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Old 07-28-2005, 08:55 AM   #12286
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Quote:
Originally Posted by azenis
i would be very keen for someone to explain this, as it goes against everything i have ever known about chassis tuning! (for real cars)
Thats like comparing oranges to watermelons, completely different.
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Old 07-28-2005, 08:57 AM   #12287
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Can anyone help me with my questions above?

Thanks
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Old 07-28-2005, 09:14 AM   #12288
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Quote:
Originally Posted by azenis
yeh makes sense i guess

and is carpet that much smoother that it doesnt need this ? (sorry we dont have a carpet track here so i have never seen the carpet you race on)
Carpet is very smooth and has a very high amount of traction. This traction causes the tires to stick to the surface, when transitioning left to right and turning around corners. this is what cause the chassis to flex. The force of the car's weight carries the car in one direction, as the tires turn to go in another. The tires stay put but the car's weight shifts over them, thus causing the chassis to flex from the pressure. A stiffer platform (chassis) and suspension reduces this effect by keeping the car's weight more centered between the wheels. The car only needs a fraction of the force you're giving it, to flex enough, to unsettle it at speed. I hope I'm explaining this correctly. Feel free, anyone, to clean this up. Just trying to help.
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Old 07-28-2005, 09:29 AM   #12289
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Quote:
Originally Posted by Fantom11
I am adding on to my questions from the previous page. What is the upper deck mod that you guys are talking about? Is the center post for the upper deck worth getting for carpet racing?
Other than the optional front diff and stiffer springs, you won't need any hop-ups to run the car on carpet. The 3mm chassis and 2.5 upper deck will help the car handle better, but is not necessary. The stock center post is carbon graphite and works fine. The carbon graphite shaft would be good for stock and 19 Turn racing, as it reduces rotating mass and increases acceleration and top speed. Hope this helps.
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Old 07-28-2005, 10:22 AM   #12290
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That's well explained, but why don't stiffer chassis' work well outdoor on low traction surfaces? I would have thought that, as other people have said, the stiffer the chassis the better, and that setup alterations are all the is needed but this obviously isn't so as all the team drivers use the thinner chassis' for lower traction surfaces.
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Old 07-28-2005, 10:30 AM   #12291
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Quote:
Originally Posted by azenis
i would be very keen for someone to explain this, as it goes against everything i have ever known about chassis tuning! (for real cars)
Guys, while RC cars draw upon real car physics. We often forget that out cars run at much higher scale speeds and g-forces than real cars are subjected to.

This is why some theories should work well in practice, but practice shows some theories dont work.

To duplicate actual RC car physics in real cars, we'd have to run them at speeds of 500km/h to see what it does to their chassis. Even a real car's chassis will flex at those speeds.
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Old 07-28-2005, 10:41 AM   #12292
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Fantom- here is a link to what to do and a great pic of it afterward.
http://www.rctech.net/forum/showpost...ostcount=11145
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Old 07-28-2005, 11:16 AM   #12293
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Quote:
Originally Posted by Skill
That's well explained, but why don't stiffer chassis' work well outdoor on low traction surfaces? I would have thought that, as other people have said, the stiffer the chassis the better, and that setup alterations are all the is needed but this obviously isn't so as all the team drivers use the thinner chassis' for lower traction surfaces.
In theory, yes, I agree - the stiffer the chassis the better. I believe it makes the car handle more predictably and consistently. Although, I believe small amounts of flex is sometimes needed. The increase in chassis flex that the thinner chassis has, gives an increase in traction outdoors, where traction is considerably less. It's really more like a controlled flex. The chassis flexes within reason to allow the weight to transfer to the wheels, which will increase traction during lateral movement.
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Old 07-28-2005, 11:36 AM   #12294
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couldnt of said it better myself. basically think of i as another shock. the softer it it the more grip you will get, but when the car flexs more (or softer spring) there is more roll and the car scrubs speed in the corner. so yes by adding flex (thinner chassis) you get more grip but slower corner speeds. this isent the case with all asphalt tracks, some tracks can be just as grippy as carpet and there for the stock 2.5mm chassis is the better choice. but we run in a parking lot. granded there is still lots of grip but the 2mm chassis tip i got is from a guy that got 2nd in last years outdoor paved nationals, so ill listen
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Old 07-28-2005, 12:52 PM   #12295
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Thanks for the help guys. I'll get working on that upper deck mod. O yea, and what is the point of the upper deck mod??
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Old 07-28-2005, 01:16 PM   #12296
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Quote:
Originally Posted by Fantom11
Thanks for the help guys. I'll get working on that upper deck mod. O yea, and what is the point of the upper deck mod??
To reduce tweak.
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Old 07-28-2005, 01:39 PM   #12297
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Default BMI Pro4 Chassis

Anyone have experience with it? I plan on running my Pro4 on mainly carpet but occasionally on ashpalt. How is it for the mixture of surfaces? I read that you can take out the upperdeck standoffs and get it to work pretty well on ashpalt. Any help would be appreciated.
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Old 07-28-2005, 01:45 PM   #12298
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Default gp3700 cells fit?

I didn't see any postings to know iif any one was using the gp3700 cells on the pro4. Before I get some I was wanting to make sure they fit.

Is anyone using them?
Did you have to modify the chassis?
Are you using both 3300 & 3700 (3300 practice/qualifer, 3700 main)? Or for different tracks which don't yet allow the 3700.
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Old 07-28-2005, 02:00 PM   #12299
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Quote:
Originally Posted by cpatel529
Anyone have experience with it? I plan on running my Pro4 on mainly carpet but occasionally on ashpalt. How is it for the mixture of surfaces? I read that you can take out the upperdeck standoffs and get it to work pretty well on ashpalt. Any help would be appreciated.
There aren't any standoffs to remove on the Pro 4. I think you're confusing it with the Xray FK 05'?
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Old 07-28-2005, 02:04 PM   #12300
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yea or the bmi tc3 or FT TC4 lol. for the pro4 you mainly can just swap out top plates and that should do it
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