Building a c2 comp rig?

[TITANIUM94010]

While making custom builds, I find that I need to find something to do that requires less constant head-scratching and frustration, and swearing like a sailor :roll:,and just something nice to sit down, relax, and wrench on. I'm still expecting to do some figuring out, but it'll be a lot more laid out and straightforward than trying to figure out how to mount a trx4 diff to a slash ifs, and having to constantly reach for the dremel to make slight adjustments.

After looking at the possibilities, I think it's time for me to finally make an actual performance crawler for once, only problem is, I don't have much of a clue as to exactly what to do.

I've got some random parts in the parts bin, not too much

-Complete Trx4 Roller minus rear axle

-Ar44 front and rear axle housings, no gears

-Assorted links

I also have tires, foams, and radio sorted out. No wheels or body, but I may just 3d print them.

I'm thinking of using a TRX4 as a starting platform, considering that I have pretty much a complete roller, but the problem is the stock frame rails and transmission probably won't be used and swapped for something lower CG, but I do want to use TRX4 axles for portals.

I'm not exactly knowledgeable when it comes to comp builds, and after digging around some comp build threads, the amount of frame and transmission choices seem to be unlimited, every new thread seems to have some new frame rail or transmission.

Heres my plan so far:

Pick up another TRX4 front axle for 4ws (It'd be nice to have for normal driving around when not doing comps, and I can lock it out)

Get a low cg comp rail and chassis, use stock TRX4 shocks. I also have a 3d printer so I can make parts from that.

Could I have some recommendations and tips from the more experienced guys out there? G-Speed seems to be a very popular option for custom chassis rails, but I've also seen builds using the TCS game changer, sherpa rails, and Toyszuki, What are the advantages and disadvantages, and how compatible are they with TRX4 axles? If there are more options that you guys think are better, please post! The transmission I'm looking at is the TGH2. low, but I find it to be too expensive, so recommendations for them would be helpful too.

Thank you!

 

[Goro Majima]

No experience on comping first hand but here's my recommendation with your info given.

I don't have experience with other flat rails other than GSpeed. But I like them for what seems to be the convenience of being able to set up your base chassis with ease, and they're California based (support your "local" businesses).

If your interior is minimalistic, you can do an Element Stealth X (around 60 bucks US). Artful Dodgers (Poland based) also has a motor mount for it to move the spur gear to the side for more interior space and lowering CG if needed (50 bucks shipped US). Last time I checked they were out of stock but they have a few in stock now.

InTheWorks custom links to get your TRX4 axles aligned to your wheelbase. If you don't already know, you choose your chassis/skid/axles etc etc in the drop down menus and you get them made. Hell, they might even already have that setup as a preset option.

Good luck with whatever setup you decide on!

 

[MOguy]

I have TRX 4 Axles on my C3 with 4ws and rear selectable locker. Works good for that but I have AR44s on my C1 and 2. TRX axles are tough, good gear reduction and have clearance but don't turn as well.

For Electronics I like my SW4 with snub nose V2 1400 revolvers. I also have Holmes Hobbies and NSDRC direct power servos. Direct power is a good option because you wont need an external BEC. On my C2 I did get a servo winch that power of the ESC's internal BEC. I had planned on using Copperheads but they just would stall so I went back to my trusty SW4s and ended up with an external BEC. They weigh almost nothing but just an extra component to deal with. I wish I went with a direct power ESC for my winch also.

Trans is a Stealth X. It is heavy, about 7 ounces and I plan on either going to either a Hamberger (2 ounces) or OG with front motor mount probably 5 ounces but with better weight distribution and more scale points.

Body is lexan right now, for C2 I will take the weight savings over the points. You can get points other ways if needed.

Sprung weight (weight above you axles) needs to be minimized as much as you can. Needed weight needs to go forward. Than you play around and see what weight you need to add and you add it low. I add to my wheels, mostly. I do have a weighted brass diff cover in back but that will soon go. Brass is soft and hangs up, as do most other metals. I favor adding weight to the wheels but some don't like weight added to their wheels because they don't want t rotating mass.

 

[HuckFlynn]

If you want the best turning on portals, go with ar45p(10.3) or capra axles (same as ar45p just wider) way more turning angle than trx4 and better caster/pinion angle

 

[MOguy]

If you want the best turning on portals, go with ar45p(10.3) or capra axles (same as ar45p just wider) way more turning angle than trx4 and better caster/pinion angle

It seems some are using the straight axle conversion in front for the off set pumpkin but keeping the rear as portals. Seems some are have breakage issues with the portals and gears stripping with the front ones.

 

[TITANIUM94010]

No experience on comping first hand but here's my recommendation with your info given.

I don't have experience with other flat rails other than GSpeed. But I like them for what seems to be the convenience of being able to set up your base chassis with ease, and they're California based (support your "local" businesses).

If your interior is minimalistic, you can do an Element Stealth X (around 60 bucks US). Artful Dodgers (Poland based) also has a motor mount for it to move the spur gear to the side for more interior space and lowering CG if needed (50 bucks shipped US). Last time I checked they were out of stock but they have a few in stock now.

InTheWorks custom links to get your TRX4 axles aligned to your wheelbase. If you don't already know, you choose your chassis/skid/axles etc etc in the drop down menus and you get them made. Hell, they might even already have that setup as a preset option.

Good luck with whatever setup you decide on!

Thanks for the reply, It looks like a lot of TRX4 based crawlers are based off of Gspeed chassis, which might be the way I go, but there's also a lot of Brazin RC chassis. I think my final choice will be between those two.

 

[TITANIUM94010]

I have TRX 4 Axles on my C3 with 4ws and rear selectable locker. Works good for that but I have AR44s on my C1 and 2. TRX axles are tough, good gear reduction and have clearance but don't turn as well.

For Electronics I like my SW4 with snub nose V2 1400 revolvers. I also have Holmes Hobbies and NSDRC direct power servos. Direct power is a good option because you wont need an external BEC. On my C2 I did get a servo winch that power of the ESC's internal BEC. I had planned on using Copperheads but they just would stall so I went back to my trusty SW4s and ended up with an external BEC. They weigh almost nothing but just an extra component to deal with. I wish I went with a direct power ESC for my winch also.

Trans is a Stealth X. It is heavy, about 7 ounces and I plan on either going to either a Hamberger (2 ounces) or OG with front motor mount probably 5 ounces but with better weight distribution and more scale points.

Body is lexan right now, for C2 I will take the weight savings over the points. You can get points other ways if needed.

Sprung weight (weight above you axles) needs to be minimized as much as you can. Needed weight needs to go forward. Than you play around and see what weight you need to add and you add it low. I add to my wheels, mostly. I do have a weighted brass diff cover in back but that will soon go. Brass is soft and hangs up, as do most other metals. I favor adding weight to the wheels but some don't like weight added to their wheels because they don't want t rotating mass.

Thank you for the recommendations! I checked out some 10.3 and capra axles, but they'd set me back around 150-200 for a set vs the single 50 dollar axle I need for a TRX4 based build.

Maybe I can find somebody with a set of 10.3 portals that they swapped out for the straight axle kit?

As for the transmission, the element stealthX looks like a good option, especially with the additional dig. But I do really want to get the motor up front for better weight distribution, and points, but I don't know if I'ts a good choice to have to run another driveshaft from motor to transmission. I'm going to be trying to max out scale points with this build, as I am probably no good at driving. So far the forwards motor mounts I found are really expensive, are there any options for something less expensive? (3d printed will work too)

 

[MOguy]

Thank you for the recommendations! I checked out some 10.3 and capra axles, but they'd set me back around 150-200 for a set vs the single 50 dollar axle I need for a TRX4 based build.

Maybe I can find somebody with a set of 10.3 portals that they swapped out for the straight axle kit?

As for the transmission, the element stealthX looks like a good option, especially with the additional dig. But I do really want to get the motor up front for better weight distribution, and points, but I don't know if I'ts a good choice to have to run another driveshaft from motor to transmission. I'm going to be trying to max out scale points with this build, as I am probably no good at driving.

If you are building a C2 you can't use dig. StealthX doesn't have dig. There is an Axial setup with dig. The Gates are 12 inches wide in C2. Capra Axles are wide. There are wheels with enough Back spacing to over come that but they are $$$$$.

For motor up front you need a Tcase type trans and forward motor mount, skid and drive shafts. I just ordered the Tcase and FMM from TGH. The tcase and FMM was almost $200.00 I still need a skid and drove shafts. A StealthX trans is about $50 plus skid.

With FMM different chassis, axles and different skids need to match. You have to think about out you want to do your OD and how much. IF you go the FMM route find somebody that did it and you trust and do what they did.

If you do SORRCA comps everybody maxes out their points. You have to do points smart. The stealth X works great but it is heavy and no addtional points. Going the FMM is a bit lighter maybe but you get points and the weight sits better. There are even lighter ways but they don't get points. Hard bodies are easy points but heavy. I would rather have the added weight in my tcase FMM, less points than a hard body but lower and do offer a real benefit other than just points.

You can't get a drop bed and those points in a lexan body but if you get a body that fits front and rear seats you can do an interior that gets more points even if lexan. Even with lexan some bodies are heavier than others. The body is the highest things so saving weight there is good.

 

[TITANIUM94010]

If you are building a C2 you can't use dig. Gates are 12 inches wide in C2. Capra Axles are wide. There are wheels with enough Back spacing to over come that but they are $$$$$.

For motor up front you need a Tcase type trans and forward motor mount, skid and drive shafts. I just ordered the Tcase and FMM from TGH. The tcase and FMM was almost $200.00 I still need a skid and drove shafts. A StealthX trans is about $50 plus skid. Different chassis, axles and different skids need to match. You have to think about out you want to do your OD and how much. IF you go the FMM route find somebody that did it and you trust and do what they did.

If you do SORRCA comps everybody maxes out their points. You have to do points smart. The stealth X works great but it is heavy and no addtional points. Going the FMM is a bit lighter maybe but you get points and the weight sits better. There are even lighter ways but they don't get points. Hard bodies are easy points but heavy. I would rather have the added weight in my tcase FMM, less points than a hard body but lower and do offer a real benefit other than just points.

You can't get a drop bed and those points in a lexan body but if you get a body that fits front and rear seats you can do an interior that gets more points even if lexan. Even with lexan some bodies are heavier than others. The body is the highest things so saving weight there is good.

Sorry about that, completely had a brain fart and meant to say front overdrive.

The Tcase and FMM seems to be a decently affordable trans option. I'll look in to them more.

I'm 99% sure the body will be 3d printed, It's going to be heavy but I can try to mod files to make the walls thinner. I think it'll make it look good when driving outside of a comp setting too.

I'll probably get a trx4 metal front housing to get that weight down lower.

I'm going to create a parts list later today, I'll get a good idea of cost and incompatibilities that I may have thought over.

 

[twade984]

Don’t rule out a vfd trans. Forward and low motor position, 6.5% o/d, 20% gear set available, tcase points and only $110 brand new. Will only work with offset front axles though (like Trx4 axles).

Weight is comparable to a TGH fmm, extra driveshaft and t case.

Personally, based on what you have, I would get a matching Trx4 axle, g speed rails, gmp, Vader skid and drill jt for the vfd. Then add some custom hardcore or itw links, Trx4 shocks, and Robert is your mothers brother.


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[MOguy]

Sorry about that, completely had a brain fart and meant to say front overdrive.

The Tcase and FMM seems to be a decently affordable trans option. I'll look in to them more.

I'm 99% sure the body will be 3d printed, It's going to be heavy but I can try to mod files to make the walls thinner. I think it'll make it look good when driving outside of a comp setting too.

I'll probably get a trx4 metal front housing to get that weight down lower.

A heavy body is probably the worst thing you can do as far as performance. C2 I think is only 50 points, you should be able to get there with lexan.


TRX axles are about the heaviest there are they do not need to be heavier and metal doesn't slide as well as plastic. Maybe brass knuckles maybe, I do my weigh in or on the wheel. You can get vanquish brass rings that go in the wheels. If you need more you can get some brass hubs. You shouldn't need more than that if you build it right.

 

[MOguy]

Don’t rule out a vfd trans. Forward and low motor position, 6.5% o/d, 20% gear set available, tcase points and only $110 brand new. Will only work with offset front axles though (like Trx4 axles).

Weight is comparable to a TGH fmm, extra driveshaft and t case.

Personally, based on what you have, I would get a matching Trx4 axle, g speed rails, gmp, Vader skid and drill jt for the vfd. Then add some custom hardcore or itw links, Trx4 shocks, and Robert is your mothers brother.


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That maybe be a simpler option, less money and work just as well. It may but you motor up a pit higher, not sure if it would work with Servo on axle but you may not want servo on axle if points are a concern. 6% is not much OD for comp but you can add to it in your axles.

 

[TITANIUM94010]

Yep, I looked in to it more and I think for me, vfd is the way to go, I also like the scale look. I can always overdrive the front diff itself.

Do I go with carbon or aluminum rails? Carbon will be better for performance but I kind of like the look of aluminum, should also look more scale from the bottom. Also what skid do I use for a VFD and trx4 axles? It looks like I'll have to drill custom holes either way, but which one do I start with?

 

[Goro Majima]

Yep, I looked in to it more and I think for me, vfd is the way to go, I also like the scale look. I can always overdrive the front diff itself.

Do I go with carbon or aluminum rails? Carbon will be better for performance but I kind of like the look of aluminum, should also look more scale from the bottom. Also what skid do I use for a VFD and trx4 axles? It looks like I'll have to drill custom holes either way, but which one do I start with?

I like the stock skid for the VFD. Looks nice in the GSpeed rails and people hack off the upper link mounts of it to fit it. It sold me for my next V3 build.

You'll be just fine with the aluminum chassis.

 

[TITANIUM94010]

To confirm, the Gspeed v3 Carbon Fiber chassis is C2 Legal right?

 

[Goro Majima]

To confirm, the Gspeed v3 Carbon Fiber chassis is C2 Legal right?

Yes sir.

 

[TITANIUM94010]

Hopefully complete parts list.


Gspeed Chassis TGH v3 74.98
Multiplatform Panhard mount 14.98
Spacers 14.98
Servo Mount 29.98

Custom Links 60.00
TRX4 Axle 46.00
Amazon Wheels 45.00
CI Foams 47.90

VDF Transmission 120

Castle Copperhead 120.00
HH PP Stubby 99.00

Total: 672.82

Not too bad, not too great, but it's a start.

I already have servo, radio, and tires.

 

[twade984]

Don’t see shocks on the list, otherwise looks good!


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[tigris99]

I'd read up on the rules to make sure on some things because at some point flat plate chassis are not allowed. Not sure if it's only class 1 or 1 and 2.

Here's what I referenced for rules the other day. Might be old or whatever not sure.

https://thecrawlspaceco.com/sorrca-rules#:~:text=Class-2 "Trail" Details,the cab at the doors.

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[TITANIUM94010]

Don’t see shocks on the list, otherwise looks good!


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Oops, yep forgot shocks. I have a set of TRX4 90mms, which should be good.

I'd read up on the rules to make sure on some things because at some point flat plate chassis are not allowed. Not sure if it's only class 1 or 1 and 2.

Here's what I referenced for rules the other day. Might be old or whatever not sure.

https://thecrawlspaceco.com/sorrca-rules#:~:text=Class-2 "Trail" Details,the cab at the doors.

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I think it's TVP (twin vertical plate) chassis that are illegal, I was confused as to what that meant but it looks like tvp is a a chassis that's a lot more vertical (Like monster trucks) while flat plates are like normal rails but in plate form. I've looked at SGB's builds and Matt uses flat plate for both his C1 and C2 builds.