I really enjoyed
testing the HPI Hellfire for the June ’06 issue of RCCA, and I’ve been
racing it regularly ever since. You might remember that I had a couple
of durability issues with the truck; specifically a broken CV axle
drive pin holder and a faulty rear diff. I also broke a front
suspension arm shortly after completing the testing and turning in the
article. The broken CV axle and diff were flukes because I did not here
of any such failures at the track or on the various RC forums, but
broken suspension arms were common enough to make HPI design new ones
and send them out to their customers who reported problems. I have a
lot of respect for HPI because they’ll admit when there’s a problem and
work overtime to correct it.
I really enjoyed testing the HPI Hellfire for the June ’06 issue of
RCCA, and I’ve been racing it regularly ever since. You might remember
that I had a couple of durability issues with the truck; specifically a
broken CV axle drive pin holder and a faulty rear diff. I also broke a
front suspension arm shortly after completing the testing and turning
in the article. The broken CV axle and diff were flukes because I did
not here of any such failures at the track or on the various RC forums,
but broken suspension arms were common enough to make HPI design new
ones and send them out to their customers who reported problems. I have
a lot of respect for HPI because they’ll admit when there’s a problem
and work overtime to correct it.
Ok, enough about problems because my truck has been holding up well and
it has gotten a whole lot better after adding a few factory and
aftermarket racing components. Check it out…
RACE MODS
As I mentioned, I installed a few upgrades since
the original testing. The parts that I installed have made the truck
stronger, more rigid and easier to start. They also make my truck
handle better and look factory. I’ve had many racers come over to my
pit table to get a closer look and now you can too.
PARTS LIST
HPI Hellfire RTR – 10500; $599
CHASSIS
Speed Tech RC
Quasi-grade graphite upper deck – STHF001; $109.99
Ladder frame design aluminum chassis braces – STHF005; $59.99
SUSPENSION & STEERING
Speed Tech RC
Aluminum rear hub carriers with bearings – STHF004; $49.99
Quasi-grade 3mm graphite steering plate – STHF002; $14.99
HPI
Billet heavy-duty shock tower – 86587; $43
DRIVE TRAIN
Speed Tech RC
Oversized graphite vented brake disks – STHF003; $13.99
BODY, WHEELS AND TIRES
Upgrade RC Graphics
Up Icon wheel graphics (black) – UPG1611; $9.49
HPI
Mounted Nubz tires (yellow) – 4928; $46
DRX Hellfire body (clear) – 7198; $35
ELECTRONICS
HPI
Roto-Start 2 for K-series engines – 87131; $65
SF-2 metal gear conversion set – 80587; $39
Nomadio
Sensor 2 2.4GHZ radio system – NOM-100; $450
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The Speed
Tech graphite upper deck is thicker, wider and more rigid than the
stock aluminum upper deck and it’s also lighter. It’s made from
high-quality quasi-grade graphite, which resists flexing more than
conventional grade graphite. The upper deck is milled out around the
areas that bolt onto the front and rear bulkheads for a perfect fit.
The mounting platforms for the chassis braces are milled too. The upper
deck set includes a 3mm graphite center diff plate and 5x8mm flanged
ball bearings for the brake cams, which is a huge bonus.
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The Speed Tech machined-aluminum chassis braces add an amazing amount
of rigidity to the stock chassis. Combine them with the graphite upper
deck and the chassis will have virtually zero flex. The upper braces
have flanges that press into the recesses in the stock upper deck as
well as Speed Tech’s own graphite upper deck. The braces are a lot
lighter than they look, so they do not add much weight to the chassis.
The braces are sold in sets of three and they bolt on with the original
fasteners.
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Speed Tech’s aluminum rear hub carriers are made from high-quality 7075
aluminum for extra strength. The hub carriers are CNC machined to
reduce as much weight as possible without sacrificing strength. They’re
surprisingly not much heavier than the stock plastic pieces. They also
have extra camber link mounting locations for increased adjustability,
and as an added bonus, 4 quality rubber-sealed ball bearings are
included. The bearings are the same size as the stock bearings, so
you’ll have spares in your toolbox just in case.
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I installed Speed Tech’s 3mm thick quasi-grade steering plate. The
steering plate will not bend like the stock aluminum unit, which can
bind up the steering system. It has 3 different mounting options to
adjust Ackerman just like the stock steering plate and it also weighs
less. Speed Tech also sent me their oversized graphite brake rotors,
but I did not install them – yet. I’m happy with the feel of the stock
braking system, but I’ll bolt them on the next time I tear down the
chassis for a thorough cleaning.
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The HPI billet aluminum shock tower is tough as nails. It’s thicker
than the stock shock tower and milled out to reduce weight. The tower
will not bend as easily as the stock unit, so I can bash on the
Hellfire with complete confidence. The beveled edges and etched HPI
logo add a touch of style to the chassis.
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The
HPI pre-mounted Nubz tires provide awesome traction and long tread
life, which is rare in racing. The Nubz tires and dish wheels are
considerably lighter than the rollers, which lowers rotating mass. The
Hellfire accelerates faster and the engine runs cooler with the Nubz
pre-mounts installed.
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The stock SF-2 steering servo in my Hellfire never failed on me, but I installed the metal gear conversion set just in case.
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The
bevel gear diffs are sealed with O-rings and gaskets but they’re lubed
with grease to simplify the assembly process. Filling the diffs with
quality silicone fluid improves handling dramatically. I used Kyosho
silicone fluid (3000 wt in the front, 10,000 wt in the center and 1,000
wt in the rear). Power is transferred to the front and rear wheels
evenly, so the front tires do not expand as much during acceleration.
The truck also feels more planted in the rough stuff and steers more
aggressively with the oil in the diffs.
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CONTINUED
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