Steering on the D4 is handled by twin vertical bell cranks - with a built-in servo saver on one side. There isn't much in terms of innovation here to talk about, just good quality. The steering as you'd expect is ball raced on the main pivots - the moulded steering rack which stretches between the two cranks pivots on metal bushings.

There is a slight problem here in that the supplied screws weren't really long enough to get a good purchase into the nyloc nut above - and over-tightening the screws would bind things up to an unacceptable level. We used a dab of threadlock on the screws and it seemed to be 'OK'.

Two steel 'steering posts' attach to the main chassis from below, and the assembled steering slips over along with the ball races and some spacers. The servo saver is adjustable and unless you are running a cheap plastic servo you'll want to crank this pretty tight to get the best performance - it makes more difference than you'd imagine, especially on a high grip surface.

Twin top decks tie everything together nicely - the front extending from the front gearbox to the centre bulkhead, and carrying the front body post and aerial mount. The shorter rear top deck likewise stretches from centre bulkhead to the rear gearbox.

The top decks have enough clearance to allow you to remove the centre slipper assembly without any major disassembly.

The front top deck also screws onto the steel steering posts, which together with the beefy construction - makes the D4 feel very robust.

The power on all four corners is transmitted to the wheels via long steel 'CVD' style drive shafts. The actual joint is the opposite from the usual 'MIP' type - it's basically inverted but works in exactly the same way.

The pins are secured in the joint with a small grub screw - this is usually sufficient but after reading a japanese D4 blog, and later experiencing two drive shaft failures (one front and one rear centre) it seem to be a good idea to actually put a small flat on these pins to prevent them from backing out.

The manual seperates the front and rear drive shafts between stages - the rear coming a little later in the build manual. I thought it was a little odd to seperate the builds of these since they are identical in the construction - only the lengths of the shaft and axle differ. The front uses a long shaft and short axle, whilst the rear uses a short shaft and longer axle to give a fairly similar overall length.

Since this is, for the most part, a Metric car - the car uses metric ballraces throughout. To give the best compatability with existing wheels (more on this later) the actual wheel mounting area is imperial, and 'steps up' to a slightly larger diameter which spins inside the bearings (the ground silver area on the axles).

The front hubs and hub carriers are reminiscent of those seen on the Losi XX4 - and it can't be a bad thing as the same design is seen on a number of current 4WD competitors. The actual hub carriers are supplied in two flavours, a 10 degree and 7 degree for each side comes in the kit - the 10 degree carriers are suggested in the manual and there doesn't seem to be any mention of the differences between these and the 7degree items. The 7 degree should give a more aggressive steering setup. It's a nice touch to include this setup option, and also acts as a spare part if the worst should happen.

We found the hubs a little tricky to assemble since three washers need inserting between the hub and steering knuckle - this gives the option to raise or lower the steering knuckle, but it's not something we'd usually ever adjust so it's more irritating than anything.

The hinge pins on the Cyclone D4 are all captured in neat ways - the outer hinge pins are captured with a small grub screw in the hub carrier which sits against a reduced diameter area in the middle of the hinge pin - stopping it from backing out. The grub screw only needs light pressure thanks to the recess in the pin.

The previously assembled front drive shafts are inserted and secured in place with the wheel hex and pin - Or not. The pin is such a loose fit in the hex / axle, that it simply falls out and would rapidly become lost in the carpet if we attempted to carry on with the build with it in place. The manual does suggest the use of 'rubber cement' to hold the pin in place, but since we didn't have any we just left the front drive shafts on the table and carried on with the build. Thick grease on the pin would help keep it in place.

If you want to use Losi style wheels on the front of the car an optional 'losi sized' front hex and roll pin are available for the D4 on release.

The suspension arms front and rear on the D4 are again similar in dimension to other leading cars - clearly HotBodies have looked at what works whilst designing the car. The arms look and feel quite tough with plenty of bracing and some 'solid areas', but only time will tell.
The way the suspension mounts onto the chassis is the main innovation in this area. As previously mentioned, all four suspension arms are supported in tough rubber bushings - these rubber mountings should absorb some of the stresses of hard impacts, protecting the suspension arms, hubs and the rest of the car. Not quite a 'crash back' system like on the old Schumachers, but a modern equivelent.

The front suspension arms attach to the alloy bulkhead and the hinge pins are inserted from the front - these are quite tight in the rubber mounts so needed a few gentle taps with the handle of a screw driver to drive them home.

An alloy brace - again with rubber inserts in place, is pushed over the exposed ends of the hinge pins and screwed to the bulkhead to give the front arms a nice secure mounting.