Idler Tension Conversion for 1/16 Tamiya Tiger II (King Tiger)  Pictures below for Reference

The problem: The Tamiya Tiger II (King Tiger) 56018 kit has known issues with the idler tension mechanism failing or loosening under continuous running.

The solution: The idler tension system is based on the proven Tiger I idle r tension system that has been heralded as a reliable design. This system uses commonly available material that is inexpensive and is relatively easy to modify without dismantling the tank.

Parts needed: Two 3 inch 1/8 spring wing toggle bolts 6-32 thread, two lock nuts 6-32 thread and two self tapping screws (Tamiya type MA3 from “Screw Bag A” extras from Tiger I kit) all for a few dollars.

Tools needed: Variable speed  Drill with 3/32, 1/8 and 5/32 bit, Dremel tool with narrow cutting wheel and needle-nose pliers.

Step 1: Disassemble the spring wings discarding the spring and one wing (with slotted hole) and keep the studded threaded piece and the other wing. Note the similarity of how the mechanism works just like the Tiger I tension adjuster.

Step 2: Use the Dremel to carefully shave out the bolt-through slot extending about 1/8 inch more. This will allow room for the bolts adjustment through a wide angle. Drill a 1/8 hole near the other end on the flat portion of the wing. Reassemble the threaded piece to the shaved out wing carefully bending the guide holes back onto the studded threaded piece.

Step 3: Remove the top of the tank to get access to the rear idler. Remove the tension spring clamps from the idler drum and discard. At this point it is optional but recommended to remove the springs in the idler drums as these are generally useless especially when used with metal tracks. The spring tension is just not strong enough when using metal tracks and bottoms out. This modification does not require the drum springs and will be easier to complete without them.

Step 4: With the tracks loosed or removed, move the idler wheel back as far as it will go applying gentle pressure. While holding the idler wheel, rotate the idler drum in a forward motion until a stop is felt. With a permanent felt marker, mark the top (12 o’clock) position of the drum. If choosing to remove the drum springs, mark the drum at about the 1 o’clock position. Drill a 3/32 hole at the mark indicated near the rim edge such that the bit penetrates the rim side of the drum and not the solid portion of the drum. The drum can be removed and milled on a drill press if so desired.

Step 5: From underneath the tank, drill a 5/32 inch access hole through the bottom aluminum plate hull. Locate the hole halfway between the outside edge of the tank and the torsion bar stay mounting screw. Insert the 6-32 bolt through the bottom and add the lock nut screwing it down to nearly touching the hull plate. Allow enough play with the nut backed off slightly from the hull to wobble in any direction about ½ inch or so. Wind down the threaded wing with the open side up to a point level with the tension drum. 

Step 6: Use the MA3 self-tapping screw to attach the idler adjuster to the drum. Help in holding the idler may be necessary to line up the holes to accept the screw if the drums are spring loaded. Be careful not to set the screw completely as this will gouge the brass collar and the cast drum may strip if too much pressure is applied. Be careful to remove all metal shavings from inside the tank.

Step 7: Adjust the tension bolt with the tracks on to the desired level in similar fashion as the Tiger I and check before closing up the tank. Now your done and ready to run!


        Parts required              Disassembled parts with wing cutout                 Bolt hole location for idler adjust with bolt inserted


Idler adjuster in place and prepared to attach to the drum                                   Complete idler adjuster assembled





Southeast Armored Division

Tech Notes - Page 3


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