Thloftus’ Rock Rey Basher

[JatoTheRipper]

The Rock Rey was designed to use 3S minimum. I think that spacer can be taken out to use larger batteries if you so choose, but I'm not sure. I'll be rocking 2S.

[Thloftus]

Originally Posted by JatoTheRipper

The Rock Rey was designed to use 3S minimum. I think that spacer can be taken out to use larger batteries if you so choose, but I'm not sure. I'll be rocking 2S.

None of my batteries fit, so looks like I’ll be taking out the spacer. I found some $4 yoga blocks on the internet (high density foam) that I’ll be cutting up to make a new spacer, !


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[Thloftus]

Few more goodies showed up today!


Savox 1210SG digital waterproof servo, a receiver, and an aluminum SSD HD front bulkhead. Many thanks to RPP for their New Year’s day sale! The 1210SG has 440 oz-in at 7.4 V and steel gears. I looked at several options and agonized as appropriate for this kind of monumental life choice. This one was the best combination of torque, water-proofness, and budget friendliness. Plus I’ve used it before with good luck. Should be up to the task; we’ll find out regardless, Lol! The bulkhead seemed like a must after reading other threads and seeing how many parts of the front end tie into this one part.

We were also inspired by JatoTheRipper’s thread to figure out an upgrade for the kit-supplied plastic tie rod that connects the servo horn to the steering bellcrank. You can see Jato’s thread here:
Jato Tries to Define Rock Rey

We went with rod ends / spacers, hollow balls, and screws to attach the rod ends to the servo horn and bellcrank. The Hot Racing aluminum bellcrank (one of the first upgrades I bought for the kit) accepts standard 3 mm screws. Hopefully the same is true for the Losi aluminum servo horn. We’ll have to rethink out plans if it doesn’t, ! Two options emerged from our spare parts bin, top and bottom in the image. The plastic tie rod supplied with the kit is in the middle


The top one uses a 13 mm spacer and ‘mini’ rod ends from my TF2 kit that are meant for the shifting servo on the two-speed transmission. The spacer is a combination of a 12 mm rod from eBay and a 1 mm spacer left over from the TF2 kit. The bottom one is two aluminum rod ends and a 3 mm spacer; overall length is 38 mm center-to-center. I think the rod ends are from a set of Boom Racing Boomerang Type I shocks.

Here’s a better picture of the three tie rods that shows they’re the same length, or at least very close


I think we’ll go with the aluminum rod ends. I’m not sure how long they’ll last, but it’s better than leaving them unused in a parts bin!


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[JatoTheRipper]

Thanks for the shout-out. I don't know if you saw my update but I ended up using the stock, plastic link for now. I need to determine the threads of the ball studs so I can replace them with screws.

[Thloftus]

Originally Posted by JatoTheRipper

Thanks for the shout-out. I don't know if you saw my update but I ended up using the stock, plastic link for now. I need to determine the threads of the ball studs so I can replace them with screws.

You’re right, I couldn’t get my ball studs to screw into m3 threaded holes either - although m3’s fit fine in the HR bellcrank.


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[Thloftus]

Opened up the front diff again to drill out the ring gear and swap in the Traxxas screws. Third time, it’s a charm! Quick work with the titanium drill bit

Here’s the final evidence; bit of a greasy mess, but hopefully built to last


The SSD bulkhead is very nice in person and I’m happy to have the larger pinion bearings


With the gears installed and prior to re-greasing


The driveshaft bearings are a tight fit and require some patience to install without getting them stuck part way (as they should be). I used some bearing oil on the sidewalls of the seats to make this easier.

The bulkhead is held together with a single screw at this stage. I initially tightened it all the way down, reassembled the front end, installed the drive shaft to the center diff, and only then realized there was some ‘grunching’ at a particular spot during each full rotation. I actually considered moving on and letting the gears wear in, but you know, poor example for the kids. So full disassembly again - seems round three was not so charming after all, Lol!

The conflict was due to a slight front-to-back rocking of the case about the middle. This led to partial binding between the ring and pinion gears when the screw was tightened firmly. I’m not sure of the cause. I tried to press the driveshaft bearings further into their seats, thinking it was operator error, but this didn’t have any effect. In the end, I backed the single screw off slightly (very light tightening), which gave smooth rotation all the way around. This seems fine given all the other fasteners that tie the two halves together. Anyway, I was out of ideas, so time to move on!

And, shazam, fully reassembled front end!



The SSD part is beautiful and definitely better equipped for future abuse! I’m still waiting for the Boom Racing aluminum front upper link mount. It should be here this week and we’ll swap out that last glaring piece of plastic, !


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[JatoTheRipper]

Did you use shims in the front bulkhead?

[Thloftus]

Originally Posted by JatoTheRipper

Did you use shims in the front bulkhead?

Just the one called out in the kit manual. I bet that’s the problem? Didn’t occur to me in the Japanese game show-like experience that’s building kits with my kids, Lol!




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[JatoTheRipper]

Originally Posted by Thloftus

Just the one called out in the kit manual. I bet that’s the problem? Didn’t occur to me in the Japanese game show-like experience that’s building kits with my kids, Lol!

It's possible - that's why I mentioned it. I used shims in some places and not others. I forget where though. I believe I did state on my thread though.

[Thloftus]

Originally Posted by JatoTheRipper

It's possible - that's why I mentioned it. I used shims in some places and not others. I forget where though. I believe I did state on my thread though.

Nice, I’ll go back through it.


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[Thloftus]

Onward progress, back to building!

Hot Racing aluminum servo mount installed on the chassis. Looks great, fits perfectly, hoping it holds together.


And with the Hot Racing aluminum steering bellcrank


I had absolutely no idea how much to tighten the spring for the servo saver and instead let my kids decide. We cranked it down at first, but they didn’t like how this made the spring look ‘crooked,’ so I backed it off until thumbs up from the judges. Still feels tight so it must be right?! I have no idea. I’ve only ever used a servo saver on my nitro Slash and I pulled that one since it didn’t seem manly. Guess we’ll be fine until the servo explodes and if it doesn’t, all rights to claim perfect assembly!

Next step is attaching the front end to the chassis. Fair amount of colorful language for this part; tricky to line everything up while keeping the driveshaft to the center diff and the bellcrank in place. Fine once it’s all together; like those CAD models that look so clever and minimalist until you realize there’s no way to do the assembly, Lol! Thankfully I got two rounds of this action when I realized the center diff was geunching slightly - as expertly explained in a previous post. More opportunities for personal growth!


Anyway, sweet to have it together!

I still need to check into the shims in the front end diff; also need to check with the bosses and see if they’re up for taking the front apart again if there’s a misplaced shim that should come out, Lol!


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[JatoTheRipper]

Servo savers, like slipper clutches, should be tightened down with all your strenght! That's what I do anyway.

There's a lot of leverage on the Rock Rey with those massive tires so I think it'll need to be pretty tight honestly. You won't know until you run it though.

[Thloftus]

Originally Posted by JatoTheRipper

Servo savers, like slipper clutches, should be tightened down with all your strenght! That's what I do anyway.

There's a lot of leverage on the Rock Rey with those massive tires so I think it'll need to be pretty tight honestly. You won't know until you run it though.

Cranking it down was my impulse too; just have to wait until the bosses aren’t watching, Lol!


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[Thloftus]

Servo unboxed! I’m not the first person to use a 1210SG, but they sure are nice to look at. The cord is short and probably won’t reach the default position for the receiver. But dang, look at the finely crafted lettering and awesome shade of teal!


Batman-like plastic bit installed in the rear end! It’s great to see how the chassis is reinforced and the parts fit together perfectly


The rear shock towers are the weirdest part of the whole kit. My kids think they’re dinosaurs and took offense at the front-to-back placement in the picture since they should be walking in the same direction. The plastic is bendy and the cantilevered mounting to the chassis is different. The faux fan at the back braces them together, but my guess is there’s more aluminum in our future!


Servo installed and more rounds of admiration. Really nice lettering on the case. Ahhh, sweet packaging and box art - the ultimate marks of a premium product! If only the servo teal and Hot Racing blue didn’t clash, !


And boom! Dinosaur prongs in place!



It’s getting too big for my shop towels. Starting to appreciate how large it’s going to be in the end!

I still need to check the shims in the front diff, hopefully this weekend, !!


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[Thloftus]

Originally Posted by JatoTheRipper

It's possible - that's why I mentioned it. I used shims in some places and not others. I forget where though. I believe I did state on my thread though.

Thanks again, Jato! We opened up the front diff this morning and pulled the shim. No more rocking and I was able to tighten the case screw all the way without any binding!


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[Thloftus]

Up next were the rear sway bar and upper link mounts. The link mount are from Boom Racing and are the second half of the kit we installed earlier.


Installed on the chassis; the sway bar is on the left. The link mounts are very, although the gap was a little too small for the hollow balls in the link mounts. Easy fix with a sanding wheel on the Dremel.


Faux fan in the back along with the mud guards in the front. The guards are gray, but I’m not sure I like the gray color and may paint them black; could also use Rit dye, but that requires standing outside with a camp stove - wife not a big fan of me boiling dye in the kitchen, !



And on with the back axle!



Even more too large for my shop towels now





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[JatoTheRipper]

Originally Posted by Thloftus

Thanks again, Jato! We opened up the front diff this morning and pulled the shim. No more rocking and I was able to tighten the case screw all the way without any binding!

Glad to hear it! Your build is looking good.

[Thloftus]

The rest of the sway bar went together easily. The instructions weren’t explicit about how far to insert the wire into the link; I made it flush with the output side.


I had a pair of stock rear shocks from my Bomber available; I took them out of service when I swapped Powerstroke XT’s onto the Bomber. We decided to skip ahead and give the Bomber shocks a try on the RR. I’m guessing they’re better than the kit shocks and are close to the right length? It’s hard to tell. They’re 110 mm. I couldn’t find any listing for the length if the Losi stock shocks. I might move them to the front-most position on the top since they look a little short where they’re sitting now. Do any of you know the length for the stock shocks? I might need to build them to find out, Lol! In the long run, I’d like to swap in Powerstroke XT’s, which are apparently a little too long but work anyway. They’re sweet shocks, just need to replenish the budget!


Next is more bits from Boom! This time it’s the front upper link mount.


The part is nicely made and fit perfectly. Here’s before (kids got ahead of me and backed one of the screws part way out)


And here’s after


It’s great to have the aluminum part and I like the extra mounting positions for the links.


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[Thloftus]

Originally Posted by JatoTheRipper

Glad to hear it! Your build is looking good.

Thank you, definitely enjoying your build also!


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[Thloftus]

The aluminum servo horn arrived so it was time to finish the steering links


I wanted to pair m3 fasteners with the drag link we made earlier. This works fine on the bellcrank end since the Hot Racing part is tapped for m3, but not so well with the Losi servo horn - which is tapped for the kit ball stud threads (4-40’s according to Jato’s thread). I’m confused by the Hot Racing part since it’s incompatible with the kit by design, but no matter, time to press on!

I wanted to stick with my original plan and so ‘tapped’ the Losi servo horn for m3’s. Slightly untrue since what I actually did was use a stainless m3 fastener as a tap and just worked it back and forth slowly. I really do need more tools. It worked out fine. I used bearing oil for tap fluid since I don’t have any of that either. I tried to be sparing so as to not inhibit future thread lock. Thinking ahead! Here’s the final product with the drag link attached to the servo horn


I centered the servo and attached the horn. I think the ideal position is for the horn to be at a right angle to the face of the servo when the servo is centered. The horn didn’t exactly line up this way. I took up the slack by adding another 1.5 mm to the length if the drag link; required swapping the spacer I used earlier for two others. Here it is installed in place



I’m happy with how it turned out. Will be interesting to see how long the rod ends on the drag link last since; I’m hoping they don’t get sloppy too fast!


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