Exchange the coupler of Class 91 into close coupler.
Before modification, comparison of Class 91 and DVT. The height of buffer is different, and the gap between the front skirt and the body of Class 91 is too wide.
The coupler height of Class 91 and modified Mk4 coach is also different.
So I decided to attach the buffer/skirt part of Class 91 onto the body side.
Before Modification. Bogie frame can be detached from inside gear frame by pulling downward.
(It's better to remove the Chinese oil before modification, for your health.)
Replace the Arnold coupler with Tomix latch type TN coupler (no. 0381) which is compatible with the close coupler of modified Mk4 coaches.
Cut out the skirt/buffer part from bogie frame, and replace the coupler.
Bottom view of the body. Measure the inner width of the body. Front end is tapered and the shorter span at frontmost position shall be measured, too.
Cut out 5mm width pieces from 1mm thick plasticard, trim the length into the inner width of the body (front end one shall be tapered), and glue onto upper surface of the skirt/coupler parts.
Glue the skirt/buffer parts onto bottom edge of the body, and install the power unit.
Comparison of coupler height. Same as Mk4 coach.
After modification.
I'll replace the pantograph with Fleischmann or Minitrix part, because the collector head cannot be horizontal....
Working head/tali lights are another issue.