The measurement on the manual assumes you're using a Sanwa servo. If you're using other servos, the measurement needs to be different...

Cut and paste from a posting I did sometime back...

Cut the metal (the stock rod linkage) down to 17 mm. Stock lenght of the rod linkage is 23 mm from tip to tip.

As for the plastic, trim the length of the ball cups. The picture attached shows the top one being the original (and uncut) and the bottom one is the one that was trimmed.



This combo gives the total length of the ball cups and rod linkage assembly as 39.5 mm instead of 44.5 mm as per the manual.

At neutral position, the steering servo horn is not in the center. It should be leaning forward in front slightly at neutral position with this linkage mod.

Download the 710 FAQ. I believe Mark included this and other basic stuff in there.