Peterbilt 6x6 Medium Hauler

[Tommy R]

Hey y'all,

I've always wanted to build a Tamiya semi truck. They're just so cool looking and I've been a fan of big rigs since I was a kid (maaaaany moons ago!). I've spent hours and hours watching those incredible expos in Europe where people build and drive their amazingly detailed trucks through scale cities, but sadly, it doesn't seem to be very popular here in the States. :cry: So that means if I were to build a semi truck, I would likely have to run it with my crawler buddies. Now I know converting one of these trucks to all wheel drive will absolutely NOT make it a crawler. However, I should be able to do mild trails with it and honestly, that's all I care about for this truck.

So which one to buy? The Euro cabover trucks like the Scania, Mercedes, and Volvo look fantastic, but all the front overhang and such a short wheelbase would combine to make an already ill-performing offroader nearly useless in our terrain. I would really need something with a slightly longer wheelbase and minimal front overhang. So I looked into the US trucks like the Globe Liner, King Hauler, Aeromax, Grand Hauler, etc. Some had a wheelbase that was just too long so they got ruled out. I also figured this truck would have a bit of a "heavy hauler" or "construction" type look so that ruled out the trucks with tall sleeper cabs. That left me with the Globe Liner and the King Hauler. And since I won't go full bore "heavy hauler", I felt calling it a "medium hauler" was appropriate.

And after months of researching them and what it would take to make them all wheel drive, I opted for the King Hauler. The longer cab would likely give more options for drivetrain and the mandatory sound system! :mrgreen: Tower Hobbies hooked me up with a generous gift code and I already had a gift certificate so they got the order. Three days later....

BAM!


The first order of business is to do a stock 6x4 build with RWD only. It's crazy, but after being in the hobby since the '80s this will be my first Tamiya build! I can't believe they still use philips screws, but oh well. Once it's built I plan to convert it to a 6x6 and I'm still trying to decide which method I want to follow because there are plenty of options! I also figured I'll do some bodywork during this time. Since the King Hauler isn't really a Peterbilt or Kenworth or any other specific brand, I would like to put some effort into making it a Peterbilt. I'm not yet sure how far I plan to go with that, but it may include front fenders, a grill, and some badges. That would likely be all I'd consider, to be honest. Specifically, I'm after the look of a Peterbilt 359. Now let's build!!

Chassis all done!


For the axles I had something in mind. I didn't want to fully lock the axles because I'd like the truck to have a reasonable turning radius on concrete. However, it needs a true 6 wheel drive to get anywhere and open diffs just won't cut it. So I decided to try an experiment with some Gravity RC 2.5 million weight diff grease. My hope is that offroad it will lock up enough to spin all the tires, but allow diff action when turning on grippy concrete. Time will tell if it works! Here's the goop going in.


Roller status!! I also installed a Savox 1256 servo for the steering. It's only got about 277 ounces, but I think that might be fine for this type of rig.


Transmission coming together. I'll lock it into first gear for now, but eventually I'll have a servo to shift it.


Trans and an Integy 55t motor installed with the stock 10t pinion. I hear these things are way too fast with the stock gearing so I'll have to address that for sure.


Now the body and accessories. The base build is pretty much done.

[Tommy R]

Check out that crazy articulation!! LOL


My plan all along has been to run a Tamiya TLT front axle in this thing. Same gear ratio as the semi rear axles and a good width. They're increasingly more difficult to locate these days, but I found one on ebay and guess what arrived from Canada over the weekend? I gave it the same treatment as I did for the rear axles.


Then I greased up the gears, along with a coating on everything else in there to prevent rust since it may see some light water crossings.


And so much for an assembled truck! I yanked the front axle so I could figure out how I want to attach the TLT axle.


I am now at a crossroads. I need to determine how to mount the TLT to the leafs. The stock leaf spring has no holes in it. That would mean I'd need to drill two holes in order to attach it to the axle. Not sure how well this steel will drill since I suspect it may be spring steel? I also have Hi Lift springs, which has three holes in it. I may look into installing it, but am not sure if it will be stiff enough to support the weight of this truck. If anyone has thoughts or suggestions, I'm all ears!

Lastly, I still need to determine my transfer case choice, as well as my gear reduction method. But whatever I choose, it's looking more and more like I'll need to run the TLT upside down.....or maybe run my rear axles upside down if that's easy enough to do. Haven't looked into that yet, though. Again, any input is appreciated, but I've giving strong consideration to this transmission/transfer case:
1/14 rc car truck for tamiya 2 position 2wd/4WD Metal Transmission Planetary gear box

[trucker n]

to mount front axle use the leaf springs from the hilift truck they have the holes in them

[Lil Giants]

I drilled my leaf springs, a good quality bit no problem. Did one hole at a time, bolting it in place as I proceeded, managed to keep everything straight.

Two trks this way, years later & many scale miles, everything still intact.

[Tommy R]

As luck would have it, I had purchased a set of Hi Lift springs YEARS ago for a project, but never used them! Sure enough, the outer holes of the springs line up well with two of the holes of the TLT, which is great. However, I assumed I would need to drill through the axle housing to secure the springs to the housing, but I just threaded in some screws and was surprised to feel how strong it felt!

Could it really be this easy? These are the longest screws I felt comfortable using. I think the screw was close to bottoming out in the hole.


The screws are pretty short, but the spring really feels secure in there! If this holds, I would just need to slightly space out the leaf spring hangers and shackles from the chassis since the TLT's spring mounts are a little wider tha than the stock axle.

[Tommy R]

Originally Posted by trucker n

to mount front axle use the leaf springs from the hilift truck they have the holes in them

Originally Posted by Lil Giants

I drilled my leaf springs, a good quality bit no problem. Did one hole at a time, bolting it in place as I proceeded, managed to keep everything straight.

Two trks this way, years later & many scale miles, everything still intact.

Thanks, fellas! Good to know I can drill out the leafs if I need to. Last time I tried that, I was drilling through a lawn mower recoil spring and maybe my bits were old, but it didn't drill worth a darn.

Now I just need to determine what kind of transfer case I want to use to determine the orientation of the front axle.

[Tommy R]

Before mounting it up, I measured the side-to-side spacing of the stock leaf springs is 74mm. The TLT's spacing is 79mm. So I'd need to space the leaf spring hangers and shackles out 2.5mm per side. I just used some 2mm spacers because that's what I had.

Front (hanger): I'd like some longer screws here. Not too confident in the lack of thread engagement, but I lack the proper screws at the moment.


Rear (shackle):


And installed! I'm just using 6mm long screws (4 total), but the axle really feels secure. That could be sufficient, but I will likely drill all the way through it for a little more peace of mind.

[Stuff]

Looking good!

[roadranger]

I'm also building up an off road construction semi and found the following Utubes useful;

For spacing out the springs on TLT or F350 front axle;all the parts come from an included kit parts sprue.

https://www.youtube.com/watch?v=XW_b...QteXToZiELTMwW

This one shows road speed with the transmission/transfer box before and after using a gear reducer between the 55T motor and the transmission to slow down the truck more;
You'll need to mount your trans. far enough to the rear to fit the gear reduction in position. You WILL need this GRU if you want to run with your crawler buddies…

https://www.youtube.com/watch?v=osZC...ELTMwW&index=9


For even MORE tandem axle articulation, remove the shocks. But then there might be too much articulation that will let the stock inter-axle dog bone fall out,
and the dog bone will need to be replaced with an aftermarket driveshaft.

You could also go with aftermarket $$$ servo controlled locking axles if that super grease doesn't work out...

[Tommy R]

Hey, I know that guy! LOL Yes, Dean's videos have been very helpful, but I hadn't seen the one with the gear reduction installed. Thanks!!

[Tommy R]

Well. That escalated quickly. Sold the stock wheels/tires and removed the body to do some work to it while I wait on the new wheel/tires to arrive.

[ScottLay]

looks good Tommy.

[Tommy R]

I was asked on another forum what my plan is for wheels/tires. Here was my reply....

Here's what I'm getting. These are the rear Lesu tires:


Here's the wide fronts:


Rear wheels:




Front wheels: Gotta make sure to order the correct ones because standard fronts use bearings/bushings, not a 12mm hex drive like I'm used to!


What it looks like installed. It's the closest I could get to the look I was after without spending an absolute fortune!

[Tommy R]

Originally Posted by ScottLay

looks good Tommy.

Thanks, Scott!

[Tommy R]

Trying to visualize the final product. I plan to keep it with a 5th wheel. I'll eventually pick up a flatbed trailer for it and I plan to challenge it with hauling heavy loads of bricks and such across various terrain. I can also put drifters on it when we're have a drift event. I'm going to make it like a nice looking, well cared for truck that isn't quite a "heavy hauler", but is designed to haul just about anything.....anywhere. Hence the driven front axle. I may also consider building a removable flatbed for it.

For the final product, imagine a mix/match of these trucks:

[Lil Giants]

Your tie rod should be behind the axle or it's not going to steer very well, nor very sharp.

[Tommy R]

Thanks for the heads up. I haven't started working on the steering yet, but I appreciate the input!

[Tommy R]

I was trying to decide how far I wanted to go to make this look like a Peterbilt. Well, I guess I decided.


My string method for cutting styrene needs a little help, but whatever. At a minimum, I plan to fill in the front fenders to make them smooth and maybe go with this grill/light assembly. It's a bit pricey, but I like the look. Hmm.....I wonder how LEDs/wires would look with this setup?




What I now need to decide is if I want to just stop there or if I want to just replace the fenders altogether. I've never bought anything from Shapeways, but these look rather promising. Curious if this may be easier than filling in the headlights and marker light openings on top of the fenders. Does anyone have experience with these or other fenders from Shapeways??

[TRUCKMAKER]

If you haven't decided on a transfer case, take a look at an Axial transmission. Remove the motor plate and do a little modification to the input shaft and it gives about a 3:1 reduction, its also less expensive than most t-cases available.

[Tommy R]

Thanks! I believe I have an Axial trans that I could use. My concern is that the front driveshaft will be all into the transmission and that I would need to raise the transmission to clear it. I'm hoping to keep my interior intact with minimal hacking. I suppose I could raise it while not having to cut into the dash area, but not sure if that would be enough. If so, I'd consider it! It would definitely be cheaper! Pretty sure the Axial trans is 2.6:1 so I'd likely still get a 2:1 bolt-on reducer up front, as well. But still, that's way cheaper than the other options!

I definitely want to keep a multi-speed trans, though. And I like the idea of having a 3 speed where first gear will be for suuuuuper slow speed crawling. Most normal putting around would be in 2nd gear. 3rd gear would be used for those rare occasions where a walking pace would be required. I don't have a need or desire to go any faster than that!