Mission Possible – Schumacher Mi4

Middle
Moving to the middle of the Mi4 chassis we see the new 2.5 mm carbon fibre chassis with milled out Mi4 logo and lowered contact patches for the bulkheads and under the differentials. This should make for the lowest CG possible. The chassis plate features a clever design with five openings for five cell Sub-C NiMH battery packs and a sixth opening consisting of two locating holes for LiPo battery packs with location knobs. On the opposite side of the battery compartment the completely redesigned rear bulkhead/motor holder dominates the middle part of the chassis. The motor holder is of a clamp design as found on Schumacher’s 4WD Off-Road buggy CAT SX. The motor clamp is screwed to the middle layshaft holder that offers a static layshaft which reduces the rotating mass in the drivetrain.

One of the most noticeable changes, beside the motor mount, is definitely is the angled top deck. It sits relatively high above the chassis not only making way for the motor underneath it but also allows for the much needed clearance for the inner battery connector. If you ever tried to put one of the new LiPo batteries into an average ’07 or ’08 touring car you will instantly notice that the battery pack, or at least any connectors, most likely will collide with the rear bulkhead. The new Mi4 will do away with such fears. Even 25 mm LiPos fit with no problem but you have to use glass fibre LiPo locaters or Schumachers LiPo locator frame/strap with them to securely mount them on the chassis.

A new design feature are the ‘trans links’ brackets that connect the layshaft mount with the rear bulkhead. By using thicker or thinner trans links brackets (in fact the thickness of the material remains the same but the width of the bracket varies between 1.4 and 4.4 mm) you can change the flex of the rear chassis parts and therefore adjust the amount of rear end grip generated by the chassis. Supplied with the kit are the medium soft 2.4 mm plates ideal for low to medium bite tracks.

Underneath the trans links the new designed layshaft assembly is located. This ‘fixed layshaft’ construction consists of a 85 tooth spur gear that is attached to the one-piece 20T pulley gear. The front and rear belts are separated by a floating ‘fence’. The spur gear/pulley construction is double ball raced and rotates on a fixed hollow alloy layshaft that is screwed trough the layshaft holder. This sounds complicated compared to other cars but uses of a minimum of parts and therefore is very easy to handle when changing spur gears etc.