Thucydides

Speaking of dyno charts, Disaster was kind enough to volunteer his new and unused Raceland shocks for dyno testing at Stewart Development.

Bernie dynoed the shocks today, and here are the results.

There's a lot more to this story, as Bernie had a look inside while the shocks were there. What he found was a bit surprising, but I haven't seen the photos yet so I'll leave it at that.

WonTon

iTrader: (17)

So......good or bad? i dont do well with charts....

Thucydides

Could be better, could be worse.....

Keep looking and some not to difficult to see characteristics should stand out.

ssmith

iTrader: (10)

They aren't very consistent are they...

WonTon

iTrader: (17)

the only thing i noticed is that each shock put out a diff number...

one front had i higher compression and decompression numbers than the other side, same with the rear?

im curious to see these pics you speak of...

Thucydides

Not particularly, but I think you'd be surprised how few shocks actually are consistent from side to side.

WonTon

iTrader: (17)

If you know which ones are weaker than the others couldnt you put those on the pass side of the car seing how there would be more weight on the driverside more often than not? (weight from the driver)

rbluemx6

iTrader: (2)

They have a similar curve to another shock, I just can't think of it at the moment...???

Disaster

iTrader: (1)

Shocks aren't really handling the vehicle weight...more the unsprung weight, so you'd be better off compensating by gluing some weights onto the A-arm...but I wouldn't seriously recommend that.

The big thing that struck me was how much less rebound damping there was on the rear shocks. I'm not sure why you'd want less rebound damping on the rear suspension....especially that much less.

I'd also be curious to see how these compared to the stock OEM Koni's and a typical aftermarket shock, like the GR2's.

Braineack

iTrader: (62)

Looks like a decent aftermarket shock (similar to the Xida curve) in the front and a stock shaped curve in the rear (similar to Koni sports or AGX on soft).

People are saying these things are smooth on the highway?

Thucydides

They're reported to be comfy for those who leave some bump travel in their setups. I suspect they'd reach their limits and become quite boingy on a rough road pretty quickly; especially the back.

What struck me is that the rears have more bump damping than rebound damping. First time I've seen that in a dyno graph.

Braineack

iTrader: (62)

They both have a lot of bump dampening.

18psi

iTrader: (76)

Mine are still doing great. Its been exactly a year now. Still no problems. Street car though, no trak.
One thing I want to change: soften up the back. Its WAYYY too stiff. The fronts are fine over bumps and potholes, the rear shudders from time to time.

90R

iTrader: (4)

who knew?

now if Bernie would post his pic's and comments on the dissection.

I have yet to experience that

PhilMD

Horrible, IMO. They're just underdamped in general.

Front, Bump - Poor low speed damping for the spring rates. High speed gradient too aggressive
Rear, Bump - As above, just worse.

Front, Rebound - No low speed control for transient control. High speed rate a touch too aggressive
Rear, Rebound - As above, just worse

Classic mistake of tuning for spring rates ie a stiffer spring needs more damping. That's not the case, as you're tuning ride frequencies not spring rates.

Phil
PS Does Bernie have a F vs PV graph as that would be the raw data rather than averaging which provides another view of the data?

Disaster

iTrader: (1)

Could that shutter you are feeling be because there isn't enough damping and the rear isn't being controlled like it should?

We've got a 2009 Hyundai Genesis that has this exact problem. A lot of people on the forums complaining about the shocks and springs being "too stiff" but in reality, it is a bit underdamped, which can allow the suspension to get excited over surfaces that it should not. Some people say they've hit sections of highway pavement where the car starts porpoising back and forth. The spacing of the waves in the pavement overwhelms the dampers. I'm looking into buying upgraded components from the 2010, but it just occured to me that maybe someone like Bernie could tune the shocks we've got on there...though I don't think my wife would be too happy to have her car up on blocks for a couple weeks. :-D

The only obvious underdamping I see, is the rear's in rebound.

The compression doesn't look that far off from some other, highly touted shocks (Xida's for example.) However the slope is a bit steeper...particularly the front slope. Maybe it's harder to get a flatter slope with a twintube?

The front rebound curve doesn't look to dissimilar from a trace of another good shock. The rear just makes no sense to me.

The spring rate changes the frequency, doesn't it?

I imagine he has all the typical data that dyno testing would provide but he's also got customer's shocks to work on, so more data and analysis, from him, will have to wait.

90R

iTrader: (4)

the spring rates out of the box are jacked. There's just no way to work around it. an 88% F/R bias on the RL and a 92% bias on the Rokkor's just sucks.

Disaster

iTrader: (1)

True, so it is a combo of too much spring and not enough rebound damping. I'd have to pair these with considerably softer rear springs because the car is weighted toward oversteer as it is...or maybe I'd have to disconnect the rear sway.

90R

iTrader: (4)

275-300# rear spring with a stock rear bar if you have an LSD

PhilMD

Really? There's less damping than an OE damper there.