Tein Flex A

[Trettiosjuan]

Preload adjustment is not advertised, height adjustment is. The double collars are just how the lower spring perch is locked in place. A short spring also allows for maximal height adjustability. So not strange at all.

[bfrank1972]

Huh.... I have about 4mm preload on front and rear, with no problems over speed bumps, potholes, construction, etc. I'm not a professional though, so my scientific method is 4mm from "slightly snug" so may not be a true 4mm. They're all consistent, that's what I was focused on. Also mine are street flex, but I'm pretty sure they're very close to the flex z and a. But you're right, I don't see them advertising preload adjustments for these even though it seems like you can. Did you by chance measure coil clearance on both front and rear vs travel?


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[Trettiosjuan]

4mm preload is not much. But on the Flex A, no use with more in front, spring will bottom out first thus reducing HBS function, and droop is also limited...

[Trettiosjuan]

Originally Posted by shattered_memory

Does anyone know if these coilovers have less suspension travel vs stock? I'm interested in getting these and setting them at a very mild drop (.8 to 1 inch drop all around).

Less travel than stock. Most kits are a (lot) shorter, only in part compensated by harder springs. Too bad nobody makes a consumer grade high travel kit like they have for the Impreza.

[Trettiosjuan]

Originally Posted by Trettiosjuan

The HBS works well, but I noticed quickly it has it's limitations: it cannot compensate for the lack of front bump travel. On bigger bumps and speedhumps, the front bottoms out a lot sooner than the RCE, and does so more violently. This is confirmed by my calculations, front wheel has approx 38mm bump travel, rear has 64mm. This is not entirely unsuspected, this is a problem with all lowering coilover kits that run short shocks and springs in front to be able to go down 2" or more. Surely the Flex A is impressive at that height. But at 1" lower which allows for more speed over bumps, this is a limitation which I tried to overcome by choosing the Flex A. Alas, the HBS can do no miracles. Luckily it's easy to change springs and adjust damping, I'm trying to source a 7kg 15mm longer spring that will have the car sit higher in the shock and allow some minor preload, again increasing bump travel and together should be good for 54mm bump travel. Will report how that goes.

First update:
I had two candidates for the front springs, the Tein standardized spring ID 70 7kg 175mm and the Swift Metric coilover spring 7kg ID70 7". Ordered the latter as it was available quicker. It is 28mm longer than the original and sits approx 8mm higher because of the higher rate, 36mm higher in all. But if I want to keep the same height I have now, I only have 26mm to lower the car before all the collars sit together. Solution would be to remove one collar -10mm and have the spring sit at the wheel hub carrier with the two remaining collars. Height adjustability gone, but the swift spring allows for 7mm preload without contact between coils (usable stroke). Can't wait.

[shellslinger]

Originally Posted by shattered_memory

Does anyone know if these coilovers have less suspension travel vs stock? I'm interested in getting these and setting them at a very mild drop (.8 to 1 inch drop all around).

I have the Flex Z's and there is definitely less travel than stock. As long you don't run thicker sways in the rear, you won't be doing the three wheel dance getting up your drive way.

[Trettiosjuan]

Originally Posted by shattered_memory

Does anyone know if these coilovers have less suspension travel vs stock? I'm interested in getting these and setting them at a very mild drop (.8 to 1 inch drop all around).

For a .8 drop, a set of RCE Tarmac Zero, ST coilover or KW v1 (or v3 if adjustability is wanted) would give you a good amount of travel with reasonable spring rates for DD. Those are single height adjustable so going lower on them directly eats away bump travel...

[Trettiosjuan]

So, I am disappointed? Do my experiences contradict those of e.g. DeaconRoc?

No. On a fast back road drive on a bumpy road, the Flex A is very controlled and stable over bumps. Impressive. Yet on a simple speed bump that I could take at 20mph on the RCE yellow (not 'comfortably' but without a 'Dang'), the Flex A bottoms flat out at a mere 16mph.

I think I understood why now. The hydraulic bump stop (HBS) does not fuction as a normal bump stop. A normal bump stop is always there. The HBS works with ramping up damping force at the very end of the damper bump stroke. Like damping, this means that the HBS is speed dependent. Speed of the damper. And by deduction, speed of the car.

On a speedbump, the speed is low, the damper is compressed relatively slowly but the compression continues as, bluntly, the whole car has to be lifted up. As the spring compresses, the speed at the end of the stroke will be quite low. Yet if the bump travel is not sufficient, the damper will bottom out, almost as if there is no bump stop at all to my feeling. As I understand now, because damper speed is low.
Is this a problem? I just don't like slowing down for speed bumps, I go over them faster than most people even in SUV's... I could just slow down a bit more. But I have also bottomed out on sharp bumpy turns, too early for my taste, hence why I am changing front springs...

Going 50 mph+ over a bumpy back road, compression is much faster and the HBS works very well. I had some fears it would bottom out earlier than I would like, but it just doesn't on quite sizeable bumps and the suspension is really enjoyable. That said, I haven't dared pushing on really hard - I have a little bridge I like to jump, but that probably no longer qualifies as 'normal use' For me, increasing front bump travel should only make the suspension even more performant when pushing on. Gotta love it.

[bfrank1972]

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[Trettiosjuan]

Haha!


More than once

[solidONE]

Originally Posted by Trettiosjuan

So, I am disappointed? Do my experiences contradict those of e.g. DeaconRoc?

No. On a fast back road drive on a bumpy road, the Flex A is very controlled and stable over bumps. Impressive. Yet on a simple speed bump that I could take at 20mph on the RCE yellow (not 'comfortably' but without a 'Dang'), the Flex A bottoms flat out at a mere 16mph.

I think I understood why now. The hydraulic bump stop (HBS) does not fuction as a normal bump stop. A normal bump stop is always there. The HBS works with ramping up damping force at the very end of the damper bump stroke. Like damping, this means that the HBS is speed dependent. Speed of the damper. And by deduction, speed of the car.

On a speedbump, the speed is low, the damper is compressed relatively slowly but the compression continues as, bluntly, the whole car has to be lifted up. As the spring compresses, the speed at the end of the stroke will be quite low. Yet if the bump travel is not sufficient, the damper will bottom out, almost as if there is no bump stop at all to my feeling. As I understand now, because damper speed is low.
Is this a problem? I just don't like slowing down for speed bumps, I go over them faster than most people even in SUV's... I could just slow down a bit more. But I have also bottomed out on sharp bumpy turns, too early for my taste, hence why I am changing front springs...

Going 50 mph+ over a bumpy back road, compression is much faster and the HBS works very well. I had some fears it would bottom out earlier than I would like, but it just doesn't on quite sizeable bumps and the suspension is really enjoyable. That said, I haven't dared pushing on really hard - I have a little bridge I like to jump, but that probably no longer qualifies as 'normal use' For me, increasing front bump travel should only make the suspension even more performant when pushing on. Gotta love it.

Sound like this is worth the extra over the Flex Z. I've thrown around a flex-z equipped FRS at 5 clicks out and the damping, particularly in the rear, felt lacking. It would wallow during hard cornering (from lack of damping). With it jacked up to -1 from full stiff it was a little better. If those hydraulic bump stops works as you describe, then it would probably not have the same problem. Although this is the only complaint I'd have. Over the rough stuff and for normal driving it's soooo compliant. I don't think you can get anything better for the $800 price tag of the Flex-Z. that extra $250 for the extra compression damping at the end of the stroke is probably worth it, I think. I'd have to try for myself to be sure though.

[CSG Mike]

Originally Posted by solidONE

Sound like this is worth the extra over the Flex Z. I've thrown around a flex-z equipped FRS at 5 clicks out and the damping, particularly in the rear, felt lacking. It would wallow during hard cornering (from lack of damping). With it jacked up to -1 from full stiff it was a little better. If those hydraulic bump stops works as you describe, then it would probably not have the same problem. Although this is the only complaint I'd have. Over the rough stuff and for normal driving it's soooo compliant. I don't think you can get anything better for the $800 price tag of the Flex-Z. that extra $250 for the extra compression damping at the end of the stroke is probably worth it, I think. I'd have to try for myself to be sure though.

That sounds like a spring rate problem, not a damping problem. In other words, I think you expect the behavior of a stiffer spring. A lack of damping would result in a rear that swings around like a pendulum during rotation, not wallowing/slow response.

I've had no issue with the FLZ in terms of damping.

[solidONE]

Originally Posted by CSG Mike

That sounds like a spring rate problem, not a damping problem. In other words, I think you expect the behavior of a stiffer spring. A lack of damping would result in a rear that swings around like a pendulum during rotation, not wallowing/slow response.

I've had no issue with the FLZ in terms of damping.

This is with the same 6K spring that came stock on them. Increase of compression damping will stop the walloing. That and maybe a bit more damper stroke. I've tested different setups with 6K spring offering much more compression damping. That works much better under hard cornering.

[CSG Mike]

Originally Posted by solidONE

This is with the same 6K spring that came stock on them. Increase of compression damping will stop the walloing. That and maybe a bit more damper stroke. I've tested different setups with 6K spring offering much more compression damping. That works much better under hard cornering.

Damping does not work in a linear fashion. Do you have data to actually verify that there is more compression damping?