Peterbilt 6x6 Medium Hauler

[Tommy R]

Originally Posted by egronvold

Looking good! Will be interesting to hear your experience with the new setup.

Thanks! Well, the output shaft of the 3:1 GRU is too small for the press-fit pinion that the Lesu trans requires (pics coming soon) so I'll have to figure something else out there. I was thinking 3:1 may not be low enough anyway so maybe I'll just get a 4:1 now. Given the tiny pinion of the Lesu unit, though, I'm concerned how easily it'll strip.

Originally Posted by 9W Monighan

Changing the subject some, What's the yellow Wrangler?

That's my '01 TJ. This is what it looked like when it was still on the road:


However, it's currently under the knife as I do some major surgery. I'm adding 15" to the overall length (converting it to an LJ), adding one ton axles, and building all new suspension. This pic is a bit outdated. Frame is now lengthened and welded back together, but still have a long way to go!

[9W Monighan]

WOW you are really into that TJ I see lots of travel in your suspension.

Here's my sons rig. 98TJ He drives it every day in the summer. Luckily he is 2mi from his work because he put 4:88 gears in it. Dana44 air locker rear,high pinion 35 in the front. Rubicon long arm suspension. We have a beater Cherokee too
Now is see why you just had to make that PETERBILT into a 6X6

[Tommy R]

Nice rig your boy has there! That's the exact axle and locker combo I ran for years. With 35s it was great, but with the 37s I'd have preferred 5.13s. After wheeling the Jeep since '07 I decided to finally put some big axles in it so I no longer have to worry about breaking them. New combo will be Ford Dana 60 and Sterling axles with air lockers and 5.38s. Stepping up to 40" tires, too. I plan on keeping the good road manners as I drive this thing all the time and love taking it on road trips.


And if you're interested, I'm documenting the Jeep build on my YT channel:

https://www.youtube.com/channel/UCQg...uSHByWUvBjNK8w

[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.


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.

[frizzen]

Truck looks great, but i'm guessing you'll take it back apart for paint later. Very nice looking trans

Cool TJ stretch project! Are you just going up to LJ length, or going even longer?

[Tommy R]

Originally Posted by frizzen

Truck looks great, but i'm guessing you'll take it back apart for paint later. Very nice looking trans

Cool TJ stretch project! Are you just going up to LJ length, or going even longer?

Thanks! Yeah, I'll be tearing it apart again for what I hope will be its final paint job, but I'm waiting to have a better idea if I'm done with any fab work beforehand. Case in point, the front axle was sitting too far to the rear of the fender opening so I've been working on getting that aligned better. I'll get some more pics/updates posted hopefully later today.

Regarding the Jeep, the body will be LJ length so I can use an LJ top and cage. However, I backhalved the Jeep 5 years ago and got about 6" of wheelbase added to the rear, putting me at just over 99". With the extra 15" length of the LJ conversion added in, I'm hoping to have a similar wheelbase as a 4 door Jeep, which is about 116". I'll also be stretching the front a bit.

[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.

[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.

[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.

[kaptain Jack]

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