Matt’s Schumacher CAT SX – January 2010 Update

It’s been just over a year since a trip to Northampton saw me emerge with one, an ex-demo Schumacher CAT SX built by Phil Booth himself. I had travelled up there to conduct an interview with some of the Schumacher staff and during which, I took Phil up on the offer of trying a car and have not looked back since. Despite the car originally coming with a NiMh chassis and layout, the SX design was based around LiPo so after just a few weeks, the LiPo chassis was fitted. My next meeting with Phil saw him take away a pack of my cells with the moulded bumps in the bottom and a new stiff LiPo chassis was the result and is the one that’s still available now.

I had a good year in 2009 and with three A finals during the National series, just missed out on a spot in the championship top ten. Much of the pre-season testing focused around making the car easier to drive and reduce the rear-end’s tendency to kick up on the bumps. Along with fellow Schumacher driver Grant Williams, we drilled out the pistons which meant that the very light oils we had been using could be increased, whilst the pack was being reduced too. Grant and his dad Mike had been testing the car with a lead plate under the chassis and it wasn’t until June that I fitted a similar plate and found that in high grip conditions, I felt that I was driving the car rather than it driving me! The combination of drilled pistons and lead plate has been the perfect starting set-up and Grant exploited its potential with his best season to date.

The car was fully rebuilt over the winter complete with a brand new Spektrum H6040 servo that I had been offered to test by Horizon Hobby UK. The Petit RC Race was an opportunity to run the CAT SX again and all it needed to get it working perfectly for me was to move the front shocks out on the wishbone and the fitting of the thinnest front anti-roll bar. Just these two minor changes were all that was necessary to reduce the amount of grip generated by the front on the high grip track at Maritime. I did have to rebuild the front diff at the race, which I think was down to the plates slipping on the diff half causing a weird feel and random slipping.

The set-up worked well throughout the weekend and it was just down to my errors as a driver that saw me qualify in the middle of the B final rather than higher up. At the end of the month, it’s off to the revamped Indoor Finals that is now called the BRCA Winter Open. The venue at Worksop is home to the Schumacher Winter Series so lets hope the link between manufacturer and venue will help me. Apart from reverting to my usual starting set-up, I will have some changes equipment-wise that I will divulge in next month’s update.

Matt’s Schumacher CAT SX Specification

• Car: Schumacher CAT SX
• Radio: KO Propo Vantage III Universe
• Receiver: KO Propo KR-302F
• Servo: Spektrum H6040
• ESC: LRP Sphere TC Spec
• Motor: LRP X11 5.5T
• Batteries: LRP 5300 40C LiPo
• Charger: Much More ACDC Silent Charger Platinum LCD
• Gearing: 21/83

Set-Up

• Front Suspension
• Oil: 
40wt
• Piston: Three-hole drilled to Losi #55
• Spring: Schumacher Grey (old)
• Track Washers: 1mm front and back
• Anti-Roll Bar: Thin
• Shock Position Mount: Middle
• Shock Position Wishbone: Outside
• Front Rake: 10-degrees
• Caster Block: 10-degrees
• Washers: 0mm
• Front Link Bracket: 38mm
• Washers on Hub: 0 (hub carrier filed down to level)
• Rear Suspension
• Oil: 35wt
• Piston: Three-hole drilled to Losi #54
• Spring: Schumacher Red (old)
• Wheelbase: Short
• Toe In: 3.25mm
• Anti-Squat: 1.3-degrees
• Rear Link Bracket: 37.5mm
• Washers: 3mm
• Shock Position Mount: Middle
• Shock Position Wishbone: Inside
• Hub Position: Middle
• Anti-Roll Bar: None
• Transmission
• Rear Diff Height: Low
• Front Diff Height: Low
• Layshaft Pulley: One-way
• Front Drive: Diff
• Gearing: 83/21
• Internal Ratio: 23/33

Notes

• Schumacher Yellow Minipins
• Front firm insert
• Rear soft insert
• Front tyres with a row off inside and outside
• Diaphragm centre cut out and removed
• 130g of lead plate between chassis and undertray located centrally

Thanks to everyone who assists me with my racing including:

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