modified struts & suspension

im glad you gave some thoughts about your current setup vs what needed to be tweaked. I know the AWD also helped out there!

what did kierian think about the feel of your FX vs his?

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side note, I found a muffler guy who is willing to weld the fronts for me, but he only has a wire fed welder. He insisted that he has welded frames and other things before and never had a problem. should I trust him or find someone else? I was thinking of going to a small local harley shop (the guy builds bike there)
 
a wire feed mig could do the job although a tig is better, if I was to do mine I woulda mig welded it too, sure it'd be fine if he gets good penetration, gotta really be careful of too much heat though, make sure he understands that the cartridge is pressurized & can blow if he heats it too much, although it really would take a lot of heat to do that really, but any heat directly on the tube & it could blow a hole through the tube from the pressure in the tube too ...


keran was not as impressed as much as I had originally imagined he would be, I mean he did say that it felt good. when we were all done I did ask him if he thought that it handled much better than a stock fx & he did say yeah, he'd say so, but then again, also realize the kinds of machines that it takes to really impress him on the track too, I mean he gets to drive some real monsters out there, & lets face it, the fx is still just an fx, especially with mine having less power than his 45 even right now.

the track was a lot more bumpy & dippy than I imagined it would be, & there is one hard corner right after the long straight that is a pretty bumpy turn. the rear of the fx didn't like this bumpy turn & the rear did get a little out of shape in this section, I noticed this bumpy turns problem even before on the street even & yeah, additional rebound dampening is needed like I said before & that should really help this too. he did comment that all fx's did this, although personally I think this particular problem is reduced quite a bit in my fx from what I feel anyway, but still there to a certain extent... think i'll ask him again for any input he could give,

he was also pretty tierd by the time he got to drive my fx too, was like his 8th session or something for that day, where he normally does just 2 or 3... he was a bit fatigued & I felt bad making him drive my fx & asking him to really push it too but he did & I was really glad that I was able to experience that...
 
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This is where the braces really help. Although I totally agree with the lack of power, they greatly help with the understeer problem. Your ride is different in alot of ways with the new suspension, but since there was such a dramatic improvement on a standard dropped fx, I'm guessing it will apply to yours too.
 
Ok, I don't have time right NOW to read through all of the pages and reply to specific points but John did ask me to give my input in terms of taking his FX on the track. Here's what I wrote blindly not knowing what has or had been said. I'll go back when I have a moment to read through the 7 pages and make any comments I can. It's been an exhausting few days. I calculated this morning that I had ridden in or instructed over 500 miles on the track and driven another 400 miles - all in 4 days! And then drank late into the night with friends I only get to see every few months. Anyway....

I have to admit that I was surprised at how well John's FX handled. I have always been told and have experienced first-hand that cutting coils in springs is a bad thing to do. Everything I have read about the subject has convinced me that it is not a good idea. I relate it to the Honda that you see pogo'ing down the highway as it rides over expansion joints. Before John showed up, I was pretty set that I wasn't going to like the ride because of the cut coils. In speaking with fellow instructors, they believed that it could be done (cutting coils) as long as the spring did not have a progressive rate and you were not cutting on the wrong end. I SORT OF believe the theory but still am not 100% sold. Like I said, I was (pleasantly) surprised by how well John's FX handled and the chopped springs were only evident in ride height. Now that's not to say that I am totally sold on cutting coils and that I'd recommend people go out and do it. Just that I'm less against it I guess.

Anyway, John was at the track on Saturday to do the hyperdrive. For $50 they allow you to do one classroom session followed by a controlled lead-and-follow in a train of cars at a slower pace to see if you'd enjoy this sort of thing. I think John's hooked now :) So John showed up early and I was able to take him out for a ride in my car to show him the track. He was amazed at how well my car handled (240k miles on the original OEM bushings and rubber up front, 10-year-old Falken Azenis, blown struts/shocks, but a decent driver). After John's hyperdrive, I took him out in a friend's car that handles 10 times better and has more HP. I think John enjoyed that as well.

The last session of the day I took John out in his FX. As an instructor I can kind of get away with stuff. The rules say no SUV's but they allow me out with my FX and this is the third other FX they've allowed on the track. The guy letting cars onto the track was like "no way, you're not going out" but another guy who knows me better just waved me out. We got a good 20 minute session in. Now granted I was exhausted from a long day Friday as well as a long day Saturday but I was definitely able to push the car a bit. In the infield it felt pretty decent but still rolled like an SUV would despite being low. I think a major part of that is just the height of the vehicle and no matter how much you slam it, you will not be able to overcome how tall the vehicle is. Unfortunate but a reality. Don't get me wrong; the thing handled like a real champ given what it is! For the body roll it might benefit from swaybars but I'm not sure if there's even a company out there making them for the FX? I wonder if aftermarket bars from a G or 350 might fit at least in the front? The damping seemed to be there both compression and rebound. The only time the car really got unsettled was over a patch in the pavement under a transition part of the track under heavy cornering. I've felt it with my FX on the street where there's a slight depression (like a depressed manhole cover) on the highway as you are going around a bend. It makes the rear end hop around a bit and is a very discomforting feeling especially after doing several laps on the track and really starting to push the car through that section. The car might also benefit from some pretty heavy springs. Not sure what rates the Eibachs are John but they're probably pretty mild. They may even be less than stock as they're probably just meant to lower the car. Some stiff springs (with appropriate struts/shocks to handle the additional spring) would probably minimize body roll too. Key there is appropriate struts/shocks as doing stiff springs with stock shocks would just ruin them in no time. I don't know if there is anyone out there making anything though that could handle decent spring rates. You'd probably be looking at rates of over 1000 pounds. I'm thinking of doing 800 front and 1000 rear on my 2800 pounds SE-R. A 4700 pound (I think) FX would likely want at least 1000f/1200r to handle decently. To maybe compromise to get decent driveability maybe back it off to 800/1000 or even 600/800? To fix the hopping around over the transition I'm thinking it might be because we have an active rear beam and it might be just a bit too stiff (believe it or not) When I used to have a pretty "normal" suspension on the SE-R and I'd go "full hard" it'd hop around like that. When I upgraded to the current suspension, it didn't do that at all. I think it's partially the beam and partially being too stiff. What I'm saying is that even stock it's probably a bit too stiff for the rear beam. Introduce a little more flex and it shouldn't do that (I don't think)

John, in terms of extra power, I think the only place you're missing it is the straights. On the infield you wouldn't have really benefited from more HP. In fact, you might remember there were some places where I was screaming "don't do that" in terms of the tranny downshifting on me. I had a similar problem on the east course which is much tighter of an infield. I didn't notice it except for one place when I drove my FX somewhat hard at Monticello last fall. But there were 2-3 places between the two infields where, if I gave it a little too much gas, it'd downshift and the car would just want to understeer off the track. I guess I could've negated that with manual shifting but I hate shifting manumatics. If you were going to add more HP John, it'd have to be progressive somehow so that you don't get too much power and wind up being pushed off the side of the track by your car!

All told it was definitely fun. I was slowly catching an E30 M3. Another 2-3 laps and I would've been able to pass him. Like I told John, there was a crowd gathering that was watching the underdog SUV catching up to the M3. I spoke with other people later who said that they were laughing as they were watching me muscle the FX around. People love to see it!
 
thanks keiran for taking the time to give your input here.

there is one thing I'm not too clear with though on what you're saying. at first you said:

"...The car might also benefit from some pretty heavy springs. Not sure what rates the Eibachs (I'm on H&R's btw) are John but they're probably pretty mild. They may even be less than stock as they're probably just meant to lower the car. Some stiff springs (with appropriate struts/shocks to handle the additional spring) would probably minimize body roll too...."


but then after this you said:


"... To fix the hopping around over the transition I'm thinking it might be because we have an active rear beam and it might be just a bit too stiff (believe it or not) When I used to have a pretty "normal" suspension on the SE-R and I'd go "full hard" it'd hop around like that. When I upgraded to the current suspension, it didn't do that at all. I think it's partially the beam and partially being too stiff. What I'm saying is that even stock it's probably a bit too stiff for the rear beam. Introduce a little more flex and it shouldn't do that (I don't think)..."

from reading this I'm not sure if your suggesting that it's too soft or too stiff?

I'm also not too clear on what you mean by "an active rear beam suspension" we have a dual link, unequal length, non parallel bar independent rear suspension on the fx....



I do realize that I still have a bit of work to deal with as far as the body roll, that combined with not enough front negative caster & just the excessive weight of the fx will contribute a lot to wards understeer, & I'm sure the staggered wheel setup with the wider contact patch in the rear doesn't help this any either. my goal for better handling will be to reduce this understeer & try to bring her closer to neutral or even a bit towards the oversteer side of things ideally. I do believe that she does now handle better than a stock fx, but I don't believe at all that this is as good as it can get, I intend on making her handle even better than she does now, at least now I do have a target & a baseline to go from...



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now, on the subject of cutting a coil spring....

as far as cutting a coil, I knew you were a big opponent to this in general & I do understand why, I also agree with you that it is not a good idea to just advise "sure, go ahead & cut them" as this can certainly have the potential of turning a safe car into the pogo stick ricer your talking about no doubt, BUT I do believe that there are certain times & certain situations where cutting a coil can actually be beneficial too, & I do know a lot of pro car builders that will even do this in some situations. I agree this shouldn't just be done blindly or without fully understanding the cause & effect of what it is your actually doing though, but as far as my spring cut goes, it is not too hard to actually calculate the effects either, I calculated mine to be an increase in spring rate of a bit less than 20% increase in spring rate,~16% increase or so, while still not allowing the spring to fully compress & allow the spring rate to rise to infinity of course.

realize one thing, all coil springs that are designed as a continuous coil on one end, by design, are "cut" or ended at some point, a coil spring is just a long torsion bar that, for the sake of compacting the design, is wound into a continuous coil which is then "cut" or ended at some point. the only difference is that where they are actually "cut" is initially determined by the manufacturer & is determined by the end desired spring rate & overall height of the spring design as intended by the manufacturer. the overall spring as designed is specified to be in such a way that will suit the average user in the average use of the spring. when you do cut additional material off you are #1 increasing the spring rate & #2 you are obviously shortening the overall spring length & therefore the static ride height. you are also of course decreasing the usable "stroke" & the spring will bottom sooner as you take length out of it.

I always stress that no spring should ever be cut at a formed end unless you are prepared to properly alter the spring seat to compensate for this, which is why I'm against cutting the rear fx spring at all. that's just not safe, as the end of the spring is specifically designed to mate to the spring seat at a certain angle, & if this tail is designed to be at a different angle than the continuous coil by a formed end, then the cutting of it will alter this angle & put additional stress on the spring at the transition point at or just past the seat & theres a good chance the spring will actually break at this point, as it is seeing more stress at this point than anywhere else along the length of the spring. same thing applies to a variable rate coil... a variable rate coil will have a certain portion of the coil wound progressively tighter than the rest, & is designed in such a way that at a certain point of travel the coil will actually be proportionally bottomed in this progressively tighter coil area, thereby leaving only the remaining coil to act as the sole spring, & the fact that this portion of the coil is now effectively shorter, it will of course have a proportionally higher spring rate at this point, which is how a progressive spring is formed to begin with.

as long as the coil is continuous until the very end with no forming at the end, & it is not a progressive design, then cutting the coil is a matter of math, the spring rate is calculated by the torsion bars resistance to twisting times the length of the torsion bar, which determines the amount of leverage on the torsion bar, so if a coil at stock length has a value of X as a spring rate, then removing a portion of the length will have a direct impact on the overall spring rate by as much as is removed. in other words, if a coil spring has a total of almost 5 active coils (not all of the coils are actually active), & you go & remove one half of one coil, you will be increasing the spring rate by less than 20% overall, so the resulting spring rate will wind up being ~ X -(15%) = Y (new spring rate). as long as the new spring rate & height is enough to still not cause the spring to bottom, then the end result will be exactly the same as if the manufacturer of the spring happened to spec it at a rate of Y to begin with.

don't get me wrong, I'm not trying to convince you to believe other than you do on this subject, just trying to share my understanding of what's actually involved with the cutting of a coil spring... I do agree 100% that cutting of coil springs is usually done without the full understanding of what the end effect will be in many cases & in many cases the end results are not good, many guys just think that cut the coil & lower the car, of course it is not that simple, but I do believe that in some cases it can be a not so taboo thing either & if you happened to ask a spring manufacturer to alter the spring rate of one of there coils one possible way they would design a spring with a higher rate would be to use a bit less total length of the torsion bar that a spring is made from, effectively cutting the coil spring. we as end users don't have the luxury of specifying an alternate torsion bar diameter to increase the torsion rate of the spring steel itself, which is of course another way that a spring manufacturer can increase a spring rate significantly, thicker bar with more coils, thinner bar with less coils... in the end though re engineering the spring by altering the total length of the torsion bar is not as detrimental as some would believe...


all this being said, by cutting a 1/2 coil in my fronts, & not cutting the rear at all, I have winded up making the front spring rate proportionally higher than the rear at this point, & this is also something that can & does affect the overall balance of the vehicle. I am compensating for this atm with my adding of an air shock to the rear, effectively adding to the rear spring rate & balancing out this imbalance to a certain extent, but I am still considering other ways of correcting this without so much of the band-aid approach that the air shocks are... one thing I am considering is using an eibach spring in the rear as they are known to have a higher spring rate than the H&R's, there def more stiff than the H&R's out of the box, & a H&R front with 1/2 coil removed may wind up being proportionally more correct to a stock rear eibach.


I will continue to work on improving the handling of my fx & I think we'll both see just how much better I can get this to be by the time we hit the track again... I won't be satisfied until I can get this thing to really handle like a beast. anti roll bars is another area that I can work on too & I'm pretty sure I can come up with something.


to build the fx to be the best it can be on the drag strip can take tons of $$$$ but to do the same on a road course track is more a matter of tinkering & testing & tuning... def a fun thing, thanks again for your initial push to get me to try this, now I wanna be able to more easily beat an m3 on the track though :tongue: ...
 
thanks keiran for the insights.



btw I didnt know the "Stig" was driving your FX? lol




1
 
had to google "the stig", didn't know wtf you were talking about :rofl:

dave, I'm glad to see you have that much confidence in the bars after installing them on your fx, I hope to see a nice difference with them, if they help with the wiggly ass it'd be really cool, & if they do help some in the understeer that would be even better, but I don't think that they alone would just cure all, even if they do resist flex & resist the front camber roll a little I don't think they could fully solve it, right now my footprint & contact patches in a hard turn like pictured above looks something like this:


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the bars might help a bit, the more the better, but it'll still have the problems of the uneven front contact patch & the excessive body roll I think. really for best results it'll probably take realigning the car for track setup before hand, & then realigning again for normal everyday driving after. aside from springs & shocks & anti roll, the alignment plays a big part too, more negative camber for a flater contact patch on the outer front wheel would help a lot. be nice to have an adjustable plate type setup at the top of the strut so camber changes can be made easily, might be able to adapt something for this...
 
Dunno. It was night & day for me once they went on. I guess every setup is goon react differently, but I have to say, I'm sooo dialed in right now. Before, I was pushing terminal like a bonehead pretending that I could actually track the thing
 
guess you'll be in the shop tomorrow makin some mods . . that is unless you're gonna work through the night. I'll expect a 10 page writeup tomorrow
 
haha, no, not going to screw with this any more any time very soon... rides & handles good for now, I'm done for a little while, just had to at least get the drop done so the wheels really fit, done enough at this point really, later I'll get back to it, most I'd do soon is try to swap out the rear springs for eibachs & swap out the rear shocks maybe...
 
sounds good John, just realized its 3:00 where your at.. :coffee: lol

I was thinking, your brought a street car to the track and it was hanging with the "track" cars :rock: wow. of course stiffer suspension would be ideal for the track,but it would be too bumpy for the streets. (as you know)

turbocad, your FX is a streetcar and bad ass one at that!
 
You are definitely walking the path that I hope to. The difference is that I'm not an experienced fab guy. So when you figure out the parts, I'll be installing them, as long as I can buy them!

My vision for my FX is pretty much the same - I just want well rounded street beast. Handling is important and I want to retain the FX luxury SUV core feel (which is a sport inspired cross-over), so I won't be making hardcore track mods.

I have the full set of GT Spec braces and there really is a big difference. My rear end still hops around when cornering fast on uneven road, but I think the right set of tires would help out a lot too. Body roll is a problem just because of the weight and height of our car. If you stiffen up the springs /suspension, I think it will feel tight and rough at normal driving speeds, and then soften up at higher/track speeds. Cool if that's what you want. I have seen adjustable coil-overs that might give you the best of both worlds - daily adjustability for your driving application. Might need to fab a bracket or interface for it to fit up with our FX - but that's well within what you can do, based on what I have seen.

The write up and your baseline is invaluable. Great information.
 
Jumbo, you're spot on. Your sneakers are holding you back, & handling will be drastically different with a low profile & wider tire. One thing to add on John's dream Luxo feel, are those braces again. They remove the vibration out of the road, so you really get that Lux feel at the wheel.
 
if anyone just skims this thread, or doesn't read everything I post in my long novels here, at least fully read this post:




guys, let me just say that all the time I'm talking about my fx handling really good, I'm pretty much talking relative to a stock fx, not relative to a track car at all. it would be exagerating big time to insinuate that my fx now handles anywhere near as good as a track car, trust me, that is not the case at all... it handles pretty good right now for what it is, but it is no where near a monster yet.

I don't want anyone to get the wrong idea & to think that I believe, or that I'm insinuating that my fx now handles as good as a great handling car, trust me, it does not... not yet at least. the fact that we were catching that m3 could be due to many reasons, we really don't know how hard that m3 was really pushing his car, nor how great of a driver was behind the wheel of the m3 to begin with, & the fact that kieran happens to be a really great driver does come into play a lot here too...


I do intend on trying to get it to be good enough that it can handle close to as well as a good handling car, but also realize that there are laws of physics that are much more difficult to overcome, just the sheer weight & mass of the fx alone will dictate that it will probably never really out handle a real perfomance car that is much lighter & much better suited to the job.

I'll keep this post short & sweet so no one misses what I'm trying to say here. the main reason for all this posting & all this track feedback is just to simply show & to even prove that it is possible to drop the fx significantly by modifying the suspension without ruining the ride & handling, & maybe even improving it at the same time, not that the fx will be a monster with just this mod...

the main point of this thread is to show how I modified my suspension to give a 3" drop while not taking anything away from the ride & handling of the fx, not to say that I have created a monster here, it is very good & very impressive for what it is, but don't want anyone to believe that it is more than it really is...
 
On any forum there are only a few top-tier cars and on the scene, yours has gotta be up there. We're all FX enthusiasts here and while some of us have had other more capable track cars, most of us are just trying to make the FX all that it can be, because it rocks and we want it to rocketh even more. The only real limitation to that is time and money.

I'd never assume you can compete with a similarly equipped WRX or EVO, but I wouldn't want to. If I wanted that, I'd buy it! But I do appreciate what you are saying, even though your standard seems to be much higher than mine will ever be. More power to you though - the top tier car guys are the ones who discover the limits for the rest of us.
 
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