BROlando

So my TSX is my daily driver. I've owned it about 5 years now.

Here she is, sitting at the grocer's.


It was dropped on Tein Street Advance (SA) coil-overs. I had about 75K miles on the SA's...and about 4 years of use. They've taken me comfortably, on many trips to NYC, Detroit, Upstate NY, Colorado, Toronto Canada, etc etc etc.

Tein SA's for the 1G TSX came with spring rates of 8KG/mm front and 4KG/mm rear. So they were soft and comfy.

At the height pictured above...the SA's Were at about the limit of their comfort zone. They were also 75K miles old. They still worked great...but weren't as crisp as the day they were put on (obviously).

I had sneaky spec slipped the front lower fork all the way up the shock body, as far as they could go.




This provided ample front shock travel at my pictured ride height. But the problem with this added travel and these soft springs was that on really big bumps...the UCA would just tap the shock tower.

The other issues were that:

-The rear shocks had no sneaky spec adjustment at the bottom. The spring had to be brought almost all the way down. This was the issue with ride comfort. The rear shock would engage the bumpstop very often. The ride quality was still great. But...could be better.



-SA's are...soft. So the damping is a little lazy. It's hard to describe. When they're newer, this can be masked by just cranking the damping adjuster closer to stiff. But they still didn't react as nicely as a more "sporty" shock. The early SA really was a great budget setup. They even included a damper dyno in the user manual. You can see some of the laziness in the softer setting. There's almost no damping force at the lower piston speeds.


I also took a trip out west and decided to drive my 1G because manual cars are more fun in the mountains. And because we weren't bringing any bicycles or pets.





After this trip...I kinda started digging my TSX. It was paid off, it was the right blend of old enough to park in the city, and nice enough to drive without being embarassed.

Plus, we started leasing a new place in a cool area, and my commute was short. And when I got home, I'd ride my bike or walk everywhere.

So I decided that maybe I'd buy something in the fall. Maybe.

IDK....

My TSX had 163K miles or something, at the time. So, I thought....why not refresh the TSX a bit? Even if I only keep it for a year, I'll enjoy it for the year.

I knew for sure I wanted a different suspension. I drove a TSX with Buddy Club N+, and I thought they rode pretty well. I also helped my friend install Fortune Auto's on his S2000...so they were another consideration.

A few weeks after getting back from the wild wild west, we had another trip planned...but this time, to NYS and NYC. We were going to the Adirondacks first...and I wanted to bring my bicycle. So we took a station wagon instead of my car.




Guess what kinda suspension it had on it. Nevermind; guessing is hard AF. I'll just show you. It was a much newer set of Tein SA's.


I was missing my car's ride being all crisp like it was when the shocks were new. To cure my thirst for crispness, I ordered a bucket of extra crispy chicken with krispy kreme donuts as dessert. I even tried watching both, Back To The Future 1 and 2, in order to check if seeing Crispin Glover would cure my desire for crispness, and that perhaps the soggy suspension wouldn't bother me anymore. But alas. In the end....I had to succumb to making the car all crisp again.

I could have, at that point, bought a new set of Tein SA's. They were discontinued. but some suppliers still had their end-of-stock leftovers. They were going to be under $600 at this point (not the Z version. The Made in Japan, rebuildable/revalvable, original SA).

Instead of doing this, I thought...maybe I'll try something new. Something more customizeable in terms of ride heights and shock travel. And something that could handle a light amount of track duty.

Does it seem dumb to stray from a known thing to tread into the dangerous waters of exploration? Yes. But I'm not as smart as I look.

So this is how I narrowed down what suspension I wanted.
-I wanted something with customizable travel. Independent ride height and preload.
-I needed something with excellent corrosion resistance.
-I *kinda* wanted to track the car a couple times for fun in the summer. So something that would work on a track would be great.
-The car MUST ride well. As well, or better than stock.

Basically...a "GT" style suspension.

I narrowed down my choices to:
-The Buddy Club N+/Sport :
Pros: The ride quality was great. And I think they are monotubes. Felt like they were.
Cons: Had a terrible experience with Buddy Club Seat Rails before. And I wasn't sure about the coating they used.
Verdict: The Buddy Club N+/Sport was attractive. But after my Buddy Club Seat Rail experience...I was like...nah.

-JDM Ohlins DFV
Pros: I loved the way my Ohlins rode on my S2000. They're str8 up amazing, m8. Easily rebuildable. Huge range of spring rates on the base valving. So COT dang nice.
Cons: Good luck finding a used set. I kept seeing them a while back..but I wasn't ready to pull the trigger. Now I couldn't find any. The cost of buying them and them re-valving them, and buying new springs is also a downside.
Verdict: I couldn't find em. So I wept.

-H&R SP
Pros: Bilstein monotube shocks!
Cons: They're German Monotubes...so they're going to hate being low. And they're zinc plated. I live in IL, where they don't just salt the streets. They put down MF'ing SALT, MF'er. And they're not independent ride height adjustable, nor do they have damper adjustments.
Verdict: Ehhhhhh. Mayyybe.

-Tein Street Flex Z (SFZ)
Pros: Independent height adjustable. Impressive Tein quality/corrosion resistance. Cost. Familiarity. Availability. Curiousness about how they rode.
Cons: Twin Tubes. Not necessarily a boner killer....but monotubes feel so much nicer. My old Flexes were great in terms of quality. But the ride was awful.
Verdict: Probably tryinna get these tho.

I'm not very good at creating suspense. I ended up with the Teins.



I figured....Tein had come a long way in ride quality since I had my Flexes 15 years ago. And I knew a whole lot more now. So maybe the ride won't be so bad. And....there was the curious quandry of, "can I make a $700 full body adjustable shock actually ride well? Can it be used on road and track?!


Hmm.

BROlando

INSTALL DAY!

I only had a few hours to get this done...because I was going out later. On a date with a pretty girl.

Got the car pulled up in the garage's gutz.



to any succesful suspension install is to measure measure measure.

Step 1.a) Unbox the Teins and take them apart to measure and sketch them dimensions.



Clock is ticking.

Step 1b.) Measure how much force the car puts into each spring.

Remember, I still have my Tein SA's on the car.

So I measured the STATIC HEIGHT SPRING LENGTHS with the car on the ground.

FRONT:




REAR:





The above photos were truly difficult to get. But it's easier to explain like...:





I already know some things about the Tein SA springs because it's all in the user manual.





Free Spring Length is the length of the spring without any load on it. Just sitting on a shelf or something.
The FREE SPRING LENGTHS on the SA are 8.85" (225mm) and rear on the Tein SA are 9.84" (250mm).








Data for future reference:

We're using Freedom Units...so we'll use inches and LB's.

The equation to figure out how much force each corner of the car is putting into the spring is

Free Spring Length - Static Height Spring Length) x Spring Rate = Sprung Force.

For the front, it looks like:
(8.86in-6.13in) x 447LB/IN = ~1215LB.
and the rear:
(9.84-6.88) x 225LB/IN = ~660LB

Those are not the sprung weights. Those are sprung FORCES.

Meaning
My 2006 TSX with a manual transmission, full of fluids, full tank of gas, and empty otherwise, on a flat surface, puts approximately these forces into each spring:





More to come.

cu2wagon

@CCColtsicehockey should be able to help.

And I'm now ghetto subbed because, although this is for a 1G, I love learning suspension stuff from you and I want to hear more.

BROlando

Thanks! contacted him to remove posts 1 thru 3.

BROlando

I noted my car's current ride height. I did not want to lower or raise the car from this height. I was happy with it.


then put the car on jackstands and loaded an empty (no spring or bumpstop) set of stock shocks in the chassis. In order to....

Step 1c.) Measuring Motion Ratio (MR) and Limits of Travel.

I put the car up on jack stands.


I removed my old SA's



Then I installed a set of junk ass, blown, front and rear shocks to use to do my measurements.

Front shown. Rear also installed.





MOTION RATIO (MR):
The wheel hub and the shock move at certain RATES. Meaning that as the wheel moves up and down due to suspension compression/extension, the shock also moves. Motion ratio is the RATE at which those two components move, relative to each other.

I am literally the worst guy ever. So I went ahead and made a model of the front suspension to demonstrate.

Some cars have a 1:1 MR. The TSX does not have a 1:1 MR.

The MR is a result of the differential differences of the LCA pivot to Hub face and Shock Attachment point difference, as shown thusly:

You can see, that as the suspension moves, the shock moves LESS than the hub.




Via my tape measure, I measured a MR of:


Front: 1.57 (hub) to 1.00 (shock). OR 0.636 inverse.
For the front suspension, the shock travels 1 inch for every 1.57" of wheel hub movement.





Rear: 1.18 (hub) to 1.00 (shock). OR 0.847 inverse.
For the rear suspension, the shock travels 1 inch for every 1.18" of wheel hub movement.




The STOCK LIMITS OF TRAVEL are when the stock shock will completely bottom out.

By completely, I mean with the bumpstop removed. I am measuring when the shock hits the tophat bushing and completely stops.



On the front suspension, I noted that when the shock completely bottomed out , the UCA was about 0.6'' away from hitting the shock tower.


The reason Acura leaves this fairly large gap is because even though the shock is bottomed out...if the bump is big enough, it will compress the suspension bushings slightly as well. Plus, automotive makers use a huge factor of safety. This is done to ensure that there is virtually NO chance of the UCA hitting the shock tower!

This measurement was taken with a stock ball joint and UCA.


I'll pause slightly from the suspension install to give yall a

If you are feel you want to install a camber adjuster using an extended ball joint (Like SPC, Ingalls, etc), I would recommend AGAINST doing this. The extended ball joint raises the height of the UCA by almost 1''. That means that the UCA will hit the shock tower on large bumps.


The reason I say this is because the TSX has a front UCA that sits outside of the wheel barrel.

For cars like the TSX, I would not use an extended upper ball joint in the front suspension. I would be very cautious about using an extended lower ball joint as well. Remember that the risk exists, and will only get worse as you lower the car...especially with a full body coilover like the Flex.


Again...

BROlando

It is noteable that UCA to shock tower contact is also a risk with ANY full body adjustable coilovers like the Flex Z.

The reason is that you can lower the car's ride height by shortening the shock body while leaving plenty of shock stroke available.





I removed the shock altogether and measured when the UCA would actually hit the tower.

It happens at this height. This is where the suspension stops. I don't care what you're lowered on. If your ride height reaches this point..the UCA will touch the shock tower. That's the inconvenient truth...but it's good to know.



Now that I've taken all the fun out of it...my next set of posts will move on to the initial install and initial impression of the Tein Flex Z.

BROlando

The actual install.

For reference, Tein already supplies these coilovers fully assembled. If you recall, I had taken them apart to measure their travel, etc.

I reassembled my Flex Z's as per the Tein instructions. I wanted to assemble and install them as a casual user would...right out of the box.




Tein provides measurements to check against, to ensure the coilovers are set up the way they have thought was most advantageous. Their measurements are a little complex.

Also for reference, Tein specs close to 0 preload on the springs.

The only thing I did differently was to apply anti seize on the threads.
This is probably not entirely necessary because Tein's coating on the threads is so dang good. I think they use PTFE to coat the threads. Smart. But I did it anyway.

I installed them on the car. Yall know how to do that...so I won't spend too much time on it.



When I put the car on the ground, I was surprised that Tein's height reference measurements were so spot on. The manual states that if you set up the coilovers exactly as shown, then your ride height (fender to hub centre) would be something like 13.25F and rear. I don't remember. Who remembers this shit?



I set the damping, as Tein recommended. -8 from full stiff in the front. -10 in the back.
Full stiff is 0.
Full soft is -16.




Whenever you change the damping setting on a shock (not just Tein), always turn the adjuster to full stiff first.
For Teins, full stiff is completely clockwise.






I knew, from what I head measured in the posts above...that the Tein factory setup was pretty compromised...and it may not ride very well. BUT, I would need to take a ride in it first, before changing anything. And who knows...maybe I was wrong. Maybe they would ride just fine.

For those of you interested in how long the install takes....

• The install, including all my ridiculous disassembly, measuring, reassembly, and inability to focus on anything, was about 3 to 4hrs - from start to finish.
• If I were to have just taken them out of the box, set them up per the manual, and put them on the car like a normal person, it would have probably taken maybe 1hr from start to finish. They're pretty easy to install.

It was time then, to go on that date.

The drive that night would take us on all kinds of roads. City, highway, and around town. So it would be a good time to figure out how the Flex Z rode.

After getting the car on the road...I find it hard to choose just 1 word to sum up how they ride. I could probably do it in 2 words, though.



It was completely awful.

This has to be one of the worst riding suspensions I have driven. I mean...I've driven worse. But...this was so bad.

The car jumped and bounced and jigged and crashed into every bump on the road. It was harsh...but floaty. It inspired no confidence because the nose of the car went bouncing everywhere like it was a sniffing dog, and it irritated TF out of me by first SLAMMING over ever joint and crack, and the jiggling for seconds after the bump had gone.

I stopped at a gas station and re-set the damping a bit stiffer. Maybe some more rebound damping would help.

I set the fronts at (-4) and the rears at (-6). While the ride was greatly improved...it was still unacceptable.

The next day, the plan was to tune the setup a little bit to make it more driveable.

sockr1

iTrader: (5)

great write up so far...but need the "after adjustment" posts!!!
this makes me feel better when i hated my tein flex at first, it wasn't just me. with the new settings that you helped me with it's 100x better and i've been passing on those specs to everyone that says they have tein flex in the TL world

BROlando

lol. I know. I know. I gotta get to the point.

I've been ultra busy. I should be able to update it sometime this weekend, if I'm home. It went a lot further than just adjustments.

sockr1

iTrader: (5)

haha just giving you a hard time man, great write up so far! it's crazy how badly riding the flex are without the proper adjustments

BROlando

Lol, no worries.

I'll post the "setup lite" and "setup right" options.

If you're looking for a setup purely for street use, you can use the measurements above to formulate something more customized fairly easily.

I'll post what worked for me, though. People are welcome to try what I did.

Shadow2056

Great write up!

I just got Flex Zs for my TL. I've had Tein before and never had an issue with their ride quality. Always been more on the soft side. Having it on full stiff could possibly cause the harsh ride. Putting it on full soft then adjust for firmness from there.

BROlando

Thanks!

Unfortunately, in this case, less damping (softer shock setting) meant less comfort.

The shocks are terribly under-damped in rebound at the softer settings. Anything softer than -6 or so will make the car wallow and float and jump. Trampolines are soft...but aren't comfortable.

With the base spring rates and preload settings, the most comfortable damper settings were set fairly stiff (-4 to -6).

The issue with the stiffer settings is that, it seems Tein favoured a really heavy amount of compression damping rise. I just wanted more rebound, dammit.

So, as it sat, the coilovers really couldn't be dialed to drive like an actual car and not an unloaded box truck.

Remember...a proper street setup should handle better than stock, but have absolutely minimal ride quality penalty.

I can't really accept a crap ride because I lowered the car. No point in buying massively adjustable coilovers if "yeah whatever" is acceptable.

It just takes some tuning in to get it right.

I'll detail it out further. y'all will find all my boring measurements come into good use.

BROlando

**I am assuming you followed the steps above and are at Tein's ~1 to 2mm preload setting BEFORE installing the shocks in the car. If you did not, you will need to REMOVE the shocks from the car and set them up that way before starting the steps below.

Tuning.

3a.) Preload

I added preload to the front and rear springs.

I'll cut to the chase before explaining why.

To do this, first make a mark with a paint marker on ALL FOUR spring seat rings.


Then, loosen the lock ring (the one right below it)



And turn the spring seat upward to compress the spring. The spring should be getting shorter.

Your best bet is to measure TURNS, not actual length dimensions. Tein uses a 2mm thread pitch. Every 360 deg of rotation is 2mm.




Re-tighten the lock ring and spring seat together when you're done.

Doing this will raise the car's ride height if you put it back on the ground. So...you want to shorten the shock body the same amount you preloaded the springs.
From the above,

• Front: 5.5 turns.
• Rear: 5 turns.

Re-tighten the lower mount's locking ring after you're done.



When you put the car back on the ground, the ride height should be the same as before.
Because you raised the spring perch the same amount as you lowered the shock body.


I went for an initial drive using my previous damper settings of:

• Front : 4 clicks back from full stiff
• Rear: 6 clicks back from full stiff

Right away, I noted that the ride was quite a bit better than before.
The suspension was softer overall, and the shocks had more room to recover from bumps.

I also noted that with this new found travel and softness, I could dial down the dampers a little bit. But how much??

I went for another drive after re-setting my shocks using the Tein factory supplied damper settings of:

• Front : 8 clicks back from full stiff
• Rear: 10 clicks back from full stiff

Too bouncy, too floaty, no control, front end sniffing the road, and I'm being bobbled around. WTF is up with these -8 and -10 settings?? Who does this cater to??

I drove around for a few days to play with the damper settings. I went from stiff to soft. Basically,

• I set it to full stiff...then drove it. It was clearly over damped. It was very jiggly and bouncy because it was over reacting on every bump.
• Then clicked backward 1 click at a time (same drive).
• Once the suspension became floaty, I stopped. That was as soft as I could set it. I hate floating around like I'm driving a helium shitballoon.

I settled on:

• Front : 6 clicks back from full stiff
• Rear: 7 clicks back from full stiff

Those were the best compromise settings I could use. For ride comfort, I am using stiffer settings than those that Tein recommends.

Tein's settings of -8F and -10R were way too soft to control the spring. Again...trampolines are not comfortable. So just dialing down the damping to soft is not always the answer.

Ride comfort is different for every man and woman...so YMMV. Set yours how you like them.

If you are happy with the ride after these steps, then...you're set already. Just remember:

• Increased preload adds to the risk of the UCA hitting the shock tower (depending on your ride height)
  • Measurement is key to this type of tuning.

I will, however, say that I was still not entirely happy with the ride quality, even though it was improved quite a bit over the settings that they came with.

In my next post, I will explain why I chose to do the steps above.

Then I'll let y'all know what I tried next, to improve further.

cu2wagon

Not to over use the cliché meme, but this is a better love story than Twilight.

BROlando

I know, right?!

My fav is the part where the story's hero goes on a date with a girl, and she's all "why is your car like this?!"

And then he vows to win back her love.

BROlando

Here is why I added the preload to the springs.

To preface TF out of this MF,
Preload does not alter the spring rate. The spring does not get harder or softer via preload.

I added preload to this spring to get more shock travel without using a harder spring.

Its the same reason Honda used a shitload (metric measurement) of preload on the stock spring. Soft spring...but maintain shock travel in a limited space. Easy peasy.

Preload adds compression travel.






Ya feelin me what I'm sayin, mon??

However, with this added preload, you need to shorten the shock body to keep the same ride height. Remember?

There's pros and cons to this method:



The trick is to outweigh the cons with MASSIVE pros.

As seen above, using preload to add compression travel will increase the amount of time the suspension has to absorb the bump and then release that energy to put the spring back into its neutral position.

Bumpstops are also harder than springs. With added preload, fewer bumps will be big enough to hit the bumpstop. So...the car will ride smoother.

The important things are:

• Finding a ratio of droop and compression travel that is satisfactory
  
• Measuring your risk. Adding preload will make it more likely for the UCA to hit the shock tower because the suspension will compress MORE before the shock bottoms out. You're adding shock compression travel.

BROlando

My bad. Forgot the update.
So I finally did make them ride like I wanted.

To recap:

The suspension started out with the Tein factory supplied rates of 12K/7K.

IMO, Tein is overly ambitious with their spring rates. There's no way the dampers are valved properly to handle 12K/7K.
I could not find any setting out of the 16 clicks that worked worth a shit with 12K/7K springs.
This is how I would translate the damper settings:



So naturally, I started buying softer springs to try out.

To make my life easier, I bought a 65mm spring perches from Tein.
I used optionsauto to buy these...and I would highly recommend them.


I bought this because Tein supplies the Flex with front 65mm ID and rear 70mm ID Springs.
65mm springs are cheaper and more common than 70mm.
And 65mm springs can be interchanged with 2.5'' ID springs which come in standard rates (LB/in).
LB/in has more resolution than metric KG/mm or N/mm

The perches shown above are what the spring sits on.
I bought the above for the rear shock. They will fit the fronts too....but the fronts are already 65mm.

First combination I tried was:
10K fronts. I left the original Tein 7K rears on initially.


I also didn't like how the Tein front spring just sat on the metal top hat. I felt that this would create paint chips and rust.
So I bought 3.5'' OD x 2.5'' ID polyurethane tube (85D Durometer), and cut it using a band saw.
This is nice...because it's a cushion as well as a thrust bearing to make preload setting easier.
I used a small amount of silicone paste where the polyurethane touches the tophat and spring.





Then I tried the 10K fronts pictured above with 330LB/in (6KG/mm) Eibach rears.



Finally, I found the winner.

I took the rear Tein 7KG/mm rears and swapped them to the front.
I then used these beautiful Eibach 250LB (4.5KG/mm) in the rear.

You'll need to use the 70mm spring seat and upper spring rubber up front.
You also need to use a 65mm spring seat and 65mm (2.5'') ID rubber/poly upper donut for the rears.




I was really happy with the ride quality at 7KG/mm and 250LB/in (4.5KG/mm).

I could set the damper at like -8 or -6 from full stiff and it would ride in a very controlled manner.

This setup did not feel "soft" to me. It felt WAY more solid than the 12k/7k setup that they came with.
The car was no longer bouncing and crashing off of bumps.
The 7K/4.5K setup was very stable and confidence inspring.

I am sure it would be a little soft for track duty...but...this is a street car.

So the Tein Flex Z's valving seems to PROPERLY match up with a much softer spring.
I think that these would be fine up to about 8 or 9K up front and maybe 5K rear.
After that, you start really trading off more ride quality than I think is beneficial.

Street cars are all about FEEL. And the 7K/4.5K combo feels a lot better and inspires a lot more confidence than the 12k/7k that the coilover came with.

Don't be afraid to mod yours how you want them. Change things around and see how you like it.
It's a little labour intensive...but you'll get the most out of all the features and adjustments that you paid for.


Good luck with yours.

BROlando

Almost forgot.

Buy your springs from a reputable source.

I won't mention the name of these shitty 10K springs. I thought these were from a reputable source. But they turned out like this in 2 months.





Brands I'd recommend:
Tein makes excellent springs. Probably the best corrosion protection of anyone.

I've had good luck with Summit racing's in-house brand (I think they are QA1).

My go-to from now on will be Eibach, due to their customer service, in addition to the quality of their product. Plus, these are available in standard measurements instead of metric.

Ro_ber_toe

BROlando

1-2mm preload is virtually 0. Its really just to seat the spring.

The springs all have ~2mm of preload from Tein to begin with. Measure the spring BEFORE installing them to the car to make sure, though.

Measuring the spring itself is easier than doing the math backward.

I ended up with the TOTAL spring preload values mentioned in the thread above. So when I loaded the 250LB/IN Eibach rear springs to 13mm, that's a TOTAL number of 13mm prior to installing them into the car.

Also, remember, once installed in the car, you're better off using perch turns to accurately set preload, rather than using spring measurements.

For example, if you installed them into the car with 2mm of preload, and you want to get to 10mm of total preload:

• you need to add 8mm
• you would do this by turning the spring perches 4 full turns upward. Because each perch turn is 2mm.

I know that was a lot of numbers. But hope that's easy to follow.

Ro_ber_toe

Ken1997TL

Fascinating read!

I have Flex Z's on my RL. It rides well enough on smoother highways but I feel the springs are too stiff for daily roads that are not maintained properly. I may need to experiment like you did to find the ideal

BROlando

Yep! Springs are fairly inexpensive. So why not, right?

Eibachs are usually like $65 a spring, and they're fantastic.

MrHeeltoe

iTrader: (1)

Very interesting and very thorough write up. I'm impressed and am doing some thinking.

So my personal TSX was the test car for the first "Street Flex" kit which later because the "Flex Z." My understanding was that the tuning of those kits did not change, just the manufacturing process/damper design to a non-serviceable unit.

I found that my TSX with the Street Flex in it felt completely terrible in the rear, and once I dialed in ~3/8" preload (memory failing me a little here) it was a night and day improvement. I've done everything from 15 hr one-way road trips, canyon carving, and track days all with the same setup. I feel like I need to get back under the car to re-evaluate things, and see if the FLEX Z feels anything like the Street Flex in my car now.

Also I will share this post with Tein management. I think there would be a benefit from understanding that moving the FLEX from a mixed track-street performance kit (a decade ago) to a cream-puff tuned kit it is today has lost some of the customer base. Regrettably, customers don't like being told what they want (a properly tuned damper and spring combo), and too many of them want the wrong thing (a higher spring rate).

Marcus

BROlando

Hi Marcus! Thanks for the reply.

I'm glad you're taking this to Tein. They make an excellent product with an unfortunate calibration, in this case.

I understand that for ultra low settings that this kit allows, the 12K springs and short stroke dampers work well for safety (preventing UCA to tower contact). I understand, to some extent, why they chose their rates and damper stroke.

Other companies with these rates seem to use monotube dampers with MASSIVE stroke. Buddy Club, for example, uses a longer front stroke than stock. I think they take the "set this up at your own risk" approach.

I appreciate that Tein takes a look at user safety and lays out setup in the owner manual MUCH more nicely than others. Unfortunately, at this price point, it seems like it also means a lot of compromises if you want a "do everything" coilover in a chassis with very limited available front suspension travel

MrHeeltoe

iTrader: (1)

Tein got back and indeed my assumption was right. After 15 years in the USA market the customer base over time asks for more and more comfort on the whole (much like focus groups will continually tell car manufacturers that a car is great but needs "a little more space" and so we end up with a TLX as some kind of mutated evolution of a 1g TSX. Tragic.

We are discussing things though and feel like there may be an opportunity for a bespoke product, something more enthusiast based but great for the road.

BROlando

Right on, man.

Honestly, with like a 450LB front and 250LB - 280LB rear spring, these would be brilliant with the stock valving. Any more spring seems like too much for the shock at stock Tein valving in this case (IMO)

447F and 250R makes both ends of the car close to equal in effective stiffness. So it should ride properly like that.

L8rH8r

i enjoyed reading this. are you an engineer by any chance ? this level of detail isn't for the faint of heart. with this being said, i have to ask this. why have you not looked into swift springs ? they are a bit more pricey than Eibach but very well worth it. quality springs and very comfortable.

BROlando

Yep! I worked in R&D for a few years. Glad you liked the thread.

I haven't used Swift. I think I would if I had something that required a super low block height to prevent coil bind. People say that their springs improve ride quality due to a slightly better response and more accurate winding.

I've been using Eibach for a million years, though. Their quality and customer service are both excellent...and they're more easily available....and they're available in INCH LBS...and they have a presence at a lot of local track days. Plus I've interacted personally with dudes from Eibach.

I don't see enough advantage in Swift's overall package to deviate from Eibach. The INCH LB availability from Eibach is a huge plus, TBH.

BROlando

I did find a goodass use for those 12K springs from the flex, though!

Vezzy

When I put on my flex z for my TL, I followed someone's set up on s2ki on an s2000, 7 turns preload front and back. I set the stiffness to 5 clicks front and back, I liked it but never had much confidence in my butt Dyno until friends thought it rode well too.

BROlando

7 turns is 14mm (9/16"). I'm sure that helped a little.

I'm glad they're working for you. Maybe the Flex for the TL rides differently than on the 1G TSX.

POW8255

I hope you guys are okay with me resurrecting a thread from the past, but this is filled with so much useful information that can be used by many people including those who don't drive Acura's. I actually drive a Mitsubishi Evolution X which currently has Tein Flex Z suspension fitted and have experienced exactly what you have and this is how I stumbled upon your post.

Firstly thank you for posting your findings and such a detailed look into this problem, I would have to agree with you that Tein has gotten much to ambitious with their spring rates and I am starting to see others follow suit. In my quest to understand more about suspensions and spring rates I learnt about Natural frequencies and this is one way I also realized where coilover manufactures may be pushing things to the limits. The Tein flex Z setup for the Evo x is fitted as standard with 9k front and 8kg rear, doesn't sound too stiff but for street tires ( Including Extreme Performace Summer) we would probably easily overheat these tires as they do not produce enough grip and g's to warrant such rates. Also given the motion ratios and the AYC rear differential on the Evo, having a softer spring in the rear might not be the best idea, thankfully they are not too far off.

The front motion ratio on the Evo is 0.96 and 0.84 at the rear so ideally close to equal spring rates as the factory car is fitted with would be ideal. I'm currently thinking to go down to 7k front and rear springs to make the car usable on the road and the odd track day, with some calculations and considering the natural frequencies this seems ideal.

This is a good site to get some more information about natural frequencies and includes a calculator - https://www.drtuned.com/tech-ramblin...on-frequencies

I'm interested in finding out if the Motion Ratios you posted are correct and if you have calculated the natural frequencies for your car based on the Original Tein setup and your correct setup?

Also how has the suspension been after a few years? and have you made any other changes? Also what car do you use the Ohlins on and is it for track duty?

Again thanks for your contribution which has greatly assisted me.

rockstar143

iTrader: (6)

i read the entire thread.
also wondering if you got another chance to impress shorty with your newly tuned suspension.

POW8255

Anxiously awaiting the OPs feedback, I will post my results once I make the changes on my car

BROlando

Hello,

glad you enjoyed the thread.

I don’t know much about EVO’s...but yes, a 9K and 8k setup seems massively stiff with the EVO motion ratios that you’ve posted.

For reference to Honda/Acura people reading this, that’s like using 24K/17K on a S2000 or 21K/7K on a TSX.

The problem with the flex is that they’re a very slow reacting twin tube setup that’s trying to damp out some very stiff springs.

The dampers do almost nothing to damp the spring at lower speeds, but at higher speeds, the damper seems over reactive. So the ride ends up floaty AND crashy.

Monotube shocks would probably behave better in this application, IMO.

I am confident that my motion ratio measurement is correct. Its referenced simlarly in Tein manuals...and i measured carefully, using the whole length of the shock travel for better resolution and for less error potential.

I did not bother calculating frequency. I just went with the much harder method of trying out a bunch of springs. I also can’t claim to be a chassis or suspension expert...so I just went with seat of the pants.

Im pretty sure that “flatride” design prefers that the rear of the car oscillate at approx 1.5x the speed of the front. So...the rear should be stiffer. Which is how most stock cars are set up. Including the stock TSX. The flex came with 12k/7k springs...so obviously...that was no longer the case. 7k/4k does make the rear effectively stiffer, however. So maybe that’s why my 7K/4K felt so good.

The dampers were also hopeless with the springs that they came with. So that’s another reason the 7k/4k felt so good.

I sold my softened Flex setup to a friend, and he loves them. To be honest, the 7K/4K flex was a really great setup. The shock stroke was way too short for that soft of a spring, but it still worked. He’s been using them on his DD for years. Tein does make stuff that lasts forever.

Long story short, I’m using Street Advance Z currently and i really like them a lot. The Advance Z dampers seem more agressively valved than the Flex from full soft to about half way stiff. Weird.

The Ohlins in the picture are from my S2000. I used to track that car...but no longer do. I am slowly bringing that car back to just street spec and restoring it to look nice. I have another S2000 that I’m buidling for track use. I am using Fortune Auto FA500 with 14K/12K springs on that car. I’d really recommend FA500 as a way more useful alternative to the Flex for people trying to put together a track/street type setup. The FA’s are monotube and customizable.

BROlando

Mybad. A correction....12K/7K still does make the rear wheel rates stiffer. Its similar to the same bias as stock or 7K/4K. Duh.

I think the damping profile of the Flex just doesn't properly damp the stiff springs it comes with.

Soft springs seem to be this setup's friend.

Obviously soft springs are going to make virtually any car ride better. But I had to reduce spring rate a massive 40% to get the dampers to actually damp the spring properly.

BROlando

She ended up saying something like "yeah seems fine" in between texts to her friends.

I was like..."damn...

shes so into me."

POW8255

Thanks for replying, It great to hear back from you.

Yes the Tein 9k/8k springs seem a bit stiff and have approximately 2.2Hz Front & 2.1Hz Rear frequencies, The Evo's factory natural frequencies are around 1.4 which is already stiff. I would overheat street tires and lose mechanical grip with these high frequencies.

In regards to your Motion Ratios, I just found from calculation your adjusted rates worked out to be around ~1.1hz front frequency(7k Spring) ~1.6Hzrear frequency (4.5k Spring), with them being so far apart I wondered if one of the figures were off. I used the corner weights you posted 1215 - 660lbs. This is where the flat ride comes into play as you had it set up with the back being 50% "Stiffer". Makes sense.

I'm glad you spoke about the Tein Twin Tube design and them being slow, you can feel it and Tein themselves admit it on their page.https://www.tein.com/classroom/lesson_1.html

As you rightfully suggested a mono-tube design may be better for the application and I may very well revert to that in the future. Unfortunately I have to admit defeat and say the factory had it right and the Tein suspension comes no where near the capability to the original Bilstein setup Mitsubishi uses, or even the KYB setup which is actually valved more aggressively.

I did see the fortunes when I was buying my suspension and should have given them more thought! Anyways your write up was very helpful and added a lot to what I learned during this process and led me to a lot of other articles which highlighted with data why many coilover setups can ruin good performance cars. The Evo's roll centers get totally messed up when lowered.