Shock Dyno Data Anyone?

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Jayrdee
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Shock Dyno Data Anyone?

Postby Jayrdee » Sat Feb 29, 2020 6:30 am

So, I'm sitting here bullsh*tting at work and just thought of something that would be kind of cool, if anyone here is a nerd like I am. Would there be any interest in measuring various aftermarket shocks and comparing their compression/rebound data?

I'm a Production Engineer at Hitachi Automotive Systems building monotube shocks. The plant I work at used to be Tokico. My "section" is shock assembly, so basically we get all the components (tubes, rods, free piston, piston valve, etc) and assemble the shocks before they get moduled and sent to the customer. The majority of shocks I produce are for Ford. Like the Ford F150, Mustang, Ranger, etc.

With that being said ... I have access to "Damping Force Tester" machines which measure a shocks compression, rebound, and gas reaction specs. We also use them to verify a correct piston valve stackup is being used. All my lines have them. And the QC labs have them. Theoretically I can put any shock I want to in there, run the machine, and it will spit out its compression/rebound and gas reaction data. For example the fancy graph Fortune Auto advertises on their website for their 500 series coilovers:

Image

I stare at these type of graphs all day/everyday.

I think it'd be cool to gather various aftermarket shocks like TRD Blues, Bilsteins, KYBs, Annex, Fortune Auto, etc. and run them all against eachother, compare the data, and see how they differ. What do you all think?

Now i just need shocks .... :lol: :lol:

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totta crolla
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Re: Shock Dyno Data Anyone?

Postby totta crolla » Sat Feb 29, 2020 10:37 am

I have some TRD blue front AE86 dampers that on setting 3 seem almost perfect (for the springs used) I'd really like to know what the actual rates are! Also have AE86 Bilstein B6's Problem is... I'm in the U.K

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Re: Shock Dyno Data Anyone?

Postby Jayrdee » Sun Mar 01, 2020 12:36 pm

totta crolla wrote:I have some TRD blue front AE86 dampers that on setting 3 seem almost perfect (for the springs used) I'd really like to know what the actual rates are! Also have AE86 Bilstein B6's Problem is... I'm in the U.K


I'm sure we can work something out!
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davew7
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Re: Shock Dyno Data Anyone?

Postby davew7 » Wed Apr 01, 2020 4:23 am

I would bet that the Hitachi Automotive Systems corporate office already has hundreds of benchmarking studies on file, for all major shock suppliers. See if they are willing to share the info. That would narrow the field for any additional testing. davew7

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Jayrdee
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Re: Shock Dyno Data Anyone?

Postby Jayrdee » Tue Apr 07, 2020 6:58 pm

davew7 wrote:I would bet that the Hitachi Automotive Systems corporate office already has hundreds of benchmarking studies on file, for all major shock suppliers. See if they are willing to share the info. That would narrow the field for any additional testing. davew7


I'm sure they do, but unfortunately I'm just a level 1 engineer, still at the bottom of the totem pole Lol.
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Re: Shock Dyno Data Anyone?

Postby jondee86 » Wed Apr 08, 2020 1:48 am

Collecting the information is one thing... knowing what to do with it is another :D I used to think that
if you were clever enough you could do some calculations based on loads and speeds and phases of the
moon and then go and select shocks from a catalog that would be perfect for your car. I have since
discovered that the calculations are complex and frequently require assumptions about hard to measure
operating parameters. So ordinary folks rely on clever factory engineers and honest marketing people
to do the calculations and product testing to come up with the "best shocks for your car".

This is fine in theory, but because of the aforementioned assumptions, the shocks are tuned for one
specific performance situation e.g. fast road. When asked to perform in the same car on a racetrack
the result will be unsatisfactory. The quick fix answer is to put a knob on top to adjust the rebound
damping rate. So providing the shock is used solely for the design application and has some adjustment
(preferably compression and rebound) it will provide decent performance at a reasonable price.

Image

More recently I have discovered that even the experts having done the calculations for a particular
model of car used for a specific type of driving, build prototypes and test them extensively on the road
under their design conditions. Feedback from these tests allow the shocks to be fine tuned for the best
handling. Testing may also involve matching shocks to springs for competition vehicles.

Which brings me to the point of this post :D The magic is in the tuning of the shim stacks and is the
reason high end coilovers are supplied as a unit with carefully matched shocks and springs. Changing
from the manufacturers recommended spring rate will negatively affect the performance of the shocks.
Winding the damping up to compensate for springs that are too soft is no substitute for fitting stiffer
springs. Race cars will have multiple sets of coilovers and will change them out to get the ride height,
spring rate and damping that they require for each circuit or event.

Add to this the driver with his/her own preference as to how the car should feel and handle. There are
a lot of variables at work in suspension design. Simply knowing the shock dyno data does not mean that
it will work in a particular application... UNLESS... you have prior knowledge from actual on the road
testing of the values proven to suit that application.

So by all means add to the knowledge base. Maybe if someone can collate information on what shock and
spring combinations have been found to work "great" by a good selection of drivers, we could eliminate
some of the "wasted my money" selections and highlight some of the "better than average" selections.

Cheers... jondee86

PS: The current lockdown situation makes for spare time to write stuff like this :)
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Jayrdee
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Re: Shock Dyno Data Anyone?

Postby Jayrdee » Sat Apr 11, 2020 9:08 am

Jondee, yes you're totally right. Trust me, having the data and knowing how to read it are two totally different things. I deal with that first-hand everyday haha

I like that picture you posted because that shows where all the magic happens; the piston valve stack-up. For example, one particular model shock may have 10-20 different part numbers, which are all the same shock but with different "valve codes" (what we call the piston valve stackup). A truck going to a mountainous area, or an off-road trim level, will have a different valve code than a base model or one going somewhere flat or whatever. The valve stack up is where all the time and research go.

The shims get as small as 0.15mm in thickness, so its super easy to get the stackup wrong, or load the wrong trays in the machines because they all look the same haha.

With that being said, thats why I think it'd be interesting to put different shocks against each other.
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Re: Shock Dyno Data Anyone?

Postby jondee86 » Sat Apr 11, 2020 3:48 pm

Jayrdee wrote:The valve stack up is where all the time and research go.

And this is the reason why it is so difficult to get shock dyno data from manufacturers. They
have invested time and money in developing shocks that work for specific applications, and
they don't want to give that information away. Usually, high end manufacturers will be able
to re-valve their shocks to suit your application if you provide them with the vehicle model
and how it is going to be used.

As an example, a few years ago when I was looking at upgrading shocks on my AE86 to "fast
road and occasional track" specs, I asked the local Bilstein agent for a recommendation and
he gave me this when I asked...

Image

It was said to be the dyno of a shock with a shim stack that had been proven to work well
with the AE86 in similar applications to mine. However, for a variety of reasons I ended up
going with standard Koni shocks re-purposed from other vehicles. So I never got to find out
how much better a custom valved shock could be in comparison.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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