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TC weight reduction and lap times

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TC weight reduction and lap times

Old 02-26-2019, 09:30 AM
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I thought in scale and full size racing that lighter always means faster. A lighter car accelerates better and corners faster. It's interesting though what WTCC said, that below a certain amount it doesn't make a difference. I still remember the super lightweight car he built and tested. So if anyone knows the answer to this question, it would be him. I wonder what happens when a car gets too light?
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Old 02-26-2019, 09:40 AM
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There is a reason there is a weight minimum and no weight limit. Simple physics.
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Old 02-26-2019, 09:47 AM
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Originally Posted by glennhl View Post
I thought in scale and full size racing that lighter always means faster. A lighter car accelerates better and corners faster. It's interesting though what WTCC said, that below a certain amount it doesn't make a difference. I still remember the super lightweight car he built and tested. So if anyone knows the answer to this question, it would be him. I wonder what happens when a car gets too light?
My guess is that as the car gets too light, you loose some available traction and stability hence no further gain in lap time.
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Old 02-26-2019, 12:19 PM
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Originally Posted by glennhl View Post
I thought in scale and full size racing that lighter always means faster. A lighter car accelerates better and corners faster.
It does, the problem is, we have to control it. A lighter car will also react faster and could get too twitchy to be driven consistently, something that can be fixed with a different setup but to an extent, our reaction time will still be the same.
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Old 02-26-2019, 12:56 PM
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Originally Posted by Marcos.J View Post

Originally Posted by bertrandsv87 View Post
Ahahahah......
Yes, body weight loss makes the most difference(over one second per lap) as well as lowering the body... Assuming you setup(0.5* toe F&R) your car with a stiff enough swaybar that stops chassis scrubbing in the corner, losing rotational mass and drivetrain friction will net you another 0.5sec/lap, but there are other stuff independent of weight loss that can net you even more laptime drop like a complete car wax&anti-static treatment, increasing your speed control creep or radio sub trim, and CA your belt pullies(might be illegal), cranking the rotor's magnetic timing or slight demagnetizing effect(big can am secret), etc,.......
I think probably the only issue with doing all these things and each netting a reduction of 0.5sec/lap, is that on smaller tracks you would end up with negative lap times...
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Old 02-26-2019, 01:55 PM
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Originally Posted by johnzhou2476 View Post
I agree with everything that's said...that it's not just about lightening the car but lightening the car strategically. I'm running on high traction black crc carpet. I'm just curious what others have experienced in terms of lap time when they've strategically lighten their car. My hypothesis is that if I can get my USGT car right at legal weight limit, I’ll be able to shave 2-3 tenth per lap. The current USGT record on my track is 11.8 sec/lap. My personal best is 12.4. We run CanAm motors and fixed FDR so everything is apples to apples.
hey
if you are 98% consistency which is pretty good start. .you have to remember 98% doesn't mean you are fast.( Just less mistake ) .. gaining .6 sec faster on the big track it isn't easy ...some racer are faster in and out the corner than others .. long straight speed.. you need good lipo , perfect gearing and motor timing for the track.. I would have the person track record holder drive your car and I am sure he can point you the right direction ....
even if you are at min. weight ,you still need to find perfect setup the way you like to drive fast and easy on the track layout.
good luck

Last edited by OVA; 02-26-2019 at 02:06 PM.
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Old 02-26-2019, 02:23 PM
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Originally Posted by Marcos.J View Post

that's funny
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Old 02-26-2019, 02:42 PM
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Originally Posted by OVA View Post
hey
if you are 98% consistency which is pretty good start. .you have to remember 98% doesn't mean you are fast.( Just less mistake ) .. gaining .6 sec faster on the big track it isn't easy ...some racer are faster in and out the corner than others .. long straight speed.. you need good lipo , perfect gearing and motor timing for the track.. I would have the person track record holder drive your car and I am sure he can point you the right direction ....
even if you are at min. weight ,you still need to find perfect setup the way you like to drive fast and easy on the track layout.
good luck
OVA - You are absolutely correct, 98% consistency just means I make less mistakes. Also, 98% consistency is only when I practice, during an actual race, my consistency goes way down lol. Right now, I think the limiting factor is my car & setup (Xray T4) and being little overweight and of course me the driver. Iíve driven my friends perfectly setup AX and at minimum USGT weight and I was able get down to 12.2 which is still .4 sec behind the record holder. That 0.4 sec gain will be much much harder because although I take the exact same lines.. the way he corners in & out and his reaction time is much faster than mines. Right now, I just want to lighten my car and buy my way for a few tenth gain.

For the more experienced, Iím just curious what 50G of weight shaving will net.

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Old 02-26-2019, 02:54 PM
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Originally Posted by johnzhou2476 View Post
OVA - You are absolutely correct, 98% consistency just means I make less mistakes. Also, 98% consistency is only when I practice, during an actual race, my consistency goes way down lol. Right now, I think the limiting factor is my car & setup (Xray T4) and being little overweight and of course me the driver. I’ve driven my friends perfectly setup AX and at minimum USGT weight and I was able get down to 12.2 which is still .4 sec behind the record holder. That 0.4 sec gain will be much much harder because although I take the exact same lines.. the way he corners in & out and his reaction time is much faster than mines. Right now, I just want to lighten my car and buy my way for a few tenth gain.

For the more experienced, I’m just curious what 50G of weight shaving will net.
by shaving off 50g is a lot ...Your car will not drive the same and you might knock off .2 tenth at your best lap time you car will be quicker around the track for sure
and you will have to reset and recheck and tweek
the more time you spent on your set up and practices ,your lap time will get lower
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Old 02-26-2019, 03:09 PM
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Bert, you forgot about your advice with no paint on the A-pillars of the body, will help reduce traction roll.
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Old 02-26-2019, 04:55 PM
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^i learned something new today, thanks
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Old 02-26-2019, 05:56 PM
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Originally Posted by YBSLOW View Post
There is a reason there is a weight minimum and no weight limit. Simple physics.
The physics actually isn't quite so simple. F=MA seems fairly obvious that with a given force, less mass means more acceleration. However, less mass means less traction, so F will reduce to some extent as well. Also, when you add weight it's usually down low, which will lower the CoG which will affect handling in the corners.
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Old 02-26-2019, 06:26 PM
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If you want to drop weight, start with the heavy stuff, and work backwards. Break out your gram scale. Wire is remarkably heavy, copper is dense. Aluminum screws are 1/3 the weight of steel screws. Same for aluminum tie rods. Short shocks, and short shock towers both lower CG, and drop weight. As others have noted, take care, as "generally" when reducing weight, you also raise CG. Also, significant changes, need to address spring rates, as you reduce sprung weight, unsprung weight matters more... so things get complex.

Originally Posted by gigaplex View Post
The physics actually isn't quite so simple. F=MA seems fairly obvious that with a given force, less mass means more acceleration. However, less mass means less traction, so F will reduce to some extent as well. Also, when you add weight it's usually down low, which will lower the CoG which will affect handling in the corners.
The CoF of rubber (and many materials) is not linear. The CoF gets higher as the amount of weight on rubber is reduced. As long as we're not pulling wheelies, or rolling over, going lighter will get you faster acceleration (cornering, or otherwise)

Berts comments about rotating mass are... hilarious. And his description of what swaybars do, is just as silly.
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Old 02-26-2019, 07:01 PM
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Originally Posted by Nerobro View Post
The CoF of rubber (and many materials) is not linear. The CoF gets higher as the amount of weight on rubber is reduced. As long as we're not pulling wheelies, or rolling over, going lighter will get you faster acceleration (cornering, or otherwise)
There's also wheelspin. My FWD mini accelerated faster when I put more weight in it to reduce the wheelspin.
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Old 02-27-2019, 08:43 AM
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When your driven wheels aren't at the rear, things start to get a little less clear. And you need to consider making other compromises. My FF03 has everything, and I mean, everything, pushed up to the front of the car, to get any kind of acceleration out of it. That takes a big bite out of the cars potential cornering as it's no longer sharing the load between the front and rear tires. FWD drag people, (Can you believe that's a thing? And they've done 8`s in the quarter?) have used ballast up front to help with the same thing.

Where the weight transfers to, matters. :-)

And then.. we have the new Civic Type-R, which somehow beats some RWD and AWD cars 0-60..... Go figure.
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