Big Rock I’m a Noob that needs help how to fix Big Rock

[Lucky Socks]

Have a V3 Big Rock BLX and it did some cartwheels the other day. It appears that the rear arm is broken? I posted some pictures, is that the only thing it looks like that I need to fix? What tools will I need to fix this? Thanks.

I’m thinking I should be able to find some tutorials how to fix on YouTube. I’m just not sure what exactly is broken and what tools I need to get.

 

[Tex Koder]

You'll need a hex driver set $11 on Amazon that has 1.5mm ,2mm ,2.5mm ,3mm.

You need the Big Rock (or Typhon) 3S rear suspension arms and might as well get the front set too while you're at it.

Jenny's (JennysRC.com) have both sets for $12.50
https://jennysrc.com/products/arrma...e-senton-ar102711?_pos=6&_sid=d595edfb9&_ss=r

Oh and it looks like you lost the small/short retaining screw off the arm that hold in the outer hinge pin. So you'll need to see if you can find another similar screw.. Just look on your other rear suspension arm to see what I'm talking about.

Simple repair to DIY.
Get it done and BASH on!!

 

[Hector_Fisher]

The hinge pin ripped out of the arm. You'll need to order a new arm, part AR330540. Can use amazon, amainhobbies.com, or lots of other hobby sites. Or you can go with a kit breaker like jennysrc.

Your best resource will be to use the exploded parts view diagrams to find which parts need to be replaced.
https://www.arrma-rc.com/on/demandw...282/Manuals/ARA4312V3-Exploded-View-MULTI.pdf

 

[Mikeeeeeal]

Probably get a set of hinge pins too they're nice to have around vs trying to straighten them if they bend.

 

[Lucky Socks]

Wow thanks everyone for your help. Ok so likely just the arm then. Will get a hex driver set and search for repair video.

You'll need a hex driver set $11 on Amazon that has 1.5mm ,2mm ,2.5mm ,3mm.

You need the Big Rock (or Typhon) 3S rear suspension arms and might as well get the front set too while you're at it.

Jenny's (JennysRC.com) are have both sets for $12.50
https://jennysrc.com/products/arrma...e-senton-ar102711?_pos=6&_sid=d595edfb9&_ss=r

Oh and it looks like you lost the small/short retaining screw off the arm that hold in the outer hinge pin. So you'll need to see if you can find another similar screw.. Just look on your other rear suspension arm to see what I'm talking about.

Simple repair to DIY.
Get it done and BASH on!!

Hmm ok, thanks. That screw might be harder to find. Which part is that on the exploded view? I will see what I can find.

 

[Tex Koder]

Wow thanks everyone for your help. Ok so likely just the arm then. Will get a hex driver set and search for repair video.


Hmm ok, thanks. That screw might be harder to find. Which part is that on the exploded view? I will see what I can find.

Here's a video that will guide you through the basics ,I tagged the direct section for the rear arms >>

[ NOTE- When he states a 2mm screws.... He'd misspoke.. It's a 2mm hex driver that's needed to remove a M3 button head screw. Just a heads up. ]

Here's the SKU# for those little retaining screws - ARAC9841
Interactive Exploded View >>
https://www.astramodel.cz/en/eview/ara4312V3-bigrock/chassis.html

>>> But all they really are ,are just tiny M3 x 3mm button head screws ,so I'm sure you have some of those lying around..

 

[Moirae]

Exploded view is such a big help to figure out what you need to replace. I definitely got overwhelmed the first time I looked at it though

These guys gave you awesome advice!

 

[~Kaos911~]

Since everyone else has you covered with identifying the broken part and what you need.

I will say from experience, get a 3 pc set of MIP hex drivers. $50 at Hobby Town (my local hobby store). I started out with a neat looking Dynamite set from HT, but went back a few weeks later to get the MIP set. Even on my Big Rock I rounded the driver bits on the Dynamite set. After adding 6S rigs to my collection the MIPs have been very helpful.

While browsing through Jenny's you can pick up a set of screws as well.

 

[Hector_Fisher]

Hmm ok, thanks. That screw might be harder to find. Which part is that on the exploded view? I will see what I can find.

Part AR721303 is the retaining screw. Really it's just a short 3mm retaining screw, so you might have something laying around the house that would also do the trick.

Another option is to contact Horizon Hobby and request a warranty. I don't know the circumstances behind why the truck broke (whether it was user error like crashing into a fence post, or poor quality parts like the truck just broke suddenly), but it's always an option. Email should be in this thread:
https://www.arrmaforum.com/threads/what-arrma-warranty-email-are-you-using.54307/

 

[Velodromed]

Lots of good info above. These are a good set of cheap hex drivers. My set is still going strong after more then a year of fairly heavy use. Regarding jennysrc.com…they have great prices on most parts and are a very dependable small business. There is shipping, 5-12 bucks depending on the size of the parts ordered, so get other parts as well to maximize on the shipping fee.

Hubs are a part that tends to break often so get a set of those. It’s handy to have more shell hex and pins also, they are pretty cheap. The stock s651 Servo also doesn’t last typically. I like the s652 servo off the 6s line $20). It’s drops in, using the existing stock 23t servo saver. The steering bellcrank assemblies are really cheap also and include the servo saver. I like having a few of those around for when steering suffers.
Neewer - Set of 4 Hexagonal Screwdrivers Made of Titanium Nitride with Coloured Handles.Compatible with 1.5, 2, 2.5 and 3mm Screws. https://a.co/d/iKr0t4i

 

[RCbuzz]

Wow thanks everyone for your help. Ok so likely just the arm then. Will get a hex driver set and search for repair video.


Hmm ok, thanks. That screw might be harder to find. Which part is that on the exploded view? I will see what I can find.

If you have spare screws and a Dremel just cut one down. Have done it several times

Pro Tip, grab an extra proper sized nut to secure the screw in the vise before cutting. Then after the cut is complete the nut will actually help restore the threads when you remove it.

 

[Velodromed]

If you have spare screws and a Dremel just cut one down. Have done it several times

Pro Tip, grab an extra proper sized nut to secure the screw in the vise before cutting. Then after the cut is complete the nut will actually help restore the threads when you remove it.

That’s a good idea, your pro tip. I will totally use it. I have a ton of 30-40mm, high quality cap heads I need to cut down.

 

[Diggery]

I'll post this again as I found it helpful when starting to fix my car.

https://www.arrmaforum.com/threads/3s-platform-tool-sizes-fluid-thickness-for-reference.34544/

You could get away with just a 2mm and 2.5mm hex driver for the majority of the car and a 7mm socket or nut driver to remove the wheels.

 

[Lucky Socks]

I'll post this again as I found it helpful when starting to fix my car.

https://www.arrmaforum.com/threads/3s-platform-tool-sizes-fluid-thickness-for-reference.34544/

You could get away with just a 2mm and 2.5mm hex driver for the majority of the car and a 7mm socket or nut driver to remove the wheels.

Thanks I was just going to ask about the 7mm socket. Was watching the repair video posted above and noticed I needed a different tool for the wheels

 

[Lucky Socks]

I'll post this again as I found it helpful when starting to fix my car.

https://www.arrmaforum.com/threads/3s-platform-tool-sizes-fluid-thickness-for-reference.34544/

You could get away with just a 2mm and 2.5mm hex driver for the majority of the car and a 7mm socket or nut driver to remove the wheels.

I’m seeing a set of a 5.5mm and 7mm nut driver wrench. The 5mm nuts that are referenced in this link, will the 5.5mm wrench work? When it says 5mm in the link does it really mean 5.5mm?

Edit: Nevermind, I think they are different and I would need the 5mm wrench

 

[Velodromed]

I’m seeing a set of a 5.5mm and 7mm nut driver wrench. The 5mm nuts that are referenced in this link, will the 5.5mm wrench work? When it says 5mm in the link does it really mean 5.5mm?

Edit: Nevermind, I think they are different and I would need the 5mm wrench

Here, check these out. Sometimes specific ‘rc tools’ are priced at a premium. 7mm is what you need for the standard 3s wheel nuts.
Antrader Hex Screw Driver, 7mm High-carbon Steel Socket Wrench Screwdriver Carburetor Adjustment Tool https://a.co/d/4KOYOtj

 

[Lucky Socks]

Do you think this has the tiny screws I need? https://jennysrc.com/collections/ar...s-tools-nuts-hardware-granite-senton-ar102711

Kind of having trouble finding the individual parts, such as the screws and hinge pins. I see the part number on the exploded view but can’t seem to find to buy

edit: nevermind, i found the little screws on amainhobbies using the skew posted above. now to find the hinges

 

[Tex Koder]

Do you think this has the tiny screws I need? https://jennysrc.com/collections/ar...s-tools-nuts-hardware-granite-senton-ar102711

Kind of having trouble finding the individual parts, such as the screws and hinge pins. I see the part number on the exploded view but can’t seem to find to buy

edit: nevermind, i found the little screws on amainhobbies using the skew posted above. now to find the hinges

Yes, I see those tiny screws in the bundle.

And the hinge pins are here >
https://jennysrc.com/products/arrma...bulkhead-ar102711?_pos=2&_sid=8e816a5e3&_ss=r

 

[Lucky Socks]

Yes, I see those tiny screws in the bundle.

oh great, thanks

Ok I think I ordered everything I need. Supposed to get here in a couple of days. I'll let you know how it goes haha.

 

[Lucky Socks]

Yes, I see those tiny screws in the bundle.

And the hinge pins are here >
https://jennysrc.com/products/arrma...bulkhead-ar102711?_pos=2&_sid=8e816a5e3&_ss=r

Thanks, yeah I saw those pins but didn’t want to order all the extra stuff. Although I guess it couldn’t hurt having spare parts lying around. I ended up ordering through amainhobbies, they had all the parts I needed.