HPI RS4 MT

Introduction

Although I have never raced RC cars, I truly enjoy building and running them. My first car was a MRC 4wd buggy I received as a Christmas gift in the late 1980's. Next came two cars from Kyosho, an Ultima II and a 4wd Celica. Now after being out of the RC car loop for nearly three years, it is time to start up again.

My first move was to check what was available in lets say an electric 1/10 truck. I have always had a lot of respect for both Team Losi and Assosiated, but their prices are just a bit on the high side. So I looked at a few Duratrax trucks, a few Traxxas trucks, a Kyosho Ultima ST, and the HPI RS4 MT. Lets just say I was quickly drawn to the HPI kits. I recall when the RS4 PRO was first released, it took the on-road world by storm. Since then I have always wanted one but never really had a place to drive one. What is the next best thing? A 4wd on-road/off-road truck. There are three HPI RS4 MT kits to choose from, two on-road and one off-road. I choose the Ford F150 (501), the cheap one, and tacked on a set of Duratrax bearings (1347).

The Kit

Note: When it comes to assembling kits and such, I find myself not using the manual as much as needed. Although I had very few problems with this kit, not following the manual word-by-word could create many problems.

Although I am not going to go into detail on how to assemble the truck, here is a list of the things I liked as well as a list of problems I had:

Good Things
• Most all the plastic pieces were arranged in logical order on the trees.
• There is only one size of each type of screw.
• The belt system seems to go together well. The predifined belt tensions are right on.
• The built-in servo saver works well.
• Kit comes with a 22-tooth 48-pitch pinion.

Bad Things
• The use of uncut plastic trees of pieces made things more time consuming as well as more dificult.
• The use of bushings instead of bearings.
• The lack of turnbuckles was disappointing.
• The chassis is made from a composite material and threading screws into it very difficult.
• Assembling the shocks is difficult. Mainly due to the fact that all the plastic pieces are on trees.
• The kit calls for the use of thread lock on the clutch but does not supply any. This means you have to spend $5 to thread lock one set of treads.
• Finding room to mount electronics on the chassis can be difficult.
• With smaller pinions (smaller then stock 22-tooth), the rear belt will rub agains the motor.

For my first test run, I charged up an old Tower Hobbies 1400 pack and headed out to my front yard. After playing with the slipper clutch, the truck was ready to go. Immediately I noticed that this truck is stuck to the ground. No matter what I tried, I could not flip it over. Although driving it on the sreet was fun, I really wanted to go stir up some dirt.

The next test would be with the Dirt Hawgs installed, so I headed over to an empty lot. First let me say that this truck handles great on rough roads. What supprised me most was how it handled a section of washboard road. The truck drove straight down the road, never once trying to slide sideways on me. Looking at the past, the Ultima II was extremely difficult to drive down any bumpy roads.

Overall, the HPI RS4 MT looks to be good entry level truck and with a few extra hop-ups, it could be very competitive.

May 1, 2001 Update:

The truck can take nearly any abuse given. Where I live, I am forced to either run the truck on pavement or rocky bumpy raods. Many times the truck has been running wide open down a rough road and catch a front tire on a softball sized rock. At this point the truck is flipping airborn and landing still flipping. I have yet to break something.

The inner body does a great job of keeping grass, rocks and other larger items out of the inner chassis. The problem is that the inner body does not keep much fine dirt out. I have attemped to remedy this by adding a thin self-adhesive foam strip between the body and the chassis. It seems to have help a lot, but i still need to do some more work on it.

Thus far, I have only had one casualty. After hitting another rock, the truck went cartwheeling down a steep hill and then hit an old wooden pallet. It stripped out a ballcup on a steering tie-rod. After a little more inspection, I found that all the steering tie-rods are only threaded about 1/8" into the ballcups and this makes them very likely to fail. I plan to buy a set of Lunsford Racing 2 1/2" Turnbuckles to fix this problem. Note: The stock tie-rods are only 2 1/4" and I am going to try the longer 2 1/2".

After running several battery packs though the truck, I noticed some wear on the rear drive belt. The motor seemed to be rubbing very lightly on the belt and over time I started to see wear. Note: These belts are said to be wear items by HPI. My problem is that a new rear belt costs 7.19 + s/h.

July 8, 2001 Update:

July 18, 2001

I ordered a set of Lunsford Racing 2 1/2" Turnbuckles to fix the problem noted above, problem solved.

Setup

My current setup
• HPI RS4 MT w/Ford F-150 without wing
• HPI SS Deep MT Wheel Black
• Pro-Line Dirt Hawg 2.2 Truck
• Duratrax Ball Bearings
• Kyosho Atomic Force 17x2 w/stock pinion
• Novak Duster ESC
• Deans Ultra Plugs
• Futaba 2PC 2 Channel AM
• Futaba S3003 standard servo
• DuraTrax IntelliPeak AC/DC Mini Pulse Charger
• DuraTrax Piranha 1800mAh 6 Cell Flat packs
• Lunsford Racing 2 1/2" Turnbuckles

Near furure upgrades
• Tekin Rebel Reverse Speed Control
• Pro-Line Masher 2000 Monster Truck
• HPI MIP Shiny CVD Front RS4 MT
• HPI MIP Shiny CVD Rear RS4 MT

Pictures of my HPI RS4 MT