HPI RS4 Pro 2 Japan edition 3 Build and Review

Within the late 90’s, HPI had been making progress within the racing world. They noticed the potential of the touring class & had been producing vehicles to undertake this class.

They began with the RS4 platform in a sport format, but additionally launched a professional model. These proved to be nice vehicles & a really versatile platform.

It was solely pure that they might follow-up their success with the Professional 2 chassis. This additionally marked the beginning of utilizing purple as their signature anodising color. The professional 2 builds on the unique platform however incorporates a vary of tweaks & updates to maintain the automotive aggressive.

The event was swift & steady. They launched a particular Japan version that contained the upgrades that the group drivers thought-about important. The Japanese had been the principle improvement group behind the challenge, so it was unique solely to their home market. There was an version 2 that was once more out there solely in Japan that continued the development. There was a closing version 3 that was out there within the USA & Japan as they had been additionally concerned within the improvement. Though nonetheless uncommon, not as uncommon as the opposite editions. This was out there as a stick or saddle pack format

I am my early days of racing, I used to borrow my dad’s sport 2 that had a whole lot of Professional 2 upgrades. I used it to compete in a few HPI problem races right here within the UK

Final yr, I managed to discover a new in field Japan version 3 stick pack version. A really fortunate discover that was by no means constructed. The field has a bit fading on some sides, however every little thing seemed to be there

On the entrance, there’s a checklist of the upgrades included. Right here is the checklist

1. Dodge Stratus light-weight bodyshell 190mm

2. 33deg 24mm tyres

3. Crimson foam inserts

4. Threaded aluminium shocks

5. Blue professional linear springs

6. Heatsink motor plate

7. Aluminium aspect plate heatsink

8. Aluminium centre mount

9. A technique entrance differential

10. Aluminium 15t one centre pulley

11. Graphite diff outdrives

12. Carbon shock towers

13. Turnbuckles

I additionally discovered another upgrades that I can be becoming on the best way

1. Professional 2 dealing with pack

2. 6mm clamp hex hubs

3. Aluminium decrease spring retainers

4. Aluminium decrease entrance pivot mount

5. Aluminium 8 Deg C hubs

6. Aluminium rear higher hyperlink mount

7. Moodyfools titanium screws

The guide has an in depth format that comprises each half itemizing & sizes of elements/screws. This version has an separate guide that reveals all of the updates & totally different screw sizes the place mandatory

The Japan version has a separate guide that highlights the upgraded elements. Some plastics are additionally up to date. Some numbers had been listed in a different way than required. Some elements wanted rebuilding with the proper elements afterward.

The dealing with package additionally a separate guide, so I needed to work with 3 manuals in complete!

Rear bulkheads

These have plastic inserts that adjusts the rear belt stress. 

You will have to strip the entire rear finish to regulate the stress. The rear suspension arms are mounted to the bulkheads

The aluminium motor mount , layshaft & centre mounts are all added at this stage

Ball differential

This contains the graphite outdrives with rings that clip over to stop splitting. 

The diff rings are additionally keyed to stop slipping in comparison with the rounded ones in the usual package. Aside from that, it builds like many different ball diffs, so not a lot to say right here

Layshaft

A a method pulley is included as this was the quickest choice on the time. 

I really feel that I’ll need to use the brakes, so managed to supply a used layshaft with mounted pulleys. 

There was some slight put on, however changing the pins sorted it out!

The carbon shock tower braces the rear of the bulkhead & straightens every little thing up. It has 6 holes. The decrease 3 will make the shocks decrease, could also be used for my future plans with this automotive

Driveshafts

Again within the early days, MIP had been referred to as the group who made one of the best CVD’s out there in the marketplace. HPI knew this & commissioned them to make use of their CVD’s in a whole lot of their kits

The items are totally different entrance & rear. The rears have an extended axle, however the fronts have an extended dogbone, I am guessing it will assist with steering. The fronts additionally use an built-in information for larger inside bearings. As that is an American firm, a 0.050″ Allen secret’s offered for the grub screw. I selected to make use of CVD oil reasonably than grease & my most well-liked thread lock.

Decrease deck

As soon as the shafts are assembled, I can now assemble the rear finish to the chassis.

The chassis is exclusive to this automotive. As it is a stick pack, there aren’t any slots for saddle pack batteries. It additionally seems to be extra of a Matt end to the carbon, perhaps a particular manufacturing run?

Earlier than I hooked up it, I mounted the dealing with package. This can be a carbon half that raised the rear part to extend roll. Today, you employ shims beneath the pivot blocks, however the entire meeting must be raised for this automotive. It additionally included a carbon spacer that sits between the entrance bulkhead & prime deck to make the highest deck sit stage

Steering

This automotive makes use of an built-in servo saver on one steering arm. There’s a spring meeting that may enable motion within the occasion of a crash. I by no means had a lot luck with this once I raced in my early days, they might loosen & give poor dealing with & took too lengthy to diagnose as I’d chase different points & would not take into account it an issue. 

I selected to tighten it up as a lot as doable (with out instruments!) & I’ll use a servo saver on the servo itself if I have to. That arm does not use any bearings, so it isn’t as easy as I would really like.

The opposing arm sits on 2 bearings. The amended guide says to make use of a distinct arm, however made it sit method too low compared to the opposite aspect, so I used the unique package suggestion

The turnbuckles are 3 totally different supplies in 3 totally different colors! A mixture of alloy, metal & anodised alloy. The turnbuckle plastics threaded on okay, however are very tight on the balls. I swapped these out with the later heavy responsibility items you discovered on the Professional 4.

Entrance suspension

The entrance hubs are assembled & hooked up to the decrease pivot block. As beforehand talked about, I had some new/used alloy elements from my earlier automotive, so I used to be eager to suit them. I used the 8deg alloy C hubs together with the 2deg decrease pivot & 2deg higher mount to offer 10deg of caster. 

Quite a bit in comparison with as of late, however within the center vary of this package. Utilizing these elements gave the package caster, however utilizing totally different elements, I all the time have the package plastics if I want to vary it. 

The decrease bulkhead & entrance attaches by way of the pivot to attach every little thing up. It provides energy as every little thing is assist collectively reasonably than separate mounts.

I managed to search out somebody within the states that has made a spool entrance diff for this automotive. The automotive will now be so much simpler to drive as I can use the brakes. 

There is no such thing as a belt adjustment on the bulkheads, it makes use of the belt tensioner on the rear layshaft mount to regulate stress

After I hooked up the higher hyperlinks to the hubs, I’d they had been binding. I’ll look to grind a small part on the hub as if I weaken the plastic, it could snap off

The second a part of the dealing with package slots in beneath the higher deck earlier than fitment. This raises the highest deck to sit down stage the place the rear finish was raised beforehand

Shocks

The usual package makes use of an alloy physique that makes use of clips to boost/decrease the experience top. The decrease physique is just pressed on to carry the O rings

The up to date shocks additionally use a alloy physique, however has a threaded collar for a extra presise experience top adjustment. There are 2 O rings within the decrease physique, however a few spacers & all secured with a circlip. I used the three gap pistons as I all the time begin with 3 or 4 gap pistons in my touring vehicles. I lengthened the rear shock size by 1mm as suggested by the dealing with package

It seems, the shock oil was lacking from this package. Not an issue as I simply used 400cst as a base setup

The higher caps have a gap that may be drilled out for zero rebound. I appear to do that for lots of my kits, so drilled them out to 1.1mm to start out

The blue springs are very agency compared to the usual silver springs initially equipped. The springs are 29mm lengthy which is totally different to every little thing else I take advantage of. The shock towers have 6 gap choices, 3 higher & decrease. As I have not seen a TC with higher & decrease shock mounts for fairly a while I used the decrease place & used a shock spring that was shorter, however I now have loads of choices. I additionally fitted alloy spring retainers as they’re purple, no different purpose!

The chassis is now constructed 🙂

Electrics

I thought-about the interval right electrics for this construct. In reality, I sourced a Hara Tornado & Orion Hara spec motor however modified my thoughts!

Alongside the enduring cup, there appear to be just a few retro races popping up permitting trendy electrics. Trendy electrics enable these vehicles for use, however not value some huge cash for interval gear. I feel it is a good this as I do not miss the duty of skimming a comm!

I fitted a Trinity revtech 17.5 motor for preliminary testing. One occasion I am booked in for permits 13.5, however that is positive to check. One factor I’ve discovered is the motor will want a fan, it wasn’t widespread follow again within the late 90’s, however these brushless motors can get fairly heat.

After a little bit of thought & looking the field, the automotive got here with aspect nerf bars to stop any chassis harm from a aspect affect. I lower one down & made the floor flat to accommodate a 40mm fan. It sits to chill the endbell, however we’ll see how efficient it’s on the observe. It is higher than nothing

I had a spare Hobbywing XR10 inventory spec esc, so wired it in with no points

I mounted a SRT 8015 servo, however hooked up a servo saver for indoor use. A trusty Sanwa RX-481 receiver was fitted. The guide suggests to suit the receiver on the highest deck. With the low profile servo & small receiver, every little thing matches on the decrease deck

The lipos proved to be a difficult affair. I fitted the package stick pack holders, they NEARLY accepted a lipo. One tray won’t shut. I could not see an efficient strategy to lower them to make the lipos match & keep safe. I laid out a design & had some 3d holders fitted. They are going to safe with 2 bands, so we’ll see how they work out

The spur gear matches on its holder. I selected to make use of a 106t spur so I might get a ratio that might go well with the 17.5 motor. The guide suggests the holder might have sanding, a light-weight software on some 1000 grit sandpaper was sufficient to stop binding

Wheels/tyres

These 33deg tyres are a extra appropriate race tyre. Again within the early 90’s, management tyres weren’t widespread so every little thing was open. These tyres had been extra appropriate for races in Japan. The inserts have sat for 20 years, however folded. I fitted every little thing to let all of it sit & hopefully sit spherical after time

The wheels are the R5 5 spoke wheels. I’ve all the time thought-about these to be among the nicest wheels out there for racing. Though dish wheels will acquire an aero benefit, these look a lot nicer that I could hold these for future use! I used 6mm clamp alloy hexes as I am by no means a fan of plastic hexes

Bodyshell

The Dodge Stratus was thought-about one of the best dealing with shell design in the marketplace on the time. 

A number of producers made this physique & added their tweaks & the HPI was thought-about a reasonably good selection. That is the light-weight model, so will assist with preserving the centre of gravity low. As it is a HPI, the markings match this automotive completely!

Monitor check

A construct overview would not be full with no observe check to see the way it drives

A retro TC occasion was organized for November twenty seventh at Power raceway close to Wakefield. A everlasting indoor observe with nice services & very passionate individuals who run the entire thing. I’d suggest a go to. The observe is sweet, however the meals is excellent!

The carpet is black, unsure on the kind. Because the observe will get used 4/5 days each week, there may be a whole lot of rubber and additive laid down

There have been 2 important courses. Pre 2001 & 2001-06. Because the Professional 2 was launched in 1999, I went for the Pre 2001 class

There was a check/tune organized on the Saturday afternoon. An ideal likelihood to attempt the automotive & see what changes I wanted to make

To check, I fitted some Volante 32’s on spoked wheels. My ideas was that the grip was so excessive, this is able to calm it down

The primary run was eventful. As I used to be on a base setup, the automotive was flipping at each nook. These outdated vehicles weren’t designed for this stage of grip

Sadly, I clipped the barrier & snapped a ball cup & misplaced steering. I changed the cup & observed that one wheel was bent. I wasn’t shocked by the ball cup because the plastic is 20yrs outdated, however the wheels had been model new. I dug out some used Volante 28 MICC tyres & stored specializing in the extent of grip

In direction of the tip of the day, I used to be making progress. It was flipping much less & occasions had been getting faster.

I discovered the automotive had an excessive amount of entrance finish grip. There was an excessive amount of steering & would flip the automotive if turned too laborious. It additionally generated a whole lot of total grip. I ended up utilizing minimal additive & no additive in any respect on race day

On the final run, I clipped one other barrier with one other lack of steering. Seems I snapped one of many steering wiper arms. I had no spares with me. I rummaged by way of the elements I had & discovered the unique one I fitted that was too low. I took some measurements & discovered i wanted 5mm of spacers to make it work

Race day

I arrived on the observe & managed to supply sufficient shims to repair the automotive, wouldn’t it maintain for the assembly?

The assembly was set for some open follow, 4 FTD qualifying rounds & 1 closing. That is the way it was again within the day. I managed to work on extra setup to see what I might do

Spherical 1 was okay, however not nice. I had just a few rolls & completed fifth total

Spherical 2, I attempted a entrance a method diff to see if I might cut back the steering. It went the opposite method. The automotive would swap ends if I touched the brakes. I pulled off to save lots of harm to the automotive

Spherical 3 was my greatest run, I stored it clear with no errors. I could not push as laborious as I wished however completely satisfied to finish up 4th

Spherical 4 had the potential to be my greatest run. The automotive felt nice & I used to be pushing laborious as there was much less steering. Sadly, I pushed too laborious & had a few rolls so did not enhance. I utilized some additive so I really feel this was the issue

This meant that I ended qualifying in fourth place for the ultimate. There was potential for an honest outcome if I might hold it on the observe with out rolling. For the ultimate, I widened the rear observe & hoped it could assist.

The primary few laps had been good & I used to be staying with the leaders. The highest 3 all had incidents & I managed to make up locations. I managed to stand up to 2nd & was preserving the pole automotive behind me.  After 3 minutes, the automotive began over-rotating & spin in to the limitations. Sadly, I completed fifth however that is the thrill of racing

Overview

This automotive was a fantastic automotive to construct. This was an ideal showcase to see how the trendy touring has developed over time. HPI did determine to go in a distinct route & created the professional 3 which had a radically totally different design to this automotive

The elements luggage had totally different steps in several luggage, this may be as a result of it was the particular version, nevertheless it was a ache not with the ability to construct in bag order

Not many elements wanted fettling to work as designed, which you would not count on in a brand new package however for an outdated automotive like this, it’s fairly good. 

Because the race assembly, I’ve had a 3d printed wiper arm to restore & strengthen the steering. Ought to be so much stronger now