I changed out my DT shifters for a pair of Sora 9 speed Brifters. The rear shifting is flawless, but the front is problematic. I got the limit screws all the way out now (short of just taking it off), but it still won't shift up to the biggest ring.
Do I need to use a 9 speed FD (the original FD is for a 7speed, friction)? DP I need a shorter BB axle length?

Please help.

The only thing that you changed are the shifters, correct?

push the thumb lever on the front shifter as many click as possible, check the cable, is there any slack?

If there is slack then loosen the cable locking bolt on the front derailluer and pull the cable tight and retighten the bolt.

Pull out more of the slack while it's in the small ring. Even to the point of slacking off the lower limit screw, tighten the cable and then run the limit screw back to the lower limit so the cable is tensioned but not enough to hold the derrailleur off the travel limit. That way you get your maximum amount of cable pull. Another possible issue is that if your chainrings are older tech and don't have the ramps and pins of the later indexed systems then shifting will not be crisp unless you hold the brifter lever in an "overshift" position to aid in lifting the chain up and onto the big ring teeth. Replacing the big ring with one that has the ramps and pins would be the fix in that case. Or just live with it and hold the lever hard into the shift until the chain settles for each shift.

Problem solved!
I found a great condition 105 (new model, Hollowtech?) crankset for $50 on CL. ' had the LBS installed it and ' solved the shifting problem. Not really the solution that I was looking for, but I want it and it worked.

I still think the old BB spindle lenght was causing the problem. The new 105 Crankset is considerably shorter (spindle). Or it could be the "ramps and pins" mentioned by BCRider.

Anyway, thanks for the help guys!