1/18 Scale Electric Rally/Touring Car:

HPI Micro RS4 Sport - HPI Racing Impreza - # 620 / # 649 / # 639 - Radio Controlled Model

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History and Info for the HPI Micro RS4 Sport:

Introduced by HPI (Hobby Products International) in 2007, the HPI Racing Impreza, based on the Micro RS4 Sport Touring Car chassis, was available as an unassembled kit - # 620 - or factory assembled RTR - # 649 / # 639 - with a 380 Motor, ESC and TF-3 Radio System. The model was designed to accept standard sized 180 Motors, Steering Servos, Receivers and ESC, and run times up to 40 minutes could be achieved with 4 x AA or AAA Batteries. A number of other bodyshell options were available (Check out our HPI Archive).

The 4WD HPI Racing model is belt driven, on a double deck chassis, with gear type differentials, cantilevered front dampers, universal joint drive-shafts and a full set of ball bearings. The design also incorporates adjustable wheelbase and width.

HPI Micro RS4 Sport - 1:18 Electric Touring Car

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To race the HPI Micro RS4 Sport, it requires a high level of tuning for improved stability when cornering, to keep it on the track and give you more grip under acceleration. Even the smallest change in your cars settings can make a Big difference. Our simple to follow instruction chart will show how to attain the best Set-up for your personal requirements.

Micro RS4 Sport Update
Manual

Micro RS4
Manual

Micro RS4
Exploded View

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Radio Controlled Model Accessories:

★ HPI Racing Micro RS4 Sport - HPI Racing Impreza Chassis ★

★ HPI Racing Micro RS4 Sport - HPI Racing Impreza Chassis ★

★ HPI Racing Micro RS4 Sport ★

★ HPI Racing Micro RS4 Sport Chassis ★

Buying a Used HPI Micro RS4
Touring Car (and What to look for)

There are essentially three reasons you might want to buy a used HPI Micro RS4 Electric Touring Car; you may be a collector, looking to restore and display it; restore and sell for a profit; or simply restore and race an iconic vintage model. Personally, I used to get a buzz out of restoring an old clapped-out model, installing modern day electrics and maybe a few hop-ups, then showing the gang at our local club, just how competitive those old models could still be.

Cheap, pre-loved bargain models, parts and spares are always coming up for sale, but once you have made your purchase, the one thing you will always need, is an instruction manual. If not supplied with your purchase, they can often be downloaded from the HPI website, or purchased separately on eBay. With an instruction manual, any problems with your model Touring Car you may discover, can easily be fixed.

Make a General Visual Inspection

Dampers
When you receive your used HPI Touring Car, make a general visual inspection of the chassis, front and rear wishbones, suspension shock towers etc, for any broken parts that may need to be replaced. Then, take a screwdriver and box spanner and check each self tapping screw and nut for security, taking care not to over tighten.

Next, for those HPI models with oil filled shock absorbers, remove them from the chassis and dismantle the coil springs. The damper shafts should push in and pull out with a smooth action. If you feel a jolt as you change direction, this means the oil has leaked out and must be topped up. At the same time, change the O-Ring seals to prevent more leakage. Also check the damper shafts for damage. If they are scratched, change them as soon as possible.

Check the Body-Shell

If the body shell of your HPI Micro RS4 is broken, ripped or damaged in any way, this can be easily repaired with rubber solution glue. Also, for added protection and if available for your Micro RS4 model, fit an under guard to stop dirt and gravel entering the chassis.

Drive Shafts and Turnbuckles

Titanium Turnbuckles
Examine the drive shafts for wear and replace as required. If possible, change them for titanium. The steel shafts wear and bend too easily.

If you intend to race your Micro RS4 Touring Car model at a competitive level, I would also recommend you obtain and fit titanium pivot shafts, turnbuckles, tie rods and steering rods.

Examine the Drive System

The gearbox of your used Touring Car should be opened up to check for gear wear and lubrication. A thin coat of grease is often used on internal gears and although this is fine for basic running around on the road, if you intend to race your Touring Car at a higher level, this should be removed and replaced with racing oil (ZX1 or Teflon Oil). Of course, this should be reapplied after each race meeting.

Pinions and Spur Gears

Gears are a weakness on all Touring Car RC models. Head on collisions can easily damage the gear teeth on nylon and plastic spur gears. Heavy impacts can also loosen the nuts or self tapping screws that hold the Electric Motor in Position, allowing the pinion gear to pull out of mesh slightly and rip the tops off the teeth on your spur gear. To minimise this possibility, fit bolts with locking nuts to the Electric Motor mount and remember to check them for security after every two or three runs.

Don't Neglect the Ball-Joints

Ball joints always cause problems. For top level Electric Touring Car racing, the plastic ball connectors should be checked and if deemed necessary changed after every meeting. A simple thing like a loose fitting connector popping off could easily end your race, so better safe than sorry.

Steering Servo and Servo-Saver

Servo Gears
The Micro RS4 steering servo is also prone to damage. In high speed crash situations, the fragile gear teeth of the servo can be broken off, rendering your expensive servo useless, so be sure to obtain a good quality "Servo Saver". Check out my Servo Information article.

Stabilizers

If body roll on your HPI Micro RS4 is a problem, handling can be improved with the use of stabilizers, anti roll or sway bars, stiffer tuning springs and, or, thicker silicone oil in the dampers.

Don't Forget those Bearings

If your used HPI Touring Car comes with plastic and sintered brass bushings (ring type bearings), check the shafts that run in them for wear. Dust and grit can get into these bearings and abrade the shafts. Therefore, you should replace them all with shielded ball bearings. If the model has been run with ring type bearings, you may have to change all the axles and driveshafts. For more information, take a look at my article, How to get the best from your Bearings.

Finally, good luck with your Micro RS4 model and good racing.

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Or, check out our RC Model Car Setup Guide

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Manufacturers and Brands Catalogued, Listed and Reviewed by RC-Scrapyard.

At present, the RC Model Manufacturers, Brands and Distributors covered by us are: ABC Hobby, Academy, Acme Racing, Agama Racing, Amewi, Ansmann Racing, ARRMA, Team Associated, Atomic RC, Axial, AYK, Bolink, BSD Racing, Capricorn, Carisma, Carson, Caster Racing, Cen, Corally, Custom Works, Durango, Duratrax, ECX - Electrix, Exceed RC, FG Modellsport, FS-Racing, FTX, Fujimi, Gmade, GS-Racing, Harm, HBX, Helion, Heng Long, Himoto Racing, Hirobo, Hitari, Hobao, Hong-Nor, Hot Bodies, HPI, HSP, Intech, Integy, Jamara, JQ Products, Kawada, Kyosho, Losi, LRP, Maisto, Mardave, Marui, Maverick, MCD Racing, Megatech, Mugen, New Bright, Nichimo, Nikko, Nkok, Ofna, Pro-Pulse, Protech, PTI, RC4WD, Redcat Racing, RJ-Speed, Robitronic, Schumacher, Seben, Serpent, Smartech, Sportwerks, Step-Up, Tamiya, Team-C Racing, Team Magic, Thunder Tiger, Tomy, Top Racing, Traxxas, Trinity, Tyco, Vaterra RC, Venom, VRX Racing, WLToys, X-Factory, Xmods, Xpress, Xray, XTM, Yankee RC, Yokomo, ZD Racing and Zipzaps.

This is an ongoing project, with new and "lost in time" RC Models and Brands being added as they are found and although most of those listed above have been covered in relative detail, some are still being researched and will be completed in the near future.

RC Information and Advice:

Hints, Tips and Information

My First National

   When I first started in RC, way back in the late 1980s, I would turn up to the weekly club meeting, with my Tamiya Boomerang, Acoms transmitter, two sets of crystals, a couple of 7.2v batteries, a charger and a tool box with a wheel spanner and a few spares.
   It was three five minute qualifying rounds and a final, and every month we would have a trophy meeting. The trophies were donated by a two of the older semi professional guys who basically ran the club and over the years had collected what must have been hundreds of trophies and had no space for them anymore. The lure of a trophy always brought out the "not as enthusiastic types" and the small church function room was always packed on those nights.
   About a year in, my collection of B final trophies was beginning to clutter my room, and my dad bought me the new Tamiya Manta Ray. That was the big turning point in my RC career.
   From then on it was A finals all the way. Then one day in the summer of 1992 the club organisers (the semi pro guys) asked me if I would like to go to a BIG national meeting way down south in Malvern. I asked my dad and with a bit of prompting he said "why not".
   When we got to that meeting we found there were around a hundred competitors, with ten groups of ten. I was in group "H". a two of my friends went down with us and they were in group "I" so were on just before me.

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Hints, Tips and Information

Dampers

   Dampers, Shock Absorbers, Shocks - call them what you will, they are one of the least understood, but most important tools you have for adjusting the handling characteristics of your RC model.

   In this article, I will endeavour to explain just what you can achieve by making simple tweaks to your shocks, and how these tweaks can keep you ahead of your opposition on the track.

   In dictionary terms "Damper" is described as - "A mechanical device to absorb the energy of sudden impulses." - In plain language, they stop your car from bouncing all over the track.

So how do Dampers work?

Basically what you have is a small amount of silicone oil contained in a sealed cylinder. Through the centre of that cylinder is a metal rod, and on the end of that rod, a piston with a number of small holes in it. Pulling, or pushing the rod in and out of the cylinder, your will notice a certain amount of resistance as the oil is forced through the holes in the piston.

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