Quote:
Originally Posted by geomapguy
|
Those look familiar...
The inverted outer C rails were used in 2009 to recess the live axle bearings, so they could not be exposed directly to the bumper frame. Small wood or plastic blocks were added to provide additional backing behind the bumper (you cannot mount bumpers into the indented portion of the frame unless that frame is removed with the bumpers).
At the time this was the easy way out, but
after putting more thought into it in 2011 we were able to swap the C rail back to facing inwards. The bearing protrusion issue was solved by adding a 1/8" sheet metal shim to the inside of the center wheel and having the outer wheels inside a separate bracket inside the knocked off corners.
The bumpers we used on those frame styles generally had 1/2" aluminum posts mounted onto the frame, then sheet metal brackets added to the bumpers. They would be added and taken off vertically, with hairpin cotter pins (R-clips) used to keep them in place. The 2011 frame had segmented bumpers that were added and removed horizontally, although I believe in 2012 and 2013 they returned to bumpers that were added and removed vertically (over the top of the robot).