Feisty the "Family Car"

[ronniec687]

I don't think I did anything special, looks like I didn't even use a washer beyond the sphericals. I am pretty sure I went higher than your torque spec. May have gone 50ish. I think I use a chart from ARP here as reference for hardware. The studs are DIN 939 rated at 125K PSI?

Thanks for the feedback I will keep an eye on mine and the ones Dtulley is running.

Wonder if using the Stainless ones would make more sense. Stainless won't be nearly as hard. You would want to lube them up well to keep them from galling as they settled into position. Did you use the .875 OD or the smaller .625 OD? (no idea if that would matter, theoretically there could be more PSI across the female side?)

Sorry to jump in but i just installed some 2 deg plates. Was wondering if maybe you had some part numbers for those nuts and washers you used?

 

[Fusion Works]

https://www.fiestastforum.com/threa...my-daily-driver-into-a-track-car.21954/page-5

The nuts are just a standard nyloc flange nut. Pretty sure they are Grade 8 or 10.
https://www.mcmaster.com/99908A103/

 

[Dialcaliper]

Time to pull back the curtain on the fully custom suspension tuning I've been working on over the last year or so.

Being a mechanical engineer by trade, I'm diving in and doing the analysis work, then testing revisions to dial it in where I want. because I want both a setup that is fun to drive and meets my goals, but its also important to me to really grok the nuts and bolts of how things work and why they do what they do.

Pretty much the only shock/strut options that don't lower the car significantly are Bilstein B6 and some other basic upgrades. Aftermarket springs available universally all lower the car, which is why I started playing with custom "rally" springs. As decent as that setup was, I've decided I want more, and that if I'm going to go through the trouble, I'm going to engineer the crap out of it, and then test and dial it in. The end goal is the best "multipurpose" setup I can come up with. My FiST will never be a time attack car. But I want a track-day ready setup that at the end of the day, will still be tolerable to drive to work, stable to drive on the gnarly "B" roads in the Santa Cruz mountains, and still be tolerable commuting to work, and even on dirt roads to go backpacking and other fun stuff.

That's the dream, and I'll get as close to it as I can. The FiST is fun, but as the quote goes, you can't make a pig into a racehorse. But you can make a pretty damn fast pig!

Instead of just throw money in all directions at random parts, or just buy those parts everyone says are great without really even knowing why, or shell out for a set of Reigers and their frequent maintenance requirements, I started out with building some detailed mathematical suspension models in order to get "in the ballpark". As a result, I've discovered a few interesting things about the Fiesta.

The first consideration is the front control arm geometry is rubbish. That is to say, It was designed to be a Fiesta and has been morphed into a hot hatch and was never designed as a low to the ground racecar. "Ideal" geometry puts a FWD car's front roll center between 2-4" above the ground, and rear between 4-10" above ground. It turns out that Ford knew this, and the Stock ST ride height (which is only 0.25" lower than a base Fiesta) puts front roll center very near 4" above ground. Due to the A-arm geometry, the roll center migrates to 2" above ground with only 0.5" lowering. Even the mildest lowering springs (like Swift/Mountune) that lower the car an inch already put the front roll center beyond that range, near ground level, and something like an Eibach/Whiteline set goes subterranean. Why is this important? a low front roll center (that is to say, one with a longer "arm" between CG and roll center) induces both increased body roll (because the strut based suspension geometry makes the roll center drop faster than the CG of the car), and additionally increases front weight transfer, which reduces overall grip on the front axle, resulting in understeer, which can only be wrestled back to neutral by stiffening the rear and reducing overall grip even more, along with the more subtle tricks like adjusting alignment, tire pressure etc.

Additionally, the roll moment behavior and how it changes affects many other things, from the camber change on the tires, but more importantly to the "tactile" sensation of the steering and tires as they approach the limit of grip. I want a car is both fast and that "feels" satisfying to drive. So front ride height will be targeting between stock and 0.5" low.

Second, There are no coilover options short of high end rally stuff (Reiger, etc) that are able to properly run the car near stock ride height. Even most coilovers that can be cranked up on adjusters that high have short strokes designed for either a lowered car, which means there's not enough droop to run a properly compliant spring setup, or rally coilovers which are designed to be run above stock ride height.
Also the other dirty secret is that for even expensive coilovers to work properly and consistently over the years, they need to be rebuilt frequently. The more expensive, the more frequently they need serviced! (Ohlins for example says 20k kilometers or 50 hours of track time). Since I intend to own this car for some time to come, and it's the "family car", I'd rather not deal with that.

Below is just a tiny snip of the calculations, planning and testing revisions I've been plowing through for about the last year, and there's a lot behind the scenes that's now shown here, taken mostly from Milliken/Milliken "Racecar Vehicle Dynamics" and various other sources (along with some discussion from Shaikh over at Fat Cat Motorsports who I'll be working with to tune the dampers)

 

[Dialcaliper]

Which brings us back to Bilstein. Which while they have some shortcomings, they are high quality german monotube shocks that can be easily rebuilt/revalved, modified and still be reliable for years. So inspired by @kevinatfms, I decided the B14 front dampers would make a good starting point. Steel body inverted monotube, which means they'll be durable and up to the task. First thing to go are the B14 springs - not the rates I want, progressive in the rear and designed for a minimum lowering of about an inch, which means not enough stroke.

The rear B14 dampers however, are a problem. Lightly damped, and small diameter, not rebuildable. Since I'm having the shocks custom valved anyway, I can pick pretty much anything Bilstein offers as long as I can make it fit with some mild custom work. The damper I settled on is a 5125 inverted monotube. Because the stock rear dampers are mounted aft of the wheel, they have a remarkable 10" stroke! To match, the unit I ended up with is basically meant for lifted Jeeps! The steel body is a little heavy, but nice and beefy and the weight is not a problem since they're designed to be run inverted (damper is no longer unsprung weight). To accomodate the tall upper shaft, I had to drill out the center holes rear shock towers.

For now, drilled out rear top mounts are working, uniball lower joints with custom 40mm wide spacers and a custom bumpstop perch that I also made myself, which was actually the trickiest part of the whole thing. In the end, I could have just used the lower poly mounts they came with and thrown some spacer washers in there. The end result is an inverted monotube rear damper that has an additional 0.75" droop, and with a shorter bumpstop, additional compression travel as well. Important for keeping the rear wheels on the ground on bumpy roads, and ditching the stock design that engages the insanely tall (120mm) OEM bumpstop early to create a progressive spring effect.

For the front dampers, I crammed on an 8" 300lb/in spring with a 224lb tender. Currently too much preload but they will be modified for additional droop when they go in for tuning and I may swap the tender out for a slightly lighter one. This lets me use as much spring length as possible with the adjusters near the lowest point so coil bind will never be an issue, and the ride height is right within that sweet spot of 0-0.5" lower than stock. The heavy tender/assist spring is tuned to give adequate preload, and a dual-rate like behavior in droop to help with shock extension on rough back roads, but will be be fully bottomed at static ride height.

For the rear springs, I was aiming for flat ride (rear suspension frequency higher than front), and initially looking at 250-300lb/in in the rear. With 300lb springs to test, and even 250lb that I also tested, the rear ended up being way too stiff! I may have been overdoing it in order to hit an "average speed" target, I tossed my 200lb/in "rally" springs back on the rear, and while its still barely in the "flat ride" range, the road manners and stability are actually improved. I'm now thinking I'll end up in the 200-225lb range in the rear, lower than I first targeted for the rear, but surprisingly not far off the stiffnesses that both Swift and Bilstein ended up using for their kits. At first glance it looks oddly heavy in the front -

I'll be honest - the rear is different than what I had originally planned, and I was convinced I needed something much stiffer, but road testing has shown that it feels really stable without introducing any pitching or skittish behavior of the rear end on bumpy roads. Goes to show how bench racing and doing the engineering design work will get you in the right neighborhood, but only testing in reality will show all the variables.

For any of those suspension nerds out there, the 300lb front springs give roughtly 1.85Hz natural frequency in the front, and 200-225 means about 2.0-2.1 Hz in the rear (so flat ride rear 8-14% higher than the front). Eventually I'll confirm with a bounce test. This is in the same ballpark as what you'll find in serious modern "factory track oriented" cars (ie, Porsche GT3). But still stiffer than what you'd find in any modern sports car (which typically run frequencies in the 1.4-1.7Hz range, which is also where our stock springs are tuned, at least for the 2014-2016 cars. The post ST200 cars are a bit softer). The 1.85/2.0Hz range is also interestingly not far off of where the "stock" car tunes in when it's jacked down on the bumpstops in a corner, and the bumpstop rate is added to the main rate.

Still plenty stiff for the track without aero, but decent backroads manners. Both from the "rule of thumb" and my experimentation, Pushing too far into the 2Hz range seems to be where "roadholding" ability starts to go to crap on anything but "nice" roads - for reference, I like smooth roads and track driving as much as anyone, but I also greatly enjoy driving the car on crappy 1-1.5 lane backroads and I want a setup that will work with both. This is basically rally car territory but with some different considerations in mind.

But one of the absolutely critical things that needs to happen in order to make a setup that will work on both backroads and on-track is suspension travel, which means both shock travel and using as much of the adjustment range as possible to make sure the springs won't coil bind in compression.

In the front, That means modifying the front damper internals to gain another inch of droop, and running shorter bumpstops. With the "jeep" dampers, I'll have both more droop (by about 0.75") and with the 76mm bumpstops, more compression travel looking at total of about 6" in front and >8" in rear not including the extra from tilt in the rear torsion beam, which is about as much as is practical to achieve without "lifting" the car. (This is total travel including bumpstop compression, not just damper stroke)

The rear dampers out of the box are far too overdamped in rebound (they're meant to pair with 600lb springs on lifted jeeps!), but the ride and handling aren't actually too bad as-is. Note that with the Bilstein setup, there are no "adjustment knobs" like most coilovers use. That means cracking the dampers open

After I finsh spring testing, the shocks and struts will come back off the car. Damper valving is a bit more than I want to deal with, so they'll be headed over to Fat Cat Motorsports for revalving plus some cool internal modification wizardry Shaikh over there has some up with. More to come!

 

[Intuit]

"Optimium"... is that kind of like "unobtanium" ?

As I read that post I kept looking up to see if there really was a plane sailing over my head. 😄

 

[Dialcaliper]

Nice catch 😂

At least the first thing you noticed wasn’t the “upside down” rear springs in the photos. (Was fit for a test drive and already had them zip tied together before I was reminded that the rears need to have the tenders on the bottom to avoid the “banana”.

Also, added more pics of the rear shock setup off the car so you can see what's going on with the 5125's. The drilled out top mount works fine, but I have a plan for a "better" custom designed top mount.

Worth noting also that I also considered Bilstein's 5160 "remote reservoir" shocks, but came to the realization that at least in my use case on the rear of a car this light, the extra (steel body) reservoir and extra oil capacity is basically adding quite a bit of extra dead weight without much useful benefit. Maybe if I were actually building a real rally car or something, or making this setup on a heavier car.

 

[M-Sport fan]

I would think that a remote reservoir setup would be more beneficial on the fronts than the rears, even given the slightly higher frequency rating of that rear setup.

But given your parameter of long term functionality, without constant, incessant rebuilds (like would be required with the remote reservoir Reigers), and functional simplicity (not to mention the sprung weight savings, and location problems), doing without them is a smarter move indeed.

Now you have me wanting to hold off on any suspension plans, like just saying eff-it and going to the B6es with Swifts, until you fully develop this setup,

ANY chance at all on ever making this a 'kit', and selling them, or is this just a one-off thing for your own use??

BTW; I like and appreciate how you point out that even if one can adjust some of the current on the market (affordable) coil over kits to factory ride height, they are not really functional at those collar adjustments.

 

[Dialcaliper]

I would think that a remote reservoir setup would be more beneficial on the fronts than the rears, even given the slightly higher frequency rating of that rear setup.

But given your parameter of long term functionality, without constant, incessant rebuilds (like would be required with the remote reservoir Reigers), and functional simplicity (not to mention the sprung weight savings, and location problems), doing without them is a smarter move indeed.

Now you have me wanting to hold off on any suspension plans, like just saying eff-it and going to the B6es with Swifts, until you fully develop this setup,

ANY chance at all on ever making this a 'kit', and selling them, or is this just a one-off thing for your own use??

BTW; I like and appreciate how you point out that even if one can adjust some of the current on the market (affordable) coil over kits to factory ride height, they are not really functional at those collar adjustments.

Honestly, it seems like short of actual rallying or endurance racing, even the front remote reservoirs might be redundant. In the rear, these chunky full size (46mm) Bilsteins, which are basically the same as body as the HD's have almost twice the surface area (and oil volume) with which to dissipate heat compared to the stock, or even B6's. There's plenty of height in the shock towers for the long stroke, so the remotes don't really gain you any compression travel (at some point you'd bottom the rear of the car - either the EVAP cansister or exhaust tips I'd guess. The low maintainance is definitely one of the big appeals.

Right now it's a one-off that I'm just building - honestly you could do an even less elaborate attachment on the rear without the uniballs and just add washers on the sides (the mount they come with is a 5/8"ID poly bushing with a 12mm ID sleeve that's 38mm long. The top really just needs a stack of washers, or 12mm spacers and the stock top mounts drilled out. The main issue I think is that the damping is a little too stiff in rebound.

Honestly, if you're considering the swifts, even as a temporary solution, I'd really suggest you try the B6+Rally Spring (3.0"/2.5" 225/200lb) setup. If you're installing a fresh set of B6's, you don't even need to mess with a spring compressor (Front strut preload was maybe 50lb with the spacers in there and I was able to hand assemble it. I would say from the 3500 miles I've driven on it so far, it's at least 75% of the way to what I ultimately want. I weren't already dead set on this "no-compromises-compromise" setup with custom damping, I could easily have been pretty satisfied with the way the car was set up and taken it to work, canyon runs and even the track like that.

If you do have more elaborate desires and a budget to make an "investment" in your suspension with something on par with the Reigers, I'd recommend that you contact Shaikh at Fat Cat Motorsports. The problem a lot of we all seem to run into is that we know what we want to do with the car, but not how to build a full suspension system that actually does that, so we all end up taking a combination of random advice/marketing on what individual components to buy without actually understanding how they all work together. Shaikh basically works as a suspension consultant/concierge and works with people all over the country. While I've done a lot of the initial design and analysis myself, usually he handles that side of things, and all of his setups are completely customized with your intended use in mind, (but all designed around custom valved and modified Bilstein or H&R, which are basically the same thing). While he got his start in Miatas and BMW's, he's designed suspension setups for a huge variety of different vehicles

I have no vested interest in promoting Shaikh, but I've talked with him a lot and seen some of the results of what he's done - he's a smart guy with a passion, and I have a lot of respect for him. His website is below, and he has a youtube channel that I recommend you check out, even if you have no intention of working with him, as he's got a lot of good explanations about how car suspension actually works.

https://www.fatcatmotorsports.com/index.htm
https://www.youtube.com/@SuspensionTruth/playlists

 

[Dialcaliper]

Did a "bounce" test on the new suspension setup to check how close to my "math" models, and came out pretty damn close! 1.88Hz up front and 1.96Hz in the rear, compared to the 1.85Hz/1.99Hz my spreadsheets predicted. Why do I care? It means my motion ratio and suspension geometry models are actually pretty close to reality. If anything, the deviation is likely a combination of not having real corner weights for my car yet (and empty driver's seat), and some experimental error in getting the bounce just right (especially with the dampers still in place) and of course my phone's accelerometers not being that highly accurate. This also jives with some previous measurements I made with the stock springs (which come in around 1.4/1.7Hz)

The iOS phone app I used for the bounce test was kind of neat - Just called "Vibration" by "Diffraction Limited", and it picks up samples from the phone accelerometers and can pull out frequency measurements.

One thing this does mean is that I really am going to need to bump up the stiffness in the rear a little bit (probably 225lb/in instead of the current 200lb cheapass springs I have on now), because if I put anything more than 150-200lbs in the back (two rear passengers, kid+gear or hauling stuff around), the rear frequency will drop. If it drops below the front frequency, It will shift from a "flat ride" to "pitch" setup, and while that's fine on a stiff aero track car, it could be unpleasant on the street. I want to have enough margin so that the car will still be the useful little family hatchback it needs to be.

Also, a small thing to highlight is that I've finally sourced some legit Class 12.9 bolts, nuts and Nord-Lock washers to replace the the lower strut bolts. These are fully reusable, and produce roughly equivalent preload to the factory stretch bolts - nice if you happen to want to change or remove the front struts. The bad news was I spent way more than was reasonable on them. The good news for you all is that in order to make the outrageous shipping (from Australia) worth it, I had to buy a whole batch of bolts/nuts/washers, and so when I get my act together, I'll offer the rest up for sale here.

 

[M-Sport fan]

IF Bilstein would have marketed a B14 style kit with all of your upgrades/improvements, and Shaikh's valving graphs, they'd be on my car as we speak!

A fully double (rebound AND compression) adjustable B16 kit like yours above might be even better yet, but I would guess that the valving patterns would then get very tricky, and much more complicated, (maybe even more fragile for long term street durability as well??).

 

[Dialcaliper]

IF Bilstein would have marketed a B14 style kit with all of your upgrades/improvements, and Shaikh's valving graphs, they'd be on my car as we speak!

A fully double (rebound AND compression) adjustable B16 kit like yours above might be even better yet, but I would guess that the valving patterns would then get very tricky, and much more complicated, (maybe even more fragile for long term street durability as well??).

Mine are based on the B14 and will remain non-adjustable in damping. The reason I’m working with Shaikh is that he has devised internal mods to the dampers that can essentially “4-way”customize a shock valving in ways that you simply can’t do with an “adjustable” shock or even a custom revalve using off-the-shelf Bilstein internals.

Particularly his KBO/Ripple reducer tuning can produce low hysteresis, and an almost flat high speed damping curve.

This is a long read but good information below here. The way Shaikh writes comes off to some as a little arrogant, but once you talk to him in person you realize it’s because he is extremely passionate about what he does (to the point that he quit his tech job to start FCM and tune suspension full time)

https://www.fatcatmotorsports.com/FCM_Elite_projects_Alberto_FD_RX7.htm

Unfortunately the reason Bilstein wouldn’t do what Shaikh is doing is that each of his customer setups is hand tuned to each car and driver preference, and the dampers he puts on the shock dyno will come apart several times to make sure they give the exact tuning he wants, not just a revalve based on a shim calculator and a quick dyno to make sure it’s “close enough”

 

[foodtruck]

The first consideration is the front control arm geometry is rubbish. That is to say, It was designed to be a Fiesta and has been morphed into a hot hatch and was never designed as a low to the ground racecar. "Ideal" geometry puts a FWD car's front roll center between 2-4" above the ground, and rear between 4-10" above ground. It turns out that Ford knew this, and the Stock ST ride height (which is only 0.25" lower than a base Fiesta) puts front roll center very near 4" above ground. Due to the A-arm geometry, the roll center migrates to 2" above ground with only 0.5" lowering.

I have to say, this makes me somewhat regret getting B14 and not going with brand new stock suspension. I really wonder how all of the suspension reviews for B14s, KW, and others (including from outlets like Motortrend) state that these kits improve car handling and make it faster around the course, and they also don't exactly try to achieve stock height either. Ford themselves offered "autocross" B14-based kits which given all these numbers is very surprising. Placebo effect? Peddling the product?

I am going to try measuring what's my current roll centre is. I assume the "bushing height" is ground to the centre of the control arm bushing that meets the subframe and "balljoint height" is ground to the centre of the steering knuckle ball joint (will probably need to eyeball that one)? Right now the only measurement i have is axle centre to top of the fender arch is 24".

Thanks for sharing you project with us!

 

[foodtruck]

This probably detours from the main subject somewhat, but I'm also really curious what's Shaikh's take on the reasons for seemingly odd combination of stiffer B14 springs and soft valving

 

[Dialcaliper]

I have to say, this makes me somewhat regret getting B14 and not going with brand new stock suspension. I really wonder how all of the suspension reviews for B14s, KW, and others (including from outlets like Motortrend) state that these kits improve car handling and make it faster around the course, and they also don't exactly try to achieve stock height either. Ford themselves offered "autocross" B14-based kits which given all these numbers is very surprising. Placebo effect? Peddling the product?

I am going to try measuring what's my current roll centre is. I assume the "bushing height" is ground to the centre of the control arm bushing that meets the subframe and "balljoint height" is ground to the centre of the steering knuckle ball joint (will probably need to eyeball that one)? Right now the only measurement i have is axle centre to top of the fender arch is 24".

Thanks for sharing you project with us!

I hate to say, but being cynical for a moment there’s a certain amount of “peddling” that goes on both from OEMs and aftermarket.

Some cars, especially those with double wishbone or multi link suspension do benefit from a slightly lower ride height. For cheap ubiquitous Macpherson strut cars, some do, many more don’t - just depends on the geometry.

More people want suspension that is “good, lowers the car, even if it’s already been lowered by the factory like ours. Looks and “feeling stiff and sporty” sells to a much bigger market than outright performance. Simple question - hypothetically you can ask the opposite question. How many people (outside rally) would buy a $1000 street suspension kit that visibly raised the car back to base Fiesta height, if that just happened to be a more “optimal” design?

Second, high end Motorsport has all gone to heavy aero, where the rules change and ride height for downforce trumps any reduction in mechanical grip you might have. Most “race” coilovers use rates and damping strategies that work better for maintaining ride height for aero, and most “shocks” are designed around a car’s OEM springs first.

Bilstein actually did a decent job choosing spring rates and is a pretty great set - among the best available for that market segment, but I think the B14’s main flaw is most people in that price range want “lowered cars” because that’s “what you do”.

The other great thing about it is because it’s based on Bilstein’s motorsport stuff, it’s basically compatible with coilover springs, with only changing out the front top hats.

Measuring the geometry is basically all about getting the pivot point locations.

 

[Dialcaliper]

This probably detours from the main subject somewhat, but I'm also really curious what's Shaikh's take on the reasons for seemingly odd combination of stiffer B14 springs and soft valving

So I came up with the spring rates long before opening conversation with Shaikh, but after some suggestions from him, and testing by me, this is where I ended up. Shaikh has a lot of content out there (videos and write ups at the links I posted above) if you want to hear his “pitch”

The valving discussion is complicated. A lot of it stems from physical limits of what a company like Bilstein or anyone else can do in a mass production “digressive” damper. The short answer is that your low speed damping, especially in compression to control the car body is normally limited by the “peak” high speed damping, otherwise the car launches off bumps. So we try to control it all with rebound, and accept the “jacking down” (the bit where the car feels like it’s constantly “falling” off bumps). But we hit limits there as you eventually sacrifice grip and the car is excruciating to drive.

In the end, you want to control the car body as well as you can in transient motion, and at the same time, allow the wheel to track the road surface with a little variation in tire force as possible. The former is maximum control, and the latter is maximum grip.

 

[foodtruck]

So I came up with the spring rates long before opening conversation with Shaikh, but after some suggestions from him, and testing by me, this is where I ended up. Shaikh has a lot of content out there (videos and write ups at the links I posted above) if you want to hear his “pitch”

Yeah, I was actually watching a few of those videos and thought his argument was very similar to yours from bilstein science experiment thread. I suppose I was wondering if he had any more insight specifically on that suspension in passing (also in regards to whats going on with those rear springs). His explanation how the car can get progressively lower and lower on a series of undulations was a "huh" moment for me.

 

[Dialcaliper]

Took the front struts off to swap out the tender springs from 4k to 3k. Not sure if it will make a difference in ride, but the 3k are also slightly shorter, so the main springs won’t be preloaded as heavily in droop.

Also, made a bit of a blunder. The engine (and strut mounts) were still hot when I removed the strut tops, and 5 of the 6 studs on the DNA hats came unscrewed out of the plate (instead of the nuts). My guess is the aluminum must have expanded more than the steel studs, and with OEM nuts being locking type, the studs just came out. Reinstalled them back in the hats with red locktite (they did not appear to be bonded in place, just threaded in). Hopefully that will solve the problem. If not, maybe locking helicoils if I can find some shallow enough.

While I was at it, I have been noticing that when install the top of the strut, it seems to hang on the back of the innermost hole, and pivot around that point. So I took a file and just slightly cleaned up that inner hole - not even a slot, but about 1/16” and barely noticable. Now, when I put the strut on, and push it all the way in on the holes, it sits firmly and repeatedly in the same spot instead of wanting to twist in the holes. Should make it easier to remove and replace the strut without having to realign toe every time. The two outer holes are completely untouched. You could probably make an argument that it’s not “slotted” at all.

I was thinking it was such a small cleanup job that it wouldn’t change camber meaningfully, but combined with the tenders that are 0.2” shorter, my camber went from -2.25 to -2.75. Interesting.

 

[Dialcaliper]

Also, I managed to get some new corner weights for the car…at the dump! Dropped off the coolant at the recycling center and they had a scale - it wasn’t busy, so the attendant let me take a couple of measurements. Managed to get the whole car, the rear axle, the right side and the right rear tire and still see the scale readout. Between those I worked out the individual weights. The scale seems like it was pretty repeatable and probably decent to 10 pounds, as they actually charge by weight for big dropoffs, as I got same value for the left front by calculating it out both ways.

Between the new brace and skidplate, the spare tire and my roadside bag in the back, a mostly full fuel tank (instead of ~1/4 like last time), and the new shocks/struts which are significantly heavier (but lower unsprung weight being inverted), the car came out 100lbs heavier than last measurement. (2940lb With 150lb me in the car). Also, somehow I lucked out with a 50.3% cross weight just by eyeballing the left front adjuster, and choosing the “slightly shorter” eBay spring in the right rear

Based on the measurements, it almost looks like I could stiffen the left side springs a bit. I think I’m going to play with some spring rubbers on the left front, and maybe go to a heavier spring or rubbers on the left rear. Making right and left frequencies more closely matched should help some of the side to side “rocking” over bumps (although the sway bars are also responsible for some of that.)

Once I have the setup close to final and the shocks back from FCM, I should probably get a “real” corner balance and alignment at a good shop, just to verify my “shade tree” alignment measurements aren’t too sloppy. Also, need to make up a real toe gauge. Two tape measures flopping all over the place is getting annoying, and setting up the string box takes a bit of time to get right, especially if adjustments need to be made

 

[M-Sport fan]

That above total car weight is with a FULL interior (everything factory still in place behind the front seats), correct?

 

[foodtruck]

The iOS phone app I used for the bounce test was kind of neat - Just called "Vibration" by "Diffraction Limited", and it picks up samples from the phone accelerometers and can pull out frequency measurements.

Could you elaborate on how you performed the test? Was the phone attached somewhere at the front/rear of the car for separate measurements? Did you just drive around for a bit to get the data?