In Preparation:  Suspension Breakdown

In Preparation Suspension Breakdown

July 8, 2011 10:00am
The suspension you see working hard underneath the riders in the Lucas Oil AMA Pro Motocross Championship is certainly being tested to its limits. The speed of the bike as well as the size of the obstacles puts the fork and shock under intense pressure each and every second of every moto. The guys tuning said suspension have to be experts in the field. As we look into the behind the scenes aspects of motocross for our In Preparation feature, `we called up factory Honda’s Suspension and Chassis Director Shane Drew and get his take on what he does to prep the suspension each and every week.

Racer X: Shane, can you take us through a week in the life of your teams suspension?
Shane Drew:
The suspension is taken off the bike every weekend and we ship the fork and shock back to our shop. They go out on a Monday and we get them on Tuesday. Then we start the service work for the next race. For outdoors, the things get hammered a lot more than in supercross. So we really have to look at them closely, not that we don’t for indoors but outdoors, we really have to check things out as they are pushed to the limits. Everything gets torn down every week, all new seals and bushings, inspect the shims and the shafts.

Photo: Simon Cudby

How bad do these guys wear things out?
It’s really more precautionary than anything else, we don’t let anything get to the point where something is worn out you know? Because of the nature of motocross, we see a lot of rock dings and chips in the fork tubes. So you have to be careful and watch that closely. We put new seals in because we have them apart anyway. 99 percent of the time, everything is fine and there’s no cause for alarm but you know as a mechanic, you stripped your bike down to the frame to make sure everything checks out fine. And that’s for no real reason.

I’m sure you use a shock and fork dyno right?
Oh yeah for sure, everything is dynoed and checked out. A lot of times we dyno the stuff before we take it apart to see how it measures up against the way it was when it went out. Then we take it apart, service it and dyno it again to make sure that it follows the curve that we want.

What kind of lifespan you get with shims, do they wear out?
They definitely wear out, they get a little bend in them and need to be replaced. The guy that does the work for us on the parts is Ryo Okuda and I have to give him thanks because he is the one tearing the stuff apart (laughs)! He’s the guy that looks at all the shims, checks them for flatness and replaces and needed. Probably every two or three weeks.

Is there a rider that you’ve worked with that is notoriously hard on suspension components?
No, not really it’s not like an engine where depending on how the guy rides it, it may need replacing sooner. Everyone is hitting the same bumps!

Photo: Simon Cudby

What about springs? How much fatigue do you see in those?
What we’ll do is start each series with brand new springs and go from there. The race stuff and the spare stuff will all have new springs and at the end of that, they will become practice, test bike springs. We don’t rotate the suspension out in any way, everything is the same. We try to make them identical and that’s why we dyno them. Each thing will be a little different though, we’ll dyno six or seven shocks and there might be three that might be a little closer so all those will go to one rider.

After all that, we’ll ship everything back to the next race and the mechanics will build their bikes with the new stuff that was already on the truck. Then the stuff from the shop will become the new spare stuff.