Conversion to disc pads beefs up brake power
Conversion to disc pads beefs up brake power
Drum brakes are one of the
most abused parts of an ATV
with frequent maintenance
required to keep them in good
working order. But a Yamaha
ATV dealer hopes to have
eased the maintenance need
with a disc brake conversion.
Geoff Ashcroft reports
FITTING disc brakes to Yamaha ATVs has reduced the maintenance required and improved stopping power, according to Yamaha ATV dealer Nick Davies.
Mr Davies, who runs Nick Davies Farm Bikes at Elgwyswrw, Pembrokeshire, saw the disc brake conversion as a practical solution for a local quad bike riding centre whose intensive use of 22 Yamaha ATVs, including Timberwolfs and Breezes, saw him constantly attending to brakes.
"At the centre, ATVs cover a lot of ground and have so many different riders, that the brakes are constantly in need of attention," he says. "The leisure industry is far more demanding than agriculture and many of the ATVs cover a phenomenal mileage running around the off-road courses.
"Every week I was changing brake shoes, drum seals and sometimes drums. In addition to the high cost of maintenance, the ATVs were spending more time being maintained and less time being ridden."
The answer lay in converting the standard drum brakes into a disc brake set-up. It was an idea Mr Davies had seen on a Yamaha Banshee racing ATV and he reckoned that discs could withstand greater use and by being self-adjusting, would only ever require a change of brake pads.
"I started by fitting a disc brake to the rear axle, which worked well on tarmac, but going down hill, off-road, it simply locked the rear wheels and skidded," he says. "So we looked at braking just the front wheels instead."
The conversion uses new front hubs, brake discs, calipers, caliper bracket and a brake lever with master cylinder. With little space within the front wheels to fit the new brakes, the kit had to be carefully engineered to fit. Almost hidden within the inside of the front wheels, the disc brakes receive a degree of protection from the harsh environment in which the ATVs operate.
"We use Yamaha parts where possible, including the calipers, brake lever/master cylinder and pads," he says. "The brake disc, hub and bracket are made by a local engineering firm."
With the old brakes removed from the front axle, Mr Davies says it is simply a matter of fitting the new hub, disc and caliper, then bleeding the system and setting the position of the brake lever. The new hubs are wider than the original items and Mr Davies says the additional 2.5cm of track width gained up front helps to enhance ATV stability.
Mr Davies offers two conversion kits – a 5in diameter disc brake kit for the Yamaha Breeze, the other is a larger diamater 7in braking system for more powerful Timberwolf/Bear Tracker machines. The conversion costs about £600.
Mr Davies says the ATVs with disc brake conversions at the quad bike riding centre need brake pad changes about every three months, compared to weekly maintenance for those with drum brakes.
"The ATVs are very safe on standard drum brakes, but I believe we have made them even safer and with the advantage of reducing the maintenance aspect considerably," he says.
"It takes about 15 minutes to change a set of disc brake pads instead of a matter of hours to strip and rebuild drum brakes." *
Change will invalidate warranty – Yamaha
Yamahas Mike Bush says Mr Davies conversion does not get his firms support and any modification to an ATV will result in invalidation of warranty.
"It is entirely his responsibility, regardless of how professional the conversion is," he says. "The standard Yamaha Breeze was designed for a particular application, for which it is perfectly adequate – and the conversion implies that the ATVs are being used for applications they were not designed for.
"There are pros and cons for each braking system. Discs can be easier to clean, though the calipers are more prone to siezing. Drums with good seals, however, can keep water and dirt from reaching the brake shoes, so maintaining their effectiveness."
Yamahas latest ATVs – the Grizzly 600 and Big Bear – now come with disc brakes as part of the standard specification.
"Yamaha products are developed from watching the American ATV market, which accounts for about 300,000 units each year, compared with the UKs 3000 machines. If a competitor has features on an ATV which help to increase sales, for example disc brakes, then we would probably folllow suit," Mr Bush adds.