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-   -   Team Associated B4.2 Thread (https://www.rctech.net/forum/electric-off-road/694124-team-associated-b4-2-thread.html)

Toyman 06-18-2013 09:53 PM


Originally Posted by zzztech (Post 12269207)
My new B4.2 is wanting to roll on its side during a jump. I am using 1.6 pistons and 30/27.5 shock oil. Green front and white rears springs on grippy clay track.

Its almost like flying a plane doing an axial roll in the air. Any reason why?

Shock rebounds are all zero. Droops are even.

It didnt do it on my other buggies

Make a very close inspection, I'm pretty sure ether something is binding or one of the shocks leaked.

Waflet 06-19-2013 10:05 AM


Originally Posted by rnpnick (Post 12269130)
Momentum is the product of Mass and Velocity. So both Mass and Velocity are factors. Less mass less momentum. Less velocity less momentum.

Hideeho
My comment, while stated very tongue in cheek:D, is very accurate for 2 reasons.

1st the change in velocity from driving slower has more effect simply because the change in weight is not very much as a percentage of the initial weight.

M(mass) x V(velocity) = P(force)
1600g x 32kph = 51200
1500g x 32kph = 48000
1600g x 24kph = 38400
1500g x 24kph = 36000

2nd when you drive slower you drive more accurately & wreck less. both of which lead to less broken parts.

rnpnick 06-19-2013 10:24 AM


Originally Posted by Waflet (Post 12270681)
Hideeho
My comment, while stated very tongue in cheek:D, is very accurate for 2 reasons.

1st the change in velocity from driving slower has more effect simply because the change in weight is not very much as a percentage of the initial weight.

M(mass) x V(velocity) = P(force)
1600g x 32kph = 51200
1500g x 32kph = 48000
1600g x 24kph = 38400
1500g x 24kph = 36000

2nd when you drive slower you drive more accurately & wreck less. both of which lead to less broken parts.

The original post you made stated mass had zero effect. That is what I was correcting. It should be obvious that the factor you reduce the most will be the limiting factor.

SEF 06-19-2013 10:52 AM


Originally Posted by Waflet (Post 12268760)
Hideeho
I agree with all of that except the last part. Momentum breaks parts, not weight.

Just go slower to not break parts:lol:


Originally Posted by Waflet (Post 12270681)
Hideeho
My comment, while stated very tongue in cheek:D, is very accurate for 2 reasons.

1st the change in velocity from driving slower has more effect simply because the change in weight is not very much as a percentage of the initial weight.

M(mass) x V(velocity) = P(force)
1600g x 32kph = 51200
1500g x 32kph = 48000
1600g x 24kph = 38400
1500g x 24kph = 36000

2nd when you drive slower you drive more accurately & wreck less. both of which lead to less broken parts.

To be technically correct, it is the change in momentum that will break car parts. These cars can go pretty darn fast without breaking, but make them stop quickly or go from a stand still quickly and that's when you start to break parts. This change in momentum (in this case velocity since mass of the vehicle will be constant) will cause an acceleration or deceleration which will cause a force which will cause a stress, and if the stress exceeds a certain amount, then parts break.

Your equation should read mass times the change in velocity with respect to time equals force:D

But in any case, your equations can lead us to the same conclusions in that a lighter car will generate less force than a heavier car if they both have the exact same change in velocity.

Kellen Guthrie 06-19-2013 11:42 AM

Technically what causes broken parts is impulse as someone above partially stated.

Impulse = Fnet * delta T

So basically this means that time is the main determinant of broken parts. If the crash occurs over a small period of time (i.e. hitting a wall) you're probably going to break.

JiuHaWong 06-19-2013 12:36 PM

tsk tsk tsk!
 
You guys have it all wrong!

Mass x Velocity + Wall,pipe or other car = Broken Parts

:)

ryanpatrickgore 06-19-2013 12:39 PM

:tire:

Waflet 06-19-2013 01:54 PM


Originally Posted by Kellen Guthrie (Post 12270904)
Technically what causes broken parts is impulse as someone above partially stated.

Impulse = Fnet * delta T

So basically this means that time is the main determinant of broken parts. If the crash occurs over a small period of time (i.e. hitting a wall) you're probably going to break.

Hideeho
Too much math, & too much seriousness for what was intended as a half serious joke. So...

The old redneck's son came back from college as the 1st person from the county to ever graduate. Dad want to show off his son, so he took him down to the barber shop to show him off to all the old men. They get there & the dad says, "look, this is my son who just graduated from college. He's smart!" One of the old men says, "He don't look too smart. Say something smart." The new college graduate thinks for a moment & says, "Pi*rsq" & smiles proudly. The old men sit there stunned for a moment. Dad says, "ok boy, lets go home." As soon as they get out of hearing, one old man turns to the other & says, "He might have graduated college, but everybody knows pie are round."

rosko 06-19-2013 02:01 PM

Lol thats a good one

Kellen Guthrie 06-19-2013 02:53 PM


Originally Posted by Waflet (Post 12271234)
Hideeho
Too much math, & too much seriousness for what was intended as a half serious joke. So...

The old redneck's son came back from college as the 1st person from the county to ever graduate. Dad want to show off his son, so he took him down to the barber shop to show him off to all the old men. They get there & the dad says, "look, this is my son who just graduated from college. He's smart!" One of the old men says, "He don't look too smart. Say something smart." The new college graduate thinks for a moment & says, "Pi*rsq" & smiles proudly. The old men sit there stunned for a moment. Dad says, "ok boy, lets go home." As soon as they get out of hearing, one old man turns to the other & says, "He might have graduated college, but everybody knows pie are round."

haha awesome

Venom1836 06-19-2013 06:24 PM


Originally Posted by zzztech (Post 12269207)
My new B4.2 is wanting to roll on its side during a jump. I am using 1.6 pistons and 30/27.5 shock oil. Green front and white rears springs on grippy clay track.

Its almost like flying a plane doing an axial roll in the air. Any reason why?

Shock rebounds are all zero. Droops are even.

It didnt do it on my other buggies

I have the same issues.
I blamed it on uneven driveline drag combined with drag brake. After removing drag brake I still had problems.

Wildcat1971 06-19-2013 06:42 PM

Something is out of whack. Maybe even the jump is the issue. Check for binding, air in the shocks and maybe try different springs. its possible you got a bad spring or one that was marked incorrectly.

Leadfinger2011 06-19-2013 07:17 PM

Chasis holes stripping
 
Whats up All!!

Has anyone else noticed that the chassis holes that receive the screws that go to the rear shock tower, through the u-brace into the chassis strip relatively easily? I've now had two go in 12 months. I've heard somewhere that you just drop a few layers of CA down in there and let it dry you can get to where you can get hardware to hold, might that be true? I'm $60.00 into chassis plates and not really looking into getting more. Any input is appreciated!!!

Kevin

Wildcat1971 06-19-2013 07:36 PM

I have never stripped one out, but I dont crank on them either

aeRayls 06-19-2013 08:08 PM


Originally Posted by Leadfinger2011 (Post 12272198)
Whats up All!!

Has anyone else noticed that the chassis holes that receive the screws that go to the rear shock tower, through the u-brace into the chassis strip relatively easily? I've now had two go in 12 months. I've heard somewhere that you just drop a few layers of CA down in there and let it dry you can get to where you can get hardware to hold, might that be true? I'm $60.00 into chassis plates and not really looking into getting more. Any input is appreciated!!!

Kevin

Make sure you use the 9/16 ones in the front of the shock tower and the 7/16 in the rear of it.


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