Item no.: 6288-00
List price: $110
Shafts: 3.5mm plated-steel
Volume compensation: Reservoir
with spring-loaded piston
Mounting hard ware size: 2.5mm
+ Realistic styling
+ Adjustable primary-spring stop
+ Functional, adjustable
+ Excellent fit, finish, and
- Premium quality carries a
Assembly and Testing
;e shocks appear to be fully assembled in the packaging,
but the reservoirs are empty. It’s your job to install the
divider pistons and springs, and fill the shocks with oil. I
followed the steps detailed in the how-to video on Pro-Line’s You Tube channel, and had no trouble getting the
shocks dialed in. As with Pro-Line’s Pro-Spec shocks,
a single X-ring seals the shaft opening, so the action
is incredibly slick. Rebound is very precise too. I used
30-weight oil, which resulted in very light damping.
Relatively heavy damping is usually preferred for crawling
and trail duty, so consider using the included optional
pistons with smaller openings and/or using heavier-weight
oil (I’d try 80–100 weight).
Installing the Ultra Reservoirs on my Vaterra Ascender
only took a few minutes and was a simple “unbolt the old,
bolt in the new” process. Hoo boy, do they look good! ;e
blue and silver treatment emulates the look of Fox and King
full-size dampers, and they really make the chassis pop.
As expected based on their feel when squish-rested o;
the truck, the shocks o;er capable axle control. ;e shock
pivots are slick too, and use steel balls seated in plastic
inserts for smooth, slop-free action. ;e terrain I have
easiest access to is trail-oriented and doesn’t require a lot
of real crawling, so the light damping wasn’t a handicap (and
again, damping is determined by the oil you choose to fill the
shocks with). In fact, it made for a better test of the shocks
since the lighter damping made the shocks more active and
gave the seals a tougher workout. ;ere was no leakage or
weeping to report.
HOW I T WORKS
Reservoir shocks have been
done before, but the reservoirs
were mostly for looks and
merely added oil capacity to an
emulsion system. Pro-Line’s
reservoir design employs a
spring-loaded divider piston, so
there’s no need to mix air into
the shock oil. You might think of
the reservoir as a “mechanical
bladder.” Instead of a bladder
flexing, there’s a movable
piston. And instead of relying
on air compressed behind the
bladder to act as a spring, the
piston is literally spring-loaded.
Compress the shock, and oil
displaced by the shock shaft
flows into the reservoir, pushing
the piston and compressing the
spring. Extend the shock, and
the spring forces the oil back
into the body. Added feature: a
setscrew in the reservoir’s cap
lets you set the preload on the
divider piston’s spring, so you can adjust static rebound. Trick stu;!
;ese are premium shocks with a premium price tag, but the Pro-Line
Ultra Reservoir Shocks earn their asking price by setting a high bar for
quality, innovation, and performance. ;ey’re winners on looks alone, with
performance to match. And if you’re like me and find that RC is more exciting
the closer it gets to full-size tech, you’ll enjoy an extra level of satisfaction
with Pro-Line’s latest shocks. ;ey’re not inexpensive, but they’re the best.
;e adjustable primary-spring stop
(arrowed) lets you to set the point in the
stroke where the secondary spring takes
over. ;is allows greater ride-height
adjustability while maintaining spring
contact at full droop.
When the shock is compressed, oil
displaced by the shock shaft flows
through the cap and into the reservoir,
pushing the divider piston against the
spring. When the shock extends, the
spring pushes the piston back up, forcing
the oil back into the shock body.
;e Ultra Reservoir Shocks are sold in pairs.
Cool packaging, Pro-Line.