Thloftus’ SCX10 II father’s day build

[Thloftus]

Thanks, guys, for the tips about the TRX-4 shock springs. After days of careful research (or maybe wandering on the internet for half an hour), I've made some discoveries that I'll share here. Maybe well known already, but who knows, could help someone else since it was more painful than I expected to collect.

The stock shock springs for the SCX10-2 kit are:

For the front: AX31145 (yellow), 2.63 lbs/in
Axial Racing - Spring 12.5x60mm 2.63 lbs/in - Yellow (2pcs)

For the rear: AX31441 (white), 1.13 lbs/in
Axial Racing - Spring 12.5x60mm 1.13 lbs/in - White (2pcs)

We're going to start by matching the TRX-4 springs to the stock Axial springs, partially since we may sell the kit shocks for other upgrades and I really have no other idea where to begin. I also like the looks of the black Traxxas springs, which is reason enough,

The TRX-4 springs are listed with a unitless "rate." I think the units are N-mm; please correct me if I'm wrong. There's an on-line tool for converting between various spring rate units at:
.: Spring Rate Conversion Calculator :. | NorWest Suspension LLC
I can't attest to the accuracy, just assumed the conversions were correct. The results were reasonable. Plus it's on the internet and so must be right.

The TRX-4 options are:
TRA8042 (yellow), 0.22 rate, 1.26 lbs/in
http://www.rpphobby.com/product_p/tra8042.htm
TRA8043 (white), 0.30 rate, 1.71 lbs/in
http://www.rpphobby.com/product_p/tra8043.htm
TRA8044 (orange), 0.39 rate, 2.22 lns/in
http://www.rpphobby.com/product_p/tra8044.htm
TRA8041 (no color listed), 0.45 rate, 2.57 lbs/in, stock front for the TRX-4
http://www.rpphobby.com/product_p/tra8041.htm
TRA8040 (no color listed), 0.54 rate, 3.08 lbs/in, stock rear for the TRX-4
http://www.rpphobby.com/product_p/tra8040.htm
TRA8045 (blue), 0.61 rate, 3.48 lbs/in
http://www.rpphobby.com/product_p/tra8045.htm

Note that if you look up the TRX-4 springs at AMain, their spring table lists TRA8042 twice. The second one is the stock rear spring and should instead be TRA8040.

It's pretty easy to distinguish between the stock front and rear TRX-4 shocks if you squeeze the shocks in your hand; plus I confirmed my conclusions with a completely legit blind squeeze test with the kids.

The stock TRX-4 fronts (2.57 lbs/in) are very close to the SCX10-2 stock rears (2.63 lbs/in), so we'll use them without changes for the rear. I bought a set of the TRA8042 springs for the front - not exactly the same as the SCX10-2 springs, but within 10%, so I'm guessing we won't be able to tell the difference.

I'll give a noob-ish report about how the shocks perform once we have the truck together. I think the driveshafts are the next step for us.

[mcbartho]

Nice build. I will start a build too next days. It will be my firts rc kit.


On the holmes servo: u dont need a external bec with a mambaX.
I have bought the same servo and esc from holmes shop and they told me it doesnt require an external bec.


I hope my english is understandable

[JatoTheRipper]

Any updates on the shocks?

[Thloftus]

Originally Posted by mcbartho

Nice build. I will start a build too next days. It will be my firts rc kit.


On the holmes servo: u dont need a external bec with a mambaX.
I have bought the same servo and esc from holmes shop and they told me it doesnt require an external bec.


I hope my english is understandable

Thank you, have fun with the build! It’s a great kit and way more enjoyable to put together than the original SCX10. It also seems more complete - I’m not dying to upgrade everything from the start in the way I was with the original one.

I’m sure you’re right about the Mamba X.


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[Thloftus]

Originally Posted by JatoTheRipper

Any updates on the shocks?

I wish I did! The softer springs I ordered for the front should be here tomorrow or Thursday. We’re still at the driveshaft stage - my workforce keeps getting derailed, Lol! They’ve scheduled me in for tomorrow night. High hopes for forward progress!


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[Thloftus]

We finished a few steps today. First one was the driveshafts. Pretty happy with how they went together. I managed the lock tight, but they did the rest. The top one is for the front.

Next we installed the Vanquish top shaft.
http://www.rpphobby.com/product_p/vps08106.htm
Bummer to take a few steps back, but the “pepper grinding” gear action is gone, so it was probably worth it. The gears are super smooth now. Installing the shaft is a little confusing since the bearing on the threaded end sits at a different position along the shaft - we just pushed forward and it went together fine.



Last bit is taking advantage of a RPP weekend special on shipping to get some more parts - no reason to end the build anytime soon, Lol: LockedUp max clearance trackbar (it’s important to have maximum flex even if the kids can’t tell the difference), more Revo rod ends, Traxxas shims for the axles, SSD titanium steering links, softer springs for the front TRX-4 shocks, and a bearing to replace the bushing on the spur. For reference the bearing is 11 mm OD, 5 mm ID, and 4 mm thick. The SSD links are nicely done and have better rod ends than stock; seemed like a better option than trying to retrofit Revo ends on the axial links since no one currently has the 1.5 mm spaces that get the lengths right.


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[Thloftus]

We mounted up the driveshafts, bolted on the skid plate, put the battery holder / servo mount together, and mounted the servo. The servo mount has a crazy number of parts and the plastic is a little thin / flexible. It stiffens up a bit when the servo is mounted; hopefully more so when it’s mounted to the frame rails. I can see now why an aluminum servo mount is appealing. The guide for the line from a servo winch is pretty nice; yet another reason to add a winch! Also liking the guides for the servo leads.



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[Rekreant]

Nice job! I think the SSD rod ends are actually revo rod ends with proper balls in them. That vanquish drive shaft looks crazy beefier than the stock one, Im surprised it fit!

[Rekreant]

Also for anyone else ordering from RPP they are having a 10% off fathers day sale all month. The code is JUN10.

[Thloftus]

Originally Posted by Rekreant

Nice job! I think the SSD rod ends are actually revo rod ends with proper balls in them. That vanquish drive shaft looks crazy beefier than the stock one, Im surprised it fit!

Thank you! It’s great to know the SSD links use Revo rod ends. The Vanquish shaft is definitely beefier and I agree, it wasn’t obvious that it would fit. I almost gave up installing it but you know, setting an example and no cursing in front of the little ones, Lol!

It definitely took care of the crackling gears and seems built to last.


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[Thloftus]

Originally Posted by Rekreant

Also for anyone else ordering from RPP they are having a 10% off fathers day sale all month. The code is JUN10.

They’re definitely a favorite for me. I’d like to go to their yearly Jamboree sometime.


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[Rekreant]

Yeah I am trying to see if I can swing it this year. Whats cool is they also have an Amazon store.

[Thloftus]

Originally Posted by Rekreant

Yeah I am trying to see if I can swing it this year. Whats cool is they also have an Amazon store.

I agree, definitely a great vendor. Have fun if you go!


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[mcbartho]

Nice to hear your progress. I have also bought the topshaft.
Why use the trx4 shocks?

[Thloftus]

Originally Posted by mcbartho

Nice to hear your progress. I have also bought the topshaft.
Why use the trx4 shocks?

Thank you! For the shocks, I had poor luck with the stock Icon stocks when I tried to use them on a v1 SCX10 kit, mostly leaks and springs rubbing on the bodies. I tried several fixes listed on the forums, but wasn’t able to solve the leaks. Others have been very happy with the Icon shocks after minor tweaks; see entry 36 at
bilinvic's SCX10.2 Build Ver. 2
I’ve used a few sets of Traxxas shocks previously without any leaks. They’re also generally smooth, well made, easy to install, and robust. The TRX-4 shocks are the right length and I was able to get a great deal on eBay.


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[Thloftus]

We attached the first frame rail, getting closer to a truck! Looking forward to seeing how solid it will be with the second rail. Still can’t decide if we should upgrade the servo mount to one of the aluminum options.



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[JatoTheRipper]

Originally Posted by Thloftus

We attached the first frame rail, getting closer to a truck! Looking forward to seeing how solid it will be with the second rail. Still can’t decide if we should upgrade the servo mount to one of the aluminum options.

I'm torn on upgrading the mount as well. The stock, plastic, multi-piece unit is so spindly and questionable. But an aluminum one would probably raise the COG a little bit.

[Thloftus]

Originally Posted by JatoTheRipper

I'm torn on upgrading the mount as well. The stock, plastic, multi-piece unit is so spindly and questionable. But an aluminum one would probably raise the COG a little bit.

Yep, although I probably hadn’t thought through the COG change well enough, Lol. The servo mount seems overworked to me. It’s more solid with the frame rails installed and the concept is sweet, esp the mounts and line guides for a servo winch. But there’s too many pieces / adjustments and I agree, some of them are spindly. Also involves several parts trees, which is annoying when your work force has little-kid patience! Too much unnecessary complexity given the function and performance goals. We’ll probably go with it until something breaks, but still tempting to upgrade now.


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[Thloftus]

Attached the second frame rail. Pretty solid once the whole thing is put together. We were missing a few screws, but yay no choice but to make an extra trip to the hobby shop, Lol! The Mamba X just fits next to the receiver box, so maybe needs to go on the other side? Where did all of you put your ESC?


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[StomperCrawler]

Originally Posted by Thloftus

Attached the second frame rail. Pretty solid once the whole thing is put together. We were missing a few screws, but yay no choice but to make an extra trip to the hobby shop, Lol! The Mamba X just fits next to the receiver box, so maybe needs to go on the other side? Where did all of you put your ESC?


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Other side with double-sided tape.