fnknan Posted September 16, 2019 Share Posted September 16, 2019 I want to get rid of the A-arm flex on my cheap buggy as it is absolutely horrendous but I'm not sure what to do about it? They offer aluminium hop up a-arms but I'm skeptical over them bending into pretzels or breaking plastic parts linked to them. They don't sell any stiffer plastic ones. Would making custom Carbon Fiber arms be more viable? Or is CF not tough enough to withstand the forces that act upon A arms? I won't be doing any hardcore bashing with it. It's going to be more of a track focused build. Any help would be much appreciated. Quote Link to comment Share on other sites More sharing options...
RadioFish Posted September 16, 2019 Share Posted September 16, 2019 By stiffening one bit you send the force to the next week link.....Sent from my LG-H870 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Ninetiesbeard Posted September 16, 2019 Share Posted September 16, 2019 Okay, lengthy post incoming... What radio fish said is exactly correct. If you start beefing up areas which are designed to flex, then the next component will have an increased wear rate and fail. I actually run aluminium extended a arms on my hpi savage. This means for me, the leverage on the arm mounting points is increased as well as stiffening the material that the arms are made from. I was using RPM beforehand. Ive had a few tumbles and cartwheels and AFAIK everything is still straight and true. Although these arms are only made from 6062 aluminium, which isnt as hard as 7075 they seem to be holding up just fine; and the savage is a really heavy truck. My suggestion, is that you look at the type of driving you do, decide if the arms are likely to bend, what sort of forces they are subject to and from which direction, then make your decision. You could engineer a brace for the stock plastic arms using carbon fibre, a kind of strap that attached to the front and rear of the arm to add strength and rigidity. You could also cut a plate of carbon fibre outlining the footprint of the arm, and bolt this to the underneath of the arm to stop flex in that direction. Many ways to skin this cat, let us know what you decide to do 1 Quote Link to comment Share on other sites More sharing options...
fnknan Posted September 16, 2019 Author Share Posted September 16, 2019 43 minutes ago, RadioFish said: By stiffening one bit you send the force to the next week link..... Sent from my LG-H870 using Tapatalk Yeah I'm fully aware but the flex affects handling and I'd rather have a better handling buggy due to the fact that I'm not a very hard basher. Quote Link to comment Share on other sites More sharing options...
fnknan Posted September 16, 2019 Author Share Posted September 16, 2019 9 minutes ago, Ninetiesbeard said: Okay, lengthy post incoming... What radio fish said is exactly correct. If you start beefing up areas which are designed to flex, then the next component will have an increased wear rate and fail. I actually run aluminium extended a arms on my hpi savage. This means for me, the leverage on the arm mounting points is increased as well as stiffening the material that the arms are made from. I was using RPM beforehand. Ive had a few tumbles and cartwheels and AFAIK everything is still straight and true. Although these arms are only made from 6062 aluminium, which isnt as hard as 7075 they seem to be holding up just fine; and the savage is a really heavy truck. My suggestion, is that you look at the type of driving you do, decide if the arms are likely to bend, what sort of forces they are subject to and from which direction, then make your decision. You could engineer a brace for the stock plastic arms using carbon fibre, a kind of strap that attached to the front and rear of the arm to add strength and rigidity. You could also cut a plate of carbon fibre outlining the footprint of the arm, and bolt this to the underneath of the arm to stop flex in that direction. Many ways to skin this cat, let us know what you decide to do Yeah I was thinking about a brace/plate because the arms are very susceptible to torsion flexing. I doubt the type of driving I'm going to do will bend arms. Especially in such a light vehicle running a 17.5t motor. But I am worried about the extra weight of aluminium affecting how fast the suspension can move. If I was to make a CF plate would glue be enough to keep it down or do I want to drill holes in the arms and add screws to hold it? 1 Quote Link to comment Share on other sites More sharing options...
Ninetiesbeard Posted September 16, 2019 Share Posted September 16, 2019 I would drill holes and bolt it, but steer clear of stress points like crosses in bracing ect. The car will pick up more weight in mud on the tyres than you gain from switching to aluminium. Its mere grams 1 Quote Link to comment Share on other sites More sharing options...
mond Posted September 16, 2019 Share Posted September 16, 2019 The higher spec heat treated aluminium types weigh only marginally more than plastic. If you're not going to be doing silly stuff with it, get the aluminium arms. 1 Quote Link to comment Share on other sites More sharing options...
fnknan Posted September 17, 2019 Author Share Posted September 17, 2019 21 hours ago, Ninetiesbeard said: I would drill holes and bolt it, but steer clear of stress points like crosses in bracing ect. The car will pick up more weight in mud on the tyres than you gain from switching to aluminium. Its mere grams Ah okay thanks. How would I thread extra shock mounting holes if I choose to drill them? I assume it's different than plastic Quote Link to comment Share on other sites More sharing options...
ostewart Posted September 18, 2019 Share Posted September 18, 2019 Why do you think race buggy's use aluminium arms? They need a certain amount of flex for durability, it only takes one crash to bend an aluminium arm and that will affect your handling more than a plastic arm slightly flexing. Higher spec race buggy's use higher quality plastics Quote Link to comment Share on other sites More sharing options...
mond Posted September 18, 2019 Share Posted September 18, 2019 2 hours ago, ostewart said: Why do you think race buggy's use aluminium arms? They need a certain amount of flex for durability, it only takes one crash to bend an aluminium arm and that will affect your handling more than a plastic arm slightly flexing. Higher spec race buggy's use higher quality plastics MCD top spec cars, the ones currently winning most of the LSOR races all use aluminium arms, as do a number of other cars used in LSOR. Not disagreeing with your logic - I wouldn't use them for any scale but they are used for off road racing at the highest level. Quote Link to comment Share on other sites More sharing options...
ostewart Posted September 18, 2019 Share Posted September 18, 2019 3 hours ago, mond said: MCD top spec cars, the ones currently winning most of the LSOR races all use aluminium arms, as do a number of other cars used in LSOR. Not disagreeing with your logic - I wouldn't use them for any scale but they are used for off road racing at the highest level. Fair point I have seen the MCD ones use them, but that's about it and only really seen in 1/5th scale. Pretty much all 1/10 and 1/8 scale use plastic and some with carbon fibre stiffening plates. Quote Link to comment Share on other sites More sharing options...
mond Posted September 18, 2019 Share Posted September 18, 2019 Perhaps it's down to cost. If you're racing 5th scale outside of a stock class like FG minis, you're already paying a small fortune and let's be honest, 5th scale off road these days in Europe is barely off road. All the tracks are flat AstroTurf, with tiny jumps made from ply wood. Youve more chance of having a crash walking up the drivers podium. 1 Quote Link to comment Share on other sites More sharing options...
fnknan Posted September 18, 2019 Author Share Posted September 18, 2019 13 hours ago, ostewart said: Why do you think race buggy's use aluminium arms? They need a certain amount of flex for durability, it only takes one crash to bend an aluminium arm and that will affect your handling more than a plastic arm slightly flexing. Higher spec race buggy's use higher quality plastics Trust me id much rather use plastic too but the plastic in this buggy flexes so bad that they need to go. I can twist them almost 90 degrees lol. If there were aftermarket plastic ones they'd already be on the car Quote Link to comment Share on other sites More sharing options...
ostewart Posted September 19, 2019 Share Posted September 19, 2019 14 hours ago, fnknan said: Trust me id much rather use plastic too but the plastic in this buggy flexes so bad that they need to go. I can twist them almost 90 degrees lol. If there were aftermarket plastic ones they'd already be on the car Rather than pile £££'s into this model, it might be worth saving for a better buggy then, it'll be much cheaper in the long run. You haven't said what buggy you have btw Quote Link to comment Share on other sites More sharing options...
fnknan Posted September 19, 2019 Author Share Posted September 19, 2019 2 hours ago, ostewart said: Rather than pile £££'s into this model, it might be worth saving for a better buggy then, it'll be much cheaper in the long run. You haven't said what buggy you have btw It's a hsp flying fish that I converted into a rally car and now into a buggy. These things can handle pretty well with the right setup and still be cheaper than the more expensive vehicles. Spare parts are cheaper on this than anything besides those wltoys cars. Quote Link to comment Share on other sites More sharing options...
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