Peterbilt 6x6 Medium Hauler

[Tommy R]

Originally Posted by Trucker47

Awesome thread! You've shown me all the steps I need to take to build my project haha.

I've picked up a grandhauler and want to build in into an tridrive 8x8. Based on the oil field trucks I've seen up here in Canada.

Happy to help! Hope to have an update to share soon. Just been waiting on parts to arrive and also been doing some drilling and tapping....

[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.

[egronvold]

Some smart tips for others to use

[Tommy R]

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.

[NRS91]

Looks good, perhaps if you have someone local with a 3D printer they can make you some wheel spacers/shims? I know you can barely see the nuts but a spacer would look better and hopefully make it easier to keep all your nuts tight!
Im based in the UK but can help if youre interested, keep up the good work!

[Lil Giants]

I see your tie rod in front of the drive axle, it should be behind the axle, it will steer far better behind.

[Tommy R]

Sorry if this is a double post. I swear I replied yesterday, but didn't see it.
Anyhoo...

Originally Posted by NRS91

Looks good, perhaps if you have someone local with a 3D printer they can make you some wheel spacers/shims? I know you can barely see the nuts but a spacer would look better and hopefully make it easier to keep all your nuts tight!
Im based in the UK but can help if youre interested, keep up the good work!

Thank you so much for the offer! I do have a local friend who offered, but felt the nuts were a simpler solution. However, I would prefer a slip-on spacer that's printed provided the thickness can be held consistent.

Originally Posted by Lil Giants

I see your tie rod in front of the drive axle, it should be behind the axle, it will steer far better behind.

Thanks for the input. I considered that, but my current knuckles don't provide for that. I would need to also move my drag link behind the axle, which would complicate things. So I'd either need to get a side mounted steering bell crank or fab up a bracket to keep the drag link up front and the tie rod in the rear. Not saying it won't happen, but it would take a bit of work.

Currently, my limiting factor on steering throw is the outside wheel. The knuckle kits the axle at full lock. However, if moving the tie rod behind the axle increases the Ackerman significantly, I could certainly see if providing a nice benefit!

[NRS91]

Originally Posted by Tommy R

Currently, my limiting factor on steering throw is the outside wheel. The knuckle kits the axle at full lock. However, if moving the tie rod behind the axle increases the Ackerman significantly, I could certainly see if providing a nice benefit!

You did reply, not sure where its gone though!

Some off road racers use reverse ackermann to help pull the front end around so for an RC it would be nice to have correct geometry but not critical, it may even help stop the double drive rear end pushing straight offroad?

[Tommy R]

Originally Posted by NRS91

You did reply, not sure where its gone though!

Some off road racers use reverse ackermann to help pull the front end around so for an RC it would be nice to have correct geometry but not critical, it may even help stop the double drive rear end pushing straight offroad?

LOL, after I posted the new message the old one appeared! So I deleted it.

I just did a little test and it does appear putting the tie rod behind the axle results in more Ackerman which would turn my inner tire more than the current setup. I think my limiting factor would be the dog bones in the front axle shafts. I wish CVDs were still available for TLTs. I think I found some in Germany, but they were too pricey and I couldn't justify the cost.

[NRS91]

Originally Posted by Tommy R

LOL, after I posted the new message the old one appeared! So I deleted it.

I just did a little test and it does appear putting the tie rod behind the axle results in more Ackerman which would turn my inner tire more than the current setup. I think my limiting factor would be the dog bones in the front axle shafts. I wish CVDs were still available for TLTs. I think I found some in Germany, but they were too pricey and I couldn't justify the cost.

Yea ive been looking for CVDs too but no joy!

[Lil Giants]

Originally Posted by Tommy R

LOL, after I posted the new message the old one appeared! So I deleted it.

Sometimes you need to refresh the page to see recently made posts.

[kaptain Jack]

Are you kidding me? That's amazing !!!!

[Tommy R]

Originally Posted by kaptain Jack

Are you kidding me? That's amazing !!!!

Thank you!

[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!

[Bo Wallen]

That's good looking. I see you have lots of patience You're hired

[Tommy R]

Originally Posted by Bo Wallen

That's good looking. I see you have lots of patience You're hired

LOL, thanks!!

[frizzen]

Very sharp looking truck!

[jerry56]

Are the leaf springs you used tempered..?? I saw you drilled new holes, did you have to anneal the spring or something... I haven't had any luck drilling leaf springs, any tips would be great.

[Tommy R]

Originally Posted by frizzen

Very sharp looking truck!

Thanks!!

Originally Posted by jerry56

Are the leaf springs you used tempered..?? I saw you drilled new holes, did you have to anneal the spring or something... I haven't had any luck drilling leaf springs, any tips would be great.

I doubt they're tempered and I didn't temper them myself. They're just stock F350 springs and yeah, it was a pain to drill through them.

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.

[NRS91]

Tamiya 9805522 is the part# for the rear leaf spring of Tamiya 4x2 trucks which are pre-drilled with the 12mm spaced holes, it may be an easier option?