HDMM's 6x6 Recovery Truck Build

[HDMM]

This is my first 6x6 build, it's not going to be anything to crazy, pretty standard actually and on a fairly small budget. It's going to be a military themed heavy recovery truck. I'll be using SCX axles, OD gear set will go in front axle to help with steering, SCX frame rails, SCX trans with HR steel gears, Gmade 62mm rear shocks so mounted to the frame rails so I won't have shock hoops sticking up, Maxxis Trepadors on stock black Axial wheels, Tamiya Bullhead cab and will probably scratch build some sort of utility body for the rear. This rig will have atleast one winch on it, if not two. I'm trying to decide whether to run a 35t or 55t, I'll be running it on a small 3s pack.

It's not much right now, but it should start to take shape soon.

[HDMM]

I was able to get some work done on the axles tonight. I'm using a lot of used parts and some new parts I already had.











Sent from a galaxy far far away........

[trukkracea]

oooo ill be following this, been looking at a bull head cab for mine.
cant wait to see it finished

[HDMM]

My build will be loosely based off the USMC 7 ton trucks.

[hanjin-san]

Nice project !
Can't wait to see the result with the Bullhead body

[HDMM]

Worked on my build a little more this afternoon, was able to make up some suspension links with some left over pieces n parts, these are just to locate and attach the rear axle. The upper links will attach to the frame rails.



I made a small connecting driveshaft with some Traxxas Stampede shafts and some Axial Scorpion metal joints and yokes. I won't have mad suspension travel in the rear (going with 62mm shocks) so the short shaft should work out ok, we'll see when we get to that point.








Just mocking up the wheelbase, it's going to be longer when I'm done.





Started working on the transmission, it was a RTR transmission, note the lack of grease!



Cleaned everything up, checked out all the bearings and installed a set of Hot Racing hardened steel transmission gears. Lubricated them with Lucas Red N Tacky before putting the case halves back together.

[HDMM]

I decided to make some slightly longer axle lower links today. The connecting driveshaft between the two rear axles was just a little too short without much room to move when the suspension cycles. I didn't want them to be too long though and have the rear axles to far apart because I don't think that would look right. I took some Traxxas links and shortened the threaded part a bit and then used Traxxas ends on them. I'll paint these black.



Made a new longer driveshaft, much better now.



I will be using Gmade 62mm diaphram shocks on the rear, attached directly to the frame rails. I won't have massive amounts of suspension flex, but that's OK, It's going to be 6wd after all and I think it will be a little more realistic. Plus, I'd rather not have the stock SCX shock hoops in the way of my rear body when I add it, I think it will also help me to keep the COG a little lower.



I've never used Gmade shock before, but I think I like these, they seem to be very good quality, fit and finish.

[HDMM]

I decided to make some slightly longer axle lower links today. The connecting driveshaft between the two rear axles was just a little too short without much room to move when the suspension cycles. I didn't want them to be too long though and have the rear axles to far apart because I don't think that would look right. I took some Traxxas links and shortened the threaded part a bit and then used Traxxas ends on them. I'll paint these black.





Made a new longer driveshaft, much better now.



I will be using Gmade 62mm diaphram shocks on the rear, attached directly to the frame rails. I won't have massive amounts of suspension flex, but that's OK, It's going to be 6wd after all and I think it will be a little more realistic. Plus, I'd rather not have the stock SCX shock hoops in the way of my rear body when I add it, I think it will also help me to keep the COG a little lower.



I've never used Gmade shock before, but I think I like these, they seem to be very good quality, fit and finish.

[altd896]

Minor technicality, and I may be wrong, but I think you have to roll your 2nd rear axle housing upside down to swap the ring gear to the opposite side to the 1st rear axle.
I think if you push that forward along the bench now your 1st & 2nd axle inputs will both turn the same direction but your 1st axle output will turn the opposite way to the 2nd input.

[HDMM]

Originally Posted by altd896

Minor technicality, and I may be wrong, but I think you have to roll your 2nd rear axle housing upside down to swap the ring gear to the opposite side to the 1st rear axle.
I think if you push that forward along the bench now your 1st & 2nd axle inputs will both turn the same direction but your 1st axle output will turn the opposite way to the 2nd input.

It is upside down, I drilled, used small spacers and re attached the 4 link truss to it after I flipped it.

[altd896]

Ah well there ya go, excellent

I shall continue to observe & learn.

[HDMM]

I did a lot of reading and observing before I decided to build mine. Some it is still going to be trial and error.

Sent from a galaxy far far away........

[HDMM]

I decided to change the wheels, I wanted something more military looking so I went with the Tamiya Hummer wheels. I have some new, unmounted Trepadors so it won't be a big issue. I'm also going to add some Crawler Inovations closed cell foams to the front tires, they are made for a heavier rig, so that should also help with steering and the weight of my battery, electronics and heavy Bullhead body up front.

I'll paint these Olive Drab before mounting the tires.

[HDMM]

Time to start on the chassis. Just going to use one set of stock rails and the back half of the other set (approx 4"). I'll use some aluminum pieces inside the frame rails with screws and nuts to secure the added on frame rails.

[HDMM]

Time to start on the frame rails.....

I marked and cut off the rear straight portions of the spare frame to use to extend my main chassis rails.



I cut some aluminum stock, then file fit it so that it was a nice tight fit inside the frame rails.



Then I drilled the holes out on my drill press, then bolted everything together with screws, serrated nuts and red locktight. It's a super strong joint.



Now time to start the chassis mock up.





I changed my rear link setup a little, I removed the lower links that connected the two axles, the suspension was acting weird setup llike this. Although the shocks were not on yet, I didn't like how it was rotating the rear axle when the suspension was cycled.



Working on shock mounting.





Chassis mock up is coming along good, I need some material for the front axle lower links and I need to make a panhard bar. I mocked up the front axle with Axial plastic links for now. Also waiting for my Gmade 93mm front shocks to come in.

[HDMM]

Got the roller together and drive shafts sorted out.



The CMS parts I have just aren't working out for me, so I decided to remove the CMS setup and go back to a stock 4-link front with axle mounted servo, pretty much just gonna keep things nice and simple for now.





Painted the Hummer wheels OD Green today too, plus a couple spares.

[jmz6]

Looks great... Nice job on losing the huge rear shock hoops

[old man 52]

I'm sure this is going to turn out nice , Good job so far.

[HDMM]

Thanks!

It's been a lot of trial and error, but I think I'm getting there. I want it to be functional and durable because it's not gonna be a shelf queen, I'm gonna be using it.

I had a lot of trouble getting the rear suspension to work ok and even more trouble getting the rear most driveshaft worked out. With a short driveshaft, it was pulling apart as the suspension cycled, now I have the rear axles spaced out a little more, a little longer rear shaft and the rear suspension is sorted out so it all works well together.

The rig does'nt have a lot of flex, but I think it has enough and it shouldn't need much to work well.

[HDMM]

I had a little time this afternoon so I worked on the body mounts a bit. Made up some rear mounts and modded the front mounts to get the height I was looking for.





Cab test fit....




I also installed the electronics, pretty much everything is used, as with most of the build, it all came out of one of my old SCX10's.

Savox 1256tg servo, Axial ESC, Castle BEC, Trinity Speed Gems 35t crawler motor, Turnigy 2200mah 3s Lipo, 87t spur, 14t pinion. Ran the red LED's for the tailights and the clear ones that will go in the bumper that I will be using.



Test ran it out in the yard, everything went well. It actually steers pretty good since I put a overdrive ring & pinion in the front axle. Gearing is good to, plenty of low end grunt, not too fast on the top end.