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Layout
It quickly dawned on me that the
layout of this rig would have to be slightly off the beaten track. With
the independant front suspension using a buggy front end I wanted to go
with a pan-like chassis. However with a solid axle rear suspension, the
rear half of the chassis would require lots of free space for suspension
travel. And since I wanted to stick to the Landmax "footprint" in terms of
wheelbase it became clear that I could not make a standard 1/8 buggy pan
layout with a solid rear end "tacked on". In addition, the pair of engines
would take up a lot of real estate, so space was quickly becoming an issue
here.
Simply moving everything forward was
the solution, but not without its problems. Moving the engines forward
meant moving the tranny forward. Moving the tranny forward meant a short
front driveshaft and a longer rear driveshaft. A longer rear driveshaft
would cause suspension issues. And I had no idea where to stick stuff like
fueltanks, electronics, steering and other minor details...
After much
pondering of all these issues, and quite a bit of trial and error, I
decided on a short pan chassis, not ulike a chopped up 1/8 buggy chassis.
The front diff and suspension would install as on a 1/8 buggy, made for the Hyper 7
front end that I would be using. The engines would mount towards the rear
of the shortened chassis. The placement of the engines would then
put the center tranny up towards the front of the chassis.
The rear end of the chassis would be
cut off squarly right behind the location of the engine mount. This would
provide space for the rear solid axle suspension. The rear suspension
would then be mounted aft of the engine mount, thus placing the engines
pretty much smack dab in the center of the trucks wheel base; ie excellent
center of gravity.
Mock-up of chassis w/ engines, tranny
and suspension parts
> Pan chassis
For pan chassis
material I decided to go with
overkill (hey, why settle for less?). I cut the chassis plate from 5 mm
(!!) thick 7075 T6. This is extremely stiff and strong, and quite heavy.
So the plan was to get everything located, then trim and "slim" as
required. As soon as I had determined the overall
layout of the components, I hogged out (milled "pockets") in the areas
under the engine mount, tranny and diff housing in order to reduce weight.
I also milled a pair of cut-outs for the rear suspension arm mounts.
Cutting out the pan chassis
3
stages of the pan chassis plate after some millin' and drillin'
> Spine
In order to add to the overall
stiffness of the truck, I wanted some additional bracing running from
front to rear. In addition to provided the added stiffness, I wanted it to
provide mounting pointes for other "hardware" to be mounted on the truck
later.
I found some aluminum channel that,
with some milling & filing, hooked up to the front bulkhead and fit over
the center tranny and engine mount. I made it long enough to protrude over
the rear end of the chassis, planning on using it as a mounting point for
a future "tail section" . This "spine" would also
provide a mounting point for the center tranny.
Center
"spine".
Center
"spine" mounted on chassis
> Roll cage
In
order to protect those thumpers and give this rig a bit of a "truck look"
I made an aluminum rollcage which I milled out of 2 mm 2024-T3 aluminum.
This alloy has excellent properties for the job as it is strong and quite
"springy", so it would not bend or deform after its first "ding". The cage
would bolt straight on to the pan chassis, and provide mounting points for
the "tail section" as well as rear shocks.
The 3 stages of the cage as it was drawn
out, cut, then finally shaped.
> Tail section
The downside to
this chassis of mine is its lack of size. After fitting the engines, front
diff housing and center tranny, well there simply is not room for anything
else. So in order to fit all those nice-to-have items like fuel tanks,
exhaust system, electronics and such I came up with a narrow "tail
section" that would hang of the rear end of the chassis, keeping it out of
the way of the rear suspension.
For the "tail" I
used some 2 mm silver carbon fiber plates, which I cut so they fit the
outline of the body I planned on using, and shaped them to fit as en
extension to the center spine of the chassis. It then mounted was to the
spine and the cage.
I then intended to
hang fuel tanks and the exhaust system on the outside of the tail, while
mounting electronics inside of it.
Cage & tail section mounted (early
version of tanks & shocks seen)
Fitted with intended Landmax F150 body.
