White Bros. Monoshock Modification
White Bros. Monoshock Modification
EVALUATION
Removing The Shock From Monoshock
Our latest long range bike is a 465 Yamaha YZ. Our long range testing lets us live with selected bikes for 6 months to a year-long enough to find faults and good news about the model. Normally, changes and modifications are recorded and we tell you about them when the long range report is published.
And sometimes we run into a product or modification that makes the bike so much better that we do an evaluation as soon as possible. The White Bros, shock fix is such a modification.
We were impressed with the action of the stock G model shock and said so in our tests of the YZ465 and the 250. But new model testing involves several weeks and a few hundred miles or races; enough to compare new bike vs new bike, but not always enough to reveal all the problems.
When the 465 had about 800 miles on it. we noticed it didn’t like to turn any more.
It went straight just fine but tight turns took muscle and the 465 had lost some
The rear s
had
wrong? 1 w îuch that
off the kick stand if the bars were turned to the right. Just holding its own weight used
Hso much that bike would
!
right. Jus
three inches of travel. With a 180-lb. rider aboard, another three inches went away. The rear was down, the front was kicked out like a chopper. No wonder the thing didn’t want to turn.
Moving the spring preload adjusters didn’t raise the bike enough to talk about and made the ride uncomfortable. We called White Bros., considered the best monoshock modifiers by many racers. They suggested we bring the shock in and watch as they performed the magic on it.
The first impression of the shop is one of cleanliness. Everything has a place and the steel topped work benches and concrete floor looked clean enough for a bakery.
They started working on monoshocks back in 1975 when the first monos became production machines. They have always worked closely with racers, both motocrossers and desert/off-road riders. They presently sponsor 30 riders and input is constant. They have modifications for all years and models of monos and the shock is returned set up for the rider’s ability, weight, and type of riding or racing. Normal production for a week is 60 to 90 shocks, including about 20 of the new' G units.
First step is disassembly of the shock, the job of one full time worker. After cleaning, it is passed to Bill Rychlik who assembles the shock. Bill has been involved with the operation for some time and helps with the R&D as well as modification.
Modifications vary with the model shock being worked on. The biggest change to the G is the addition of a short spring. The additional spring is available in three rates, selected by Bill to match rider weight and use. The new spring is added to the end of the stocker, requiring machining of new snap ring grooves in the main shock body. Three new grooves are cut so spring preload can be accomplished at both ends of the spring; by using different grooves for the snap ring and by adjusting the preload nuts at the other end, preload length is increased and the sag goes away. The choice of rates makes precise set-ups for different riders and conditions easier. Spring separation and alignment is via plastic rings. Internally, the stock damping valve is discarded and replaced with one designed by Bill and the Bros. The design is semi-secret so we didn't photograph it. The new valve is die stamped from stainless steel and actually consists of two parts; the damping valve and a centering piece. These parts are inde-
pendent of each other, not weided together like the stock valving. Being separate lets the valve react to fluid movement easier and the damping valve is designed to reduce compression damping slightly. The reduced compression damping means the rider is jolted less and the rear wheel will follow the ground surface better. After the body is machined and the internal damping changed, the shock is reassembled and filled with a special Bel-Ray suspension oil that costs $42 a gallon. The large looking G shock and reservoir only hold 13 oz. of oil. Stock capacity is only 12 oz. but the Whites relocate the piston separator in the reservoir, increasing volume to 13 oz. Oil weight is another variable on the White shock. The weight selected matches the use of the bike and rider preference: heavy oil gives stifler damping than light oil. After body and reservoir are bled of trapped air, the shock is pressurized with nitrogen to 195 psi. Pressure is also variable but the Bros, say their experiments with different pressures changed the overall performance of the shock very little. Spring rates and oil weight are much more noticeable changes. We opted to leave the shock reservoir on the bike but they have a larger highly finned unit available. It isn’t really needed unless the bike is being raced by a seasoned pro. Then the stocker may not furnish enough volume and heat dissipation to keep from fading. The larger reservoir is trick looking and will be available by the time you read this. Price should be around $65.
Once the modified shock is installed the sag disappears and the back of the bike is more springy. This springiness lets the rear wheel follow all of the bumps and the bike is much more responsive to small ledges and ripple type surfaces. And the action through whoops is even better than before. Stock (before the spring sacked' u:i~ would cross whoops at The modified unit will through them even faster. Where shock let the rider know he whoops-the rear wheel could be felt hitting the opposite side-the White Bros, modification softens the wheel impact and improves rider comfort. It takes several rides on the bike before the rider adjusts to the added smoothness and raises his speed through the rough. Much higher speeds can be maintained with the same effort and control is always. Now we know why White Bros, has such a good reputation with racers-their modification works. Price for the G modification is $112. from; White Bros., 11611 Salinaz'Dr, Unit M. Garden Grove, Calif. 92643. (714) 6381653
