HumboldtEF's GCM Racing CMAX FJ40 build

[HumboldtEF]

So the first rig to get me into crawlers was a Tamiya CC01 with the FJ40 body. It was cool but not stout at all and recently I tried to beef it up a bit but decided I'd rather just build another rig as a sort of tribute to it.


Enter the GCM Racing CMAX chassis. Ever since I've seen this scale transmission I've been drawn to their kit. I really liked the idea of having it fully leaf sprung unlike the RC4WD offerings (plus I've seen their products and folks struggling with them)

I used the CMAX basic started kit since I was also using TMX front axle which has the narrow leaf mounting points (the leafs sit under the frame rails instead of outside of them) this gives the tires more room for more angle which is a bit more important when using bigger tires.


The other items from GCM Racing included their TMX axles and TMX axle hardware kit, NC Yota 152 Front Leaf Spring Mounts, CMAX Rear Leaf Spring Mounts, CMAX Tiny Shock Mounts, TMX Steering links.


For the Leaf springs I went with the Tamiya leafs springs #9808091 from their High Lift I believe (recommended by GCM).
Shocks are the EXC 213000 (also recommended by GCM)



After feeling how heavy the body was I ordered up some SSD front Weighted knuckles for the Ascender (they fit the TMX axle since its loosely based off the Ascender axle) and the SSD rear axle weights which luckily fit with 1.5 wheels (SSD D holes) using PitBull Rock Beast 1.5's (3.85" tall)

You can see above that the leafs have the RC4WD pinion angle shims, but after use the Leafs have turned into an S shape so I need to remedy that. I'm thinking that adding a leaf above and below it might help it to hold its shape, and the other option would be to link the axle to keep it located properly but I'd like to avoid that if I can.


I made some brackets so I could use the extra chassis that I cut off the rear as a body mount.

Rare earth ring magnets were used to attach the body along with the tips of some left over body posts to help keep them centered, I drilled a hole through the center of the body posts so I could fasten them to the brackets. I used E6000 to glue the magnets down and packing tape (with and x cut in the middle to allow the post to pop through) to prevent the glue from transferring to the other end. Those were all tips from the guys at GCM Racing and they worked out great. Also they said to leave the packing tape even after its dry as the E6000 tends to stick back to itself if its allow to rub against itself.

the rear body mount was just a small piece of angle aluminum (to the left of what I'm holding)

Above you can see the wiring, it was a challenge to fit under the interior, it had too be spread out to work.


My first experience with styrene was a good one, I liked working with it. I made the battery tray and electronics trays.

and the rear most tray

instead of using the rear chassis brace as a upper shock mount I made a bracket to raise the shocks a bit.

Using the SSD knuckles meant putting the steering links below the mount on it and on the other side using a 7mm spacer to get the other side inline. this actually worked better than with the GCM knuckle which hit the frame rail under compression, now it clears even better.
You can see I've bent the upper steering link for clearance

The electronics I went with are Holmes Hobbies Crawlmaster 13t (reused from another rig) a Holmes Torquemaster ESC, Castle 2.0 BEC, Spektrum reciever, HiTec 7950 Servo, and RC4WD cruiser light kit.


More to come later

 

[svt923]

Cmax FJ40?

I have one of those on the workbench waiting to be finished, look forward to some inspiration to get that done. "thumbsup"

One thing I have found is the Bowhouse knuckles have much better geometry with the leaf springs than the Vaterra knuckles. You can have the steering tierod over the springs and still clear the chassis on compression but they don't have the extra weight.

 

[HumboldtEF]

Cmax FJ40?

I have one of those on the workbench waiting to be finished, look forward to some inspiration to get that done. "thumbsup"

Yep I thought about making it a BJ40 (Diesel) but I knew I would always mix that up and call it a FJ. I hope I can give you some needed inspiration, you always give me a good chuckle with your threads "thumbsup"

One thing I have found is the Bowhouse knuckles have much better geometry with the leaf springs than the Vaterra knuckles. You can have the steering tierod over the springs and still clear the chassis on compression but they don't have the extra weight.

The clearance I got with the SSD knuckles seemed better than the GCM knuckles, but they're different than the Bowhouse ones, I'll check those out just to see where it puts the linkage.

 

[svt923]

The clearance I got with the SSD knuckles seemed better than the GCM knuckles, but they're different than the Bowhouse ones, I'll check those out just to see where it puts the linkage.

Yeah, the knuckles GCM puts in their hardware kit are just plain, old Ascender knuckles and the Bowhouse are a little different design.

With the tierod mounted on top of the Bowhouse knuckles, it puts the steering rod a little higher than the bottom of the Vaterra knuckle arms but not as high as on the top. I'll snap a pic of my truck (chassis really) when I get home.

Edit: Kunckle pic

Slight touch at full compression

 

[HumboldtEF]

I tested a friends set of super soft RC4WD leafs and they just ended up flat with the weight of just the chassis, no good but I was mostly just a test to see how they would work.

I played around with a few different locations to mount the leaf hangers to get the correct front axle forward look. I even tried out using the front shackle in the rear to drop the ride height, but with the body and interior on it sat way too low so I went back to the longer rear shackles. You definitely need to have all of the weight you plan on putting in it while setting the wheelbase due to the way leafs work, while they compress they swing backwards (or forward depending on which end the shackle is on) on the shackle altering the axle location.

To locate the front of the body I did the same as the guys at GCM racing did and notched the body so it was located by the frame rails. That was super helpful along the way as I just had to plop it down and it was centered.

I used RC4WD's rear bumper for the cruiser, this was the only bumper sold separately (comes with a rear hitch mount but no hitch). I originally mounted the bumper directly to the rear crossmember after carefully marking drilling and countersinking the holes. But as I added weight the leafs sagged and swung the axle back a bit. So I ended up spacing the rear bumper back 1/4" with 2 flat pieces of 1/8" x 1/2" flat stock aluminum and longer screws.

this rear bumper also was super helpful in locating the body as they share the same curved ends and help keep it pretty centered

I did an nice pristine paint job using Tamiya's British Navy Grey (TS-81) for the main body and matte white (TS-27) for the roof

Then I started sanding and scuffing and scratching the body to weather it. I tried my best to make it look like its gotten scratches from bushes and branches, rock chips up front, scratches in the door handle area and random scuffs scratches and chips all over.

Instead of ordering washes to weather the body I thinned out some Tamiya paints with lacquer thinner and dabbed it on with a tiny brush in the crevices and panel gaps. It works well but you simply cannot work it much as the lacquer thinner will take off the paint if you overwork the surface

I did the weathering on the grill with a scrap of foam, but the brush is much better for this kind of application. Though the foam worked well for the mesh behind the grill, I tried to give it a bit of a rusty finish.

I decided against going Diesel BTW

Here's a shot of more of the weathering done, notice the missing mirror which I broke off just handling it (I'm thinking it needs a folding mirror to prevent breakages). The tape on the rear wheel well was to help me get the rear axle centered.

I was surprised by the amount of articulation it had (trying not to say the F word)

I fabbed up a front bumper out of some 1/2" square tubing, cutting it at an angle at the ends and cutting the bottom and back off so it was angle iron/L shaped. for how simple it was I actually put a lot of time into it, there was a good deal of filing I had to do but I could only push the file a 1/2" at a time.
I used Yeah Racing's off center hooks (not my favorite brand but should do the job). I tried at first to tap the M2 holes for the hooks as theres not much room for nuts on the front most holes but my tap snapped in the hole, which made it kind of a bitch to get out, drilling wasn't happening but I was able to hammer it out with a punch. So I had to resort to grinding a flat spot in the little M2 nuts so I could use them in front where it was tight.

I then painted it with a pristine coat of black and scuffed it up a bit and weathered it with the brush technique I mentioned above but the brush strokes were too noticeable,

so I took a rag with lacquer thinner and dabbed at it a tiny bit to blend everything and that worked quite well.

 

[Natedog]

Nice thread, I saw this FJ in action at Pro-Line By The Fire and gotta say it looks great in person, scale details and all! Crawls nicely too, makes me want to build a hardbody leaf sprung truck even more. Have you played with the Tamiya middle and lower (shortest) leaves from those springs? Seems like most people using them in builds use at least two of them and sometimes the middle leaf on top (anti-wrap) and shortest leaf under the longest leaft.

 

[Shinchu]

I agree. Seeing this in person doing work was quite the sight! I have wanted to build a cmax for quite a while and started to fanboy a bit when Casey showed me that's what is under this fantastically weathered and detailed fj40. The top and rear heavy rig wallowed percarioisly on some obstacles and even did some nice teetering, as terrifying as I'm sure it was for the driver, it was one he'll of a show! And my little 1.55 Ford paired nicely so we had a great crawl at the back of the pack, slowly and scary lol

This fj40 truly is a rolling work of art and sounds like it's still going to get better! And now I REALLY want to build a cmax of my own!

Nice work brother!

 

[HumboldtEF]

Thanks for the kind words guys!

SVT923 thanks for taking those pics of the Bowhouse knuckle and linkage!
I see we've used different steering link sets and that you've mounted your front leafs further back than I have. Now that I've looked my front end over again I think I may need to raise the upper shock mount to get its full travel back. I think if I had more travel (in the shocks) that my linkage might be hitting the frame rails again.


Back to getting rid of the axle wrap, I tried out the longest leafs on top and the next shortest below the main leaf and that does the trick, but its way too stiff and raised the rear up the car up a bit too high for my liking. I also zip tied the leafs together just for looks, maybe thats not necessary though.

leafs separated

Tonight I plan on trying some shorter leafs to soften and lower it a bit

like this

or this

Due to the stiffer spring raising the rear I went back to using the front shackle which is 7mm shorter

I also took out my raised rear shock mount since the truck got lifted a bit and the shocks dont have that much travel to span any farther, so they're now mounted on the rear chassis brace.

 

[soze]

This thing is looking sweet!

 

[HumboldtEF]

Thanks Soze!
It is mostly done except I need to fab up the sliders. I just didn't have the time or patience to do the build thread as I was building since I was in a rush to get it ready for the Pro-Line By The Fire last week. I did get it running just in time for that which was awesome. But now that I have the time I'm putting up the pics I took along the way, and as someone said last weekend "is it ever finished".

 

[HumboldtEF]

On to the interior, It need to be notched just a bit to clear the frame rails

I cut some floor mats out of a shoe insole that was never used to cover the holes I had cut, its nice and light foam with a fabric top

I picked up some testors paint markers to do some of the detail work on the switches, steering wheel, shifters and glove box, I also used it for the exterior window molding, mirrors, hood latches, door panels, wipers and windshield rests. the matte black worked really well at making things look like rubber.

I took a scotch brite pad to all of the black interior parts like the seats and cage just so they weren't shiny. I also scratched up the interior a bit to make it look well used.
The floor and underside was painted with Tamiya Nato Black (TS-63) I also used it on the bottom of the electronics trays and battery tray.

I cut the gauge cluster sticker into individual pieces to make putting it on easier, I also cut the radio dial sticker down so it would go on easier

I added in some scale stuff, a cooler, toolbox, rope, and an old fuel can

 

[Shinchu]

Isnt it great having a hardbody so you unlock your full scaler potential? And you totally have! Very nice work!
Andrew really likes tour scale rope and wants some for his new rig. We have plans for that...

And no, they really arent ever done!

*that said, any plans for a driver?

 

[HumboldtEF]

Isnt it great having a hardbody so you unlock your full scaler potential? And you totally have! Very nice work!
Andrew really likes tour scale rope and wants some for his new rig. We have plans for that...

And no, they really arent ever done!

*that said, any plans for a driver?

Thanks, I'm also quite pleased to have done a weathered and beat up paint job which has allowed me to get right to driving it, the first scratches and roll overs are always painful with a nice shiny rig but not with this one, scratches are welcomed "thumbsup"


And late Friday night I actually ordered up 2 drivers, a Duke Nukem and Ash (with chainsaw and boomstick) from the Evil Dead. I'm thinking Ash will go in the FJ40 and Duke will go in the Gom.



Yesterday I tried out the shortest leaf stack for the rear and I think I'm happy with it, the rear sits a bit lower and feels soft enough. I may end up going back to the raised upper shock mounts again to get the full shock travel back.

 

[Shinchu]

Ash! lol would be so fun to build a scale, lifted version of his delta 88 or whatever that boat was lol
Those movies are AWESOME. Dont forget the necronomicon in the back seat!
* ha I was right it was a 73 delta 88!
I would need a Schwarzenegger Conan for a gom, because it sounds like CROM.

Jeez I need something hardbody!!!

 

[HumboldtEF]

So I got my Driver yesterday, Ash from the Evil Dead I guess its really older Ash from Ash vs Evil Dead

Holding onto the huge steering wheel, maybe I'll swap in a smaller one

I stuck a poloroid of the Delta 88 on the dash

and some important tools were thrown in the back (milk crate is from GearHead RC)

I used E6000 to glue him in place, on my last driver I used hot glue for its easy cleanup, but that popped loose pretty quick so I want something a bit more permanent.

I was going to try to shave some weight off of Ash but decided not to worry about it as the FJ40 body is already pretty heavy.

 

[Shinchu]

he's got the "GROOVY" hand! nice nod to the delta
looks great! would one of the axial steering wheels work?

 

[HumboldtEF]

he's got the "GROOVY" hand! nice nod to the delta
looks great! would one of the axial steering wheels work?

Thanks!

Yeah I had to get a picture of the Polaroid now because when its assembled I doubt it will be visible.

I do have another Axial wheel I was thinking of using, Its the same size but just looks a bit smaller with its design.

I did just have a look at some 1:1 pictures of the FJ and the stock steering wheel is pretty big so maybe its not far off.

 

[Natedog]

I did just have a look at some 1:1 pictures of the FJ and the stock steering wheel is pretty big so maybe its not far off.

Yep.

How about the 3d printed steering wheel that we got at ProLine by the Fire? "thumbsup"

 

[HumboldtEF]

Yep.

How about the 3d printed steering wheel that we got at ProLine by the Fire? "thumbsup"

I guess I missed out on that one. I do have another small steering wheel from the Gmade Gom but its sort of a modern sports car type wheel.

I think I'll make a judgment once I put the interior back in the truck, If I dont notice it then it should be fine.

 

[HumboldtEF]

So I yanked Ash out, I thought cleaning up the E6000 would be harder but it was easy.

I made up a booster seat for old senile Ash that way he can see over the steering wheel.

I made the booster seat out of some .060 Styrene, 1/2" tall

It doesn't look to be too noticeable from the side and it should be even harder to notice when the body is put back on top.

I also swapped out the steering wheel, even with it being very close to the same size as the other this one just looks like a much better fit.

Ah and I keep forgetting to put up pictures of the finished truck (or as it sat at Pro-Line by the fire) with Shichu's 79 F100 behind me. I really should have got more shots of this truck while I was there but Chris and I had a great run on Sunday. It was really nice to have somebody else to run at the same pace with, we both have small tires but his are way more of a challenge.