TECH FOCUS MG ZR 160
TYRES
There is a choice of tyre supplier in Class C with drivers using treaded race rubber. Dunlop Direzzas have traditionally been used, but these will no longer be accepted from next year, with competitors either using Toyo Proxes or – from the end of this season onwards – Yokohama Advan tyres.
This is another example of an area where the MG Trophy’s regulations have evolved over the years as Class C originally featured road tyres. But Cole says this meant the 160s “were a lot slower than the other classes and the closing speeds were too large”, so race tyres were mandated.
GEARBOX
A standard gearbox supplied by CMC Motorsport is used for Class C, which Cole describes as being “completely bulletproof”, in order to keep costs down. “I build all of the gearboxes for the MG Trophy because they’re sealed gearboxes and it stops people messing around bringing in different ratios and stops the costs going up,” explains Surridge. “I then seal them and everyone is racing with the same gearbox. They will last two, three or four years without needing to be rebuilt – and they’re not hugely expensive to build and refresh.”
SUSPENSION
The standard road-going suspension is used in the ZR 160s but this is one of the few areas where a limited number of modifications are allowed. Polybushes can be fitted, while lowering springs – supplied by
CMC – can also be used.
“Originally, they ran completely standard springs and suspension but, once you’ve removed all the seats and weight, the cars looked like they were on stilts!” admits Surridge, who adds the only changes to a standard road-going car have been made based on experience and to improve reliability. “The Trophy allowed lowering springs to be fitted to allow them to come down to a more sensible rideheight.” If a driver progresses up to the 170s of Class B, two-way adjustable suspension is then permitted.
ENGINE
The entry-level Class C of the MG Trophy for the ZR 160s features the 1.8-litre K-series motor. Cole stresses, when buying a car, “you have to try and get one with a good engine or get an engine built”.
Problems with the powertrain can occur but these are easily avoided with a little extra initial investment. “We recommend rebuilding every three years and only rarely do we need to put new parts in,” explains Surridge, whose CMC Motorsport concern builds engines along with a variety of other parts.
“People who are just getting into racing can go out and have a race. The last thing you want is for the car to break down all the time because you won’t get any [racing] experience.”