Yes

and what is PDS?, and what do you determine to be older shocks?
Quick Q if lowering springs dont work, how do you lower the suspension ??
Hi Santa
PDS stands for Progressive Damping System or secondary piston. This is position depended system, and velocity depended.
Installed in some OEM and top of the range aftermarket dampers.
PDS cup or valve is mouted at the top of the stroke, and about 70% of the piston rod travel .
So on the "older GS's pre LC bikes from 1150-1200 hexhead" are equipped with that system.
This can give +100% of extra compressio damping, and if you add 50N bump rubber
You will get a lot of bottoming out prevention.
If the bike is lowered below ideal position or springs to soft (lowering springs work this way ), the system will engage during the normal ride, resulting in unpredictable behaviour and a very hash ride.
There are ways of modifying the internals to get the good ride quality and correct seat height. But the shock needs to be open.
The shocks are lowered internally, and stiffer shorter spring is fitted . This way, we can get lowered bike ,coreect sag at 30% of total travel of the wheel, and springs that doest blow through the stroke.
It is worth knowing that most of the OEM bikes are fitted with the springs for 75KG rider, including GS
Custom springs along with some shimstack moddification usually transform the bike and the handling.
1200 GS works best with 55-65mm of rider sag on the rear . If you are not able to get that with maximum preload, the spring upgrade is recommended.
Ideally, I would like to see 30% of rider sag with minimum preload to allow for loading the bike.
When people are going towards aftermarket suspension, the first thing they should receive is correct spring!(on some ocasiond they dont even get that right) .
below Tractive shock diagram to visualise how the PDS system works .
In the OEM aplication, the PDS and gas chamber is inside the shock body.
I hope this explains it well.
Visit my instagram page to see daily ESA work and internals of varius dampers during the service.
@ttech_suspension
Luke
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