vorsprung LK-ZEB, LK-DM Luftkappe Air Piston Upgrade Installation Guide
- June 4, 2024
- vorsprung
Table of Contents
Luftkappe
INSTALLATION MANUAL
LUFTKAPPE AIR PISTON UPGRADE
LK-ZEB LK-DM REVISION A | © VORSPRUNG SUSPENSION 2022
The Luftkappe can be installed by anyone who already possesses the tools and the know-how to service their own fork – or by anybody who has the tools and can follow instructions closely.
Key things to note before you start:
- You need a torque wrench. Don’t try it without one. Beg, borrow, rent, buy or steal one from a friend.
- You will need 10mm shaft clamps to hold the air spring shaft. Please don’t try grabbing the shaft in a vice or in V-blocks, you WILL damage it.
- We refer to the Rockshox service manuals for all aspects of the servicing OTHER than the specific installation of the Luftkappe to the Debonair Air Shaft.
- Record your air pressure and rebound settings before you start doing anything else.
- Don’t do it drunk. Even if you’re Australian.
- The Luftkappe only replaces the piston – not the entire air shaft. We will be removing the existing piston from the air shaft, and replacing it with the Luftkappe.
TOOLS REQUIRED:
NOTE: Do not proceed unless you have the following tools and supplies on hand.
- 15mm socket / wrench
- 18mm socket / wrench
- Torque wrench
- Slickoleum (Slick Honey) grease
- 20wt WPL ShockBoost oil or Rockshox 0W30 oil
- Red Loctite
- Blue Loctite
- Isopropyl alcohol
- Clean, lint-free shop towels.
INSTALLATION
-
See the manufacturer’s service instructions for removing the stock air spring from your fork.
ROCKSHOX: https://www.sram.com/en/service/manuals–documents/service- manuals?filters=&showRecent=false&page=1
Refer to the relevant factory service instructions up until you have removed the air spring from the stanchion.
Refer to the Factory service instructions for torque specifications, lubrication specifications and general disassembly/reassembly. -
Clamp shaft in 10mm shaft clamps.
Use an 18mm socket or wrench to remove the old (red) piston.
-
Clean off the Loctite residue from the shaft threads.
-
LUFTKAPPE FOR DOMAIN ONLY:
Slide o-ring provided onto the shaft, followed by the Bumper Cup
-
Apply fresh red Loctite to the shaft thread and thread the Luftkappe stud into place by hand.
-
Slide the plastic Luftkappe piston onto the stud, and ensure the o-ring on the outside/top of the piston is greased. Lightly grease the the surface of the Luftkappe dome.
-
Apply blue Loctite to thread on piston stud
-
Thread dome onto piston by hand, and torque to 50in.lbs (5.5Nm).
- Thoroughly coat the piston & dome with Slick Honey
Luftkappe installation is now complete.
Continue servicing the fork as per Rockshox’s instructions if you are
servicing the damper or replacing the wiper seals, or skip to the reassembly
instructions.
Follow the factory instructions for reassembly, but do not repressurize yet.
Note: ensure foot bolts are done up with the fork fully extended. If
they’re done up with it partly or completely compressed, the fork will suck
down into its travel.
SETUP
STEP ONE
Your token configuration should start with two tokens less than you had
previously. The maximum number of tokens you can safely run is ONE LESS than
what is specified by Rockshox for the configuration of the fork you have when
it is in stock guise.
STEP TWO
Your starting air pressure should be approximately 10% higher than your air
pressure was before installing the Luftkappe, however, we need to get there in
two or three steps.
a) Pressurise the fork to roughly 1/3 of the final pressure you are aiming
for. You will notice the fork is now very stiff at the start of the travel and
is topped out very hard.
b) Compress the fork several times, very slowly, to allow pressure to equalize
between the positive and negative chambers. You will feel a soft notch in the
motion near the start of the stroke – if you hold the fork at that position
you will feel it get softer over the space of a few seconds.
c) Once the two chambers are equalized fully, the fork will top out
pneumatically (not hard contact between two surfaces).
d) After the two chambers are equalized, pump the fork up to roughly 2/3 the
pressure you are aiming for and repeat the equalization process there.
e) Repeat the equalization process at full pressure.
STEP THREE
Ride your bike and adjust pressure and volume configurations as you see fit.
TROUBLESHOOTING / FAQ
– After installing my Luftkappe, the fork is not extending to full travel, what is happening?****
– After installation, the fork should extend to within about 2mm of its
original travel when the fork is unweighted (lift the front wheel off the
ground to allow the weight of the wheel to pull on the fork). If it doesn’t,
this is a sign that one or more of the following things has happened:
– The foot bolts were not done up with the fork at full extension. This must
be done or the fork will have a vacuum in the lowers that sucks it down. Undo
the foot bolts and tap them loose, then do them back up at full extension.
– The piston was inserted too far into the chamber before the seal head was
installed, trapping a lot of air in the negative chamber that the air in the
positive chamber is not able to overcome in order to reach the equalization
port. You can try forcibly extending the fork to reach the equalization point,
and/or use higher pressure in there to assist you. If it does equalize but
still stays sucked down, this is not the cause.
– You do not have the correct air shaft in there. If you have changed the
shaft, this is very likely the cause – there are multiple variants of a
“150mm” air shaft for example, depending on your wheel size and which fork
you have (Lyrik/Yari or Pike). Replace the shaft with the correct one.
– There is excessive grease in the negative chamber, or the top-out bumper was
not removed. Make sure these are removed.
– There is some fault with the main piston quad ring that is preventing it
from sealing properly, such as debris jamming in between it and the stanchion.
This will typically cause a complete collapse of the fork.
– You are reading the wrong sag gradients. This happens to the best of us!
– I can forcibly extend my fork about 20mm past where it extends to before it hits a hard stop, what’s going on?****
– This is a pneumatic topout in action – top-out bumpers are not necessary for this fork. Being able to forcibly extend it a considerable distance past its proper top-out point is normal and will not occur in use.
– My fork sags just under the weight of the bike, why?****
– It should sag a couple of mm because the bike has weight. If your suspension does not sag at all under the bike’s weight then it is excessively sticky or preloaded. Think about it this way – if you, the rider, weigh 90kg (200lbs) and the sprung mass of your bike weighs 10kg (22lbs), your bike’s sprung mass constitutes about 10% of the total sprung mass. If you run approximately 20mm sag in the fork when the rider is on the bike, then it makes sense that you’d see roughly 2mm sag with no rider on the bike.
– I have to run more pressure now to get the same sag, why?****
– Part of the point of the Luftkappe is that it reduces the initial stiffness of the air spring. As a result, yes, you’ll run more sag. Besides that, measuring sag on a fork is very inconsistent and unreliable – use pressure as a measurement instead. If the fork feels like it’s riding too low in the travel due to the extra sag, it may simply be that your handlebars need to be a few millimeters higher.
Questions?
support@vorsprungsuspension.com
Documents / Resources
|
vorsprung LK-ZEB, LK-DM Luftkappe Air Piston
Upgrade
[pdf] Installation Guide
LK-ZEB LK-DM Luftkappe Air Piston Upgrade, LK-ZEB, LK-DM, Luftkappe Air Piston
Upgrade, Air Piston Upgrade, Piston Upgrade, Luftkappe
---|---
References
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>