Tein Flex Z - Detailed Info/Review Thread
 

I thought I'd create a thread showing some detailed info of these coilovers for those curious. I took a chance on these without much "hard data" out there, hoping that Tein did their homework and they'd perform well even though they're priced very aggressively. I've got to say, I'm very pleased with the result. As a bit of background on me, I've put together and driven all sorts of suspension systems on cars, from Koni, Bilstein, many of the Japanese/Taiwanese/Chinese brands, JRZ, Penske, Moton etc. I've been driving on track for 15 years now, so I get around just fine, and know what a good handling car feels like. Not saying I'm a definitive expert, but I do have a clue, and can drive a car on track at the limit consistently.

SUMMARY

Onto the coilovers - general impressions are very high overall quality. Honestly, for made in Japan coilovers, I was shocked at the high quality given the price point. The damping curves are generally good, with the car not crashing over bumps or feeling uncontrolled at a given "stiffness" (or level of damping). It's very easy to go from the comfortable for a bumpy street under damped level, to a slightly over damped setting for track or spirited driving. The travel is good, with the car staying up off the bumpstops in typical cornering. The 10k spring rates are a good blend of street vs. track. You can totally daily drive these, but they're actually very good on track too.

STREET IMPRESSIONS

My stock front dampers were leaking, so the Teins actually ride MUCH better on my car. Compared to a good condition stock setup, I'd say it'd still be a ride comfort improvement when you turn the shocks down. The car will gain a tad of additional bounceyness over big bumps, but it won't be that horrible undamped oscillation you see on cars way over lowered and on the bumpstops. You can tell the spring rate has increased quite a bit, but I still find it perfectly reasonable for street/daily driving duty. Turning the shocks up to a critically damped setup on the street is a decent amount rougher than stock as you'd expect for such a large spring rate increase, no free lunch there. Large bumps feel better on the Flex Zs with preload, as you have a stiffer spring and essentially the same shock travel as stock, so it takes a lot more to ram it into the bumpstop. The big range of adjustable damping really is key here for maintaining street comfort. On some setups with wonky adjusting mechanisms, you do not get this benefit as the adjustment window is so narrow it's impossible to tune the shocks in reality.


TRACK IMPRESSIONS

The car picked up around 6-7 seconds on a ~2:10 lap from very worn stock 2003 AP1 suspension to these. No other performance changes to the car between, and it was hotter with the Teins (~70 F stock, ~90-95 F Tein) and I was getting the 9-9.5/10ths maximum I was aiming for out of both setups. Honestly, the car in stock form was a bit of a let down on track, as there's not enough suspension travel for the spring rates, and being on the bumpstops makes the behavior unpredictable. So that 6-7 seconds gain is purely suspension changes. The stock suspension is designed to be fun on the street, and it does that well, but the Flex Z's are a huge step up for spirited or track driving. Don't think that their low price point means the car's capabilities will be less. The car will 100% be faster and easier to drive than stock.


DAMPER/COILOVER DETAILS

Here's the info that I really felt was missing, so I want to highlight this. The short story is that with moderate preload front and rear, you can have essentially stock damper stroke in compression with roughly double the stock spring rates (non-CR). This gets the car up off the bumpstops in typical cornering, and gives a huge increase in ride comfort vs. stock because you are not crashing into the bumpstops over small bumps during cornering.

Here's the front damper with the spring and top hat removed:

Attachment 159866

Here's the rear damper:

Attachment 159867

As you can see, travel/shock shaft length between the two is very similar. Tape measure starts at the centerline of the LCA mounting hole. The small groove/circlip on the shaft holds a plate that serves as the first barrier to the bumpstop.

The bumpstops are 1.6" long, and look to have a fairly sharp rising progressive rate.

Attachment 159868

Shock travel from bumpstop to stopper plate is right about 2", which yields total shock shaft travel at 3.6".


Top hats are steel and use rubber bushings, and are generally well put together. One note is that the spring is put in bending with this design (which is the same as stock) instead of putting all spring loads through a spherical bearing. On the S2000 this isn't a huge issue, as the amount of misalignment at the top hat is pretty minor.


RIDE HEIGHT/DAMPER SETTINGS

Will update with damper measurements to get a ~13.3-13.4" ride height with the below preload - the Tein manual had some conflicts and it was about 1" off on actual car height for me after accounting for preload.

These coilovers allow you to go all the way to sub 12.5" hub to fender ride heights and keep all the damper travel possible (no spring droop). That said, I personally feel this is a goofy ride height for an S2000 that's driven hard, and I couldn't see the front fender liners standing up to that since you'd have ~4-4.5" of wheel travel on a large bump.

I personally feel the optimum level of preload for a street or light track setup being 6 turns, or 12 mm front and rear. This yields roughly 1" of damper travel before bumpstop contact with a full weight S2000 sitting static, and still plenty of droop travel. If you run zero preload you will have only ~1/2" of damper travel before bumpstop contact. This is lower compression travel needed at low ride heights, but as long as you're over about 13-13.25" hub to fender ride height, go with the 12 mm of preload front and rear.

For damper settings, all settings referenced from full stiff (same as Tein manual). The last detent before it stops is very "vague" and doesn't yield a click when it stops. So I've always gone counter clockwise to the first click, then taken that as a "full-stiff" setting. So these might be 1 click off the Tein manual settings, but just being clear so you will know where I'm coming from.

Street driving: 8-9 clicks from full stiff, 10 clicks from full stiff for a very soft/under damped setup.

Track driving: 6-7 clicks from full stiff. Last time out I settled on 7 front/6 rear and the car felt great. I'll try 6/6 next time I'm out.

Each click provides a very large amount of damper force change, which honestly surprised me. I've had shocks before where you're making fairly large changes in the mid range, with no real damping force changes until you get to the extreme stiff range. So the damper has a large range of adjustment, and it feels fairly linear in the midrange - both signs of a high quality adjuster. Given that there's still a lot more range to go stiffer or softer, you could easily change the spring rates in the future on these if you felt the need and the damper can easily control them.

COMPETITION/OTHER COILOVERS

Honestly, there isn't much around this price point that would be comparable. The only others that looked remotely competitive were the ST Suspension coilovers, which are basically a plated steel version of KW V1s. That said, you'll be reusing your stock top hats, and from the measurements I saw in their installation instructions, there isn't much free travel before the bumpstops. Plus at a 8k rate, I wasn't that confident that they would not be all over the bumpstops for track usage.

I personally paid around the price of a set of Konis for mine, and I'm still blown away by the value and relative performance.


NEGATIVES

Not to sound too overly positive here, but for the price point I really can't nitpick much. I'm really that impressed with them. But for those that are wondering what they're getting going with higher priced setups, here's my take on where you're slightly sacrificing with these vs. higher end stuff like Ohlins etc:

• The damper travel could be a tad longer both front and rear. This would mean you couldn't completely dump the car, but an extra 10-12 mm of damper travel would probably go to good use IMO. They work well as designed though, and allow you to go low, which is important to some people.
• The high speed compression is a touch high for a given damper setting IMO, the car is still very controllable on a bumpy track or street, but the Japanese method of shock tuning does tend to favor a more linear compression curve which gives higher force values at high speed hits. Minor quibble again, the overall damping force curves feel very good to me.
• The steel top hats and lower mounts do add a bit of weight over a pricier setup with more aluminum there. The Flex Zs are lighter than stock, but not by a huge amount (maybe 2-4 lbs a corner? not enough of a difference for me to bother dragging out the scale really).

Maybe B Serious can chime in with how much travel off the shelf Ohlins DFVs have - I'm kind of curious as to how they compare travel wise.

You mean just free travel like...unloaded?

The rears have 2.125 before bumpstop (about 3.125 total).

The fronts have something massive like 3.2" before bumpstop...so like 4.x" total. Insanity.

Of course, after that, the weight of the car, spring rates, and preload determine how much of that you use for droop and what you use for compression.

Front

Attachment 73510

Rear
Attachment 73511

Great thread, BTW.

I have always liked Tein for their overall build quality. In the past, it seemed that the damping profile maybe wasn't up to snuff with what was out there. But...10-15 years ago, there wasn't THAT much out there...and not just for S2000's.

I think most people who have actually tried the correct application Teins have been very satisfied with them. Plus, they do their own R&D, and they manufacture that R&D into a product in-house. And they're an innovative company (the name stands for TEchnical INnovation).

Anyway, I'm glad you like them.

I will, however, say that you'll be hard pressed to go faster in a mostly stock S2000 with just a coilover install. The stock suspension is VERY good. Regardless of bumpstop use. I think your shocks were blown, from what I remember.

I'm glad you're posting this info. People can improve from their worn OEM components for a perfect price point.

Some more info that may help people:
-They're not rebuildable...but they cost as much as, or less than, a rebuild costs. And there's 0 down time.
-They can be ordered with custom valving for specific rates, as requested, from Tein.
-Their corrosion coating is extremely impressive.

I'd love to ride or drive a S2000 with these to see how they stack up to properly set up Öhlins or similar.

Thanks. Looks like both front and rear Flex Z's have about 2.5" of free travel (unloaded) before the bumpstop, so inbetween the front and rear Ohlins. I was a bit surprised the fronts didn't have another 1/2-3/4" of travel, because the shock length can definitely accomodate it, but then you can't slam the car, which was obviously a design requirement.

One front shock was definitely leaking, and the other likely was leaking slightly - so I definitely had a very worn stock comparison, but I feel most the issue was caused by being hard on the bumpstops pretty much everywhere. Texas World Speedway is a very bumpy track (not maintained well in the past ~2 decades, originally built in the mid-late 60's), so if you're using all your free travel in roll, any bumps in the corners are going to really upset the car. Just adding more preload on the Tein Flex Z's made the car handle so much better in corners by getting it up off the bumpstops when really loaded up.

The Flex Z's were also way quicker than (worn) stock when I had the damping adjustment all sorts of wonky (wanted to try it out really soft, well below critically damped). The car was unsettled by excessive motion after hitting bumps, but it was still probably ~5s/lap faster. Dialing in the shocks gave it that last second or two by calming the car down and improving some corner exit speeds by not having to wheel around mid-corner and corner-exit bumps.

I also added more negative camber due to lowering the car ~3/4" and tweaking the stock adjusters, which will definitely add quite a bit of grip, but the performance was undeniable. It wasn't just a "little faster" - the car was WAY faster. Stock suspension loaded up in a corner on throttle, and the smallest bump is going to have you scrambling to keep it together on corner exit. The Flex Z's were much more composed, probably solely due to getting up off the bumpstops in hard driving.

I do agree Tein's of the past had pretty whacky damping, with mondo-hard high speed compression, which I was honestly worried about when buying these, but I think they've learned that they need to tone it down a tad for their "it's stiff feeling" with lots of high speed compression damping. I imagine the Ohlins will have better suited low speed rebound when at a given amount of high speed compression, but these are actually pretty good overall.


On the subject of rebuilding - I've done it before (Konis), and it's a pain. The next time, I just bought new dampers because it was almost the same price once you added in all the shipping etc., nevermind the wait time. I actually like the idea of saying, "hey, it's been 4-5 years and these have a lot of usage on them, why not refresh the dampers for $400-500ish." (my guess on just damper retail cost) No downtime, no fuss really.

Thanks for this detailed review! I ordered a set of Flex Z a couple weeks ago and am looking forward to getting them installed soon.

thanks for the review! just put mine on 3 weeks ago and still trying to mess with it. my biggest question is preload. how do i proper set it? im sure im not getting the full potential of these coils on the street.

Remove. Measure. Set. Re-install. Enjoy.

It's easiest to tell when you're at zero preload when the coilovers are off the car. Remove them, then move the spring perch up to where it just contacts the spring. That's zero preload. Then from there turn it up 6 full turns from there. There are markings on the spring perch that you can count as you turn it (one vertical line is the easiest, T - E - I - N is also cast in it as well I think). 6 full turns front and rear and you'll gain ~1/2" of compression travel but still have plenty of bump travel.

I've actually been thinking of trying 7 turns (14 mm) of preload on mine, as I haven't once run out of droop travel driving around with 6 turns of preload.

for the preload, what happens if you turn too many times like too much preload? i think i went more than 7 full turns. any negative effects?