Peterbilt 6x6 Heavy-ish Hauler

[Tommy R]

Hey y'all,

I'm finally working once again on a project I started years ago and thought I'd share it here. For years I've been mesmerized by the European semi truck scene. We mostly only have crawler events where I live, however. Fearing the limited use of a RWD truck, I decided that an all wheel drive version might serve me better. It won't be as capable as a crawler, of course, but it hopefully won't get stuck every 10 seconds, either. :)

I decided I wanted something that would be a bit of a combination of the styles of these two trucks:

I picked up a King Hauler in late 2016 and got it built in stock form.

In the process of building, I decided to put some super heavy grease in the diffs. I didn't want the diffs fully locked, but fully open would suck. So far, this looks like a great solution!

But I need to have a driven front axle if I'm going to have a 6x6, right? TLT front axle to the rescue! Of course, it got the same diff treatment as the rear axles.

With some Hi-Lift leaf springs and some spacers to widen the hangers and shackles, the front axle bolted right in.

Another Hi-Lift spring was sacrificed to help tie the bolts together because they run all the way through the axle to secure the leaf spring to the housing. Yes, I changed the hardware later on. :)

This brought up a big challenge, of course. How do I get power to the front axle?

 

[Tommy R]

There's dozens of ways to convert a Tamiya semi truck to all wheel drive. I decided to use an Axial transmission as a transfer case because I already had it. It would also have the benefit of reducing the gearing by 2.6, which is good because the Tamiya 3 speeds are too fast, IMO. To get clearance for the driveshaft under the transmission I had to raise the trans quite a bit.

This meant cutting the interior floor, which is something I'll need to address when I finish out the interior.

Pics of the mounting t-case are coming below, but I got sidetracked with something... You see, the King Hauler isn't exactly a Kenworth....or a Peterbilt....or a Western Star. I couldn't have this. I needed it to be modeled after an actual truck. I did some research and some soul searching and decided this will be a Peterbilt. The main thing to address for the transformation is the front fenders. So here's the process after my order from Shapeways came in.

Incidentally, here's where the motor now resides after raising the transmission. Clears the hood great!

But hold a minute... I can't do all this work and not address the ugly antenna hole on the sleeper and "sunroof" on the cab!

Much better after some filler primer and some sanding.

 

[Tommy R]

Speaking of sanding, the 3D printed fenders needed quite a bit of it, as well.

I think the fenders have potential. I also remade the hood sides and extended them down to the depth of the bottom of the fender. I thought that looked much better.

Oh, I should mention wheels and tires. I opted for Lesu for both. Rear tires are their mud terrains and the fronts are mud terrain super singles.

The fronts stick out too far, though.

Fronts from Hercules Hobby fit much better, IMO. Hardware from Locked Up RC is required!

Now it's finally time for paint! Metallic blue, off-white, and a gold leaf stripe between them.

It's coming together!

It was here back in the summer of 2017 that I painted the chassis and I wasn't happy with it at all. The truck sat on the shelf of my hobby room until the last couple weeks when I decided to get back on it.

 

[Tommy R]

Okay so now we're back to the current day and it's time to correct the paint on the chassis and get back to work on this thing! I should also mention I picked up an aluminum grill w/lights. Purty!

I painted the trans to simulate a Caterpillar powerplant.

Time for paint....again. You can also see the Axial trans as the transfer case, along with the aluminum bracket I made to mount it.

Going back together.......temporarily.

I'm liking it, but the front is too high.....and I wonder if I should lengthen the frame a bit?

Manually de-arching the springs brought the front end down.

Not a perfect ride height, but much better!

And good news, it looks like the raised transmission clears the dash.

But 2 steps forward and 1 step back.... I've decided a couple things. I want the chassis longer so some Grand Hauler rails are in transit to me. I also decided against the Tamiya 3 speed with Axial t-case. I now have a Lesu 3 speed AWD transmission on the way. The gear ratios are actually a bit taller (faster) than the Tamiya so I plan on running a 3:1 or 4:1 gear reduction unit on it. I'll get more pics soon once the next batch of goodies arrive next week. :)

 

[imthatguy]

Fantastic work sir. Sometimes the best projects are the ones that take a few years. Love all the custom styrene work, keep it up, you're almost there!

 

[pera2008]

nice truck and love color combo

 

[Bluedually4x4]

Awesome looking truck.

 

[Frederik]

Looking awesome, awesome work! Nice body alterations, and it is very cool you converted it to all wheel drive. I never owned or touched one of those, is the suspension pretty stiff or does it allow good articulation? Given the length of the half leaf for each wheel and the fact there are 4 wheels in the back, it is probably pretty stiff (made to haul after all hahaha)

Do you plan to run offroad without a trailer mostly? If so you could mod it to be softer and just a tad higher in the back (you reference pics I think are a bit higher anyways).

Also, does the TLT axle happens to be the same pinion to ring gear ratio as the semi axles?

 

[Tommy R]

Fantastic work sir. Sometimes the best projects are the ones that take a few years. Love all the custom styrene work, keep it up, you're almost there!

nice truck and love color combo

Awesome looking truck.

Thanks, y'all! I really appreciate the kind words.

Looking awesome, awesome work! Nice body alterations, and it is very cool you converted it to all wheel drive. I never owned or touched one of those, is the suspension pretty stiff or does it allow good articulation? Given the length of the half leaf for each wheel and the fact there are 4 wheels in the back, it is probably pretty stiff (made to haul after all hahaha)

Do you plan to run offroad without a trailer mostly? If so you could mod it to be softer and just a tad higher in the back (you reference pics I think are a bit higher anyways).

Also, does the TLT axle happens to be the same pinion to ring gear ratio as the semi axles?

Thanks! Yeah, the suspension is pretty stiff....as are the tires, but that's okay by me. That also means there's very little articulation. I plan to buy or build a trailer for it, for sure. As far as offroading it, well, I definitely won't take it "crawling". I hope for it to be about as capable as a real-world 6x6 heavy hauler. I also plan for my trailers to be heavy! I want it to be a challenge to lug the trailer around some dirt trails. As far as ride height, I still have to add all the electronics which will lower the front a bit more, but I'm also considering raising the rear just a bit. Overall, though, I'm okay with the new stance. And yep, the axle ratio of the TLT is the same as the stock semi axles.

Here's an early flex shot with very little weight in the truck.

So the truck is now the closest it's ever been to finally being a runner! So OF COURSE I end up doing this:

Yeah, I'm a glutton for punishement. I decided to change two rather important things about the truck. First, I decided to change the drivetrain. A Lesu 3 speed trans will be here tomorrow and it's already set up for AWD. Second, I decided the stock frame rails made the truck look a little too stubby for my liking. So I picked up some Grand Hauler rails.

Here's the truck with the new (unpainted) rails installed. Ideally I may prefer it about one inch shorter overall, but I'm going to try it like this first. Maybe one day I'll shorten the wheelbase, but I think the longer setup fits the style of truck I'm wanting to emulate.

The Lesu gearbox has an even taller gearset than the stock Tamiya. That sucks! So to compensate I picked up a HH 80t motor and it's feeding a 3:1 gear reduction unit. I hope this new drivetrain holds up okay. I've heard bad things about some of the Lesu stuff.

 

[Tommy R]

The Lesu 3 speed AWD trans showed up. It's aluminum and pretty heavy! Comes with two sets of mounts (one higher and one lower), but the holes don't line up with the width of the Tamiya rails. *sigh*

And look at the size of this teensy tiny press-fit pinion gear! I'm going to be feeding it with an 80t motor and a GRU so it's going to be subjected to a lot of torque. I'm concerned about it's longevity. :(

Here's the "highly detailed instructions" that come with it. :lol:

The rod at the top is if you want to shift the trans from the front, instead of the rear. I may have to look into this further. I opened up the trans and tried to swap them, but it wasn't look like it was going to be worth the effort so I may just shift it from the rear. And judging by the short length of the shifter linkage, they must assume your servo is right next to the trans!

Mocking up the trans with the motor. Adding the GRU will require it to sit rearward just a bit more to clear the servo. The GRU will add about 3/4" overall.

 

[Tommy R]

My 4:1 RC4WD gear reduction showed up so I got it hooked up with the Lesu trans and the HH 80t motor. I was pleased to see how short the overall length of the GRU is, but was surprised to see so few gears inside. My biggest concern right now is if the gearing in the GRU and the trans hold up.

The front mounting hole on the frame rail was re-used, but the rear hole has to be drilled/tapped. Note that I'll lose the upper step mount, but I don't really care. It's not like it's gotta support the weight of a scale 350 lb. truck driver!

I had mentioned earlier that I'd like a bit of a gap between the rear tires so I made up a little styrene spacer to sandwich between the rear wheels. It's about 1.5mm thick. It's ugly, but is only for prototype purposes.

Here you can see the gap created by the spacer on the far wheel set. The near wheel set is stock Lesu wheels.

Ages ago I modified a set of front wheels to get them to tuck in farther. That was on the Lesu wheels I originally tried. These fronts are made by Hercules Hobby and they have quite a bit more backspacing so they tuck in better. However, I still have to run a 6mm hex for them. If I run a 4mm hex you can see the hub bottoms out against the knuckles. Also note I put some aluminum TLT knuckles on.

The issue with a 4mm hex on these wheels.

So I drop a pair of thick washers inside...

Then out comes the Dremel! I rest the cutter flush to the washers and slowly cut through the hub. Be careful here. It's super easy to get hurt if you don't take the right precautions!

And the deed is done.

Now I have great clearance even with thin 4mm hexes!

Now the fronts tuck in really nicely. They're not fully tucked, of course, but this is the look I was after.

The other side still running 6mm hexes.

 

[Frederik]

The tucker in stance looks much nicer! Good job. And the wheels gap too is a nice improvement. That is one thing that sometimes bugs me with duallies, having the tires contact or almost contact. Looks great!

 

[Tommy R]

The tucker in stance looks much nicer! Good job. And the wheels gap too is a nice improvement. That is one thing that sometimes bugs me with duallies, having the tires contact or almost contact. Looks great!

Thanks very much! :)

I decided the front axle needs to move forward a bit to get better centered within the fender. So I drilled a couple new holes in the leaf springs.

However, this moved the axle too far forward. So then I moved the hanger back and up just a bit. This would bring the wheelbase back a smidge, but also give me a bit more caster. By the way, you can see how poorly my paint is adhering to the self-etching primer. I recently picked up some touch-up paint and I'll definitely be needing it when I go to reassemble.

And here's my plan to put a little space between the duallies. First, I thread in some longer 12mm screws through the hub. I also added a dab of grease on the hub to hopefully prevent the wheels from bonding to the paint that seems to want to come off far too easily sometimes!

Install the inner wheel and then add nuts to the wheel studs. In this case, the nuts are 1.5 or 2 mm in thickness.

Now with the outer wheel installed I have a reasonable amount of space between the tires. It's not excessive like a brodozer but it's just about what I was hoping for so I'm pleased.

 

[Tommy R]

Got a nice delivery of Lesu goodies today, but the only pic I have so far is the micro servo mount for the transmission. I drilled/tapped a bunch of holes on the chassis today for the other stuff that came in and all of it should get paint tomorrow.

Anyway, here's the servo installed. With the servo arm cut down just a bit it clears the bottom of the sleeper cab. I just had to clearance part of the crossmember for the shifter link.

 

[Tommy R]

A few progress pics after some paint work.

Lesu rear suspension and some other aluminum goodies. I also should've installed the rear center caps. D'oh! :)

Scale hardware for the win!

 

[WildTrailFab]

Looking good.

Sent from my SM-G970F using Tapatalk

 

[Frederik]

Beautiful!!

 

[Tommy R]

Looking good.

Sent from my SM-G970F using Tapatalk

Beautiful!!

Thank you!

 

[Tommy R]

So we got a bit of snow on Sunday here in Austin, Texas. That's not a common occurrence for us so I figured I'd take the opportunity to take a few pics and see how it drives in some icy conditions. Well, it did great!

Then last night we got some real snow. Like....."are we even in Texas" kinda snow! Depending where you measured, we easily got 4-7 inches, which is crazy for us. Well, of course I had to test out the truck in deeper stuff today. Overall, it did really great and had plenty of traction. The limitation, as one would expect, is the low hanging front bumper and the overall low right height. Nonetheless, I was pleased!

I also got some Lesu steps for the frame, but only have one installed at the moment.

 

[Tommy R]

I knew I'd want custom plates for this truck and rather than spend money on some custom ones, I decided to try my hand at making some. Being 1/14th scale, they're only about 1" long so it won't be obvious if they're not perfect. And it costs me nothing to try so why not? I went online and copied a few JPGs of license plates I'd want. I printed them and then trimmed them out. Here's a super close-up of what my mediocre printer could do:

Then I adhered them to some .015" styrene with some glue.

Then I trimmed them out with some clear tape applied over them to protect the ink.

The thin overall thickness feels pretty realistic and from a short distance I think they'll look just fine.

Another thing I've been thinking about lately is the front bumper. I haven't found an aluminum one that I like so for now I'm going to use the stocker. I cut off the two "buck teeth" from under it to help the approach angle.

I like weight in my scale RCs. They perform more realistically that way. In fact, I'm rather disappointed the Pete is only weighing in at about 9 lbs so far. So I decided to add some weight in the form of touring car weights glued into the front bumper. I Dremeled out some room inside the bumper, glued the weights in, and will paint them silver so they're less obvious. Those 80 grams really gave the bumper some heft!