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FWD TOURING CAR FORUM - Tamiya FF01, FF02, Yokomo YRF-2, Kyosho Mantis FF

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FWD TOURING CAR FORUM - Tamiya FF01, FF02, Yokomo YRF-2, Kyosho Mantis FF

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Old 10-09-2019, 08:21 PM
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Originally Posted by Nicadrauspro4 View Post
and you started this silly "girl thing". Who's the cry girly now? :P

Next time you blabber and reply with irrelevance, comprehend the question first. Period!
what ever dude...get over .....end of this conversation
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Old 10-09-2019, 08:21 PM
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If we could just put the handbags down for a minute...
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Old 10-09-2019, 08:27 PM
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Originally Posted by Bloke View Post
If we could just put the handbags down for a minute...
Thank you
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Old 10-10-2019, 04:14 AM
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Three more users added to my ignore list.

back to topic.......
Its interesting to see the various manufacturers designs and how they've managed the proximity of the motor to the front wheel center.
The last three most recent releases with the motor in front of the front suspension all look kinda far....
I was always under the impression that for FWD, a desirable characteristic is to have the most mass as close to the axis of the front wheels as possible.
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Old 10-10-2019, 07:29 AM
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Originally Posted by simple View Post

Three more users added to my ignore list.

back to topic.......
Its interesting to see the various manufacturers designs and how they've managed the proximity of the motor to the front wheel center.
The last three most recent releases with the motor in front of the front suspension all look kinda far....
I was always under the impression that for FWD, a desirable characteristic is to have the most mass as close to the axis of the front wheels as possible.
That's a tradeoff. You've got 4 tires. A tire's available traction doesn't go up linearly with pressure. Less load on a tire, "generally" makes more traction for the given weight on the tire. This means equally loading tires gives you the most traction.

......... so I just made the augment for 4wd and around 50/50 weight distribution for best corner speed.

FWD cars apply all their motive force through the front tires. If you add weight, you can apply more tractive force without spinning the tires. This, starts to make a very strong agument for moving weight forward. If you check out FWD drag cars, all the weight is put up as close to those front tires, and in front of those front tires as they can manage. This reduces the amount of weight transfer to the rear, maintaining as much weight (and traction) on those front tires.

You can look at the setups for FWD cars. For Big, outdoor, flowing tracks, they still aim for the spread the weight out plan you see on 4wd touring cars. you'll also see setups that push the battery, esc, and everything else way forward.. which is what you'll see on shorter tracks, where acceleration matters more than corner speed.

With my FF03, I started out with the battery in the back of the battery tray. (indoor, black carpet, super shorty battery). And the car handled fine, but I was left standing still out of any sharp corner. Moving the battery forward, got me back a lot of the acceleration I was missing.

.........I suppose i'm saying it's a trade off. And moving the CG is a tuning tool. Your thought isn't wrong, just it's only part of the story.
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Old 10-10-2019, 07:45 AM
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As Nerobro stated, you still need to ensure you dont float the rear of the car, i.e. make it unpredictable. Also to ensure during braking and accelerating, you are not upsetting the chassis balance vs. traction too much.
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Old 10-10-2019, 09:15 AM
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Balance between the front and rear shock towers is one thing , granted. But what I was specifically referring to was the proximity of the motor to the front shock tower, when it is located in front.
I would suspect, the further it is forward, the harder it would be to get the aforementioned "balance"
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Old 10-10-2019, 09:17 AM
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Where the CG is, is where the CG is. Specifically where the motor is in relation to the front axle is "unrelated". Spreading the masses out changes the polar moment of inertia, which has it's own set of handling consequences, which matters when initiating rotation, and stopping rotation.
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Old 10-10-2019, 11:53 AM
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Originally Posted by Nerobro View Post
Where the CG is, is where the CG is. Specifically where the motor is in relation to the front axle is "unrelated". Spreading the masses out changes the polar moment of inertia, which has it's own set of handling consequences, which matters when initiating rotation, and stopping rotation.
I don't understand what you mean by "unrelated".
If the motor is further forward (considering that it is mounted in a fixed position, give or take a few mm for gear ratio), wouldn't that result in the center of gravity further forward from the cars reference center?
All the other electronic components (esc,rcvr, battery, etc) can be variably mounted to change handling behaviour.

All I'm asking is "Does it matter how far the motor is out front"?
From what you are commenting, I get the impression you are saying "No."

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Old 10-10-2019, 12:01 PM
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If your intent on moving the motor further forward, is to move the CG forward, then the answer is "no" Because I could do the same job, by packing the motor and other control electronics further forward to the same effect. The difference would only be that my car would (most likely) have a smaller polar moment of inertia. Adjusting polar moment of inertia is separate subject. (And why people chose different battery positions on F1 cars.) And is unrelated to drive-train geometry.
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Old 10-10-2019, 01:51 PM
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Originally Posted by simple View Post
I don't understand what you mean by "unrelated".
If the motor is further forward (considering that it is mounted in a fixed position, give or take a few mm for gear ratio), wouldn't that result in the center of gravity further forward from the cars reference center?
All the other electronic components (esc,rcvr, battery, etc) can be variably mounted to change handling behaviour.

All I'm asking is "Does it matter how far the motor is out front"?
From what you are commenting, I get the impression you are saying "No."
I think you asking about the weight balance where the motor sit further forward of the car ..answer is yes it does make a difference the way the car drive .kinda like having light or heavy front bumper .not CG
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Old 10-10-2019, 08:06 PM
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Originally Posted by Nerobro View Post
That's a tradeoff. You've got 4 tires. A tire's available traction doesn't go up linearly with pressure. Less load on a tire, "generally" makes more traction for the given weight on the tire. This means equally loading tires gives you the most traction.

......... so I just made the augment for 4wd and around 50/50 weight distribution for best corner speed.

FWD cars apply all their motive force through the front tires. If you add weight, you can apply more tractive force without spinning the tires. This, starts to make a very strong agument for moving weight forward. If you check out FWD drag cars, all the weight is put up as close to those front tires, and in front of those front tires as they can manage. This reduces the amount of weight transfer to the rear, maintaining as much weight (and traction) on those front tires.

You can look at the setups for FWD cars. For Big, outdoor, flowing tracks, they still aim for the spread the weight out plan you see on 4wd touring cars. you'll also see setups that push the battery, esc, and everything else way forward.. which is what you'll see on shorter tracks, where acceleration matters more than corner speed.

With my FF03, I started out with the battery in the back of the battery tray. (indoor, black carpet, super shorty battery). And the car handled fine, but I was left standing still out of any sharp corner. Moving the battery forward, got me back a lot of the acceleration I was missing.

.........I suppose i'm saying it's a trade off. And moving the CG is a tuning tool. Your thought isn't wrong, just it's only part of the story.

this is a great simple explanation Nerobro.

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Old 10-11-2019, 10:57 AM
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Do hatchback bodies really handle better than sedan bodies for FFWD? I would think the higher CG would be detrimental, no?
We don't run this at my track so I don't have any exposure really. appreciate the insights
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Old 10-11-2019, 11:43 AM
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Originally Posted by quantum View Post
Do hatchback bodies really handle better than sedan bodies for FFWD? I would think the higher CG would be detrimental, no?
We don't run this at my track so I don't have any exposure really. appreciate the insights
Nope, They don't handle better. There is no advantage gained. It is generally frowned upon to use a "TC" body with a FWD chassis.
We just use them because we like them, and the generally accepted convention that FWD chassis should be adorned according to the"spirit" of FWD / TCR racing.
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Old 10-11-2019, 12:06 PM
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I dunno. There's something to be said for the mass of air constrained by the body. That air counts for bumps, and will let you get away with more crap at the rear end, where there just isn't a whole lot of mass to make the suspension work. But due to displacement, it doesn't actually affect the cars "weight".

That said, if you can run rwd car bodies on chassis that are 4wd, we shouldn't have "FWD bodies on FWD chassis".
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