GFB Respons (part T9003) - Manual (Page 3)

Spring Adjustment
Contrary to popular belief, the spring pre-load DOES NOT need to be adjusted to suit different
boost levels. Unlike other valve types on the market, the Respons will stay shut under full
throttle conditions regardless of boost pressure or spring pre-load.
The spring pre-load affects how easily the valve opens when you lift the throttle, and how long it
stays open when it vents. Adjusting the spring is a simple matter of ensuring the valve opens
enough to release the air, but not long enough to cause idling problems. The guide below will walk
you through the steps involved.
The screw in the centre of the head is the spring
adjuster (figure 6), and the direction of adjustment
is labeled (+ direction increases spring pre-load).
Use the supplied 5mm hex key for this screw.
The softest spring setting is achieved when the top
of the adjustment screw is 3mm above the head of
the valve (figure 6). Do not set the screw more
than 3mm above the head (an o-ring fitted to the
screw head will become visible if the screw is
wound out more than 3mm – the o-ring must
remain below the head of the valve).
•
Set the spring to the softest setting, and
move the noise adjusting ring to at least 50% atmosphere venting so you can see the piston
through the trumpet
•
Start the car and let it warm up to normal operating temperature. Make sure the A/C is off
•
Look at the piston through the trumpet. If it is hovering open, wind the adjustment screw in
the “+” direction until the piston closes fully. If it is already closed, proceed to the next step
•
Give the engine a good hard rev. The piston should lift slightly and vent, then close slowly
and smoothly. The harder you stab the throttle, the further the piston will open (note: it will
only open fully when driving, as the turbo does not generate boost until the engine is under
load). WARNING: Keep your face away from the trumpet opening when revving the
engine. View the piston from an angle away from the blast of air
•
If the piston stays open too long, and is not closed when the revs drop back to idle, the
engine will “stumble”, or the revs will dip below idle. If this happens, wind the adjustment
screw in the “+” direction one turn at a time until the engine returns smoothly to idle after
revving
•
For the final fine-tune, take the car for a drive. Watch the tacho as you pull up to a stop - if
the revs dip below idle, tighten the spring 1-2 turns
•
If a loud flutter is heard when lifting off sharply from full boost, wind the adjustment screw
in the “-“ direction one turn at a time until the noise disappears. Note that it is not
uncommon to hear a slight fluttering at low RPM under certain conditions. This is a result of
the different way in which this valve operates compared to the factory unit, and is perfectly
normal
A video example of setting up the spring pre-load can be seen at:
http://www.youtube.com/watch?v=iqQR5WUF9lc