Stock FR-S/BRZ shock dyno & stock FR-S spring dyno

[xwd]

I'm working with a shop to develop some stock shock replacement options and went ahead and sent them a stock FR-S suspension which they are now working on modeling.

I actually have a BRZ and will be sending them a set of BRZ springs next week, so where it says BRZ on the charts, it's really OE FR-S. As of now I haven't heard of any differences between the dampers of the two cars, just the springs, and of course the dampers will be changed. The shock dyno looks very similar to the OEM WRX ones I've seen in the past.

FR-S/BRZ shock dyno:



FR-S Spring dyno:

[celica73]

That's pretty consistent with the FRS rates here:
http://www.ft86club.com/forums/showthread.php?t=10416

[xwd]

Had a set of BRZ springs tested as well. Pretty much spot on fron the other threads with the specified spring rates. I don't have the dyno plots for the shocks but they were basically identical.

[aaronosaurus]

Thanks for the data, I love data.

Are the front springs progressive? What explains that bump in rate right at an inch to 1.5?

[icemang17]

the shock dyno makes sense...... my impression on track at the limit in my bone stock FRS is its under rebound damped....looking at the chart you can see it with a maximum 250lbs rebound, but fighting almost the same in springs....

My rebuilt race shocks have nearly 250lbs of compression and almost 500lbs of rebound....much more controlled over bumps even with 800lb springs

[Dezoris]

Great thread thank you will serve as a serious baseline for doing any suspension tuning.

[Racecomp Engineering]

Just to note, the shock dyno matches what the dyno we posted on our Facebook and on here a while back very well.

- Andrew

[xwd]

Originally Posted by icemang17

the shock dyno makes sense...... my impression on track at the limit in my bone stock FRS is its under rebound damped....looking at the chart you can see it with a maximum 250lbs rebound, but fighting almost the same in springs....

My rebuilt race shocks have nearly 250lbs of compression and almost 500lbs of rebound....much more controlled over bumps even with 800lb springs

Yeah one thing I noticed about the FR-S is it is a bit more chattery in the rear over bumpy surfaces than the BRZ, but not by a huge amount. The shocks I'm going to be using for stock autox class mostly have more low speed rebound dampening, but it is increased across the board. There isn't a huge amount of suspension travel so if you add too much high speed you might be riding the bumpstops on bumpier surfaces, especially with the stock springs.

[icemang17]

Originally Posted by dwx

Yeah one thing I noticed about the FR-S is it is a bit more chattery in the rear over bumpy surfaces than the BRZ, but not by a huge amount. The shocks I'm going to be using for stock autox class mostly have more low speed rebound dampening, but it is increased across the board. There isn't a huge amount of suspension travel so if you add too much high speed you might be riding the bumpstops on bumpier surfaces, especially with the stock springs.

I agree......even on the street the traction control comes on pretty quick in any kind of hard accelerating bumpy corner!!!! My home track is pretty smooth, which is a good thing....might get a bit sketchy if it was bumpy!!!

[KKaWing]

A bit of a necro-bump but I stumbled upon Tein's shock dynos for the FR-S and BRZ.

http://teinusa-blog.com/fr-s-or-brz/

http://teinusa-blog.com/wp-content/u...FRS-Front1.pdf
http://teinusa-blog.com/wp-content/u...-FRS-Rear1.pdf

[supramkivtt2jz]

noob question alert:

what does this dyno represent? are the stock dampers over damped or under damped? are these dyno representative of a "quality" valve design?

[Sccabrz192]

Originally Posted by supramkivtt2jz

noob question alert:

what does this dyno represent? are the stock dampers over damped or under damped? are these dyno representative of a "quality" valve design?

You would need to pick a system input based on what road load you are concerned with, develop a corner model with the sprung and unsprung masses, spring rates, damper forces (comp and reb), and based on your input event, you may also want to include the sway bar rate, and that will tell you how the system will react... over/under/critically damped. With that said, OE cars are pretty much exclusively slightly underdamped.

As far as how the graphs look, I assume this dyno is designed to remove gas force since the graph starts at "0", and I assume rebound force is negative on the graph. Overall, the curves look good as far as not having any defects, and on a sample size of 2, the graphs track very consistant left to right. They are digressive, which is expected from an OE damper (some poorly designed aftermarket dampers can have a progressive damping force if the valving is improperly designed). They appear to be very simple units, nothing fancy at all, basically as you'd expect.

Are there Koni Sport graphs posted anywhere??

[themajesticone]

What do these charts tell me in relation to springs rates? Is there any correlation? I am learning...

[CSG David]

@dwx Can you tell Lex to contact me back?