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I was at RCGears tonight...first jump I broke a rear race arm

Not sure what's going on but I think the plastic is "Kyosho"!

I took one of my broken arms and could snap it in half with my hands. I remember when we first got the kit, we could bend the tab that held the rear suspension mounts 100 times and it would not snap. I wonder if the 3d plastic has a short shelf life?

I'm not sure what the deal is, but I hope boiling them will help. It's very disappointing to say the least. The have been so much money thrown into one of these buggies. Maybe I'll save mine for indoor racing where the jumps are only 2" high lol.

Are you using the replica arms or the racing arms? There's not much point in using the replica arms if you're going to run it. Likewise for the rear arm mount, hub carriers, etc.

stickboy007 wrote:Are you using the replica arms or the racing arms? There's not much point in using the replica arms if you're going to run it. Likewise for the rear arm mount, hub carriers, etc.

I'm running the full race setup... with rpm 10t rear hubs now.

Wow. That is very concerning. These arms aren't cheap either

Any chance the race arms are "too" rigid? The flex in the standards may keep from breaking, albeit at the cost of rigidity

stickboy007 wrote:Wow. That is very concerning. These arms aren't cheap either

Yea, tell me about it!

Hope the boiling will fix this!

Based on your pics...

The arm that broke is the same arm that was involved in the wreck that broke the Hub..

Looking at these two pics
http://www.rc10talk.com/download/file.php?id=98906&mode=view

http://www.rc10talk.com/download/file.php?id=98905&mode=view

there is obvious damage/wear to the rear arm at the holes on the back of the arm & towards the outer hinge-pin. Which may have already weakened the arm. I bet is was the RPM hubs.

Note, RPM has a parts guarantee to be unbreakable under normal racing conditions, so by using those tough bastards, all impact/twist forces are going to go straight to the A-arm and twist snap it as you see in your last pic... There always has to be a weak point, something that will give as a trade off..

And seeing that big long flying jump you took when you broke the hub, that's a similar big jump I tried, landed wrong and snapped my a-arm.. using plastic B4hubs, on an indoor track.. Granted, I was 7ft in the air and landed solidly on my left rear wheel - I expected to see a break.. even using normal parts..

I think the boiling might help a little, but not if you are going to stay using those RPM hubs and on that big outdoor track. I ran the original 10T with similar arm design, and I think the Orig Plastic is tougher, but I still broke a many a-arms on our similar outdoor track back in the early 90's..

It appears to me that a more durable solution is to run Dynotech or RPM arms. Same length, but admittedly not "true" '91 design. The Dynotech arms would probably flex the least and be the most durable, although it would put more stress on the rear hinge pin mounts and the front bulkhead. I guess it depends on authenticity vs. durability and where you want to be along this spectrum.

This is all a bit strange, though. Mark's NIX '91 does not break often and I have seen it at the track several times (admittedly an indoor track), with the same racing spec arms. He has abused the hell out of it and insists it is pretty durable.

Just thought I should add that I personally have noticed a pretty huge variability in the porosity, quality of the material and the printing tolerance from shapeways. Not passing the blame directly to them on this particular failure... just adding that it could be part of it.

Rod, I'm away for work during the next two races, are you going to running the NIX91 buggy? I actually got a call to go work in the field and couldn't refuse it as you know...I've been out of work for months and need the money.

I'm sure I had pre existing damage from my last crash, which contributed to my broken arm. Also, as mentioned above, that RPM hub is a beast and the arm is going to break first.

I'm not giving up anytime soon. Boiling is next and if I still break more arms I may have to retire this buggy from outdoor tracks and just run it indoors. I'd really hate to do that because I love how it handle in the dirt.

I'm drinking I'll admit, but any thought of plasti-dipping the parts several times over and cutting away the areas where hardware will need to be inserted? I know it's not rigid, but it may provide just enough tension to prevent breakage. Kinda like a condom. Plus it will keep any female Turn Marshalls from getting impregnated. I said "inserted".

THEYTOOKMYTHUMB wrote:I'm drinking I'll admit, but any thought of plasti-dipping the parts several times over and cutting away the areas where hardware will need to be inserted? I know it's not rigid, but it may provide just enough tension to prevent breakage. Kinda like a condom. Plus it will keep any female Turn Marshalls from getting impregnated. I said "inserted".

lmfao, where to start... to begin with, I don't think plastidip would add any benefit besides changing the colour to what ya want... to end with, I water resisted a lipo with 12 layers of plastidip and then wrapped it with a magnum condom, now that would save the female marshalls lol.

vintage AE wrote:

THEYTOOKMYTHUMB wrote:I'm drinking I'll admit, but any thought of plasti-dipping the parts several times over and cutting away the areas where hardware will need to be inserted? I know it's not rigid, but it may provide just enough tension to prevent breakage. Kinda like a condom. Plus it will keep any female Turn Marshalls from getting impregnated. I said "inserted".

lmfao, where to start... to begin with, I don't think plastidip would add any benefit besides changing the colour to what ya want... to end with, I water resisted a lipo with 12 layers of plastidip and then wrapped it with a magnum condom, now that would save the female marshalls lol.

I'm guessing it's still pretty nipply there too? Maybe when it warms up a bit the parts will hold up better. A few degress, especially 15 (F ) or so can make a big difference. One reason why I NEVER run vintage Tamiya stuff in the winter here, but beat the s#1+ out of my Traxxas stuff. Good luck!