My RR-10 adventures

[Zka17]

I taught that it would be nice to have all things together with my custom Axial RR-10 Bomber... I have recently built it for primarily driving it when I am hiking, but also for the sake of building

I saw many built threads here, so I was thinking that, instead of posting an another built, I would rather share my "adventures" - pictures from my driving sessions. Well, the truth is that I haven't took pictures when I was building it... Then, based on the pictures and situations, I would go deeper in details.

As mentioned before, the truck is custom built. I was trying to get the best parts available to have an easily drivable rc car. Since I am hiking quit a bit (SC Upstate has many gorgeous waterfalls!) on non-regular trails, I choose an off-road setup: based on what I have read mostly on this forum, I have chosen the Axial RR-10 Bomber.

I already tried before, just around the house, and had a major problem: it was snapping the front axle shafts. It seems that I have managed that problem... "thumbs"

So, to introduce my new toy, here are some pictures from today's driving:









While I was researching the rc trucks (specifically crawlers), I have found a local hobby store where they are selling a lot of rc stuff. But most importantly, they have some tracks! These are race tracks, one of them for off-road cars... it seemed the ideal place to learn driving before I head out to the trails...

Well this was mostly high speed driving, with some jumps. It was hot (95F) and humid (80-90%) - not sure who overheated more, me or the truck... I had a lot of water, the car's motor burned my finger tip when wanted to check it's temperature!

I read somewhere that I should keep the motor's temp under a certain limit, but how when outside is already hot?! If it burns, it burns...

[Zka17]

I had lying around a 3s Onyx LiPo and thought to see how my Bomber would take it... Previously I used a 6-cell NiMh, it snapped front axle shafts with it. Then I have driven it on the track with a 2s LiPo, and I was amazed how much faster it was!

To be completely honest, I have to mention that I was running the NiMh battery on grass, while the 2s LiPo on the track. I think the grass has a natural dampening, slow down effect on this car...

Last night, after more than half day of charging, went out behind the house. Still high outside temp and relative humidity (I think this will be like this all summer). The grass was over the axles, some places tall like the tires - one reason for driving there was to clean the tires from the previous day's dirt... then I had some driving on the asphalt...

In the grass, I was amazed how much faster the car is with the 3s LiPo, but got really shocked when observed that I'm in low gears of the transmission! Turning around was possible only if I had slowed down (no such problem with 2s LiPo, low gear), and despite my sway bar, the car was twisting on acceleration.

In high gears, full throttle is doable on straight and mostly flat surfaces only. A slightly bigger bump (a piece of rock) on one side would send the whole thing in the air - spinning around and arriving back on the top or sides.

On asphalt it was crazy fast - and unstable! Straight run is OK, but need to slow down for the smallest direction changes.

This combination, 3s LiPo and high gears, wasn't why I built it for, it is too fast, but certainly gives some feedbacks of my built:

1. I think the truck sits too high, at some point will have take some good pics to observe this
2. I must have assembled the Hot Racing sway bar wrongly (or it was just too much torque), because the body was twisting even in low gear
3. I my need to adjust my shocks, stiffen the rear ones and... do something with the front ones



I know, this picture is not too good, but bare with me, I am learning this too... I am sure it wasn't the proper setup: driving with one hand and using the iPhone with the other hand. I need to figure out fast how the pros are doing this! (any suggestion is welcome!)

[JatoTheRipper]

Nice looking Bomber!

[Zka17]

I am still under shock from the speed my truck can do with a 3s LiPo... need to go back to the dirt track! Maybe this time will be able to get some more/better pictures too...

However, the truck needed some general maintenance... tightening some screws, checking some others... While, I was there, I thought that I could do something with the instability at high speeds.

The first idea was to widen the wheel tracks:





When I moved to the front, I realized that I have a problem! The 8mm nut driver does not fit the wide wheel hubs... My wheels are Gear Head, and I had the normal and wide hubs for them:



Because the front axle shafts are the Vanquish VXD Universals, the lock nuts securing the wheels are 5mm ID, 8mm OD. I can barely secure the normal hubs with my 8mm socket, but it won't fit the deep wide hub...

I went in all the stores around to find the proper socket, but no luck... Vanquish mentions on the VXD Universal's page that a modified socket is needed, but could not find that either. I think, I need to find somebody with a lathe and file down the OD of an existing 8mm socket - unless somebody here has a better idea...

While I was driving from store to store, an another idea popped: I could do something with the shocks! I've had around some Pro-line Powerstroke shocks, so when I got home, I filled them with oil and tried them on.

With the Gmade XD Piggybacks:



And with the Pro-line Powerstrokes:



To lower the ride height, I needed to mount the longer (XT, 128mm) Powerstrokes in the very back position, but also needed to remove the sway bar... to compensate, I fitted the shorter (102mm) Power strokes right before the longer ones. In front I mounted just a single 102mm one. It came down approx half an inch. The back end is stiffer now, for sure, but will see under torque... The front may hit the servo, I used softer springs - but the servo has metal housing, so should be fine... I just simply can not appreciate without running it...

Can not wait to run it!

[BattleShrink]

Badass. I wish I had a couple extra sets of powerstrokes just lying around I'm curious to see how that rear shock setup handles too.

If you're going to use your newfound speed and stability to jump things, I would Dremel off the lip on the bumper where the servo is hitting. If it's hitting the housing it's probably not as bad as mine where it was hitting the horn/arm. I didn't touch the part where it looks like a tube, but I took off all the flat bit without any problems.

[Zka17]

Thanks for the tip! Actually not sure about that servo-hitting... it is very close, but even completely compressed, the servo horn moves freely...
Couple more hours and will be at the track!

[Zka17]

Much better weather now than last time! There were couple guys at the track, but they were just coming off for a brake...

So, the track is ours!



Did couple laps in low gear, just to get used with the turns and hoops... well mostly tried to keep the truck between the yellow thing - I am just learning to drive. After 3 laps without mishaps, turned into high gear - then the hell broke loose! This thing is fast! It was jumping over the hoops like crazy, turning in drift mode - it was real fun...

Obviously, steering is a real challenge in high speed mode... need to learn how to fine tune the Spectrum DX5R (maybe start reading the manual...). I've had few roll overs, but just put the truck back on its wheels and was going, no problem.



Until... it started spinning/drifting to the right side! Stopped responding to the steering wheel - just needed a quick pit stop:



And the front wheels are locked in that position!
I am not manually able to move the servo arm, nor it does turn from the transmitter... sometimes it does buzz though...

I did ask the other guys around, they seemed way more experienced in these things, and one of them double-checked my truck - "the steering servo is locked up" he diagnosed the problem... They were watching me and he said that it was a very mild abuse, and this not suppose to happen... well, it did...

At first look, it wasn't any binding or any sign of direct servo hit... btw, this is the Savox 1210SG... out of warranty, so thinking to take it apart and see what's inside...

In mean time I am open for suggestions of steering servo alternatives! I would prefer a waterproof one...

[durok]

Top-tier servo options include:

Savox 2290, ProModeler 470oz-in, Holmes Hobbies SHV500v2 / HV500v2...

Looks like you had a blast!

[Zka17]

Thanks durok, will check them out!

I took off the servo and hooked it up to my tester device - check video...

This thing started to work... although it feels working hard, making more noise and getting very hot... I think I will still open it...

This supposed to have metal gears, then it should have some greasing - right?
Anybody knows which oil/grease is good to make things smoother?

[Zka17]

So, I went ahead and disassembled the servo...

The electronic side does not show any burns:


At first look, the gear side seems fine too...




I have attached it again to the servo tester and wasn't OK... still could not rotate it with my hands - but found this:


There is something strange there... then I found this little piece on an another gear:


I know where this is going...


And yeah, the big gear lost one tooth, which destroyed the meshing gear:


I think, this servo is gone!
I read good reviews about it, would not expect to strip gears... It is not making sense, the whole steering was not binding, the end points were reduced to 70%... or maybe this one was a weak one...

Out to check durok's suggestions!

[ScoJac]

Too bad that happened, that’s a decent servo. If the servo is still works ok, Savöx has a replacement gear set for it for under $30

[FlatLander72]

They sell replacement gear send for the servos. It was about $35.00 for me.

Sent from my Moto Z (2) using Tapatalk

[Zka17]

Originally Posted by ScoJac

Too bad that happened, that’s a decent servo. If the servo is still works ok, Savöx has a replacement gear set for it for under $30

Originally Posted by FlatLander72

They sell replacement gear send for the servos. It was about $35.00 for me.

Sent from my Moto Z (2) using Tapatalk

Thanks guys, I have found and already ordered the new gears! "thumbs"

Does it come with instructions? Maybe some greasing agent?

[Taurus84]

I would try turning the gears 180 degrees so the damaged parts won't be stressed at all.

[Zka17]

I was thinking about that, but I'm not comfortable with the idea that something is wrong there... and now, the new gears are en route...

I am still trying to understand what could caused this? All the reviews I saw states that this servo is avery good one... in fact I found only one case when the gears of the 1210SG has stripped, otherwise most people use this servo to replace the broken other brands...

I must be doing something wrong... I am wondering if the axle shaft snappings and the servo gear stripping has anything to do with each other? The servo broke after I started to use stronger axle shafts... maybe the next thing to broke was the servo gears... Have to experiment these things further!

[durok]

Servos are one of the easiest things to break in a Bomber, they run such large tires, and have such a wide track that the leverage provided by the steering links can be quite severe.

When you stiffen up the links and servo horn by upgrading to metal ones, the force from impacts is transmitted directly to the gears.

Unfortunately, the quoted specs for that servo:

Torque @ 6v - 20.0kg/277.7oz-in
Torque @ 7.4v - 23.0kg/319.4oz-in

Are at the low end for a vehicle such as the Bomber - most people agree that 350oz-in is the STARTING point for what to use...

Were you giving it the full 7.4v?

If not, the servos torque specs rapidly begin to drop...

The servos I mentioned earlier have considerably higher numbers, the Savox 2290 has - for example:

Torque @ 6v - 40.0kg/555.5oz-in
Torque @ 7.4v - 50.0kg/694.4oz-in

The Holmes servos run between 450-520oz-in, and the ProModeler is around 440-470 depending on voltage supplied.

When buying servos that are meant for 2.2" wheels, it's best to spend some real cash to get a beast.

Otherwise, the constant gear or complete replacement adds up very fast to where you've easily spent more than you would have with choosing a higher-end model to start with.

[Zka17]

And I'm listening to what you're saying...

[durok]

Hey - for my "tiny-tire" Ascender rig (OD of tire only 4.19"), my $17.99 DS3218 servo hasn't given up in nearly 7 months of abuse...

But I ordered a HH SHV500 way back when they were first introduced (so mine is a v1, not a v2, which has been slightly re-engineered for even more power and strength) for my originally-planned Bomber.

Then, when I realized I was building a 2nd one, I ordered a ProModeler 470oz-in for it.

I even picked up a relatively inexpensive JX 12V servo when it was released, just as a backup for my v1 - so I could have something to throw in it if I had to send the v1 to Holmes for a replacement.

Unfortunately, it seems as if JX fibbed a little on their specs, or at least on their metal gear quality - as some have broken them rather easily.

I wouldn't be surprised if I break it, now... but it's always on reserve, and needs no BEC - just like the SHV500 - direct from 3S LiPo power.

So - I'm not likely to get anything for either Bomber that is rated less than 470oz-in, and also only getting a model that has had lots of good feedback on this forum.

There will always be someone who can break practically any servo, a lot of it does depend on driving style & terrain - and of course, setting up of steering endpoints... etc.

I'm not planning on driving all that fast over big obstacles - I prefer to drive as if it were a 1:1, scaled down - so, fast is OK on smoother surfaces, slow on the rip-rap!

[Zka17]

Savox did a very good job shipping the new gears - they're already here!


For some reason I put my fingers around the upper bearings on these gears (left is the old, right is the new one) and guess what? The bearing on the right (green arrow) can be barely moved...


Maybe the whole mishap started with a bearing failure?

Mounted the the new gears and added some marine grease... (have no idea how much I should add)


Then went back to the servo tester and checked how it does - it is OK!

However, could not not listen to durok... While ordering the 1210SG gears, I added something else to the cart... - yeah, that is the 2290SG!


Of course, I have tested that too... love it's sound! I think, for now I will keep the 1210SG for backup (I have an another one mounted for the transmission)... I had to mount the new servo:


It fits better with the color scheme of that axle - doesn't it?
One thing about this new servo is that it's brackets where the screws are holding it are also metal. I like that very much! The old one was flexing a little bit there...

I have one more idea for this steering setup... for now... stay tuned...

[durok]

Congrats!!!

You now have what seems to have become the king of all servos installed - I have yet to read of a failure...

Absolutely beastly...