Hello, I am researching for coilovers for my car, so I've been looking at spring rates, dampening adjustability, etc.

I noticed that coilovers will offer 24 or 36 or another number of ways to adjust the dampening. How should I compare these? How is dampening measured, is there a rating similar to springs (like 10k/12k for the megan coilovers) for some range of dampening allowed?

Some brands have mentioned revalving would be necessary if the spring rate were changed significantly from the optimal spring rate the coils come with. How does revalving work, and how is that different than dampening?

Also, are there any full coilovers out there that come with progressive spring rates?

Any helpful information would be appreciated, thanks!

 

you can't compare it unless you put the damper on a dyno. the 24 or 36 doesn't mean jack **** in the overall adjustment area.

the valving on a shock is the same as you like to call "dampening". so re-valving a shock would be to change its "dampening".

"dampening" isn't really messured. the shocks rebound and compression are messure in some type of force vs. velocity.

(the thread at the top of this forum has a ton of dyno charts)

 

From what I've seen, ususally only about 5 of the 32 settings actually make any real change in damping. This is because the "needle" type adjuster can only makes a real difference just before it closes completely. Other types of shocks (usually ones without clicking adjusters) don't use the "needle" valve, so their damping adjustment range it much more borad & effective...

Definenlty check out the "shock dyno" thread that slammed_93_hatch mentioned. It can be a little confusing at first, but they are great comparisons...

FYI: It's "damping" not "dampening". That carries a whole different meaning...


Modified by 94eg! at 10:01 AM 4/27/2006

 

Well the needle valve design can have much better adjustments than what is typically seen out there. Our dampers use the needle valve design effectively. It just requires a slight reworking of the design and valving.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PIC Performance &raquo;</TD></TR><TR><TD CLASS="quote">Well the needle valve design can have much better adjustments than what is typically seen out there. Our dampers use the needle valve design effectively. It just requires a slight reworking of the design and valving.</TD></TR></TABLE>

AFAIK the needle valve adjustment method is still very dependent on the temperature of the medium, which means that the damping characteristics change as the oil heats up from usage.

Feel free to correct me if I'm wrong.

 

Great thanks for all the info so far! I'll try looking at the shock dyno again, hopefully I'll understand it better. Do the dynos only measure performance of the shock, or are spring rates included in there as well?

Can anyone answer the question about progressive rate springs on coilovers?

Keep that knowledge flowing, thanks!

 

I don't think there are coil-overs that come with progressive springs. Coil-overs are manly designed for racing purposes or extreme lowering of street cars. The problem with progressive springs in racing conditions is a more complicated predictability. Predictability is key to consistent lap times & fast safe driving. The change in spring rate mid-corner, will change how the car handles. Not so desirable.

The other thing is that Coil-overs are made to be able to lower quite a bit (desirable for street & show cars). If you lower the car a lot with progressive springs, your springs will most likely be too soft causing sever bottoming of the shock & damage to the suspension.

The solution for using progressive rates in racing is to use multiple springs on each shock. The secondary springs are called tender springs, and they are shorter linear or dual rate springs that get coupled to your main linear rate springs to create a custom progressive rate. This makes it very easy to adjust the "progression" for a particular situation or ride height. All you have to do is swap out the tender spring. It's definitely a more advanced setup that requires precise calculation & understanding of your suspension/driving/track/etc...


The shock dyno does measure the shocks resistance without any springs in place. The force reqired to move the shock piston increases as the speed at which the dyno moves the piston increases. Each shock has a different "dyno curve". Usually you looking for an adjustable shock with a large rebound adjustment range & a nice digressive rebound curve. Digressive meaning that the shocks increase in stiffness levels off after a certain piston speed is reached...

 

I haven't been able to get any sort of data acquisition hooked up on our cars to test this but it would make sense that damping characteristics would change as the oil heats up. Use of a higher grade oil certainly helps with this, and the large shock body promotes better heat dissipitation.
Our experience during track use, and most recently at Mid Ohio, don't show significant or noticeable decrease in performance of the coilovers over the course of 20 minutes of use. At Targa Newfoundlan I believe each leg was significantly longer and the dampers held up well there as well, with no reported drop in performance. Running the 24 hrs at Thunderhill might show different results.