Matt’s Associated RC10B4 – January 2010 Update

The Associated B4 has been my 2WD car of choice for some years now and 2010 is the fourth season of running the chassis. As a result, it was originally used with brushed motors and NiMH cells but of course developments in the battery, motor and speed controller areas has seen brushless packages and LiPo cells now become the standard for competition use.

I have to admit that I have struggled a little in getting a balance in 2WD with LiPo batteries due to their reduced weight and increased power delivery. Brushless was a relative easy switch although tweaks were necessary with gearing but the lightweight LiPo design has put me on the back foot. For sure I have reaped the benefits of reduced cell maintenance and greater efficiency which means a fully charged LiPo pack of 5300mAh capacity can stay in the car for two runs – although I am pretty sure a third run would be possible looking at the figures off the charger – but the different characteristics has seen me trying numerous set-up changes throughout 2009. After an average season last year, I have been running the B4 a lot more over the winter trying to fine-tune the set-up to get it to work better for me. Recent changes have included dropping a motor wind to a LRP X12 7.5T (from a 6.5T) and gearing up, adding a RudeBits brass weight to go under the servo and fitting some of the Ghea tapered pistons.

The Petit RC Invitational 2010 would be my first major competition of the year and the 2010 event would take place once again at the impressive Maritime Raceway in Chatham, Kent. The track would be a combination of high grip carpet as well as some slippery sections so very different to the usual outdoor surfaces and conditions. For this race, the only changes to my car would be to use a new Spektrum H6040 servo as well as some changes to the suspension settings. The servo is one that’s marketed under the heli range but being a digital servo with titanium gears and fast performance, its ideal for use in a buggy. The suspension changes were necessary to make the car easier to drive on the high-grip sections without losing the balance or the ability to handle the large jumps. With this in mind, I simply moved the shocks out on the wishbone all round and fitted a stiffer front spring. The tyres were trimmed with a row off the Schumacher Yellow Minipins on the inside and outside of the fronts that would make the car easier to drive. RudeBits had kindly sent me some new parts to fit in the rear chassis triangles – these brass weights can be stacked as necessary although I would probably use just a single brass weight in each side, replacing a standard 10g lead wheel balancing weight that used to fit in there.

For practice, I actually left these weights out but chose to fit one each side for the first qualifier. A good first run and a top ten time was the result although I needed greater stability at the rear as the back of the car was rolling around too much. So the 25g of lead ballast that was between the gearbox and bulkhead was removed and the thinnest roll bar was fitted to the back. The end result saw me move into fifth place on the FTD grid and the car was even better. Unfortunately, despite an improvement in time in round three with new tyres, it seemed that the front of the car was generating more and more grip and I began to get a little oversteer. I then switched the front tyres to a more worn set in order to re-address the situation, but I was unable to improve on my fastest time in round four and slipped from sixth overall to pole in the B final. As you can imagine, I was absolutely gutted to have been pushed out of the top ten by two drivers in the last heat of the last round but that’s the FTD qualifying system! That said, I was very impressed by the Spektrum servo that worked very well and the car’s handling was perfect – so I only have myself to blame!

The next event is the BRCA Winter Open held at the popular indoor venue in Worksop, Nottinghamshire. I only race there once or maybe twice a year and with a strong entry at their regular winter series, I know I will need to tweak the set-up to get the best from the chassis…

Matt’s Associated RC10B4 Specification

• Car: Associated RC10B4
• Radio: KO Propo Vantage III Universe
• Receiver: KO Propo KR-302F
• Servo: Spektrum H6040
• ESC: LRP Sphere 2007 Competition
• Motor: LRP X12 7.5T
• Batteries: LRP 5300 28C LiPo
• Charger: Much More ACDC Silent Charger Platinum LCD
• Gearing: 25/78

Set-Up

Front Suspension

• Oil: 
35wt
• Piston: Ghea #2
• Spring: Associated Blue
• Anti-Roll Bar: None
• Shock Position Mount: Middle
• Shock Position Wishbone: Outside
• Caster Block: 30-degrees

Rear Suspension

• Oil: 30wt
• Piston: Ghea #2
• Spring: Associated Silver
• Anti-Roll Bar: Thin
• Wheelbase: Short
• Anti-Squat: 2-degrees
• Shock Position Mount: Middle
• Shock Position Wishbone: Outside

Notes

• Schumacher Yellow Minipins
• Front soft insert
• Rear soft insert
• Front tyres with a row off inside and outside
• RudeBits brass weight under servo
• RudeBits brass weight (one per side) in rear of chassis
• 125g lead plate under battery

Thanks to everyone who assists me with my racing including:

• CML Distribution
• Horizon Hobby UK
• JConcepts
• LRP
• Much More UK
• RudeBits
• Schumacher
• Trishbits
• Upgrade