6x6 big rig recovery truck

[tetracanth]

Just got rolling on my first scale rig. First, the specs:

Chassis: Tamiya Globeliner Big rig (short semi chassis)
Motor: Tamiya standard 540 can (change to 55t? )
Transmission: Tamiya 3-spd
ESC: Traxxas XL-5 waterproof
Radio: Spektrum DX3S

Planned mods:
TLT-1 powered front axle
1.9" wheels with Flat Irons or RC4WD Flashpoints
Elongate walking beam to accommodate larger wheel diameter
RC4WD R2 2spd dig transmission
Working crane

Planned body:
Fallout 3/military style - post-apocalyptic survival truck
Flatbed with A-frame crane
B-17 Betty cab (suitable to 1950s era)
Improvised appliqué armour
Headlights and roof lights

The bare chassis:


B17 Betty body fits nicely!


Building a new understructure


Cab and bed installed


Bed rear view


Comparing a TLT-1 axle to the front semi axle


Converting to the TLT-1 axle will require several modifications:

• The TLT axle is wider than the semi axle, so I'll have to either get front wheels with significant negative offset or dually rears with positive offset. The stock semi wheels are a nonstandard 1.85" diameter and the fronts have no hexes, so replacements seem in order. Maybe make custom dually rears?
• The TLT axle needs be be run upside-down so it turns in the correct direction, this will require some mods to the attachments.
• The stock 3-spd transmission has only one output shaft, so a transfer case or replacement transmission will be necessary. I have a spare R2 2-spd dig transmission, which would also allow disconnecting the front wheels for better turning, given the lack of a center diff.

Anyhow, still early, we'll see how it goes.

[tetracanth]

Started mounting the new front axle today. Using parts left over from my AX10 build. It's a droop setup using the stock ax10 shocks, which are a bit too long, but they'll do for the moment. I'm trying to use parts that are in my leftovers bin to keep the cost of this project down.

Added today:
TLT-1 Axle
4-link front suspension w/ AX10 bent links
AX10 shocks w/internal springs (droop setup)
RC4WD R2 2-spd transmission w/ dig
Hitec HS645MG steering servo

The TLT-1 axle in place


Side profile


Underneath




The AX10 shocks are too long - I'll have to find something better. Also, the current position of the transmission leaves only a very small gap between the rear of the tranny and the middle axle - not enough for a pair of universals. I may have to move the tranny forward or move the axles backward. The rear axles may have to be moved anyway if I'm mounting tires that are 4.2" in diameter.

The links are also longer than I'd like. I need to get a 3mm tap and some aluminium tube stock if I'm going to make some shorter ones.

I also flipped the rear axles over so that the front axle can be right-way-up and everything turns in the same direction - thanks to stevehastings on scale4x4rc for that idea.

[rubberovrroc]

I like it alot.I want to do a recovery rig or trail ready shop truck.

[rmdesignworks]

looks good,,also looks like you upper links on the front axle need to slightly shorter to get your caster angle better,,,you can simply cut the Axial links then thread a Black Oxide M3 screw into the end of the link and it rethread it,,,ive done it many times

[CrazyAce211]

Try a Tamiya F350 Highlift front axle it'll fit better then the TLT-1 axle

[5150bronco]

looking good. you going to stick with styrene or going to do metal bed?

[tetracanth]

It'll be mostly styrene: I don't have the tools or workspace for sheet metal work. I'll be using brass tube and aluminium to reinforce the roll bar and crane.

[eddievedder]

Very cool build. The Axial body/cab looks sweet on there! Nice job on the front axle conversion.

[shambrick]

Looks good.

How are you ensuring that the gear ratio of you front axel is the same as the two rear?

[eemmaaxxxx]

Nice project. I've always liked the look of the recovery trucks.

[tetracanth]

@shambrick - I was worried about this until I found out that TLT axles and semi axles use the exact same diff ring and pinion gears - apparently one is just a modified version of the other. The ratio is 2.66:1

[5150bronco]

Originally Posted by tetracanth

It'll be mostly styrene: I don't have the tools or workspace for sheet metal work. I'll be using brass tube and aluminium to reinforce the roll bar and crane.

yea. not too much tools required really, but i see what you mean. keep the pics coming.

[tetracanth]

Minor update: cut out the grille and headlight openings, fabricated a military-style louvered grille to match, complete with bullet holes. The headlight openings are ready for a pair of Proline light buckets with LEDs

[tetracanth]

Got some stuff from RC4WD in the mail:

• 90mm aluminium shocks + boots
• 12mm axle extenders

Still waiting for wheels, tires and a bunch of other stuff to show up at the LHS...

New shocks up front, much better length (they can compress now)


12mm axle extenders on the rear two axles get closer to matching the front's width


You can see the rear axles widths are better now. Width's good, next we work on the lengthwise positioning of the rear axles.

[Sephis]

Hmm, I never thought of using the betty body as a semi cab, but it looks great. I really like what your building here.
From the looks of that bullet hole, your gonna need a new radiator.

[super mud]

This thing looks sick great idea and work

[tetracanth]

Flat Irons and HPI stock car wheels arrived yesterday, haven't had time to do much more than a test-fit.



Looking the way I wanted, obviously the rear suspension is not ready so the tires rub each other and the ride height is low in the back. Also got some aluminium for links and long set screws so I can get cracking on the walking beam.





A small problem: the 1.9" flat irons don't appear to fit tightly on the 1.9" hpi stock car wheels I bought: the inner part of the bead on the tires is wider than the bead groove on the wheels. Do I have to trim it down? It's preventing the tires from seating into the wheels fully.

[pardonmyn00b]

The outer lip is shorter than the back lip on those wheels. Your tire is seated all the way, but you are going to have some bead showing. Those are the 0 offsets right? Have you trimmed the 2 inner rings off the wheels? I did that for a better fit with mine.

[tetracanth]

Aha, okay, that helps alot: I have not trimmed the inner rings off. Those are 31mm wide, 6mm offset wheels on the rear axles and 27mm, 0mm offset on the front axle.

[5150bronco]

that body is 1/6th scale?