how all of the automotive journalists felt the GTS was too stiffly sprung? You don’t hear them complain much about GT3RS spring rates while seated/strapped into fixed-back race seats. They did nothing but crap all over the GTS any chance they got. BMW can’t win.

[SYT_Shadow]

Bmw definitely can't win. It's such a bummer.

On one hand you have the Satan worshippers, on the other, starving people who think an M3 should cost 20k

[Track/S]

Originally Posted by M3SQRD

How many clicks does the GTS 3-ways have for LSC, HSC and R? Yeah, a few clicks should make a noticeable difference even on the street. Higher spring rates make a car feel more stable and confidence inspiring vs. a car that’s moving around a lot. KW uses similar rates to what you’re now using on the GTS 3-ways that they use on their own CS 3-ways. Makes you wonder why BMW would use softer spring rates on their ultimate track-focused limited-edition GTS? Even more surprising is how all of the automotive journalists felt the GTS was too stiffly sprung? You don’t hear them complain much about GT3RS spring rates while seated/strapped into fixed-back race seats. They did nothing but crap all over the GTS any chance they got. BMW can’t win.

BMW did a great job with the GTS, for me the suspension is perfect and spring rates too.

Dedicated track car is M4 GT4, the GTS is not designed for that purpose.

[SYT_Shadow]

Originally Posted by Track/S

BMW did a great job with the GTS, for me the suspension is perfect and spring rates too.

Dedicated track car is M4 GT4, the GTS is not designed for that purpose.

The GTS does come with great suspensions, even with those soft spring rates. We managed a 2:01.2 at VIR, stock. Still, I would prefer stiffer springs from the factory, but I am a minority.

[M3SQRD]

Originally Posted by Track/S

BMW did a great job with the GTS, for me the suspension is perfect and spring rates too.

Dedicated track car is M4 GT4, the GTS is not designed for that purpose.

I wasn’t saying BMW got the spring rates wrong. They’re great for a dual-purpose setup that’s biased towards street use which is perfect for 80-90% of GTS owners. However, KW using a similar, or exactly the same, 3-way damper has selected higher spring rates similar to what the OP is using. The KW CS 3-way is a dual-use setup but it’s biased towards track use. It would be interesting to see the same driver on the same day with the same conditions run back-to-back the GTS and KW setups to see which one laps faster. Based on my experience with 500/800, 600/900, 700/1000 and 700/1100, the KW setup should be the faster setup.

The GTS is used on track because it can be driven to/from the track whereas a GT4 requires a tow vehicle + enclosed trailer to get to/from the track. Additionally, the GT4 requires a separate storage facility/shop (it’s not street legal which complicates things) and a higher level of maintenance than the GTS (e.g., Ohlins TTX Motorsports need to be rebuilt at least twice per track season to keep them fresh, or even more times if you’re playing around with spring rates, vs. GTS 3-ways 1-2 track seasons, with 10-15k of street mileage, before needing to be rebuilt as well as allowing to play around with spring rates). Nonetheless, the GT4 would be the ultimate f82 track weapon!

[Samo6556]

Originally Posted by M3SQRD

I wasn’t saying BMW got the spring rates wrong. They’re great for a dual-purpose setup that’s biased towards street use which is perfect for 80-90% of GTS owners. However, KW using a similar, or exactly the same, 3-way damper has selected higher spring rates similar to what the OP is using. The KW CS 3-way is a dual-use setup but it’s biased towards track use. It would be interesting to see the same driver on the same day with the same conditions run back-to-back the GTS and KW setups to see which one laps faster. Based on my experience with 500/800, 600/900, 700/1000 and 700/1100, the KW setup should be the faster setup.

The GTS is used on track because it can be driven to/from the track whereas a GT4 requires a tow vehicle + enclosed trailer to get to/from the track. Additionally, the GT4 requires a separate storage facility/shop (it’s not street legal which complicates things) and a higher level of maintenance than the GTS (e.g., Ohlins TTX Motorsports need to be rebuilt at least twice per track season to keep them fresh, or even more times if you’re playing around with spring rates, vs. GTS 3-ways 1-2 track seasons, with 10-15k of street mileage, before needing to be rebuilt as well as allowing to play around with spring rates). Nonetheless, the GT4 would be the ultimate f82 track weapon!

I have to say there is something fun about driving a car to and from the track and its able to run fast lap times with all different types of cars. Then being able to drive the same car home while you see the others in trailers/trucks. In a way like the Nurburgring cars that push the limits of a what a street car is. I understand this can come at a risk as well with mechanical failures/possible other on track issues, etc. Especially when you are pushing the car.

Right now I do not want a full blown race car with a truck and trailer. Eventually I will get to that point but a dual duty track car that I can cruise around town with is exactly what I am looking for. Finally with the GTS I have the HP to hang with the faster cars like the GT3's. As the E92 I had was heavier much less hp and I still was close to most of them.

I think BMW did a great job with the GTS and it was always underrated in my eyes.

[Lienrocs]

Originally Posted by M3SQRD

I wasn’t saying BMW got the spring rates wrong. They’re great for a dual-purpose setup that’s biased towards street use which is perfect for 80-90% of GTS owners. However, KW using a similar, or exactly the same, 3-way damper has selected higher spring rates similar to what the OP is using. The KW CS 3-way is a dual-use setup but it’s biased towards track use. It would be interesting to see the same driver on the same day with the same conditions run back-to-back the GTS and KW setups to see which one laps faster. Based on my experience with 500/800, 600/900, 700/1000 and 700/1100, the KW setup should be the faster setup.

The GTS is used on track because it can be driven to/from the track whereas a GT4 requires a tow vehicle + enclosed trailer to get to/from the track. Additionally, the GT4 requires a separate storage facility/shop (it’s not street legal which complicates things) and a higher level of maintenance than the GTS (e.g., Ohlins TTX Motorsports need to be rebuilt at least twice per track season to keep them fresh, or even more times if you’re playing around with spring rates, vs. GTS 3-ways 1-2 track seasons, with 10-15k of street mileage, before needing to be rebuilt as well as allowing to play around with spring rates). Nonetheless, the GT4 would be the ultimate f82 track weapon!

I got 20k miles and two track seasons at COTA, and one at SoCal tracks, on my TTX. I sent them out prematurely to get a different mount style. I’ve also got the same amount of time on mcs triples (on my e92) and set a PB last weekend at COTA. Perhaps rebuilds are more frequent with dedicated track cars but I’ve had really good luck with both of my cars on full Motorsport damper set ups.

[M3SQRD]

Originally Posted by Lienrocs

I got 20k miles and two track seasons at COTA, and one at SoCal tracks, on my TTX. I sent them out prematurely to get a different mount style. I’ve also got the same amount of time on mcs triples (on my e92) and set a PB last weekend at COTA. Perhaps rebuilds are more frequent with dedicated track cars but I’ve had really good luck with both of my cars on full Motorsport damper set ups.

You got three full seasons on TTX dampers? How many events per year? How many sessions per day? How many days per event?

My assumption is someone that purchases a M4 GT4 is going to be frequenting the track considerably more often than someone using a dual-duty GTS (or any f8x). I’m thinking 12, or more, 3-day events with typically one day being open lapping for instructors/advanced and at least 3 sessions per day or private track rentals (race teams that invite a limited number of clients to their testing days) where it’s pretty much open lapping all day. If you’re doing 6-8 or so 2-day events per year with 3 sessions per day then you’ll get multiple seasons without needing a rebuild. It also depends on how fresh you want your dampers to be. There absolutely will be drop off in damper performance in a TTX, or equivalent damper, from just one season of use.