Q: What are the
advantages of using RPM Two Stage Shock
I don't care about the
details, give me some set-up suggestions! Click here.
Shock Pistons are for advanced suspension tech's only! It is imperative that you know how to
"read" what your vehicle is doing to make necessary suspension adjustments. If you are not extremely
comfortable with suspension set-up's and how changes in the suspension
affect handling, please do not attempt to install RPM
Two Stage Shock Pistons.
A: RPM two stage shock pistons work better than any
other R/C shock piston because they allow the shock to return to its
static ride height at a much faster rate than do stock pistons. Our shock pistons act as
miniature check valves (one way valves) that work instantaneously as the direction of the
flow of oil through the piston changes. Consider
all of the things that cause a shock to compress versus what causes it to
rebound. The following is a short list of some of those factors;
- The speed of the vehicle.
- The size of the jump or
- The weight of the vehicle.
- Driver's skill level.
With all shocks, including
piggy-back type shocks and
externally adjustable shocks**, the shock spring is the only thing that returns
the shock to normal, static height. Up until the invention of the RPM
Two Stage Shock Pistons, suspension set-up has always been a compromise.
If you set-up the vehicle for the big jumps, it usually wouldn't handle as
well over the small stuff (suspension too stiff & bouncy). Likewise, if you set-up
your vehicle for the smaller stuff, the vehicle would usually bottom out
over the jumps (suspension too soft). This is because all other shock
pistons have the same dampening (resistance) on both the compression
stroke as well as the rebound stroke.
With RPM Two Stage
Shock Pistons, the compromise no longer exists! Our pistons allow normal dampening
during the compression of the shock and increased oil flow on the rebound
stroke for a quicker recovery with a normal, soft spring. This allows the
suspension to stay planted and not over-compress or bounce.
RPM shock pistons consist of a pair of pistons for each shock; a floating
piston, and a stationary piston. As you can see by the above illustration, once the pair is keyed together
on the shock shaft, only the holes marked "A" will line up. The
holes marked "B" are the check valve holes (one way valves). Under compression,
the check valve holes close against the opposing piston and only allow fluid to pass through
the metered holes "A" (the metered holes are the holes that
determine the compression rate of the piston). As soon as the shock shaft
changes direction (rebound), the floating piston moves away from the
stationary piston and allows fluid to pass through all four holes in the
floating piston (the two primary metering holes "A" as well as
the two bypass holes "B"). Because the piston is now using four holes instead of
two, the shock is allowed to return back to static height much quicker.
So, what does this all mean? It
means that with RPM Two Stage Shock
Pistons, you can tune
your suspension to the most difficult section of the track without having
to worry about how it will affect the handling characteristics of your
vehicle in other sections because the rebound rate of the shock will be
able to recover much quicker than with a stock piston.
** Externally dampened shock
shafts (EDC) will not work with RPM Two Stage Shock Pistons. Our
1/10th scale pistons require a 1/8" dia. shock shaft and cannot be externally
Most Vehicles: Regardless of piston choice, 30
- 40wt. oil is the best starting point. A variation in excess of 10wt.
either up or down should be met with a piston change (next lighter
dampening piston at 20wt. or next heavier dampening piston at 50wt.) to
return your settings back to the 30 - 40wt. range.
- Use only with short A-arm, lightweight vehicles such as buggies or if
your application requires very light suspension dampening.
- More general use. Long A-arm buggies, 1/10th scale stadium trucks,
monster trucks, & sedans.
2wd & 4x4 1/10th scale trucks:
Start with stock springs and 40wt. oil in both the front and rear shocks.
Using the RPM #80430
kit, replace the stock pistons in the front shocks with RPM
green pistons and RPM Purple pistons in the rear shocks.
This is an excellent choice for most racers and bashers although we highly
recommend fine tuning the spring preload, oil weights and piston choices
to match your driving style and conditions where you drive.
T-Maxx & E-Maxx:
Use stock springs for most trucks unless heavily modified with
aluminum parts, then a slightly heavier spring may be necessary as well as
different weight oils may be needed from what is listed below. As a rule,
please start with the set-ups listed below using stock springs.
Best Piston set-up: RPM Purple pistons from
- medium to heavy set - in all eight shocks (which requires a second package of RPM
#80430 Pistons) with 30wt. oil in the front shocks & 40wt. oil in the
Alternate set-up: (Uses one package of #80430 Pistons) RPM
Purple pistons in the rear four shocks and RPM Green pistons
in the front four shocks with 40wt. oil in all eight shocks.
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