Spring rates for aftermarket springs?

[Victorofhavoc]

M

I'm not sure quite what it is exactly that makes my brain slowly turn off when reading about suspension physics. I'm not denying that I might just be dumb, but I think it's more that I feel like you just kind of have to be a true expert to really be of much use when it comes to topics like this. Kind of like, I have to feel like I know virtually everything about it or I may as well know nothing.

I'm in a technical field by trade and oftentimes I realize that there are certain things that I would just have to truly bench myself to learn (e.g., assembly for reverse engineering malware comes to mind...) and without a practical requirement it will remain one of those things that I wish I knew but never could muster the energy to actually learn to a functional extent. Suspension design is another one of those things, to me at least.

In other words... I feel like I can follow that article well enough... but extracting practical knowledge that will help me figure out ideal suspension configuration for my street car? Not much help to be honest.

I also am not the biggest fan that the article seems to exclusively reference 30+ year old cars (the article was written over 10 years ago...), and refers to "modern" suspension design as being in the 70s and 80s. It's good fundamental information, but I feel like I personally would benefit more from a similar article that was more specific to our cars, specifically the DE5/FL5, because I think there's enough nuance to justify that, as from all the marketing and media noise around the topic, this "dual axis" design is apparently some sort of breakthrough anyway.

All in all, what will end up being my approach to all this is to see how this setup with the Eibachs hold up to this coming Saturday's autocross. I've said before, I'm not actively going for class-based competition; I'm just trying to see how close I can come to the guys who take this shit really seriously. If that makes sense.

I actually did NOT pull the strut pins- I decided I'll probably end up doing the Whiteline camber kit eventually anyway so I didn't bother telling the shop to pull them (I still don't think they would have done it anyway but that's another story...). So right now my car is sitting at ~1.5 degrees negative camber in front, ~2.5 degrees out back. Bump stops were cut by 20mm front and rear as per the instructions from Eibach. If my times start sagging, and I don't feel like I have as much control of the car as I've gotten used to with the stock setup, then I'll get the Whiteline camber kit sooner rather than later, and probably a rear anti-roll bar. I don't think I'm going to screw with the front. At least not until a refreshed article comes out, or someone can explain it to me like I'm 4 years old on how it's still relevant to our cars' specific suspension geometry.

Also FWIW, Zygrene as always has amazing track content that IS specific to our cars, and his latest vid he feels like his car is dialed in better than it ever has been, and he's running the Whiteline kit and -4.2 degrees negative camber up front. No other suspension mods other than the Ohlins coilovers (with pre-production rates that I'm also waiting to become available...). When I get more serious about taking the car to an actual race track on a routine basis, pretty sure this will be my move.

The McPherson strut name has stuck around because the design hasn't changed. Yes the article is old, but nothing about it is untrue and all of it is applicable to these cars.

The dual pivot spindle has the benefit of changing how the cv axle angle affects rotation at the wheel. In traditional systems, it's the uneven length of the cv axles that causes torque steer (think holding out a 12 foot pole and rotating it vs a 4 foot pole, one is stiffer and moves easier). With the dual pivot design you can bring the wheels in more over the cv axle, effectively changing the length and also limiting how much the cv axle itself changes angle. That's also why such high offset is beneficial for torque steer on this car, and reducing it has negative effects.

I don't know zygrene and haven't driven with him, so I can't comment on what his driving style or experience means in terms of suspension pattern for this platform. I've driven cars built by national champ drivers that I've found horrendous. My own racecar was originally built by a national champ who won two endurance series in it, and when I got the car it felt like it understeered too much for me. I ended up changing things for my personal driving style and it's worked out better. I'm certainly not perfect, but I'm pretty fast and I've made a lot of slow drivers fast, so I generally like to think I have an adaptable pattern of driving and thinking.

I will say over 4 camber is nuts for driving on the street, and that's territory for a slick only since most 200tw or even 100tw tires peak performance around the low 2s to 3s. It might be necessary if you cut your bumpstop a whole inch and don't have enough bar or spring to limit roll.

I'll have some better things to say after the 23rd,but so far I'm not feeling or seeing much understeer in this car, even in factory alignment setup. I'll still take it a bit more aggressive before going out with it.

Driving style has a big impact on what you feel. It's super common for intermediate drivers of fwd cars to start shouting "understeer" as they get faster because they cook it into the corner and then come out pushing on the other side. I've spent a lot of time coaching novice, intermediate, and advanced drivers out of bad habits like dropping the brake on corner entry, trail braking too hard, braking too late, braking too early, releasing the brake too early, not modulating brake pressure on corner entry, and turning in too early which will all cause understeer. Unlike rwd where some power can quickly correct some of these, fwd is not so forgiving. It takes more skill to drive a fwd car fast at 100%, but getting to 90% is easier compared to a rwd car. It's why my fwd car guys tend to build the worst habits for braking zones.

Sponsored

 

[optronix]

M

The McPherson strut name has stuck around because the design hasn't changed. Yes the article is old, but nothing about it is untrue and all of it is applicable to these cars.

The dual pivot spindle has the benefit of changing how the cv axle angle affects rotation at the wheel. In traditional systems, it's the uneven length of the cv axles that causes torque steer (think holding out a 12 foot pole and rotating it vs a 4 foot pole, one is stiffer and moves easier). With the dual pivot design you can bring the wheels in more over the cv axle, effectively changing the length and also limiting how much the cv axle itself changes angle. That's also why such high offset is beneficial for torque steer on this car, and reducing it has negative effects.

I don't know zygrene and haven't driven with him, so I can't comment on what his driving style or experience means in terms of suspension pattern for this platform. I've driven cars built by national champ drivers that I've found horrendous. My own racecar was originally built by a national champ who won two endurance series in it, and when I got the car it felt like it understeered too much for me. I ended up changing things for my personal driving style and it's worked out better. I'm certainly not perfect, but I'm pretty fast and I've made a lot of slow drivers fast, so I generally like to think I have an adaptable pattern of driving and thinking.

I will say over 4 camber is nuts for driving on the street, and that's territory for a slick only since most 200tw or even 100tw tires peak performance around the low 2s to 3s. It might be necessary if you cut your bumpstop a whole inch and don't have enough bar or spring to limit roll.

I'll have some better things to say after the 23rd,but so far I'm not feeling or seeing much understeer in this car, even in factory alignment setup. I'll still take it a bit more aggressive before going out with it.

Driving style has a big impact on what you feel. It's super common for intermediate drivers of fwd cars to start shouting "understeer" as they get faster because they cook it into the corner and then come out pushing on the other side. I've spent a lot of time coaching novice, intermediate, and advanced drivers out of bad habits like dropping the brake on corner entry, trail braking too hard, braking too late, braking too early, releasing the brake too early, not modulating brake pressure on corner entry, and turning in too early which will all cause understeer. Unlike rwd where some power can quickly correct some of these, fwd is not so forgiving. It takes more skill to drive a fwd car fast at 100%, but getting to 90% is easier compared to a rwd car. It's why my fwd car guys tend to build the worst habits for braking zones.

^This is a great example of why I'll probably never get ultra-serious about racing. It feels like so much of it is subjective, and dependent on this nebulous concept of "driver style".

Also, and just know this isn't a direct response to you, it's just a reaction based on years of personal experience- Maybe I've just had a couple bad coaches, but that's another thing... as a novice, it can't be understated that whoever ends up in your passenger seat as an instructor is going to have unimaginable influence for the ~60 or so minutes they're out there on the track with you. For me, it was just my luck that I had a guy that mumbled so I heard absolutely nothing of what he was saying. Served as more of a distraction than anything... and even with other coaches, when I felt like I had a good coach, I'd notice he'd tell me things that were nearly the exact opposite of what someone else said previously. Makes it really difficult to be able to decipher who actually knows what they're talking about.

So while everything you're saying makes sense, and you gave me some great feedback in the other thread based off a video of an autocross run I shared, and I sincerely learned from it- it's tough to completely take everything at face value, especially when it delves into such an excruciating amount of engineering detail. It's sort of like that oil thread on CivicXI where the Honda engineers start arguing with themselves. I can't find a single source of truth on everything.

So while chats like this can be fun, until I'm getting paid for it, I'm content to just be safe and have fun... and extract what I can from any available data point without trying to pretend to be an expert!

 

[Victorofhavoc]

^This is a great example of why I'll probably never get ultra-serious about racing. It feels like so much of it is subjective, and dependent on this nebulous concept of "driver style".

Also, and just know this isn't a direct response to you, it's just a reaction based on years of personal experience- Maybe I've just had a couple bad coaches, but that's another thing... as a novice, it can't be understated that whoever ends up in your passenger seat as an instructor is going to have unimaginable influence for the ~60 or so minutes they're out there on the track with you. For me, it was just my luck that I had a guy that mumbled so I heard absolutely nothing of what he was saying. Served as more of a distraction than anything... and even with other coaches, when I felt like I had a good coach, I'd notice he'd tell me things that were nearly the exact opposite of what someone else said previously. Makes it really difficult to be able to decipher who actually knows what they're talking about.

So while everything you're saying makes sense, and you gave me some great feedback in the other thread based off a video of an autocross run I shared, and I sincerely learned from it- it's tough to completely take everything at face value, especially when it delves into such an excruciating amount of engineering detail. It's sort of like that oil thread on CivicXI where the Honda engineers start arguing with themselves. I can't find a single source of truth on everything.

So while chats like this can be fun, until I'm getting paid for it, I'm content to just be safe and have fun... and extract what I can from any available data point without trying to pretend to be an expert!

All very fair and good points.

One of the problems with various grassroots orgs is how lax they've been for people to become coaches. A lot of people get into it to save a buck in fees and don't really take the time to learn who's in their passenger seat.

NASA in my region has gotten really serious about it and there's now a program you have to go through to become an instructor. Having a comm system in car also certainly helps. There's a lot more consistency now in what's taught, but there's also a few instructors that stray from it. My favorite example is the older guys who still believe that your drive type magically needs different racing lines.

Regardless, I'm sorry you've had poor coaching experiences. I strive to ensure every student I work with is meeting their own personal goals for the time we spend together, and it's very aggravating when I see instructors intentionally being lazy or dropping the ball. It shouldn't have happened to you, and I hope you get someone much better at another time.

If I'm in your area for an event (and I sometimes am in the early season), I'll let you know and maybe we can drive together . I know I'll likely be out at NCM next spring, but not sure about VIR. I usually only do events within 12hrs so I don't have to drag the trailer around for more than a day, but VIR is worth it to go a little further.

 

[StingertimeNC]

Love the info and thoughts from both of you!!

I’ll be at VIR October 31 for two day event. Grand course first day.
Would be amazing to see some fellow forum members there. $625 for 4 hours track time for novice and 6 hours for everyone else. Best deal out there. So far there are less than 80 folks signed up.

Sponsored