Many shock pistons come molded on a parts tree, and it's up to you to
trim the excess plastic off them before you install them; even 0.5mm of
material that isn't cut away properly can cause extra friction inside
the shock. With Losi's Tool you can also match your shock pistons so that
two will function identically. It's best to do this with a fresh set of
O-rings, so match your pistons during the initial building or during a
STEP 1. Assemble the shocks without fluid or springs and mount
them on the tool.
STEP 2. Compress and expand the shocks. The gauge indicator will
point away from the shock that has more piston drag during the compression
stroke and toward the one with more drag during the tension stroke.
STEP 3. Remove the piston that shows more drag, and carefully remove
any excess material by lightly sanding the edges; a Scotch-Brite pad does
an excellent job of smoothing the edges of the shock piston.
STEP 4. Remount the shock and test it until the indicator stays
centered during expansion and compression.
Keep an extra set of shock mounts handy so that you
won't have to remove the ones from your car when you use the tool.
If you run cars that use a mixture of metric and Imperial
hardware, also set aside a set of metric countersunk screws and
matching nuts to mount on the tool when you match different shocks.
Measurements will be most accurate if the shocks are
mounted with the shaft parallel to the tool. You might need to use
spacers on the upper or lower mounting positions, so keep a few
pairs of different sizes handy. Washers will do just fine.
The needle indicator on the tool is made of plastic,
so take care to protect it, and make sure it's straight when you
Team drivers will attest that the difference between a carefully built
car and one that is hastily put together can be the difference between
making the A-main and sucking it up in the B-main. Losi's Shock Matching
Tool lets you use some of the same techniques as Losi's Team drivers use
to get their cars to consistently perform at their best. The downside
is that now it will be harder to blame bad shocks for your poor showing
at the track.