Roche P12 Rapide Build tips and Review

In 2004, Roche started out making optional parts for various cars. Their main attention was given to 1/12^th circuit. They quickly made a name for themselves and when the announced in 2015 that they were collaborating with Xenon to create a car of their own there was a real buzz. The car was released at the end of 2015 and it instantly made an impact in a racing class that has been around for over 30 years!

A quick phone call to Zen Racing (official UK distributor) & a kit was quickly dispatched.

This review will highlight some areas of interest and build tips I can offer

Here are some the key features of the Roche Rapide P12

• 2.5mm high grade graphite materials for main chassis
• Wheel base +/-2.0mm adjustable on front lower aluminium suspension block (199mm/201mm)
• Caster adjustment : 1.8/3.25/6.15 deg
• Low friction coating pivot balls and ball studs
• Front upper arm mount pin brace
• Polished kingpin and upper hinge pin
• Hard coated aluminium steering turnbuckle (M3x42mm)
• Spring steel upper arm turnbuckle (M3x15mm)
• High grade composite front suspension plastic parts from Xenon Racing
• Mini and micro size servo compatible
• Micro centre damper with POM CNC machined piston
• Narrow design aluminium centre damper mount
• Inline alignment and cross-chassis alignment battery placement
• 7075 aluminium rear chassis brace mount
• 7075 aluminium easy adjust side spring holder
• 7075 aluminium motor mount and left rear bulkhead
• 7075 aluminium main shaft holder, precise adjustment ride height by spacers.  +/-1mm forward/backward main shaft position adjustment. 
• 2.5mm graphite rear motor pod bottom stiffener
• High precision ball differential and reliable carbon main shaft
• 64P 90T (16 balls) spur gear from Xenon Racing

Unboxing

The box is a small size, but all the parts are neatly packaged and the bags are clearly marked. 

All the parts are well made and come clearly bagged up

You will not need to open bags in the wrong order to get certain parts, and the instruction manual is very clear and precise

Carbon prep

Every single car I use has the carbon parts sealed to prevent splitting in case of accidents and make the whole chassis stiffer as a result. Speaking with David Spashett, he advised full sealing is not needed for a 1/12^th circuit car. As he is a multiple national/European/ world champion in this discipline, I took his advice!

No sealing is needed, although sanding the rough edges is recommended

I just sanded the edges with 1200 wet/dry to remove the sharp edges. Always remember to take precautions when working with carbon fibre as you do not want to breath it in or get it into your eyes or on your skin.

Side spring plates

These parts retain the side springs are allow 2 methods of side spring adjustment/tweak removal. This is done by the set screw that holds it to the side plate and there is a special nut that holds the spring in place. I found it very tight to fit the set screw. 

Using a regular screw to thread the carbon

I found the best way to fit the set screw was to tap a thread into the carbon with a regular M3 screw and a little grease to act as a cutting compound

Side dampers

These are a fairly new design that uses shock oil to control side pod movement. 

Using shock shaft pliers to get a good grip

I used shock shaft pliers to fit the bottom links which prevented shaft damage. The kit advises 1000 cst to dampen. This is suited for high tractions. On Primafelt in UK, I have now changed this to 15000cst. In Japan, their grip is very high; in the UK the traction is a lot lower. This allows the side dampers to slow their movements and allow the tyres to gain traction

Rear Pod/ Axle

One of the most crucial parts of a 1/12^th circuit car is the rear pod movement. A smooth & well built pod will enable great handling. If the pod is not free, you will encounter handling problems. It took a good deal of time to get a 100% smooth pod fitment. 

The Pod movement needs to be smooth and free

The 2 nuts sit in eccentric holes. I found that I set the plastic nut holder at an angle which gave me the smooth pod movement I needed

The ball diff unit is a simple affair, but must be built correctly to ensure a smooth diff action

The 0.2mm shim is used for perfect axle float

To achieve the 0.2mm axle float, I used a 0.2mm shim wedged between the axle & hub; I tightened the screw up on there. I then removed the shim and the perfect axle float was achieved

Centre Damper

This builds similar to a conventional touring car damper although, the ball cup/ spring retainer just secures to the shaft with a 1.5mm set screw rather than having the shaft threaded

Take time when screwing on the collar

The only issue I had was fitting the shock collar. The O ring felt like it was a little bit too big and wouldn’t allow me to fir the collar to the body easily. This has to be precise as it’s a very fine thread & can be easily cross threaded. A lot of patience is required, but once fitted, it won’t move very easily when the car is being used. This prevents any unusual damper issues during a race

Servo mounting

I used a Futaba S9650 as this is the servo of choice for 1/12^th racing

The car doesn’t some with a servo saver. I used a Kimbrough item as recommended by Zen Racing

The servo case was shaved to ensure smooth operation

Due to the layout of the holes & low profile of 1/12^th racing, I was unable to fit the steering turnbuckle links to the ball joints when fitted to the servo saver. I shaved a little material from the servo saver, ball links & servo. 

Also some material was shaved of the servo saver to stop binding

Not a massive amount was removed, but enough to enable smooth operation

Front suspension

There is not much to say on this part, just follow the instructions and make sure every part is built the right way round. Due to the various areas of adjustments, this can be easily built incorrectly

Electrics

I used a Hobbywing V3.1 1s (inbuilt voltage booster) & a Trinity Revtech 24k 10.5 motor with Sanwa radio gear. 

The electrics were fitted with thin AWG wire to allow free pod movement.

As you want the pod to move freely you should always use thin motor (14 AWG) wire. Thick wire is not needed for the electrics that are used in the 1/12 class. I JFT tyres were trued and fitted to the car

Track Test

I visited Newbury radiocontrol car club as they have a big circuit & are very accommodating for 1/12^th circuit cars. They use black ETS style carpet which yields high grip

Due to time constraints, I fitted an old Protoform body from my AE RC12r5.1. This fitted perfectly on the posts for the Roche

The track was a good mix of technical & high speed sections. In qualifying, I was learning the car and the driving style. I felt I was getting better every run, but too many mistakes on my part were not enabling me to fully achieve the best result. 2^nd place was my result

The old shell from the Associated RC12 r5.1 was a perfect fit

The final was a case of making as little mistakes as possible. I got past the leader and was able to win. If I used my final time to qualify, I would have taken pole position by 10 seconds!

Post race analysis

I built the car by kit, so used 1000cst in the side damper oil. I personally found the car to be very erratic & snatchy in the corners. It turns out that the pod fixing was not aligned correctly and was very notchy/ tight in movement. I stripped the car down & rebuilt the pod linkage. A Blackart shell was painted up & fitted for the next meeting

Race 2: CWIC

Next up I chose to enter this an event at CWIC, to see if I could adjust to 1/12^th circuit driving.

New Blackart shell painted in my racing colours!

I struggled in rounds 1-2 of qualifying as I was making silly mistakes & the front end was biting too much. It turned out that I was using too much additive on the front tyres. I changed from 2/3 coverage (25 minutes) to ¼ coverage (10 minutes) this transformed the car! It was so much easier to drive on the limit and I was able to take TQ by nearly 5 seconds!

Final 1

I was able to make a good start and drove clean for the first few minutes.

Car 2 was closing in on me. Unfortunately, I caught the barrier and lost the lead. Car 2 crashed and I was able to retake the lead. I got caught with a backmarker I lost the lead with 2 laps to go. When I was marshalled, I finished 2^nd

Final 2

I chose the wrong side of the grid to start form and ran wide at the 1^st corner allowing car 2 to take the lead. Unfortunately for car 2, he was taken out by a backmarker and he was pushed out in my direction. We tagged, but I was able to recover and hold on to the win

Overall

1/12^th is a very different class to touring car which I usually race. The car requires lightening quick reactions & a smooth driving style to be competitive. The Roche Rapide is an ideal car to use. Apart from different springs, you do not need and additional parts to be competitive. So it it is a highly recommended chassis for anyone looking to take part of this perennial racing class.