jmarinheiro

Hi guys, what are your thoughts on progressive damping vs linear damping... with or without progressive springs ?

Nerobro

iTrader: (2)

Progressive damping isn't really a thing. There was a time where a company sold pistons with tapered pins that varied the flow based on shock position... but generally speaking, the "factor you need to consider" is piston speed not piston position. Also, what might be more important, is piston direction. Recently I've seen released valved pistons, which mimics what you find in good real shocks, where there is a seperate compression and rebound circuit.

Progressive springs.. are also not commonly used. They show up more where travel is insufficient. On real cars, they have snubbers which act as rising rate bits of the suspension. For us, that's just going to be the foams in the tires compressing.

This.. is something you should pick up suspension tuning books on. :-) The rules are the same weather it's 1/28th scale or 1/1 scale.

Brian10811

iTrader: (4)

To be honest, I have not tested enough to know if it has any effects. I have tried them and it is like any other spring change. Sometimes they work and sometimes they don't. In theary it sounds like a good move to run them.

TurnNBurn

Progressive springs were tried years ago - as far back as the early 90’s when I was at my peak competitive level. I had to get out of the hobby shortly after, so I don’t know how long it lasted, but given that you don’t see it anywhere today, I’m guessing that one or more companies determined that it doesn’t really work well at these small scales.

glennhl

iTrader: (16)

Most of the Team Associated drivers went to the progressive dampers. I never tried them, but I heard good things about them.

https://www.associatedelectrics.com/..._shock_system/

tbrymer

iTrader: (10)

Hagberg often uses progressive dampner on the front of his xray. Must be good. LOL

jmarinheiro

I've tried those shock inserts on all four dampers... in a TC7.2, low grip asphalt, large track, 13.5T Blinky... don't have clear thoughts ... yet. But it felt better... at least in theory should be better.

DirkW

iTrader: (1)

Actually progressive springs are fairly common on touring car fronts.

duckman996

iTrader: (14)

Progressive Springs are almost a staple locally for on-road carpet racing - especially as the traction increases. While a linear spring may render faster lap-times, the progressive spring on the front tends to settle issues with minor traction roll down. A local racer who is pretty fast explained that the soft rate of the progressive spring allows the car to lean over to obtain steering - and when the softer portion of the spring collapses - the harder part of the spring keeps the car from flipping. I found similar results where the progressive front spring took some of the edginess away from my TC when switching from a typical linear set-up.

Erhard

It is very difficult to say whats best. First of all one would need a Damper test stand to measure the true properties of a damper. All other is try and error with often erratic results.

What I can say from suspension theory is that linear spring and linear damper is the best to get optimum grip.
What is a linear damper? It is, when damping force goes up linearly with piston speed.
In contrast progressive damping is when damping force goes up more than linearly (=progressive) with piston speed.
Progressive damping is easy to acchieve due to non linear force to speed law, when liquids are just pressed through narrow gaps or holes inducing turbulence (quadratic law for speed vs. damping force - double piston speed --> 4times damping force). It is linear damping only for laminar flow. High viscosity oils and large holes in a piston help for laminar flow and are more linear but unfortunately temperature dependent, as viscosity changes very much with temperature.

https://www.associatedelectrics.com/..._shock_system/ This is not progressive damping in the common wording of suspension theory. It is travel sensitive damping! (it depends on the piston position, not the piston speed.

Next thing to increase traction is less damping in compression than in rebound.
Awesomatix had a system providing this in TC but it was given up, as drivers were overstrained with the complexity of all the setup options.

Finally - not always you want optimum grip to prevent cars from roll or you need other things like bottoming resistance after jumps.
Here progressive damping and springs can help. But it is a misfit. A travel sensitive spring is combined with a speed sensitive damping, which never produces optimum response of suspension. What happens on impact to a bump? In the first moment the piston has to move with the highest speed and springs are still extended. This means due to the high speed and progression of damping with such speed overproportional damping in the moment, when spring is soft - this is not good and the car will be reflected upwards by the bump.

What fits would be a progressive spring combined with travel sensitive damping like this: https://www.associatedelectrics.com/..._shock_system/ This is pretty cool!!!!

Best regards,
Erhard

gigaplex

iTrader: (2)

MTS have tapered shock bodies so their damping is progressive. Xray also has progressive damping with their no-hole pistons and triangular inserts. This is probably what they're asking about.
https://www.teamxray.com/teamxray/pr...34&kategoria=0

Progressive springs are very common. It's pretty much the baseline setup in my area to use progressive fronts and linear rears, regardless of brand.

Erhard

https://www.teamxray.com/teamxray/pr...34&kategoria=0
same as
https://www.associatedelectrics.com/..._shock_system/

Unfortunately teamxray belongs to the ones that use the word "dampening", where damping is meant - so they don´t built dampers, but dampeners? A dampener is a device to make something wet or moist.
Maybe worse than Aluminum, where Aluminium is meant. (Ask a chemist - there is no chemical element called "Aluminum")
(oh yes - i am a nit-picker )

Nerobro

iTrader: (2)

AAAAAAAAAAAAAAAAAnnnd i'm wrong.

Bry195

The damper on the awesomatix has a lever arm. The lever length can be setup to change during compression and rebound. You can adjust the starting length and there are a couple methods to adjust the dynamic length.

Separately you can widen the pivot of the spring to create 15 or 25% progression rates. You can also fine tune this by adjusting the length the eyelet on the spring is from its end stop.

at my level I dont notice allot of benefit but I do notice 1 thing. Its easier to get a feel for the limits in a corner when its progressive before it goes over the edge.

Erhard

The awesomatix damper/spring unit I remember had an option to have compression and rebound damping the same or asymetric comp / reb. For this a part of the damper rotated only in rebound and was not engaged in compression. For this a one way clutch was implemented.
Of course one would have to change the oil viscosity for asymetric action to compensate the lack of total damping (comp + rebound gives total damping, which should still fit with the unchanged mass and spring constant)