HumboldtEF's Gmade Gom Build

[HumboldtEF]

Well I've been watching the Gmade Gom from the sidelines long enough, I ended up finding a new kit on Ebay for a decent discount, The guy selling them seems to be auctioning off one at a time, if you're interested here's a link

I started off by rounding up a ton of parts mostly from RPP:

Holmes Hobbies Torquemaster BRXL
Castle Creations 10 amp BEC
Spektrum SR415 receiver and Spektrum signal voltage boosters (to make the Hitec servos play nice with the Spektrum receiver)
Gearhead BEC RX bypass adapter
Traxxas Titan 21t brushed motor (lightly used in my TRX-4)
I rounded up some Hitec servos, HS-7950TH for steering, D645MW for the shifter (chosen because its the least expensive programmable Hitec servo)
Vanquish 24t servo horn
JConcepts 2.2 Scorpios (6" tall)
I'll be reusing an old set of Incision Method wheels (MR307, black anodized)
Crawler innovations comp cut double deuce foams, medium up front firm in back.
some Gmade Gom upgrades, front upper link, rear lower links (trailing arms), Sway bar for the back, rear shock brace, Junfac driveshaft, rear secondary shocks, front CVA axles, Panhard chassis and axle mount, slipper clutch plate


I cleaned up in preparation for the incoming mess that I knew would be epic

So far I've got the Axles, tranny, transfer case, links, the electronics all soldered up, and a tiny bit of the cage put together.

I always like to see the tires mounted up so this was one of the first things I completed. I've never tried any JConcepts tires so I'm curious to see how they do, just by feel they dont jump out as being as soft as Pitbull or Proline tires, again thats just my impression from touching them.

I hooked up the electronics last night and started to setup the shift servo. I got it to match the specs in the manual but in action its pretty spotty, it tends to get stuck between high and low gear and once stuck it tends to stay stuck instead of popping in place after playing with the throttle a bit like most other setups I'm used to.
I did the washer mod on the shifter cover but that alone isn't solving the spotty shifter. I plan on replacing the servo saver with a normal servo horn and dialing in the EPA.
On my brother's Gom we had eliminated the servo saver, dialed in the EPA, used some different length springs on the shift forks and the washer mod on the shift cover. I'm going to try these things one by one in an effort to pinpoint what the solution might be.

The springs we used in my Brothers build were pen springs cut to length (stock is the black one on the right)

I'm curious to hear whether folks are using the servo saver on the shift servo or not.

Oh and watching the KOH has made me a lot more interested in a race livery as opposed to my usual plain Jane paint jobs, I'm yet to nail down a design but it will be white, silver and black

A few things I plan on doing eventually are to make a dust cover for the shift channel/slot and to come up with some sort of support structure for the rear winglets that stick up in the back, I've seen how one good roll can destroy these

 

[HumboldtEF]

I removed the servo saver on the shift servo and reset my end points, it already seems to have improved a bit. I was testing it without having the tranny mounted firmly so it was deflecting at times which cant help so I'm gonna move on from testing the shifter for now and continue with the rest of the build.

I used a Protec 25t servo horn using the outer hole which is a slightly farther out, 20mm vs the 19mm of the servo saver (this D series Hitec servo uses a 25t horn and they skip the oddball screw used to mount the horn and use a 3mm "thumbsup")

The steering servo has some little spacers that depending on the direction installed have different offsets. The Hitec 7950 needs to have these installed opposite of how the manual shows it, the 4 should be facing up. this puts it in the spec the manual calls for, sticking down 3mm

 

[thewildblue77]

Did you trim the plastic underneath the motor mount at all...I didn't when putting in a 550 and it didn't sit right. I'm on a 540 currently.

 

[soze]

WIll be watching to see what you do with yours!

 

[HumboldtEF]

Did you trim the plastic underneath the motor mount at all...I didn't when putting in a 550 and it didn't sit right. I'm on a 540 currently.

Thanks for the reminder, my brother had mentioned this too. So far it seems like I might have gotten lucky with getting my 550 motor to fit, though since I haven't completed the cage yet I'm not positive. It does clear the can and the positive and negative leads by a few MM though clearing the leads is dependent on how the motor is rotated.

Here's a few shots though I'm not sure how good the clearance will show

So is it just this lower area (the piece with the receiver box and steering servo mount) that I should be checking?

 

[thewildblue77]

I'm not 100% sure as I didn't do mine...someone else had posted. I found mine went in fine, but once complete and I was trying to adjust mesh I couldn't rotate the motor.

Sent from my SM-G935F using Tapatalk

 

[HumboldtEF]

I was hooking up the steering and noticed the servo horn I picked up was just a touch too long, I like to grab the version with the two holes even though I might just use the closer hole, one at 20mm and one at 24mm just in case I want to use it elsewhere. Servo horn is from Vanquish, 24t 24mm.

Anyway just a little trimming with a razor gets me the clearance I need for this longer servo horn.

I was assembling the coilovers and wasn't really liking the fact that the springs front and back are the same (spring rates) as I like to be able to fine tune them. I noticed that Gmade sells different spring rates, but first I had a rummage through my spares and found a bunch of spings from a Proline powerstroke spring assortment kit



I installed them as single stage springs first, but the preload needed to be wound down almost all the way which put the pre-load adjuster collar right up against the cage, no good it was rubbing and binding.

I went back to the spares and did some more rummaging and found a Proline rebuild kit I had bought for the seals but it also had the little collar used with the dual rate spring setups

So now I can use the top springs too. These springs put together are slightly longer than stock so with the pre-load backed off all the way you still need to compress the spring 1/8"- 3/16", still better than not being able to tune them though.

As it sits now I'm stuck waiting for ideas on paint and good weather to paint. I know it will be white with silver and black accents though, but beyond that I'm not sure how it will go together.


EDIT I forgot a few things, I found another useful item in my spares, a spare tire mount from a BGR cage for the wraith. Its just an M4 bolt and 2 nuts, the first nut is to secure the bolt to the mounting point on the Gom cage and the second holds down the tire, it has two metal rods tacked to it to make it into a knock off nut.

And going along with the spare tire the panel farthest back (the winglets) doesnt fit with the spare tire and I've seen these break off after a roll. So I'm going to do what most others have done here and cut this panel down so it fits the cage and doesnt stick up, it ends up a triangle instead of being a diamond like stock.
But in order to get this winglet look back I plan on cutting new panels for the second to last panel on the side. The spare tire should protect these I think.

And I'll add in a little winglet to the rear of this panel, something like this:

Since I'm waiting on paint and a bit stalled at the moment I could resist assembling the rest of the cage even though I'll have to tear it down later on

 

[soze]

I'm using the same servo arm, and ran into the opposite issue. If you look at my build thread, with the servo I'm using, I actually had the issue of the arm being too low. I had to put washers between the servo mount and servo to raise it up a little.

 

[HumboldtEF]

I'm using the same servo arm, and ran into the opposite issue. If you look at my build thread, with the servo I'm using, I actually had the issue of the arm being too low. I had to put washers between the servo mount and servo to raise it up a little.

I see what happened with yours, the Savox servo mounting tabs are too thick to use the spacer Gmade provides, it makes sense you had to come up with your own.

 

[HumboldtEF]

I made a few tiny changes, I found a set of Vanquish 12mm clamping hex's to replace the stock ones that like to come loose and let the drive pin fall out . I went for these since I had them but its probably a much safer bet to just pick up the more standard flat faced ones.

these hex's left a bit of space behind the drive pin up front and the bearing was wondering outwards, I found a 1mm thick washer fit nicely between them and left enough play to be safe.

I also chose to bore out the stock wheels to make make these hex's work with them, I dont have metric bits so the closest I could come up with was a 1/4" bit, I first drilled straight in and then I used the same bit (using the side of the bit) to slowly enlarge the hole.

I also noticed my spare tire mount without a stop for the wheel was going to lead to wonky wheels, it was clamping the tire up against the cage leaving flat spots. So I just added a few nuts and tightened them into each other. Leaving 10mm of the bolt sticking up puts the tire in the right spot for me but thats gonna vary based on the length of bolt used.

 

[metalry101]

Looks great man!

Those Scorpios look fantastic! I'm really happy with my stock tires...but now I want to try a set of those on mine! I used the 1.9 flavored ones a couple years ago on my 1.9 Wraith project and liked them a lot.

Did those Vanquish hexes slide over the stock axles with no mods? I'm running the stepped Axial hexes and they needed to be drilled out to fit over the axle.

I like the way it looks with the spare too. I bought the mount, but haven't ever bothered with the spare since I haven't been able to get a matching wheel.

Great work man! I can't wait to see more.

 

[HumboldtEF]

Looks great man!

Those Scorpios look fantastic! I'm really happy with my stock tires...but now I want to try a set of those on mine! I used the 1.9 flavored ones a couple years ago on my 1.9 Wraith project and liked them a lot.

Did those Vanquish hexes slide over the stock axles with no mods? I'm running the stepped Axial hexes and they needed to be drilled out to fit over the axle.

I like the way it looks with the spare too. I bought the mount, but haven't ever bothered with the spare since I haven't been able to get a matching wheel.

Great work man! I can't wait to see more.

Thanks, I'm exited to try this rig and the tires out but I'm really trying not to rush anything. The stock tires seem like they'll do decent on the rocks, but thread depth might be a little shallow for mud and dirt.

I did try an older set of vanquish hubs that use a set screw instead of the newer clamping style. The older set screw version did need a bit of drilling out to get the hex to seat properly while the new clamping style did not. After drilling it out carefully I noticed that one of them had stripped threads so I just didn't mention it. I ended up having to order 2 more of the clamping style to complete the set.

Last night I started a bit of the painting, and this afternoon I hope to continue with the paint. I've come up with a simple enough paint scheme that I'm confident enough to go for. My other ideas were a bit complex and left me felling like I was about to ruin the body.

 

[HumboldtEF]

Paint is done, time to go scratch this beauty up! :ror:

I used some silver paint to accent the steering wheel and shifter

I made my own design for the 2nd to last panel since I cut down the last panel to fit the spare, I just wanted to add a little winglet. though its easy to miss since its black

I'm exited to go test this thing out!

 

[soze]

Your GOM came out really nice!

 

[HumboldtEF]

Well I had a blast running the truck last night on my backyard rock pile

I really blew it on gearing though, I was going off of my brothers build and though it needed more wheel speed but I forgot he's running 2S and I'm on 3S. I put in a 16T pinion and set a very gentle throttle curve with Castle Link, but the gears were so tall that it was pretty terrible at crawling speeds, I though I was in high gear but it was low, lol

I took the opportunity to swap out the Traxxas 21t Titan motor for a Holmes Hobbies Trailmaster Sport 550 21T. I had lent that motor to my brother for his Gom and just recently got it back.

I switched the 16T pinion out for a 13T. then I proceeded to struggle to mesh the gears for a few hours
I forced it to work finally, got a good mesh, but it made a horrendous noise as it wasn't spinning in the same plane, it was angled a bit (I've heard my brothers Gom maker this noise before)

I'd heard people saying some shaving is needed to get a 550 to fit so I just though I needed some clearance below so I did this

But that wasn't my problem, I had simply been orienting the motor adjuster plate wrong. :lmao:
You can either spin it clockwise or counter clockwise to get your mesh but I had forgotten you need to spin it counter clockwise. Doing that wrong makes it so the motor hangs too low.

Sheesh, I wasted a lot of time on something pretty simple but hopefully this cautionary tale can save others

I did need to notch the plastic piece under the motor to clear the lead on the 550 HH motor. This must be what people are actually having to do to fit the larger 550's

Started with a drill bit, cleaned up with a razor

 

[Drvon]

How did you months your LED's? Looks mean!

 

[soze]

How did you months your LED's? Looks mean!

There are screw holes in that area under the hood that you can mount the lights at.

 

[HumboldtEF]

How did you mount your LED's? Looks mean!

Yeah I didn't realize how angry it was until I took that picture from the front

There are screw holes in that area under the hood that you can mount the lights at.

Yep, it has a few holes under the hood

I wanted to try using a different spot than what others were doing, I actually though I'd have to come up with my own mounting point to put the lights there I was happy to see it was built in.


After a quick run out back I just experienced what others have with the CVA's, I was messing around with dig being reckless and snapped a pin, the snap ring then let it loose. I though it had just come loose but it did actually snap.

the pin just doesn't seem the right length as thewildblue77 has mentioned in another thread

So its a fault from Gmade then...the CVA pins need to be larger...I think they are 11.4mm, but trying to find 12mm pins that fit....well I struggled and failed...

I'm trying to contact CREEPERBOB about making some titanium axles for the Gom. For now I'll just pick up some 12mm pins in hopes that can help. I did measure the axle cup end to end with calipers and it looks to be just under 12mm, 11.8-11.9 would be perfect but 12 is likely okay if that's the closest length.


For now I'm back to using the dogbones and doing 20 point turns :roll:

 

[Drvon]

Were your CVA's pre assembled from GMADE? mine ended up coming pre assembled.

 

[metalry101]

Were your CVA's pre assembled from GMADE? mine ended up coming pre assembled.

Mine came from Junfac because I didn't want to wait any longer and they were assembled. The ones hanging on the wall at my LHS are unassembled though. Same part number so I have no idea why they're different.