Doing some more research on shocks and have read the shocks/springs sticky a few times, but I'm wondering if anyone has any insight/feedback on the "ripple control" aspect of the OEM shocks. According to Infiniti:

"Both front and rear suspension designs utilize aluminum components to reduce unsprung weight and incorporate “ripple control” shock absorbers with damping control lips for suppressing high-frequency, micro-amplitude vibrations. As a result, tiny ripples in the road surface are absorbed to deliver a smooth, comfortable ride."

http://www.freshalloy.com/site/cars/...g35/home.shtml

It could be more marketing hype than anything real, but has anyone who has swapped out OEM shocks for Tokicos or similar noticed increased vibration/harshess beyond what you would expect from a stiffer shock setting? Is there anything to the "ripple control" feature?

 

Shocks are normally speced at a specific distance of change in a second: 1 ft per sec or 3" in 0.25 seconds.

Vertical movements above a certain frequency are passed thru shock as if it wasn't there.

I'm sure you could build in a parallel [internal shock system] that could be tuned to a certain frequency [speed and type and depth of ridges in road].

An often overlooked component is the changes in rubber mounts and isolators that change with age and ozone and detune the high frequency vibrations.

http://www.me.mtu.edu/~mrao/et-shock-paper.pdf
https://kb.osu.edu/dspace/bitstream/...tic_System.pdf

Lighter aluminum suspension arms became necessary when larger wheel and tire weight, rotor and caliper weight increased in size - to try to maintain or improve unsprung weight.
Pretty tough job with a 8 pound increase and only 2-4 decrease by use of aluminum since springs and sway bars still need to be made from steel.


Historically few measurements of vibration transmission above 30 HZ were done now 500 Hz tests are routinely conducted.

"A poorly damped isolator (typically made from natural rubber or
silicone), that is soft enough for good vibration isolation, may
require more sway space for deflection during a shock input
than the product’s design can provide. So a stiffer isolator may
be needed to prevent crashing or bottoming out, but this could
have a negative effect on vibration performance."
http://www.earsc.com/pdfs/engineerin...arts/pg2-3.pdf

 

Lots of good info, Q45...not quite sure how to inerpret vis-a-vis my question. Assuming no one is going to build a parallel shock system, and taking worn rubber components out of the equation, is it possible that picking one of the settings on an aftermarket adjustable shock will approximate the high frequency damping of the OEM shocks? Or are you saying we should assume that the OEM shocks are designed and tested to handle a certain high frequency and that most aftermarket shocks are not, and thus if installed would cause a degradation in vibration handling ability?

 

To a suspension engineers low freq is up to 10-13 Hertz and High Frequency is up to <100 Hertz. These new antivibration [dampening] are for 100-500 Hertz.
Adjustable shocks don't consider > 50 Hertz.

Above 50 Hertz is adjusted by tuning the racing seat suspension and the driver wearing gloves.

 

OK, so what's the real world comfort impact in going to adjustable shocks? Is it only closely spaced expansion joints on the highway (high frequency) where one would feel the difference? Has anyone noticed increased HF vibration w/aftermarket shocks?

 

Expansion joints 44 feet apart and traveling 88 feet per second would be a 2.0 Hertz frequency. High freq would be less than 1.7 feet apart.

Rumble strips:"the grinder cuts perfect 12" center-16 3/4" wide-5/8" deep shoulder corrugation at 12'/minute in natural aggregate concrete." ~~ 88 Hertz

 

OK, so in other words, aside from running over lots of rumble strips (>50Hz) I shouldn't be too concerned about losing "ripple control" were I to switch to aftermarket shocks.

 

NO

Don't get caught up in marketing.

If you need adjustablity and desire a quality shock that is valved better then oem, go with Tokico D-specs

If you do not need adjustablity, go with Bilstein H.D. Why? Monotube construction and low to no internal pressure imbalances (hysteresis) that effects most all twin tube shocks. You will notice a shock has hysteresis most in a ride and drive situation on freeway expansion joints where the lay of the land delivers repeated up and down motion's in a series. The shocks inablity to recovery from the last event, leaves in ill prepared for the next motion and you will feel the lack of control as a bounce or porposing. And if the shock does have adjustablity it will drive you crazy as your try in vain to adjust the shock, but can never find the right setting. It also cut's into the performance bottom line and cost's grip under the right circumstances, though shock manufactuers that make products that have the issue will NEVER admit it exists or show you the shock dyno plots that prove or disprove the presence of hysteresis.

 

The major problem is a temperature change in shock, how to adjust for every 20F change in shock oil temperature.

Thank goodness 95% of buyers are so insensitive that they don't feel the changes.

 

"Both front and rear suspension designs utilize aluminum components to reduce unsprung weight and incorporate “ripple control” shock absorbers with damping control lips for suppressing high-frequency, micro-amplitude vibrations. As a result, tiny ripples in the road surface are absorbed to deliver a smooth, comfortable ride."
>>>

sounds kinda gimicky to me...

 

Thanks all for the feedback.

 

Even the Z, that is many times moreover lilely to see the chance of some track use, has twin tube shocks. If shock temp effects mattered to them, they would have equipped the car with monotube shocks which as you know disapates heat much better.

I have a dial caliper and could check shock body temp, but have little interest on a oem shock and I now run a monotube which I'd rather stress on the shock dyno if I were concerned about the issue, which I am not.