Tein shock absorbers adjustment

[inquirer]

I use Koni struts and shock absorbers which offer only rebound adjustment. Now after an unexplained failure, I'm moving to Tein struts and shocks which have simultaneous adjustment of compression and rebound.

I have installed higher rate reinforced springs on the rear axle of my car. For the Koni shocks I had to set them to a harder (slower) rebound setting for better performance with the stiffer springs.

I have 2 questions regarding the Tein struts and shocks:

1. When moving the adjuster towards a stiffer setting does this mean that both compression and rebound become stiffer or do they adjust towards opposite directions?
2. With higher rate springs slower rebound (I know that from experience) and I guess softer compression is needed, right? How should the Teins get adjusted in order to cooperate better with the stiffer springs, since both compression and rebound get adjusted simultaneously? Should I adopt a softer or harder setting for the shocks in order for them to provide better grip with the stiffer springs?

 

[Pew]

1.) Opposite. The stiffer the setting, the slower the compression and rebound.

2.) Either start at the max + or the max - and then adjust until you feel the sweet spot for you. What I was taught is to start at max - and add + from there until the ride is compliant for me. Generally speaking if you want max grip, you want it soft but there's so many variables; do you want better turn-in response like AutoX? Do you feel too much understeer during corner entry, mid-corner, or exit? Etc etc. You'll have to find a track or an empty road and run it over and over, and adjust your compression/rebound until you eliminate over/under steer or until you make the handling how you want it.

 

[inquirer]

1.) Opposite. The stiffer the setting, the slower the compression and rebound.

2.) Either start at the max + or the max - and then adjust until you feel the sweet spot for you. What I was taught is to start at max - and add + from there until the ride is compliant for me. Generally speaking if you want max grip, you want it soft but there's so many variables; do you want better turn-in response like AutoX? Do you feel too much understeer during corner entry, mid-corner, or exit? Etc etc. You'll have to find a track or an empty road and run it over and over, and adjust your compression/rebound until you eliminate over/under steer or until you make the handling how you want it.

1. ΟΚ. (I personally wouldn't call that opposite. I would call opposite the situation where one of them was getting slower, while the other faster.)
2. The problem is that there is no access for adjusting the rear shocks. They have to be out of the car. My experience with the Konis is that a slower rate of rebound would make the car feel unsettled during spirited driving on windy roads, while it worked fine with stiffer springs and that's something to be expected. Judging from that, I would say that a faster / softer compression is needed with stiffer springs, but in order to achieve that – if both compression and rebound become slower or faster simultaneously as you said – a shock absorber with independent settings would be needed.

 

[Pew]

Are they 1-way coils? It might be rebound-adjustment only.

 

[inquirer]

Are they 1-way coils? It might be rebound-adjustment only.

Actually I'm going to install EnduraPro Plus which are OE shape, because I don't want to lower the car for clearance reasons. They have simultaneous adjustment of both compression and rebound, as the Flex Z do.

 

[Pew]

Ah okay. You can get away with a stiffer damper settings with stiffer springs but you don't want to go to much to the extremes of too stiff or too soft in order to match the springs to control the car's oscillation.

Although I would like to mention, it's a good idea to get the coils revalved when changing springs.

 

[inquirer]

Ah okay. You can get away with a stiffer damper settings with stiffer springs but you don't want to go to much to the extremes of too stiff or too soft in order to match the springs to control the car's oscillation.

Although I would like to mention, it's a good idea to get the coils revalved when changing springs.

I don't think revalving is available for this specific product, at least not officially by Tein. I think though the stiffer springs will be within the adjustment range of the shocks. As far as I remember Tein offers some of its high end coilovers with the option to combine them with a range of ±2kgf/mm spring rates compared to their standard spring without revalving.

Tein gives a recommended value that suits each vehicle and for the Endurapro Plus that is selected to be 8 clicks. They suggest to start working from this value. I will probably stay around that setting, but the question is towards which direction should I adjust softer or stiffer? If only rebound was adjustable the answer would be clear, a stiffer setting would be undoubtedly needed. Now that both compression and rebound get simultaneously adjusted I'm not so sure. Maybe I should just stay at 8 clicks after all.

 

[Pew]

I don't think revalving is available for this specific product, at least not officially by Tein. I think though the stiffer springs will be within the adjustment range of the shocks. As far as I remember Tein offers some of its high end coilovers with the option to combine them with a range of ±2kgf/mm spring rates compared to their standard spring without revalving.

Tein gives a recommended value that suits each vehicle and for the Endurapro Plus that is selected to be 8 clicks. They suggest to start working from this value. I will probably stay around that setting, but the question is towards which direction should I adjust softer or stiffer? If only rebound was adjustable the answer would be clear, a stiffer setting would be undoubtedly needed. Now that both compression and rebound get simultaneously adjusted I'm not so sure. Maybe I should just stay at 8 clicks after all.

I'd stay at 8 too and adjust from there. If you have grippy tires go stiffer like a couple clicks of + but if you have 'normal' tires start at 8.

 

[inquirer]

I think I will start at a setting close to 8, 1 or 2 clicks stiffer.

Hopefully, that will work and I won't have to remove the shocks in order to adjust them again.

I had set the rear Konis to 90°, if I recall that correct. With the OE springs when driving fast on windy roads with elevation changes, the rear felt a little bit unsettled and lighter while cornering, to be more precise while the car was changing directions while driving through consecutive corners. Obviously having better tires helps, but in any case surely that setup didn't allow the car to take full advantage of the potential of the tires, because they were obviously losing a little bit of contact with the road.

Then I moved to reinforced springs for the rear axle and without changing the setting of the Konis the car felt planted on the road again. I don't know if that was the optimum setting, because I didn't test any other rebound levels for the shocks, but the difference was more than clear.

If the shocks were externally adjustable I obviously would test different setups, as I had done with front ones.

 

[TiGeo]

I use Koni struts and shock absorbers which offer only rebound adjustment. Now after an unexplained failure, I'm moving to Tein struts and shocks which have simultaneous adjustment of compression and rebound.

I have installed higher rate reinforced springs on the rear axle of my car. For the Koni shocks I had to set them to a harder (slower) rebound setting for better performance with the stiffer springs.

I have 2 questions regarding the Tein struts and shocks:

1. When moving the adjuster towards a stiffer setting does this mean that both compression and rebound become stiffer or do they adjust towards opposite directions?
2. With higher rate springs slower rebound (I know that from experience) and I guess softer compression is needed, right? How should the Teins get adjusted in order to cooperate better with the stiffer springs, since both compression and rebound get adjusted simultaneously? Should I adopt a softer or harder setting for the shocks in order for them to provide better grip with the stiffer springs?

They are both getting "harder" as you increase damping. This is similar to how Bilstein does the damping adjustment on their B16 coilovers...both rebound/compression are adjusted at the same time. Higher rate springs = more damping to control the motion is the simple explanation and with both getting higher, you slow/control the compression of the spring as well as the rebound.

 

[inquirer]

Higher rate springs = more damping to control the motion is the simple explanation and with both getting higher, you slow/control the compression of the spring as well as the rebound.

If compression of the shock absorber is set to a harder setting doesn't that add to the stiffness of the spring?

My experience with setting the Koni Sport which has only adjustable rebound was that with higher rate springs a slower (harder) rebound of the shock absorber worked better, because I guess it fights the tendency of the springs to move the wheels towards the road surface prematurely and then bounce.

With the same logic as the spring rate gets higher and springs stiffer I would expect that the compression should get softer in order to allow the wheels to move up when they have to (for example over a bump) instead of delaying their move and thus making the car to jump.

 

[TiGeo]

If compression of the shock absorber is set to a harder setting doesn't that add to the stiffness of the spring?

My experience with setting the Koni Sport which has only adjustable rebound was that with higher rate springs a slower (harder) rebound of the shock absorber worked better, because I guess it fights the tendency of the springs to move the wheels towards the road surface prematurely and then bounce.

With the same logic as the spring rate gets higher and springs stiffer I would expect that the compression should get softer in order to allow the wheels to move up when they have to (for example over a bump) instead of delaying their move and thus making the car to jump.

Higher compression damping will reduce/slow the spring's compression velocity over a given force (bump/hit). It doesn't change the spring rate. Your comment regarding rebound is correct, a higher rate spring will want to rebound faster so to offset that/slow the rebound of the spring de-compressing, you run more rebound damping which should reduce bounciness.

 

[inquirer]

Higher compression damping will reduce/slow the spring's compression velocity over a given force (bump/hit). It doesn't changing the spring rate. Your comment regarding rebound is correct, a higher rate spring will want to rebound faster so to offset that/slow the rebound of the spring de-compressing, you run more rebound damping which should reduce bounciness.

OK! We agree about the rebound part of the settings.

Now regarding the compression: What I meant about the spring rate is not that it will get altered itself, but that if the compression of the shocks is set to a stiffer setting the wheel will eventually move up slower (and in the same time frame it will move up less) imitating the effect of a stiffer spring.

In that sense I would expect that the higher the spring rate is, the less compression damping is desirable, so a softer setting would be optimal.

 

[TiGeo]

OK! We agree about the rebound part of the settings.

Now regarding the compression: What I meant about the spring rate is not that it will get altered itself, but that if the compression of the shocks is set to a stiffer setting the wheel will eventually move up slower (and in the same time frame it will move up less) imitating the effect of stiffer spring.

In that sense I would expect that the higher the spring rate is, the less compression damping is desirable, so a softer setting would be optimal.

Yes, that's one way to look at rebound damping. I always find that rebound is easier to understand....basically a screen door on your house that you fling open and it slowly closes - how fast do you want it to close? Slam shut or shhhhhhhhhhhh . Increased compression damping will make the car firmer over bumps for sure but it's not the same "stiffness" as just a spring's contribution from it's rate - b/c it's the velocity at which it compresses you are changing - even a higher rate spring may need more compression damping to not feel bouncy/harsh. I think you are overthinking it a bit TBH - dial up the damping to feel good and send it!

 

[Asterix]

There's a ton of info on the web about this. I found this article to be a great place to start. The video is quite a data dump, but it's all true.

Basically, if you have too much damping, the tire has too much of an effect. Tires are high-rate springs with little damping, so make a lousy suspension.

 

[inquirer]

Yes, of course it's the velocity that changes, but that's true regarding both compression and rebound.

I'm overthinking it for 2 reasons:

1. To avoid removing the shocks in order to change their settings
2. Because I want to understand the physics and the mechanics in order to be able to set everything properly instead of experimenting in the dark.

Searching around I found this: https://vorsprungsuspension.com/blo...understanding-compression-damping-part-5-of-6

I guess my logic was right, but there is a catch. Increasing compression damping to one point decreases the peak elastic potential energy of the spring and that's obviously indirectly affects rebound. Surpassing that certain point would make what I initially said true. That's what I understood by reading the article of the link.

 

[TiGeo]

Yes, of course it's the velocity that changes, but that's true regarding both compression and rebound.

I'm overthinking it for 2 reasons:

1. To avoid removing the shocks in order to change their settings
2. Because I want to understand the physics and the mechanics in order to be able to set everything properly instead of experimenting in the dark.

Searching around I found this: https://vorsprungsuspension.com/blo...understanding-compression-damping-part-5-of-6

I guess my logic was right, but there is a catch. Increasing compression damping to one point decreases the peak elastic potential energy of the spring and that's obviously indirectly affects rebound. Surpassing that certain point would make what I initially said true. That's what I understood by reading the article of the link.

Interesting that article - I have a lot of experience with mountainbike suspension since it came out in the early '90s, spent a lot of time with it dialing it in, working on it, etc. It's my basis for undestanding auto suspension as the principals are the same. My current fork/shock have both high and low-speed compression damping. So I have my low speed set up to allow it be more sensitive over small bumps but the higher speed setup to handle the bigger hits. Rebound is separate on my stuff and setup to handle the terrain I ride on so not big hits - kind of set up on the lower side of the adjustment so it doens't "pack up" over small studder type bumps where too much rebound will not allow the fork.shock to rebound fast enough to be set of the next bumps.

On my car, I run Bilstein B8 dampers with H&R sport springs so no adjustability but it works well enough.

I understand the PITA that the dampers with adjustment that needs the shock out - my son runs Koni yellows on his car and the rears have to come out to adjust - we just set them at the softest and went with that.

 

[inquirer]

@TiGeo

I have no experience with bicycles, but indeed the core principles of all suspensions are the same.

Of course car dampers with separate settings for low and high speed compression are very expensive and only available for high end cars. For most cars you can't even find shocks with a separate setting for compression and rebound.

On the other hand, if you have dampers that are highly adjustable you should know how to take advantage of them and regularly tweak them to suit the route you are going to drive, otherwise it probably is unnecessary to pay for high adjustability, if you are not going to use it.

B8s are designed to work along with lowering springs for your car, so it is expected for them to work fine. They are made for that purpose and it would be a surprise if they didn't perform well. I would consider B6, but Bilstein does not produce them for my Lancer, it only produces B4. They have a reputation of being too stiff and uncomfortable though. I have never tested them myself, but judging from B4s I would say that probably B6 / B8 are less comfortable than their competition.

As for the Koni, with the OE springs most probably the softest setting is the most suitable for the rear axle. At least for the Lancer that was definitely true. Even adjusting it at 90° had a definite negative impact on the car's cornering performance. I didn't bother to take them off though. When I changed the springs with stiffer ones, 90° worked fine, but I will never know if this was the best setting, because testing them with different settings would be a big hassle.

 

[TiGeo]

@TiGeo

I have no experience with bicycles, but indeed the core principles of all suspensions are the same.

Of course car dampers with separate settings for low and high speed compression are very expensive and only available for high end cars. For most cars you can't even find shocks with a separate setting for compression and rebound.

On the other hand, if you have dampers that are highly adjustable you should know how to take advantage of them and regularly tweak them to suit the route you are going to drive, otherwise it probably is unnecessary to pay for high adjustability, if you are not going to use it.

B8s are designed to work along with lowering springs for your car, so it is expected for them to work fine. They are made for that purpose and it would be a surprise if they didn't perform well. I would consider B6, but Bilstein does not produce them for my Lancer, it only produces B4. They have a reputation of being too stiff and uncomfortable though. I have never tested them myself, but judging from B4s I would say that probably B6 / B8 are less comfortable than their competition.

As for the Koni, with the OE springs most probably the softest setting is the most suitable for the rear axle. At least for the Lancer that was definitely true. Even adjusting it at 90° had a definite negative impact on the car's cornering performance. I didn't bother to take them off though. When I changed the springs with stiffer ones, 90° worked fine, but I will never know if this was the best setting, because testing them with different settings would be a big hassle.

One note on the B6 vs. B8 (I actually hae B6s on my W8 Passat with the factory sport springs and the B8s with my H&R springs on my Sportwagen). They are identical dampers w/r to valving. What makes them "for lowering springs" is simply a spacer to reduce the shaft travel by 1". Why? To ensure they can maintain some preload on a shorter lowering spring at full extension. That's it. You can certainly run B6s with lowering springs if they are the typical Eibach/H&R that are essentially the same lenght as stock spring (they just use dead coils/helper coils typically to gain the lowering). It's like Koni Sports (yellows) - OE replacement length but can work with either stock or lowering springs. I find the Bilsteins to ride superbly - a nicer firm well sorted sport suspension type ride.

 

[inquirer]

Well, it's time to give an update.

I installed the Teins only to the front axle 2 weeks ago, because the company had mixed a wrong rear shock in the package and yesterday I installed the 2 rear ones.

I also changed all the bushings to poly along with the front struts.

So for a period of 2 weeks I drove with Teins on the front and Konis on the rear. During that period the front axle felt stiffer than what it used to be and that was true with all the settings I tried (10 to 2 clicks). I decided to leave the front struts at 6 clicks.

Today, I got installed the rear ones. I set them to 7 clicks. Well, now the car without he 2 Konis in the rear feels way softer, even regarding the front. Does this make any sense?

Since there is no access to adjust the rear shocks, I'm thinking of drilling the towers in order to be able to adjust them any time without removing them. The idea is to create a similar design with the Evo X. It's safe to drill the rear towers, right? They are not part of the chassis, correct?