6x6 Peterbilt Semi Truck

[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. :mrgreen:

My string method for cutting styrene needs a little help, but whatever. :ror: 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.

 

[STANG KILLA SS]

whats the second grill for?
my fear with 3d printing is always surface finish, but could always be sanded smooth. what does it take to buy the printed fenders? ive always thought shapeways seemed pricey for what you get.

 

[Tommy R]

whats the second grill for?
my fear with 3d printing is always surface finish, but could always be sanded smooth. what does it take to buy the printed fenders? ive always thought shapeways seemed pricey for what you get.

Not sure (yet) on the second drill. There's a wire mesh behind the stock grill so maybe it gets sandwiched between the grills?

The Shapeways fenders are like $40, if I recall. Not cheap, but it would take me a few hours to fill/sand the headlight holes and marker light holes, plus these are more accurate to what a real Peterbilt fender would look like. So it could be worthwhile, depending on how they mount.

It looks like there's a couple mounting holes on the Shapeways fenders, but what would they attach to? With the old fenders cut away, you'd have to add some styrene to the hood sides. Or at least that's my best guess? :|

 

[Tommy R]

Didn't have much time to mess with the truck until this evening and when I did I decided to focus on my gear reduction and transfer case solution. First things first I looked into how the tranny is going to interfere with a front driveshaft. Obviously, that's definitely got to be addressed! :ror:

I think I've narrowed down my drivetrain choices to these:
1. Use an Axial 2.6:1 trans as a transfer case and possibly a 2:1 planetary gear reduction in front of the Tamiya transmission.
2. Use a planetary gear reduction (probably 2:1) and add a t-case like the 2.18:1 RC4WD Disruptor or the 2:1 t-case from wtbcar.com:

In either of these solutions, the stock Tamiya tranny needs to be raised up fairly substantially....for two reasons. As mentioned, the tranny will prevent a driveshaft from reaching the front axle, but the 2:1 planetary will hit the steering/shifting servos because it'll push the motor forward. My best guess shows a height of 15-20mm is needed. Here's a rough approximation of the height required:

The floor will need to be trimmed, but I'm okay with that. I can always just build a simple cover for it so the trans is hidden from sight. My first estimation of where it'll need to be cut (everything within the white markings).

So before I order some standoffs I made some temporary 15mm spacers to see how that would work.

Driveshaft clearance should be okay with the trans raised 15mm, especially since the trans output will be fairly low.

Front view showing the height of the motor compared to the servo. It'll be reeeeally tight, but I can easily add a few more millimeters of spacers if need be.

Thinking this is what I'll need to cut away to accommodate the new trans height.

So now I need to decide what to do about the transfer case. I have an Axial trans so that's the cheapest solution. I'll just have to fab up a bracket for it. And it'll definitely get the outputs low enough to clear the stock trans. The wtbcar.com t-case looks like it would bolt in after drilling a couple holes so that'd be super easy, but it would cost me ~$50 and time to wait for shipping from (presumably) China. Not sure I'm patient enough to do that. Ha!

 

[Tommy R]

Axial transmission (all metal internals, of course) ready to be used for the new t-case. I just need to trim off the excess on the input shaft.

 

[Itali83]

Use what you already have. Love it. Like this build a lot. Keep up the good work.
Ben

 

[chino63]

I did exactly that on the Mean Green 6x6, raised the transmission. I also used an Axial trans for the t-case. However, I wanted a more centered input so I cut the top of the Axial trans and flipped it so it would be centered. I used JB weld to reattach it.

If it will help you, here's the build thread: http://www.rccrawler.com/forum/1-9-scale-rigs/108770-mean-green-6x6.html


Edit: I just remembered that I flipped the transmission upside down to keep the motor weigh lower.

 

[chino63]

Thought I posted earlier but i guess i didn't. Anyhow, good to see you building again and looking forward to seeing what you come up with!"thumbsup"

 

[Tommy R]

Thanks, Ben and Dean!

Dean, I've very familiar with Mean Green. It was the inspiration for me to want to build a 6x6 or 8x8 years ago! I'm excited to be building again. The comp side of scalers is less appealing to me these days what with the extremes people are going to make "scale" looking trucks. Building something like this is a breath of fresh air for me! "thumbsup"

Got the rear wheels in the mail today! Only issue is that I don't have a hex driver small enough to fit the nuts to secure the wheels to the hub. The Tamiya multi-tool is too short to reach down in there. I'm guessing it's a 4mm or 4.5mm hex? Anyone know for sure? FYI, these are Lesu wheels.

 

[Tommy R]

So whichever transfer case I end up with, I'm pretty sure I'm going to need a gear reduction. Using an Axial trans/t-case and a 2:1 gear reduction unit (GRU) would get me to 5.2:1 reduction over a stock setup. That's pretty darn low, but not sure if it'd be TOO low. However, I can't locate any 2:1 GRUs. Closest I can find is a 3:1 unit. It's cheap so I went ahead and ordered it.

Doesn't look to add much length to the motor.

Now I'm thinking the Axial t-case may be too low so I may consider a unit with a little taller ratio like 2:1. I have several options. I'm open to suggestions from those of you who've geared down your trucks. Knowing I plan to take this thing offroad and pull reasonably heavy loads with it, what kind of overall gear reduction should I look for? 3:1? 5:1? 7:1? 8)

 

[chino63]

I think the 3:1 might be a bit much unless you run a 1:1 t-case. I ran the stock transmission and a cobalt 7t combined with the axial transmission as the transfer case, I was able to pull a trailer with an iron small block cylinder head on it. I think the motor was a Holmes Cobalt 10t on 7.2v.

 

[Tommy R]

I think the 3:1 might be a bit much unless you run a 1:1 t-case. I ran the stock transmission and a cobalt 7t combined with the axial transmission as the transfer case, I was able to pull a trailer with an iron small block cylinder head on it. I think the motor was a Holmes Cobalt 10t on 7.2v.

Thanks, man, that's good to know! I sent a request to cancel my 3:1, but if it's too late that's okay. I'm sure I'll find a use for it eventually. ;-) So I guess it's time to move forward with the Axial t-case install. Jeez, it's been so long since I've done any RC fab work, I'm not sure I'll remember how to do it! :ror:

 

[Tommy R]

Today I picked up a 4mm hex driver and it allowed me to finally put together my new rear wheels Love 'em!

 

[Tommy R]

Since the fenders are on the way, I decided that I may as well start on the one thing that I've been dreading......bodywork. I'm okay with styrene, but it's been awhile since I've done any detail work with the stuff. And in an effort to make it as easy as possible to replace the hood sides I wanted nice, square cuts and edges. Eventually, I decided to just jump on in and make it happen.

I decided to remove the fenders first to make it easier to cut by the cowl area. First I outlined the cut areas with a thin Sharpie marker. Then I used string to cut through the fenders and removed them.

Next I measured the styrene of the body to be .060" (1.5mm) thick so I used my calipers and scribed a line at the .060" mark. Applying black ink beforehand made it easier to see. Then I used the string method to cut along the line as carefully as I could. Came out rather clean! That's encouraging!

Now with the fenders removed I was able to use my razor saw to get nice, straight lines along the cowl and the horizontal line near the top of the hood. Using a combination of sawing with the saw and scoring with the Xacto blade, I was eventually able to cut the sides out. Honestly, it went quite a bit smoother than I expected.

They look nice and square to me! Mocking up an uncut piece of styrene confirmed my suspicion: nice and square. Good stuff!

An update on other components....

The front wheels and all the tires should arrive to the States any day now. The posts to raise the motor/trans will be here Saturday along with a bunch of hardware in my goal to replace as much Philips head hardware as possible! And I was able to cancel my order for the 3:1 reduction unit. Sweet!

I've got to pack for a camping/offroading trip this weekend so time is tight, but if I get some time I may try to bond the new, uncut hood sides to the KH. It still has a long way to go, but progress is progress!

 

[XSRCdesign]

Glad to see you building again. Dean's rig always had my interest and this one does too!

Interesting always cost me money...

 

[Tommy R]

Glad to see you building again. Dean's rig always had my interest and this one does too!

Interesting always cost me money...

Thanks, man, I appreciate that. I was rather disinterested for a while, but happy to say my enthusiasm for building is returning.

 

[chino63]

Looking good Tommy, very nice work with the string saw. "thumbsup"

Where are you going wheeling? Our weekend trip to Death Valley was cancelled due to mud.

 

[Tommy R]

Looking good Tommy, very nice work with the string saw. "thumbsup"

Where are you going wheeling? Our weekend trip to Death Valley was cancelled due to mud.

Thanks, Dean! I literally believe it's been since 2009 since I used string to cut styrene. LOL! It was for the stretched TJ I built many, many moons ago.

Bummer about your trip! We're going to the Llano, Texas area. It's part of the central Texas "hill country" and we're lucky to have several offroad parks out that way. It's anywhere from a 1-2 hour drive from Austin, depending on where you go. This time we're headed to a small park that isn't always open to the public called Stillwater Ranch. I'll post up a link to pics when we get back. "thumbsup"

 

[Tommy R]

Tiny update...

Wanting this styrene work to be plenty stout I decided to take a couple minutes and build some plates and bonded them to the OEM plastic. This will give me a nice, flat surface(s) to attach the new hood sides and it will provide a lot more strength. I'll wait to get the fenders in before I bond the new hood sides. The reason being I want to make one side and trim it to fit the new fenders and then will use it to make a template so both sides are as symmetric as possible.

Passenger side cut and mocked up.

 

[chino63]

Thanks, Dean! I literally believe it's been since 2009 since I used string to cut styrene. LOL! It was for the stretched TJ I built many, many moons ago.

Bummer about your trip! We're going to the Llano, Texas area. It's part of the central Texas "hill country" and we're lucky to have several offroad parks out that way. It's anywhere from a 1-2 hour drive from Austin, depending on where you go. This time we're headed to a small park that isn't always open to the public called Stillwater Ranch. I'll post up a link to pics when we get back. "thumbsup"

Cool, looking forward to pics from your trip. I've seen a few videos of wheeling in Texas. Looks pretty good to me. Some day, I'd like to take a trip with the FJ40 and check out that area.