Slipping steering clutches

I have my HD6B up and running pushing a lot of dirt but I think I have a slipping clutch problem. When I put the clutches together...using all exiting bi metal plates.... I had to add steel plates two per side to get the proper stack height. I put them together the first time just like the manual states which is the friction plate against the pressure plate. In doing this, the first friction plate( once installed in to the flanges) was just on the edge of the drum and came misaligned with the stack. This caused a very hard removal of the steering clutch. I removed both clutches and rebuilt them with the steel disc up against the pressure plate which put the friction discs teeth further in the drum. Is this causing the slipping problem or are my discs worn out. They spec’ed out at around .148 thick. The book said they were good till .125. Another indication of the slipping is when put into gear (2nd forward and reverse) it has a bit of a run up to speed and if I am going up a incline it’s a bit of a struggle to get full speed. Sorry for the long description

Seems steering clutch slip - unless they are oil soaked composition is a rare thing - now have heard splines hanging up on bi-metal but unusual . 
 Might pay to check master clutch further as suggested above 

Unusual that both steering clutches would slip the same. Master clutch is the common point if the drive is equally weak side to side. Check the master clutch as others posted.

I don't understand the dimension listed.  Is it the dimension setting the clutch lever?

The new stering cluch is 2 7/8 inchs but can be use until 2 11/16 inchs and you should have 3 inchs free travel when measured at the top of the lever and you should have 1 3/4  inchs to 2 inchs free travel on brake pedal.