Kinked Tunnels

"Dear Ralph" July 15, 2007 0
Dear Ralph: Have you guys heard anything about bent tunnels on Crossfires, or had any problems with yours? Some people in various forums have...

Dear Ralph:
Have you guys heard anything about bent tunnels on Crossfires, or had any problems with yours? Some people in various forums have posted pictures, and claim that they weren’t riding hard when they bent. But others have ridden theirs for thousands of miles without a problem. They seem to bend right behind the reinforced area where the front arm bolts to the tunnel. Is there an engineering defect here, or are some people abusing their sleds?
Darrell Eckert

We haven’t seen incidents that would be considered abnormal, as one can bend and kink most anything. Sleds of all makes and models get bent up all the time. We have thousands upon thousands of miles on numerous Crossfires over the years, with the only real damage coming from hitting that deer in the U.P. a couple years ago. And, it’s not like we abuse them, but it’s not like we ride them gently, either.
Typically, the tunnel kinks come from tail landings that induce forces at angles and locations that the suspension can’t deal with as effectively (placing the impact force horizontally into the end of the rear axle transfers the energy to the tunnel instead of being absorbed and dissipated by the shocks and springs).
That being said, and with the emphasis on making sleds as light as possible, one can look at the structure of the aluminum tunnel on all sleds and wonder why the rear arm mount and the front arm mount are not tied together by a full-length frame doubler plate (like AD Boivin adds with their suspension kits) or like BLADE does with the Delta Perimeter Frame that triangulates these mounting points for a more-solid backbone. We’re told the other OEMs can’t do it like BLADE due to patent issues. Something as simple as a plate on the outside of the tunnel running between the two mounts would seemingly strengthen the area, but again, apply impact forces at the wrong angle and something has to give, somewhere. This is why this kind of damage is logically considered abuse, even though the rider may not realize exactly which landing did the damage.

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