Our W124 wagon has developed a slight pull and steer to the left under heavy braking. We've noticed that at heavy braking at 5-MPH causes the car and steering wheel to turn left.

We have done the following:

1) swapped left & right tires;
2) swapped with new 205/55ZR16 tires vs. 215/45ZR17 tires;
3) flushed all brake calipers;
4) installed new front pads;
5) installed new front brake hoses;
6) checked rotors for warping.

Pistons in calipers (1994 500SL) freely move and there is no leaking.
Front suspension (bushings (SportLine), ball joints, links, springs (SportLine), struts (Bilstein Sport) ) were all changed out about 1.5-years ago.

Any other ideas? We haven't ruled out rebuilding the calipers, but highly doubt it.

PS: Since we changed out from 300TE to 400E hubs, do we need to change out the links (tie-rod, draglink, etc.) to those for the 400E or is that only necessary if we change out lower-control arms?