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Old 10-28-2012, 09:33 PM   #31
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Interesting feature I was told on the BD7 that seems new to TC design. I guess now you can change the diff tension without removing the bulk head clamps? Wow nice, if that's true. Just another great design feature that makes things easier for the pit guy. Anything that makes adjustments quicker and more efficient. I hope this feature will become a manufacture standard in the future.

Xray's was the first to start the what is standard in servo mount design now. Will Xray's short shock design become more popular?

Tamiya started keying the center bulk heads to help with tweak?
Not sure if it was Tamiya or Losi. The original Jrxs had all of the bulkheads and topdeck keyed together.
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Old 10-28-2012, 10:06 PM   #32
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Changing the layup of the carbon weave in the CF will change which way it flexes. I am not certain which ways make it the stiffest but its a combination of 3 layers and 2 angles. Like 45/45/45 or 90/90/90 or 45/90/45. Meaning each layer is laid in a different direction or angle from the previous layer to get different flex. Some will flex a LOT from corner to corner and be super stiff front to back. Others will be super stiff corner to corner but flex a lot front to back. Its all in what the manufacture recommends.

Another thing is thickness. When companies buy graphite its in say 2.4mm +/- 10%. So it can very in thickness. Most think the thinner is not as good but its not true. They use the exact same materials by weight in each sheet. Some just compress more than others. Generally a 2.4 sheet that comes out 2.3 will be stiffer than a 2.4 sheet that comes out 2.5 because of how it cured and was compressed.

Its why you see so many pro TC guys with so many chassis plates. Even though they look the same you have to actually feel them to see if they are the same.

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Quasi-isotropic layup provides the stiffest material. It is comprised of layers at 90* and opposite layers at -45*. This is what most chassis' are made from which provides the lowest deflection rate.
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Old 10-28-2012, 10:32 PM   #33
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Default re carbon

bit off topic but everyone is getting cf technical.
what is most people's opinion on edge gluing.
we have made tooling for aerospace layup and i have a mate who does mil spec armor composites and he laughed when i told him they ask you to edge glue. his opinion if carbon is made correctly glue will do absolutely nothing. i can see rounding edges as good but gluing ??
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Old 10-28-2012, 10:46 PM   #34
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bit off topic but everyone is getting cf technical.
what is most people's opinion on edge gluing.
we have made tooling for aerospace layup and i have a mate who does mil spec armor composites and he laughed when i told him they ask you to edge glue. his opinion if carbon is made correctly glue will do absolutely nothing. i can see rounding edges as good but gluing ??
RC carbon is CNC machined. After machining the multilayered edges are now exposed and susceptible to splitting during impacts. Early in my RC experience I did rush RC assembly and neglected to seal the edges and after a couple hard impacts, the layers began to delaminate. Costing about a hundred bucks to replace. But keep in mind, aside from glueing, a good sanding and rounding of the carbon is recommended so as the edges have a radius, not a sharp edge to catch obstructions. Haven't split a chassis split since.
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Old 10-28-2012, 11:23 PM   #35
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The Losi type R has center balance holes, (very handy), External diff adjustments (belt and ball diff tension) 5th body mound in the front of top deck, and front and rear suspension blocks that adjust toe and roll center by flipping over. Oh the spur comes off with an e-clip. But in watching cars like xray and tamiya,the Type R does not make the traction, or mechanical grip on low traction surfaces it appears.
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Old 10-29-2012, 12:26 AM   #36
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Questions??

I have a question regarding tc design - apologies in advance if i'm being retarded, my question is; Why aren't we running our shocks upside down with the heavy end at the bottom for a lower center of gravity?
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Old 10-29-2012, 12:52 AM   #37
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I have a question regarding tc design - apologies in advance if i'm being retarded, my question is; Why aren't we running our shocks upside down with the heavy end at the bottom for a lower center of gravity?
Because the weight would then become unsprung...
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Old 10-29-2012, 12:53 AM   #38
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I have a question regarding tc design - apologies in advance if i'm being retarded, my question is; Why aren't we running our shocks upside down with the heavy end at the bottom for a lower center of gravity?
Won't inverting the shocks will create more unsprung weight?
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Old 10-29-2012, 04:52 AM   #39
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RC carbon is CNC machined. After machining the multilayered edges are now exposed and susceptible to splitting during impacts. Early in my RC experience I did rush RC assembly and neglected to seal the edges and after a couple hard impacts, the layers began to delaminate. Costing about a hundred bucks to replace. But keep in mind, aside from glueing, a good sanding and rounding of the carbon is recommended so as the edges have a radius, not a sharp edge to catch obstructions. Haven't split a chassis split since.
CA glue wont stop that.
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Old 10-29-2012, 04:53 AM   #40
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TC's in the past had external belt tension adjustments. It was a bearing on a post that slid perpendicularly to the belt, in a slot on one of the bulkheads.
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Old 10-29-2012, 08:36 AM   #41
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CA glue wont stop that.
Ca glue alone won't stop delamination. A combo of radiusing the egdes and then sealing with ca glue will help prevent delamination. Never said it will eliminate delamination.
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Old 10-29-2012, 10:50 AM   #42
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Getting off topic but yes, CA can help prevent delamination but it's not as important as it used to be. Some of the old CF's, like the stuff composite craft and the old AE stuff was really easy to delam. You absolutely had to CA the edges or it would on the first good hit. Fortunately modern stuff is MUCH better. I haven't had a chassis delam in years and I'm lazy so I only CA them about half the time.
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Old 10-29-2012, 11:03 AM   #43
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Would have figured some discussion would have come up about push rod suspension by now. Anyone know if the benefits outweigh the cons?
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Old 10-29-2012, 11:25 AM   #44
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Quasi-isotropic layup provides the stiffest material. It is comprised of layers at 90* and opposite layers at -45*. This is what most chassis' are made from which provides the lowest deflection rate.
Yes, Quasi-isotropic carbon typically is spec'd with fibers arranged in 5 directions 45/90/0/90/45 or 90/45/0/45/90.

A manufacturer can spec any order or thickness of each layer they feel is best.

Some spec just 0-90 fiber orientation for more twisting flex. This is not quasi-isotropic.

You can cut chassis with the 0 deg core along the center or across. This changes the longitudinal stiffness.

As EA said most of the top companies buy from a US Carbon manufacturer. That said the Chinese can also make top quality carbon. I have seen samples every bit as good as the US made stuff.

Also, to a point thickness has little to do with stiffness. By altering the solids to resin ratio you can get big difference in overall weight and stiffness. The type of carbon fibers used also makes a difference. You can buy different diameters and tensile strength fibers.

BTW, this is all useless for most people. Manufacturers will never tell you what the specs are for their carbon. This is also why 3rd party hop up chassis can be hit or miss performance wise....although everyone always says they are awesome since no one ever drops $100 on a chassis and says it sucks.
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Old 10-29-2012, 11:37 AM   #45
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Would have figured some discussion would have come up about push rod suspension by now. Anyone know if the benefits outweigh the cons?
Not needed. The main advantage of a pushrod suspension is aerodynamic to get the shocks inboard and out of the air on open wheeled cars. This would have no effect on a TC. There are some other interesting things you can do with pushrods but they are mostly benefits for high downforce cars, again no help for a TC. Downside is more unsprung weight and much more complexity.
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