SCAX-MT Grave Digger Monster Truck Build

[johnfm3]

Spent last night working on the Montster Truck build. Here are the parts I have purchased.
Axial 27T motor
Axial 87 Tooth Spur
Robinson Racing 13 tooth pinion
ScrewzRC SCX screw set

Since most people have installed motors an gears, I am not showing any progressive pictures of that. But I am excited to show the tranny mocked up an in the chassis. I gota say I am very pleased with how it turned out.

In a prior post, I had pictures of where i was planning on mounting my suspension links. You will probably quickly notice that is not where they ended up. My planned upper link location was going to interfere with the tranny an motor. Ended up relocating the upper links higher an moving the lower links on the outside of the chassis rails an in-words so that the axle pinion angle was decent. I def need to work with the links. I suspect that the suspension is set too low for starters. C-Hub clocking will be in my future. More details on that in future posts.

So at this point, I am now fully setup with a rolling chassis an more or less happy with the results. At least so I thought.

What I didnt notice till this morning was that as much as I liked how the link setup worked around the drive shaft, the uppers impact the steering servo. I will get pictures of that this evening as I sit an thing about how to deal with it.

I am having a bit of trouble locating a shop who will help me with the paint on a Grave Digger body. I am really trying to avoid stickers. One shop just didnt respond (their loss) an another hyrdro dip shop said it was too much of a project for them an passed on it. So I am thinking of throwing on the body which came from the AX-10 I bough. (These pictures are not that good, really need to redo this with new pictures)

Thoughts?

More to come later tonight. "thumbsup"

 

[johnfm3]

So I will have more pictures to show tomorrow, but I wanted to report a successful test run.

The main major issue I ran into was the rear links being too short an causing the drive shafts to bind an restrict the movement of the RC. I was trying to mod modify the chassis an continue to use non modified links. I ended up having to pull the wraith upper links off an using SCX Rubicon links for the uppers. An pushed the rear axle back further. This was caused by using the Wraith tranny which required the rear axle be pushed back further to compensate. I would an still may consider using the SCX tranny, except there is no 1 piece Robinson Racing output gear, which I have installed in my Wraith tranny.

Another issue I ran into, the transmitter had to have the throttle reversed for the RC to drive forward. This bugged me as when I went from Rev to Forward, I had to pause for 3 seconds. This also meant I had no usable brake for when driving forward. So what I ended up doing was flipping the diff gear around so that the the RC would drive forward with the transmitter set up correctly. I am not sure if I will continue to use the Venom 320 ESC.

A more minor problem/issue I am running into is the steering. The servo's are not as strong as I would like, so when driving on dry pavement, when moving forward the front tires wont turn much at all but the rears will steer all the way. The moment you get into the dirt, all 4 wheels are turning nicely. This could also be partially caused by the locked axles which causes the left an right tire to rotate at the same speed, creating too much resistance for the servo to over come with the larger tires. But again, a larger servo should solve that.

All in all, I am very happy with it. Its an absolute blast to drive. An the Axial 27T motor with a 13/87 pinion/spur combination is working great.

Like I said, more pictures to come tomorrow. I want to take it out an get some good shots of it running, then clean it up an take some poser shots.
John

 

[johnfm3]

So I got some running shots of this thing. It pretty sweet. The 27T motor is not getting overly hot. The Venom 320 ESC is a bit glitchy. Will need to replace that in the not so distant future. Maybe a possible Tekin FX-R with brushed 35T motor. The speed out of this thing is fun. Its not as fast as a TMaxx, but has a decent speed to bounce over things an be controllable. The other cool thing I have come to notice is its ability to crawl over items. An it climbs hills much better than my wraith. Probably has something to do with the the 6.5 inch Clod Buster tires.... lol

So I will let the pictures do the talking....

Poser shot.

Some crawling over things

 

[johnfm3]

So now for me to work with it a tad an see about a grave digger body.
If anyone knows a good paint artist, I would be interested in seeing images of their work.

 

[HDMM]

Looks good! I'm also a big MT fan. Hey check out this site; Radio Control Monster Truck Network

I am also a member there, lots of MT info. They have a section just for Axial based MT builds also. "thumbsup"

 

[johnfm3]

Looks good! I'm also a big MT fan. Hey check out this site; Radio Control Monster Truck Network

I am also a member there, lots of MT info. They have a section just for Axial based MT builds also. "thumbsup"

Thanks for that piece of info. I did a quick browse an like what I see. Would def consider that another good source for info.

 

[johnfm3]

Ok, so I needed to do some gear ratio comparison an thought I would share what I have.

So my stock wraith tranny is running a 3:1 gear ratio.
My Spur/Pinion ratio is 87/13 resulting in a 6.7:1 gear ratio.
This combination is giving me a total gearing ratio of 20.1:1 (6.7*3).

What brought this to light was my buddy who wanted to try the clod buster wheels/tires on his wraith has a 2 sp tranny with a 1st gear of 5.05:1 an 2nd gear ratio of 1.78:1. An we were trying to see if we needed to change his spur/pinion combination to get it close to my setup. Come to find out that 1st gear with his current 4:1 spur/pinion gives a 20.2:1 final which is close enough to my setup for testing.

I will say that currently with a stock axial 27 turn motor, this thing is running strong an not getting hot enough to worry about. The motor does get warm, but nothing like a 20 turn motor running in a stock wraith. Running time with a 5000mah 2S lipo (ran with a 25C an a 35C) shows to give me a good 20 to 25 min of run time. All in all I am very happy with it as it is. A upgrade is in its future, but still recouping from the build so far so I can invest large funds in the body an paint.

John

 

[johnfm3]

Ok, so I stumbled across a body which I would be happy with at RC-Recycler.

I am hoping its still available after I get paid this fri.

It does not have a few things that I wanted. Including the grave digger logo. An the skull in the moon.

Whats everybody thoughts?
John

 

[T I N Y]

To me....If it doesn't have the skull and moon the big red letters saying grave digger. It's not grave digger.. BUT thats just my opinion...."thumbsup"
It's still a cool looking body....But it's not the digger.

 

[johnfm3]

To me....If it doesn't have the skull and moon the big red letters saying grave digger. It's not grave digger.. BUT thats just my opinion...."thumbsup"
It's still a cool looking body....But it's not the digger.

Zielke Racing did the air brush painting. I am curious as to what it would take to add the bold lettering Grave Digger an the skull in the moon. The other thing is there may be copy right reasons why it couldn't be done. I am with you on your opinion, which means if I do end up buying this body, it will only remain till I can get a better one done.

Thanks for your comment.

 

[johnfm3]

For the most part, I have been very happy with how the monster truck has been running with the drive train I have. An since nothing has broke yet, I have to up change it. When I planned this build, I knew I wanted beadlocks from rc4wd. Currently I am running stock clod buster wheels.

As stated much earlier in my thread, I am running a axial 27T motor, Venom 320 esc (don't know much about it), with a 87/13 spur pinion gearing combination. All powered by a 5000mah 35c 2S lipo.

Here are my options...
Delrin wheels @ 11.9oz / 340g
Aluminum wheels @ 18.9oz/537g

I really like the idea of running beadlocks an no foam. Currently I have no foam, but my wheels have holes to all the tires to vent. It seems to hold the rig up ok. But I am hoping for a better response with sealed rims. I also like the look of the beadlocks from RC4WD.

So what are others thoughts on the heavier wheels? Am I concerned over nothing? In the crawler world people weight down the wheels. But by how much, I am not sure.

John

 

[johnfm3]

Well a update. I have officially bought the un badged grave digger body from RC Recycler. The body has been drilled for side body post. An I am looking into how to make use of those an not drill in the body again. Also I want the body up high enough that you can see the chassis.

Still looking for feed back on the wheels an whether I am paranoid over the weight issue.

John

 

[johnfm3]

OMG.... I dont care if its not badged as Grave Digger, this thing looks freaking bad.

Most importantly, I want to send another thanks to Rob at RC-Recycler for going above the call of duty on this one.

Keep in mind, the body is not mounted yet. Just resting on the rig.

Rob, if your reading this, you will be happy to know that I have a solution to allow me the ability to make use of the existing side holes an not force me to drill the top of the body.

I am totally stoked on how this is turning out. "thumbsup"

 

[johnfm3]

Not much has happened to this rig since building it. The servo's have failed as I really didn't spend the money needed to get good ones. That's being changed now. Also I pulled the Axial 27T motor out for my sons SCX-10 leaving this rig heartless. Looking into updating the electronics and such this summer. Right now its a shelf queen and drawing a lot of attention at work. Contastntly getting compliments about it. And I still love this thing. It was so worth building.

 

[Natedog]

Pretty cool rig, I would do some link length calculations and buy an assortment of VP titanium links and Revo rod ends to play with, that way you can get the suspension setup you want. Also would run both diffs open using some spider gears with good grease in the diff cups, maybe use HR aluminum diff cups while you're at it.

EDIT: What wheels did you go with? They look great!

 

[johnfm3]

Pretty cool rig, I would do some link length calculations and buy an assortment of VP titanium links and Revo rod ends to play with, that way you can get the suspension setup you want. Also would run both diffs open using some spider gears with good grease in the diff cups, maybe use HR aluminum diff cups while you're at it.

EDIT: What wheels did you go with? They look great!

Yeah, I need to work on the links. But mainly for cosmetic reasons. Functionally this things articulates great. Amazingly well. And I have to agree with the recommendation of VP titanium links.

Opening up the diffs would probably help my Steering issue I am having. Do they sell open diff components for Wraith axles?

The wheels are the stock Clodbuster wheels. Sadly, they have been drilled thru so 5 bolts and locking nuts could hold them to a adapter of some sort. I have these on the radar for my wheels. Need to buy them soon before they are gone.

Universal Monster Truck Beadlock Wheels V2 For Clod Buster (Aluminum)

Thanks,
John

 

[Natedog]

Yeah, I need to work on the links. But mainly for cosmetic reasons. Functionally this things articulates great. Amazingly well. And I have to agree with the recommendation of VP titanium links.

Opening up the diffs would probably help my Steering issue I am having. Do they sell open diff components for Wraith axles?

The wheels are the stock Clodbuster wheels. Sadly, they have been drilled thru so 5 bolts and locking nuts could hold them to a adapter of some sort. I have these on the radar for my wheels. Need to buy them soon before they are gone.

Universal Monster Truck Beadlock Wheels V2 For Clod Buster (Aluminum)

Thanks,
John

Traxxas Revo links work well and are cheaper and steel is strong.

Yes would help steering and high speed handling. Yes, just look for gears for HPI Wheely King, there are some others that are the same and will work too, don't remember what at the moment.

Oh, OK sometimes you gotta do it. Those look like nice wheels.

 

[johnfm3]

Traxxas Revo links work well and are cheaper and steel is strong.

Yes would help steering and high speed handling. Yes, just look for gears for HPI Wheely King, there are some others that are the same and will work too, don't remember what at the moment.

Oh, OK sometimes you gotta do it. Those look like nice wheels.

Its looks as if I had not updated the most recent pictures. Since my Sept 2014 post, I have taken my RC body to Monster Jam and got some of the driver signatures on it including a drive of the Grave Digger which was there. I will see if I can get a picture of that added soon.

 

[Stricklinator]

Very nice truck you have built! It looks great. I agree that you should switch to open gears in the axles for this application. What servos are you upgrading to?


Sent from my iPad using Tapatalk

 

[TrailDawg362]

Very cool! With the original Clod wheels, what adapters did you use and were there any clearance issues with the AR60 knuckles?