MS6 Suspension Data & DIY Bilstein Coilovers

[phate]

Before we start a debate about knobs and whatnot, let's talk about driver consistency. This is actually part of what I wrote to BC racing (lol) and never got a reply back:

For the adjustment stuff - I absolutely love the idea of being able to adjust everything, but I don't have any sort of data acquisition system to analyze changes. I'm a fairly consistent driver, but looking back over this season's autocross results (16 events), I know that the majority of my runs (94% - 2 standard deviations) fall within ± .96 seconds of my average run. If I make an adjustment and it doesn't make the car faster or slower by a huge margin, I don't have any idea whether it's a good adjustment or not. Whether or not the car feels better could be the result of decreasing grip on one end and ultimately being slower. Analyzing changes could take multiple events, and even then it may not be enough of a difference to definitively say whether it is faster or slower.

[Code Monkey]

Just dropped off my perches and talked a bit more about my alignment specs, will post more details tomorrow in my coilover thread but one of the main points is that our (ms6) suspension geometry is such that it requires more negative camber in rear than in front. Also, the maximum they would have the front lower than the rear on this car is 6mm, has to do with the rake angle.

[phate]

Sounds right. To get even heat across the tires last season, I was running -2.1° camber up front and only -1.5° in the rear. The front doesn't gain negative camber as fast as the rear in the first portion of wheel travel from stock height.

[Code Monkey]

Originally Posted by phate Sounds right. To get even heat across the tires last season, I was running -2.1° camber up front and only -1.5° in the rear. The front doesn't gain negative camber as fast as the rear in the first portion of wheel travel from stock height.

Sorry, edited above -- more camber in rear than in front. I will post my alignment sheet once I get the car, I am supposed to pick it up tomorrow after work.

[jbbuie]

I also have been in contact with BC about custom valving. They said they could valve to my specs and could supply a shock dyno upon request. Still skeptical about that though. I actually was trying to get a elite setup from Shaikh and had email convo about what my setup should be, but didn't happen due to bad ordering timing i guess you call it. So since I had no patience, I ordered the BC instead and swapped the springs and spring rates (500 front 375 rear). Once Shaikh contacted me after I purchased the BC he was kind enough to dyno test the front and rears and it was pretty much what we figured, generic valving.

Also, @phate @codemonkey thanks for sharing all your info with your setups as it has proved very informational and pertinent to me setting up my car.

[KevinK2]

For sprung mass frequencies, you need a target to shoot for. If someone has a Mazdaspeed that's at the Nationals for autox, or is always the fastest in road course events, racing or HPDE, use those frequencies if available.

One frequency violation I could justify is more front biased spring rate to minimize dive and geometry changes during hard braking from high speed.

One way to understand sway bars is to first focus on the more conventional front bar. Then recognize that for cornering, in most cases, the suspension on the outside compresses, and on the inside the suspension extends. So the sway bar lever arm swings down on the extending inner side of the car, and swings up on the compressing outside. With equal but opposite rotations of the lever arms, in the ideal case, you find that at the mid-width of the bar (center point between bar bushings) the bar does not twist at all.

It is as if it were welded to the frame at this mid point. So in a corner, steady state, it's like having a pair of torsion bar springs, like those used on most older Porsches. The sway bar behaves just like a spring, and has it's own spring rate, and Motion Ratio, so just like with a coil spring, you can calc the effective spring rate from the bar, at the wheel.

.

[phate]

Originally Posted by Code Monkey Sorry, edited above -- more camber in rear than in front. I will post my alignment sheet once I get the car, I am supposed to pick it up tomorrow after work.

Interesting. Was that a suggestion from Shaikh?

[Code Monkey]

Originally Posted by phate Interesting. Was that a suggestion from Shaikh?

Never got a straight answer from him:

"Ultimate camber depends upon tire temps. You got to have a pyrometer - you already do, right?? But depending upon the loading on the tires you will make the camber settings different as the tires tell you. I can't tell you *exactly* how much but again, tire temps and overall handling balance will help you (and me) decide what to use. That sound reasonable to begin with - what are you current tire temps? (am I making my point strongly enough?? ."

I am not upset, Curt at the suspension place gave me a similar answer -- it depends what I use the car for -- ok, road racing -- do I go into turns aggressively? what tires am i running? what are my lap times?, etc. I will start with the recommended setup from him and we will go from there.

[phate]

Originally Posted by KevinK2 For sprung mass frequencies, you need a target to shoot for. If someone has a Mazdaspeed that's at the Nationals for autox, or is always the fastest in road course events, racing or HPDE, use those frequencies if available. One frequency violation I could justify is more front biased spring rate to minimize dive and geometry changes during hard braking from high speed. .

No one has prepared an MS6 to that caliber that I'm aware of. Code Monkey and I are probably on the extreme end of things, we've been learning as we go, and there's definitely going to be more learning to come.

[KevinK2]

The answers you have been getting on camber are correct ... it depends.

The stiffer the roll rate, and the wider the tire (with less aspect ratio), the less camber you should need.

These recomendations were for an Rx7 TT, but they cover a lot of cases and may be of use:

pettitracing Alignment Guide Table

This was a MS6 alignment guide I put together some time ago, and some others replied back with what worked for them.

speed6-alignment-spec-not-good-enough

.

[Mazdazilla6]

@jbbuie; How do you like your BC set up? So did you get swift in the front? And what spring are you running in the rear?

[phate]

Start a new thread.

[jbbuie]

Originally Posted by Mazdazilla6 @jbbuie; How do you like your BC set up? So did you get swift in the front? And what spring are you running in the rear?

I am running QA-1 springs front(500) and rear(375) I would have went with the swift but they couldn't get close enough to the 500/375 spring rates i wanted, in fact the guy at BC said the only spring that they offer for the rear is the progressive rate 450lbs spring. After swapping out springs, I like it much better. From the dyno test, Shaikh recommended not going over about 12-13 clicks from soft and that seems to work much better with the softer springs.

[phate]

Everything should be in the car this weekend! I just received a tracking # from FCM and expected delivery is Wednesday. I'm going to put a bracket on the front upper spring perch to hold the spring in place under full droop before it goes together, but I think everything else is set.

The earliest I'll be able to corner balance it is some time next week, but it may not happen until the week after.

[KevinK2]

Originally Posted by phate .....The earliest I'll be able to corner balance it is some time next week, but it may not happen until the week after.

Do you disconnect the bars when balancing? I had a friend's car on scales, bars connected, and moving a battery side to side in the trunk caused unexpected results on the scales. I would think disconnect them and weight the driver's set, then connect bars same condition with no preload.


.

[phate]

Yes. Bar's unhooked on one side with driver (or equivalent) in the car. I made adjustable end links so I could set the bar angle and avoid preload.

I may actually corner balance the car with a passenger, since I'd guess I have a codriver or passenger >90% of the time. I'll have to see how much a passenger throws off the corner weights. It might not be enough for me to worry about.

[phate]

And on that note, I've been running these up front for the past few months:



Not sure why I never added them to the thread, but they're really cheap end links that were pretty easy to make. They're ~40% of the cost of AWR rod end end links, and the rod ends themselves are WAY cheaper to replace. I'll post later with the details of them and add the info to the second post, also.

[phate]

We've come a long way. Everything is installed and went together great! The worst part was fitting the shock boots through the 2.5" springs up front, lol.



Bump stops in the front and no bumpstops in the rear for now (more on that later).

Since I hadn't test fit the entire front assembly before today, I started with it. I was mildly concerned with having the spring unseat at full droop so I went ahead and made little brackets to hold the spring to the spring perch. They do their job.




I wanted to set up initial ride height at the minimum I thought was acceptable - which is having 3" of bump travel from normal ride height. The front suspension tops out when the UCA contacts the shock tower, when the wheel center is 11.0" away from the top of the fender. So, I set front ride height to 14".


^You can see in this pic that the brake line is on the opposite side of normal. I swapped the left and right shock fork things so it put the brake line towards the front. The passenger side was showing signs of rubbing behind the shock so I thought it best.

Up top is what I showed before, it just has a shock going through it now, haha. I used the shorter standoffs because it doesn't need any more height. Don't mind the double flange nut, I didn't have any jam nuts for the shock rod. I'll get those later.



Front end looks something like this for now:







In the rear, I checked for ride height by topping out the suspension where the LCA stop contacts the frame stop. That occurs at 11.25", so I set ride height to 14.25".



While I was back there, I inverted the Bilsteins



The rear looks the exact same as when I tested it, just with inverted Bilsteins. No pics because it's late. I'll get pics of the car after it is aligned and corner balanced tomorrow!

Initial impressions say it is more tame than I expected. You know it's there, but it's not at all harsh. We took it for a test drive and it takes bumps like a champ. Body roll is significantly reduced and the car feels sharp (but definitely needs an alignment). I'll have it out autocrossing next weekend, so that will be the real test.




Overall, I'm pretty happy with it. Everything went together smoothly, no issues that I had to fix, no crazy sounds on the first drive, haha. So far so good!!

[TiGraySpeed6]

What's the benefit of flipping the rears again?

I'm also looking forward to your thoughts after getting a few auto-x & some miles on em!

[KevinK2]

inverting them can:
- possibly make damping adjustment easier
- puts the heavier housing end attached to the frame at the top, and the lighter rod end at the bottom, to reduce the added unsprung weight.

BTW, the upper rears need to be installed and tightened at an angle, so the upper bushing is not twisted in the parked condition. I'm sure phate did that.

.

[phate]

Originally Posted by KevinK2 inverting them can: - possibly make damping adjustment easier - puts the heavier housing end attached to the frame at the top, and the lighter rod end at the bottom, to reduce the added unsprung weight. BTW, the upper rears need to be installed and tightened at an angle, so the upper bushing is not twisted in the parked condition. I'm sure phate did that. .

Yep, I did it because it moves a small amount of unsprung mass into the sprung mass. Not a big difference, but it doesn't cost anything and didn't take any extra time.

The rears are just a pain. They were put in at an angle, I'm not sure if the picture really shows this. They weren't binding when I attached them to the knuckle.

[KevinK2]

I read the links you posted about selecting springs, and frequency targets. I agree with their point about the front's having a higher freq vs the rear, in most racing cases. That will reduce brake dive and the related suspension geometry changes.

And when I hear someone like Shaikh saying forget the physics involved when looking at the rear spring and the obvious small motion ratio, and telling phate that .75 seems to work better, that big change tells me his program, or logic, is not correct.

I have a working Excel program I developed for my M6 based on a fellow Mechanical Engineer / racer, Fred Puhn. It does not include frequency calc's, but includes the effect of sway bars. You would have to do a bench test on a rear bar to get an accurate rate. I've bench tested bars for my Rx7 FD bar set.

I used the program to select a rear sway bar for my stock M6, looking for just a little bit of understeer, and the Steeda 22.5mm rear I have now vs 18mm oem, does exactly that, with NO fudge factors used. On a 25 mph, 200 degree entry ramp, I was doing 55 and at the limit the car would 4 wheel drift with a trace of understeer. Perfect for DD, but more bar would be needed for Autox or track events.

The program was intended for my use, so there are calc's all over the place, but clearly labeled. It needs some explanation on how to use it, but you are welcome to use it and then use it as a check with the program you are developing.

BTW, This thread is EXCELLENT ! Great work

.

[Code Monkey]

Originally Posted by KevinK2 And when I hear someone like Shaikh saying forget the physics involved

Where did you hear it, I must have missed it.

[KevinK2]

From phate's 1st post:

"Rear LCA Pictures: Pic 1 - Pic 2 - Pic 3 - Pic 4 - Pic 5

The bump stop point is an estimate, but the three important dimensions (similar to above) are:

Dimension A: 10.27"
Dimension B: 17.93"
Spring Angle: 0° (there is some deflection because the spring is bending slightly, but I'm planning to take care of that later on)

So we get a spring motion ratio of: .57

***Edit*** - The spring motion ratio found using actual ride behavior, determined by Shaikh at Fat Cat Motorsports, acts more like a .75 MR. I will be using this figure unless I find otherwise after it's all together. "

Since the wheel rates are based on the MR squared, then the resulting excessive rear wheel rate is 73% higher than the laws of physics and any paper on suspension design says it should be.

.

[phate]

I agree that it doesn't make sense, and I want to investigate why it doesn't follow the standard. But, I believe Shaikh has a degree in physics and he has an excellent track record of making winning suspensions.

From the little bit of driving we did last night, I think he was spot on. If the rear had lower than necessary roll resistance, which it would if the MR was way off, I would expect it to be an under steering turd. It wasn't, though, even with more negative camber in the rear than necessary.

[KevinK2]

Originally Posted by phate ... From the little bit of driving we did last night, I think he was spot on. If the rear had lower than necessary roll resistance, which it would if the MR was way off, I would expect it to be an under steering turd. It wasn't, though, even with more negative camber in the rear than necessary.

There is a reason why it was not an understeering turd.

I recall your natural frequencies were (2.2/2.4Hz front rear), using a ficticiously high rear MR. The typical desired frequencies, based on the the informative links you posted on the subject, would have a front bias of 10%. By selecting the high rear frequency, he apparently gets acceptably high rear spring rates. (Note a 10% bias means the spring rate is increased by 20% over a neutral balance, due to the square root.)

You add that to the increase in rear bias for the sway bar pair, and understeer is not a problem.

At .75, the motion ratio by definition is way off, but suits his less than logical, successful methods.

.

[phate]

Originally Posted by KevinK2 I read the links you posted about selecting springs, and frequency targets. I agree with their point about the front's having a higher freq vs the rear, in most racing cases. That will reduce brake dive and the related suspension geometry changes. .

I think the sources I linked suggest a higher rear frequency than front, by 10-15%. That's just to achieve "flat ride", where the rear settles at the same time as the front over bumps at speed. No matter the MR, I would have gone higher in the rear than the front. Numerous publications cite those splits, though the physics behind them is gray beyond saying it is to achieve flat ride.

[KevinK2]

Originally Posted by phate I think the sources I linked suggest a higher rear frequency than front, by 10-15%. That's just to achieve "flat ride", where the rear settles at the same time as the front over bumps at speed. No matter the MR, I would have gone higher in the rear than the front. Numerous publications cite those splits, though the physics behind them is gray beyond saying it is to achieve flat ride.

You are right, the links suggest a higer rear frequency, to avoid pitching after a bump across the road.

Personally, I was never concerned with ride freq's when I made my spread sheet. For me, it's all about the weight transfer balance and roll in a steady state corner. A frequency check is good to see how stiff the ride will be, as you can bend your knees and move up and down at 1 cycle per sec, 2, and 3, and you can predict a rough ride at 3 hz, that will be useful only on smooth tracks. But for mixed use cars, frequency would be important.

This site is full of smart automotive engineers. There is a good frequency question, and some say not to worry about it for a tracked car.

www.eng-tips.com sprung mass natural frequencies

On my first couple years autoxing, I had built my Triumph to the scca DP class rules, + trip DCOE webers. It had no rear bar and needed it, so I designed one, 9/16" 4140 rod with 5 holes in the lever arm, and 5 sets of bushing mount holes so the endlink was always vertical. I used the mid point at big tracks, and 1 step stiffer for autox, winning my classs in years 2 and 3. I did have one major problem with severe pitching on a concrete highway. The seams in the slabs created perfect excitation. My head was almost hitting the roof bottom. A freq check would have been a good idea.

EDIT: For those that are setting shocks just for track events, this Link includes an excellent article from Koni about how to adjust your shock's damping, compression and rebound:

rx7club.com/suspension-howard-colemans-fd-chassis-setup

Just as I would install a stiffer sway bar set on my Rx7 just for the HPDE season, one might do the same with shock damping adjustments.

.

[phate]

Originally Posted by zenit An alternative to the bearing is a single sheet of Teflon or swift's spring sheets. Cheap, thin and not prone to contamination.

I used teflon sheets in the rear to help the adjusters move while the suspension was loaded. Before, I couldn't turn the adjuster when there was any pressure on the rear spring seat and had to unbolt the LCA. That was a huge pita. I cut some rings out of a sheet and put 2 on each spring. I can now turn the adjusters very easily to adjust height by just unloading the suspension. Works great, thanks for the idea.

[MS3johanna]

I'll leave the more thorough review to Clint, but I've gotta say- the coilovers are wonderful. We co-drove the hell out of his car this weekend, averaging 8-9 runs each per day. The courses were varied too, offering a chance to test it out on virtually every course element.

First, a quick word about the first time the setup has been driven on all seasons during our our way up. The softer sidewalls don't appreciate the stiff suspension. They were super reactive. It almost felt like they were sucking into every small adjustments. But anyway, those are just all season. That's not what I'm really here to talk about.

The car is an absolute joy to autocross. It can transition aggressively without getting upset, and handle sustained turns very predictably. It really rewards smooth, fast input; I found that it doesn't really need more than that to make it around any course element. Thankfully it has also lost that "slow" turn-in/transition that I've always attributed to the 6's (and pu's). All in all, it's reactive, predictable, quick, and a TON of fun. Thanks for designing such an awesome setup, Clint!

[phate]

I've done 7 autocrosses with the new setup, so I figured it's time to write some follow up for the suspension.

Driving Notes

Good lawd everything is simply BETTER. Reduced body roll in corners, reduced dive under braking, and reduced squat under acceleration. Grip is way up, and braking power seems to have skyrocketed. Everything happens faster - the car settles so quickly from input to input that I'm able to give inputs faster one after another and I don't have to wait or worry about upsetting the chassis or tires.

That means I'm able to stay on the gas longer, get into the brakes much harder and later, and I don't have to turn as early because I'm no longer waiting on the car to change direction. That has really taken some time to get used to. When I first put everything in, I found myself starting to brake way too early and coasting to corners. I also found myself turning in too early and mashing cones with the front of the car, haha. I've really focused on that and have found major improvements in driving the car effectively.

Installation Notes

Everything went together without any changes The top hats need to be assembled in order, but it doesn't take much time at all. Attaching the springs to the upper perches in the front suspension is nice since I can pull the shock separate from the assembly. The fronts are easy to adjust, similar to most coil over setups. The rear is now easy to adjust with those teflon sheets. I definitely recommend using them, it'll make corner balancing much faster.

I had the car corner balanced and aligned immediately after installing everything. We achieved 50.0% wedge with only a driver in the car. Johanna codrives ~90% of the time, so we checked it with both of us in the car and it only shifts it .1%. Driving it both with and without a passenger, I usually can't tell a difference.

While installing everything, I noticed the SS brake lines showed signs of rubbing on the shock tower behind the spring. I swapped the lower shock mount between the two sides, which puts the brake line on the opposite side. Seems to have alleviated the issue.

If you have the Whiteline rear ARB and want to use the stiffer setting, you may have to clearance the portion of the LCA where the end link comes through on top (the squarish cutout on top). You need to check the clearance between the end link shaft and the control arm through the suspension's entire range of travel (pull the spring out and jack it up). The clearance decreases as the suspension compresses, so it takes more room than you might expect initially.

Setup and Fine Tuning Notes

Now that I've driven the car at several autocrosses, I'm finding that I like more rotation now that it is able to oversteer more easily. I went from the softer setting of the rear ARB to the stiffer setting for the last autocross. It definitely helps, and seems to have picked up some front grip at the same time. With this setting, though, it's nearly picking up a rear wheel in corners...I also don't like how this setting handles bumps that aren't hit straight on (where the tires hit bumps at different times), so I'm likely going to try a stiffer spring in the rear to start with and go back to the soft setting on the ARB or maybe even go back to the stock rear ARB. Shaikh has given me the green light and said the damping will be able to handle this increase (same for the front, if necessary).

The alignment is a work in progress. I thought I was close to optimal, but stiffening the rear ARB threw things off and it needs altered again. I'm using the heat gradient across the tires to set my alignment.

Damper revalve and Fat Cat Motorsports

I wrote this over here, already:

This suspension was designed primarily for autocross, and my typical surface is a bit rough. We are on old concrete and adjoining slabs can be uneven, which makes cornering over them at full tilt a little tricky. The suspension had to be able to handle this at full speed without upsetting the tires or chassis. When I went through the consultation process with Shaikh, we discussed this at length. We talked about what I was doing with the springs and coil over conversion, so he was familiar with what I was doing and what I had in mind. We talked about damping characteristics for my driving style and preferences. They pretty much nailed it. Damn is it impressive. The car sucks up bumps like you wouldn't believe, and I have sprung mass frequencies of ~2.1/2.3 Hz front/rear. Even driving it around town it's good. It is most definitely firm, but in no way harsh. I don't feel any jacking up or down over successive bumps at any speed, so there doesn't seem to be an excess of either compression or rebound. I can't find anything bad to say about the damping. The process of getting the shocks revalved took much longer than I expected. Overall, I'd say it was worth the wait. I cannot find another company that offers this level of service for anywhere close to this price. Coupled with the fact they're using Bilsteins and you've got a great combo. Today, I was impressed once again by Shaikh. I emailed him some follow up information about how the car was handling and some info about setups and what I had changed and the effects of those changes. He sent me back some seriously good information about fine tuning the car to get the most out of it. So, it's not like you pay them some money for some black magic and they disappear - you get post process advice to maximize your setup.

And a few pics from the last autocross:








Future plans

I'm going to go ahead and try the poly bushings in the inner side of the front LCA (the small, straight arm). I know CanyonRider had some issues with them wearing out quickly, but that set is only $30 so I think it's worth a shot.

I'm going to work on the rear suspension bushings over the winter. Mainly converting things to poly, and working with eccentric bushings to attempt improving a few characteristics. Much more to come on that front

[TiGraySpeed6]

Are you doing your own alignments now?
Seems like it would be something you could benefit from if you're not, especially so if you're going to start tinkering with LCA bushings again.

I finally opened up the rear LCA for the end links- I ended up opening it up all the way forward, but didn't go any more inboard. There's very little clearance to the rear/inside of the end links tho, so I will probably open up that side of the hole as well.

[phate]

Originally Posted by TiGraySpeed6 Are you doing your own alignments now? Seems like it would be something you could benefit from if you're not, especially so if you're going to start tinkering with LCA bushings again. I finally opened up the rear LCA for the end links- I ended up opening it up all the way forward, but didn't go any more inboard. There's very little clearance to the rear/inside of the end links tho, so I will probably open up that side of the hole as well.

Not yet, haha. I would need to make some adjustable height pedestals so the car sits level, and they need to have a sliding plate on the top so the suspension can unbind. I also need a camber gauge and toe gauge, both of which I can make. I'm not totally convinced I'll do it, but I've been considering it.

[KevinK2]

Congatulations phate, taking the slow but tecnically correct path has really paid off.

I like your idea of going with more spring in the rear, vs a bar at the stiff setting that works in some crazy endlink-to-bar angles. You may even use the slotted hole method to get that link vertical in the laden position. Your target F & R ride freq's will not change much as it's based on the SQ-RT ( K/M ), so 20% stiifer rear springs will only change the rear freq by SQ-RT [( 1.2K/M )/(K/M)] = SQ-RT (1.2) = 1.095, ie 10%.

It will be interesting to see how much more rear spring you need. Remember FCM altered the true MR of .57 based on geometry, making it more efficient with a FCM supplied .75 MR, which provides less spring rate.

Do you have same courses or close compediters to compare times with, to measure improvement?

Again, well done!

.

[phate]

Thank you. I'm really happy with it and more importantly, I've learned a great deal throughout the process.

We don't run the same courses, but we do have a few "measuring sticks" that I keep tabs on. Very fast and very consistent people, some of whom have trophied at the national level. It struck me over the past weekend that I really was going faster because I was within half a second of one of them and wasn't much more off at the event prior, where last year I was around 2 seconds slower.

I have ~4 weeks until the next autocross, so I have some time to mull things over. I think I'm leaning towards stiffer springs, because I don't want to wait for bump stops to engage after the initial turn in.

I'm a little disappointed that it took so long, because I don't have much time for fine tuning before the season ends. We have 2 weekends left until we take a 3.5 month hiatus for that "snow" stuff.

[KevinK2]

Originally Posted by phate ... I have ~4 weeks until the next autocross, so I have some time to mull things over. I think I'm leaning towards stiffer springs, because I don't want to wait for bump stops to engage after the initial turn in. ...

I forgot what front bar you went with, but increased front roll stiffness wll result in quicker turn in, and less roll to prevent the rear inside wheel from lifting. The chassis is stiff enough to assume the front roll angle is equal to the rear roll angle. I know steeda has a 26mm front bar, and there is a 28.5 out there.

Did you use one of the online suspension calculators, that I previously linked, to check out the roll stiffness bias? You have already measured all the difficult data needed.

Lastly, could you get a pic of the side of the car parked? Nice to compare it to the side shot on the track.

.

[phate]

Originally Posted by KevinK2 I forgot what front bar you went with, but increased front roll stiffness wll result in quicker turn in, and less roll to prevent the rear inside wheel from lifting. The chassis is stiff enough to assume the front roll angle is equal to the rear roll angle. I know steeda has a 26mm front bar, and there is a 28.5 out there. Did yoy used one of the online suspension calculators, that I previously linked, to check out the roll stiffness bias? You have already measured all the difficult data needed. Lastly, could you get a pic of the side of the car parked? Nice to compare it to the side shot on the track. .

I still have the stock front bar, and I think I'll leave it for now. When I moved the rear bar to the stiffer setting, I noticed more front end grip - it felt better and it started to heat the outside of the tires more than it had been (even though there is more total roll stiffness). I think it's just too much front bias right now. Since I put the suspension on, we've noticed the front tires are getting worked much harder than the rears, in terms of wear. I'm going to continue increasing the rear roll stiffness while leaving the front (for now), because it seems to make the front tires much happier, and I have available play items in the rear to offset the reduced grip from the extra load. Meaning I think I'll be able to bring up front grip while maintaining rear grip.

I put together my own suspension calculator (based on Staniforth's methods) that includes calculations for roll stiffness/roll stiffness proportion, weight transfer, tire loads, roll angle, and suspension frequencies. I think we discussed it a bit in this thread - it's the one I made that doesn't include ARB info; but not knowing the rate of the WL bar (since it has multiple bends...and not knowing if the standard formulas apply) makes it moot. If I can ever get a few weights, I'll test and add that section to the calculator.



Here's a picture of the car at current ride height. I have at least 3" of bump travel from this height at all corners. When I set it up the first time, I set all corners to have almost exactly 3" of travel, and we corner balanced the car by only raising corners. No bump stops in the rear, and the front bump stops don't engage under peak cornering conditions (only peak corning + bumps).



One thing I didn't measure, and really should have prior to setting ride height and corner balance, is bump steer. That's another piece of this puzzle that's really important.


@TiGraySpeed6; I just talked to the guy who did my corner balance and alignment about home alignment stuff. He gave me some good tips on how to do it cheaply so I'll probably start putting things together for it.

[Code Monkey]

Originally Posted by phate I'll probably start putting things together for it.

Please do another how-to/DIY thread when you do. Between my MS6 and the Miata I go through 4-6 alignments a year, at $75 a pop that adds up quick, especially if you want to tweak just the front or rear and still have to pay the full price.

[TiGraySpeed6]

Interested to see what you learn/think/decide about the process.

From what I've found so far various sources & opinions range between stupid easy to amazingly complex depending on what they're selling and/or the quality of the result achieved. I suspect reality, as it so often is, lands somewhere in the middle. I think it would be easy enough to build the tool (insert canyonrider reference here...) but since I'm without a paved work space I suspect repeatable results won't be easy to come by.

Shocks & springs are done, and next up I'm swapping all four front LCA's and the outer tie rods the next weekend with nice weather, so there's darn sure an alignment in my future.

[phate]

Originally Posted by Code Monkey Please do another how-to/DIY thread when you do. Between my MS6 and the Miata I go through 4-6 alignments a year, at $75 a pop that adds up quick, especially if you want to tweak just the front or rear and still have to pay the full price.

Will do. It's mostly going to consist of a base plate and floor tiles to level the car, a homemade camber gauge, some string between two posts to set toe, and a good alignment to start off with. I've used this method before to set my initial alignment before driving to get a real alignment, but haven't gone to the trouble of making leveling pads.