DC is a shortened way to to say dual speed compression, you may also see the abbreviation DSC. This option can be found on Elka suspension when you order a 2.5 DC reservoir kit. That is a 2.5″ diameter or 56mm aluminum shock body with a separate reservoir. Sorry this option is not currently available for the IFP or internal floating piston shocks(non remote reservoir smooth body).
DC allows for you to change the rate of the compression stroke with the turn of a knob. In fact Elka provides 2 knobs, you can change the rate of high speed compression and low speed compression on the vehicle without special tools. Below is a more technical explanation of what is high speed and what is low speed driving situations. In simple, high speed are quick movements like a pot hole or bump and the low speed are slow shock movements like body roll or brake dive.
Having DC on your shocks can possibly save the costly endeavor of removing the shocks to internally change shock valving to help you dial in your desired ride performance. Some common situations when DC is advantageous would be people with extra weight over stock, fluctuating load weights on the truck and a change in driving style or speed.
Elka has helped us out below with a detailed tuning guide for the shocks. If I could try and help to simplify how I use on my truck. I run the high speed knob as open or counter clockwise as possible. I will turn clockwise to firm up if I’m super heavy from all my camping gear or if I’m driving more spirited and my suspension is bottoming out on the bump stops. The low speed knob I use for controlling body movement, usually a little bit firmer as I don’t run sway bars on the truck.
This weekend I was wheeling with a friend and his Tacoma on Dutch Creek road. This is not a smooth road! We were both aired down to 15 psi and he was falling behind the Tundra. Next time we stopped I checked and his Elka and they were pretty firm on the high speed knob, so I turned them from 6 down to 0. It wasn’t long and he was on the radio and he said the truck was riding 10 times smoother!
For both adjusters:
Fully open = softest setting = less hydraulic damping = turn counter-clockwise to reduce
Fully closed = harder setting = more damping = turn clockwise to increase
All recommended click positions below are measured from fully-out (FFO) position to help comprehension
HSC = High-Speed Compression = Bigger black knob
Affects high-velocity shock movement:
Potholes and big g-outs
Rock, roots and other obstacles hit while driving
Initital moment when the wheels touch when landing from a jump
Chatter bumps and high-frequency vibrations
Basically any time the wheel want to move faster relative to the chassis than the chassis wants to move vs. the ground
LSC = Low-Speed Compression = Small red knob
Affects low-velocity shock movement:
Squatting under acceleration
Front-end diving when braking
Undulations of the road and smooth transitions
Articulation while rock crawling
Basically any time the chassis is moving more vs. the ground than the wheels are moving vs. the chassis
To optimize your settings, the general rules are:
Softer HSC is good for comfort and to erase everything
Start with HSC in fully open position and add only when needed if suspension is using too much travel upon impacts
Harder LSC stiffens the ride making the vehicle feel more planted and stable, increases traction and reduces chassis movement
Start around the middle of the adjustment range of more, reduce when needed if you feel too much harshness
Incresing LSC will help manage additional payload
Recommended initial settings:
LSC: 5 to 8 clicks in FFO
HSC: 0 to 4 clicks in FFO
Softer LSC is good is good for comfort and more articulation
Start with LSC in a soft setting and increase if chassis dynamics are too active
Harder HSC helps absorb impacts and reduce wheel travel used upon impacts
Start with HSC near middle of the range, increase if bottoming or reduce if too harsh on impacts
Avoid driving with HSC fully opened while off-road as it reduces the effectiveness of the LSC and could cause harsh unexpected bottoming
Recommended initial settings:
LSC: 2 to 5 clicks in FFO
HSC: 5 to 8 clicks in FFO
The rest is personal preference according to your driving style and conditions.