BRZ/FR-S Suspension Options List (Springs and Coilovers)

[DarrenDriven]

Added my review of the D2 Racing RS coilovers:
http://www.ft86club.com/forums/showthread.php?t=13553

[DetroitJake]

Firstly this thread is awesome and DarrenDriven is a mad man for putting this sort of stuff together.
Respect man.

However, I am wondering further about this subject.

What about compression and rebound damping?
Do manufacturers give values for this sort of thing?
The unit should be something like Newton per m/s (force per velocity).
In other words, the faster you hit it, the more it resists movement.
(viscous fluids such as oil have this behavior).

I believe there's much more to a shock than just spring rates.
There's constant rate springs, progressive rate springs, constant damping and variable damping, etc.

I don't have any practical vehicle level experience with this, but I've raced model cars a bit, and suspension set up is quite important.

I'd love to lower my FR-S, but when you restrict available motion, you'll probably need more damping as well to absorb the force in a shorter period. (Michigan is full of pot holes)
Probably this aftermarket stuff already considers this sort of thing, but maybe not. Maybe just a stiffer spring (spring rate increase) is enough to handle it?

Just I'm wondering this subject. Can anybody comment from practical experience? Do any of these coil overs have adjustable damping?
And how do you adjust it? Do you need to remove the shocks or is there access to valves for example?

[DarrenDriven]

As each spring or coilover is installed and reviewed by forum members I will link to their individual topics which should contain more information on each part. I am just about maxing out the amount of info I can cram into a table in the first topic already.

[DarrenDriven]

Added info for the K-Sport coilovers, which appear to be the same as the D2 product.

[Racecomp Engineering]

Originally Posted by DetroitJake

Firstly this thread is awesome and DarrenDriven is a mad man for putting this sort of stuff together.
Respect man.

However, I am wondering further about this subject.

What about compression and rebound damping?
Do manufacturers give values for this sort of thing?
The unit should be something like Newton per m/s (force per velocity).
In other words, the faster you hit it, the more it resists movement.
(viscous fluids such as oil have this behavior).

I believe there's much more to a shock than just spring rates.
There's constant rate springs, progressive rate springs, constant damping and variable damping, etc.

I don't have any practical vehicle level experience with this, but I've raced model cars a bit, and suspension set up is quite important.

I'd love to lower my FR-S, but when you restrict available motion, you'll probably need more damping as well to absorb the force in a shorter period. (Michigan is full of pot holes)
Probably this aftermarket stuff already considers this sort of thing, but maybe not. Maybe just a stiffer spring (spring rate increase) is enough to handle it?

Just I'm wondering this subject. Can anybody comment from practical experience? Do any of these coil overs have adjustable damping?
And how do you adjust it? Do you need to remove the shocks or is there access to valves for example?

Hey Jake,

Most (though not all) coilovers have externally adjustable damping. For large scale changes you may need to send the shock to the manufacturer to be internally revalved.

Usually it's one external knob that adjusts compression (aka bump) and extension (aka rebound) together, though sometimes it only adjusts rebound.

A few coilovers have two knobs...an adjustment for rebound and a separate knob for compression. KW Variant 3s are an example of a "2 way" coilover.

Fewer still will have 3 or 4 knobs. These separate out the damping into high and low piston speed situations. 3 ways are rebound and high + low speed bump. These are usually very expensive, race-only parts. 4 ways will run you around $10k.

Occasionally you'll see a manufacturer say something like 30 way adjustable damping. This just means that they have 30 clicks of adjustment. This isn't the proper terminology, just like the word dampening isn't really correct (vs. damping).

Number of clicks isn't really as important as the valving itself, total range of adjustment, consistency, etc.

Manufacturers occasionally release shock dyno plots, which are usually force vs. piston velocity charts. They are also sometimes displayed as force vs. displacement.

Shock valving is a little complicated...but the basics aren't too bad. It's not as simple as soft vs. stiff like a spring. Higher end shocks can be tuned to behave digressively instead of linearly (or progressively). You're right though, it's very important and there is much more to a coilover than the amount of drop and the spring rates. Unfortunately it's data that's often not released and much more difficult to interpret.

- Andrew

[DetroitJake]

Originally Posted by Racecomp Engineering

Hey Jake,

Most (though not all) coilovers have externally adjustable damping. For large scale changes you may need to send the shock to the manufacturer to be internally revalved.

Usually it's one external knob that adjusts compression (aka bump) and extension (aka rebound) together, though sometimes it only adjusts rebound.

A few coilovers have two knobs...an adjustment for rebound and a separate knob for compression. KW Variant 3s are an example of a "2 way" coilover.

Fewer still will have 3 or 4 knobs. These separate out the damping into high and low piston speed situations. 3 ways are rebound and high + low speed bump. These are usually very expensive, race-only parts. 4 ways will run you around $10k.

Occasionally you'll see a manufacturer say something like 30 way adjustable damping. This just means that they have 30 clicks of adjustment. This isn't the proper terminology, just like the word dampening isn't really correct (vs. damping).

Number of clicks isn't really as important as the valving itself, total range of adjustment, consistency, etc.

Manufacturers occasionally release shock dyno plots, which are usually force vs. piston velocity charts. They are also sometimes displayed as force vs. displacement.

Shock valving is a little complicated...but the basics aren't too bad. It's not as simple as soft vs. stiff like a spring. Higher end shocks can be tuned to behave digressively instead of linearly (or progressively). You're right though, it's very important and there is much more to a coilover than the amount of drop and the spring rates. Unfortunately it's data that's often not released and much more difficult to interpret.

- Andrew

Great answer. Thanks for the post. I plan to feel out the stock suspension for a while, but after I'm familiar with how it feels, I'm going to start looking at this stuff. I'll definitely check you guys out. Thanks again Racecomp Engineering.

[Nitro22]

Here is the link to the Hotchkis Coil Springs:

http://www.hotchkis.net/2013-scion-f...l-springs.html

Cheers

[switchlanez]

The STI springs lower by 15mm (0.6") front and rear.

[DarrenDriven]

Added STi BRZ Springs:
http://www.sti.jp/news/2012/12024.html

[DarrenDriven]

Originally Posted by Nitro22

Here is the link to the Hotchkis Coil Springs:

http://www.hotchkis.net/2013-scion-f...l-springs.html

Cheers

Thanks! I updated the link on the list.

[DarrenDriven]

Added review of the Hotchkis Sport lowering springs
http://www.ft86club.com/forums/showthread.php?t=14816

[bpracer]

In case you wonder why the FR-S is a bit tail-happy...

The FR-S spring rate ratio front to rear is by far the most aggressive of all the spring rates of the OEM models and even aftermarket (non-coilover) makers. Of course there may be some variable effects of the lowered springs heights for the aftermarket but you get the idea...


Model Fr Rr Fr/Rr ratio
FR-S 2.3 3.8 .605
BRZ 2.7 3.5 .771
GT-86 3.0 3.3 .909

Tein H 3.0 4.6 .652
Tein S 3.3 5.0 .660
Hotchkiss 3.3 4.7 .702
Eibach Pro 3.8 5.3 .717
Eibach Pro 3.6 4.9 .734

[ill86]

Tein has different specs listed on site. I don't believe it was always listed as such.
http://www.tein.com/tech_info/q54.html

S-Tech ride height changed
H-Tech ride height and spring rate changed.
Now 2.9/4.8 (.60417 - see above post)

[bpracer]

Originally Posted by ill86

Tein has different specs listed on site. I don't believe it was always listed as such.
http://www.tein.com/tech_info/q54.html

S-Tech ride height changed
H-Tech ride height and spring rate changed.
Now 2.9/4.8 (.60417 - see above post)

They did change didn't they...

I'm coming to enjoy the FRS handling (only had it for 5 days!). The oversteer I first encountered seems to be limited to tight, low speed situations, where it is difficult to weight the rear end.