MAZ 537: Rolling chassis complete

I made some progress on the MAZ 537, completing the chassis and installing all the assorted differentials and suspension bits. The chassis can now take wheels to test for stance.



Judging by online photos, the kit drivetrain is not entirely accurate, but I'll let it go. As it is, there are 4 final drive units, each presumably with a differential, and a fifth differential splitting between front and rear pairs.




The suspension consists of 8 independently sprung wheels, so there are 16 A-arms, 8 hubs and 8 halfshafts, not to mention 5 additional driveshafts joining it all to the motor. (The actual vehicle would have had seven driveshafts apart from the halfshafts, according to one Interweb source.)



The engine in the picture is a spare Cummins NHC-250 from AMT's White Freightliner kit. This 14 litre inline 6 makes a measly 240 hp, but a sturdy 685 lbf-ft of torque. This is a bit down on the WWII tank engine in the MAZ (the 39 litre Karkhiv V2 is a V12 making 525 hp and 1591 lbf-ft), a gap which I propose to rectify by the addition of a turbocharger or two. Of course, putting a 1/25 engine of 14 litre displacement in a 1/35 chassis is the equivalent of a 1/35 motor of 38.4 litres, so in actual fact it's all fine, but hey, a turbo never hurt anyone. (See math below).



Next will be deciding what to cut to make the White cab and Cummins engine fit. So far I have built up the MAZ completely stock. As a result, the option remains to buy a resin motor for it and continue with a stock 1/35 build. The picture shows the motor in the chassis, which is resting of 4 of its 8 wheels, with both MAZ (1/35) and White (1/25) bodies. The tires are humongous, filling the White fender wells even though the scale is way off. I foolishly didn't make a note of the tire sizes on the MAN in Iceland, but they were easily 4 to 5 feet in diameter.



Stay tuned!

Appendix A: for the math nerds.

Displacement D is number of cylinders, N, times cylinder volume V. In turn V is piston area A times stroke S. Finally piston area is πb²/4, where b is bore. Assuming bore and stroke are both equal to d, we have D = 0.25πNd³.

So an engine at 1/35 scale would have displacement D = 0.25πN(d/35)³. For one at 1/25, D = 0.25πN(d/25)³. 

So the ratio of the two scale engines, assuming the same 1/1 dimensions and number of cylinders, wold be (25/35)³, or 0.364. Put another way, a 1/35 model of an engine of 10 litres displacement, put into a 1/25 kit, is equivalent to a motor of only 3.64 litres; conversely a 1/25 model of that same 10 litre engine, dropped into a 1/35 chassis, is the equivalent of a 27.4 litre motor.