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PostPosted: Sat Jun 03, 2017 9:12 am 
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I am pretty sure the original poster is not listening to this discussion.

Lou

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PostPosted: Sat Jun 03, 2017 10:04 am 
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Supercharged
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Joshie225 wrote:
The forces which cause body roll do not include the presence or absence of a sway bar.


jcc wrote:
You are talking forces,I''m talking tire contact patch loading, which directly relates to understeer characteristics, we are not focusing on the forces that cause body roll, more what reduces body roll, ie a swaybar, and the price paid for that reduction, to stay on track.


You are way into the weeds. Loading at the tire is caused by the forces involved. Ignore the forces and you're lost. It's all about weight transfer and, in this discussion, transferring the same amount of weight with less body roll.

Wikipedia: "The total amount of weight transfer is only affected by four factors: the distance between wheel centers (wheelbase in the case of braking, or track width in the case of cornering) the height of the center of gravity, the mass of the vehicle, and the amount of acceleration experienced."

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PostPosted: Sat Jun 03, 2017 10:07 am 
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Dart270 wrote:
I am pretty sure the original poster is not listening to this discussion.

Lou


I'd bet that's true.

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 Post subject: Re: Front-End Body Roll
PostPosted: Thu Jun 08, 2017 7:01 pm 
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Joined: Thu Nov 06, 2014 5:12 pm
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Location: north bergen nj
Car Model*: 68 dodge dart 270
suurthing wrote:
68 Dart 270--My sweet slant has alot of front body roll. Beacuse i installed 4" front disc breaks-(unbelievable inprovement!!)...i cant go with a sway bar. Question: Could i purchase x heavy duty shocks to lessen my crazy roll? OR?..... As always-any info is greatly appreciated for this awesome Slant 6 Forum.
HAPPY MOTORING


UPDATE-I went with Hotchkis Sport Suspension 1.5 Street Performance Series Shocks 70020013 from Summit- as suggested here by Lou (dart 270)
- $115 a pop-they showed a video with 3 classic boaty rides (old shocks) and did the cone maneuvering deal. Then they showed the same cars with the hotchikins upgrade and the wildy improved handling--I Was Hooked! The install took 20 minutes. WOW! Amazing improvement!! I still cant believe the handling!! My dart is now is FUN to drive--taking those tight turns like a pro...(My bro has a 65 GTO-hes put way over 100,000 miles on his beauty-and he cant believe the insane improvement with these shocks on my 68 dart)....just sayin... As alwayz-- Thanks to all who posted their views.
SLANT SIX FORUM ROCKS!
Happy Motoring!


Last edited by suurthing on Tue Jun 13, 2017 4:36 am, edited 1 time in total.

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 Post subject:
PostPosted: Fri Jun 09, 2017 3:57 am 
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Glad that worked out for you. The very first improvement I made to my 68 Dart after I bought it in 1988 was good shocks all around. Big improvement. Lots of other things will show improvements, but those are high on the list. You can build from there, and meanwhile enjoy the more confident ride.

Lou

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 Post subject:
PostPosted: Fri Jun 09, 2017 9:07 pm 
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Joshie225 wrote:
Joshie225 wrote:
The forces which cause body roll do not include the presence or absence of a sway bar.


jcc wrote:
You are talking forces,I''m talking tire contact patch loading, which directly relates to understeer characteristics, we are not focusing on the forces that cause body roll, more what reduces body roll, ie a swaybar, and the price paid for that reduction, to stay on track.


You are way into the weeds. Loading at the tire is caused by the forces involved. Ignore the forces and you're lost. It's all about weight transfer and, in this discussion, transferring the same amount of weight with less body roll.

Wikipedia: "The total amount of weight transfer is only affected by four factors: the distance between wheel centers (wheelbase in the case of braking, or track width in the case of cornering) the height of the center of gravity, the mass of the vehicle, and the amount of acceleration experienced."


In regards to the effect of a swaybar, until you understand, IMO, the fallacy of your bold marked above comment, we have little more to discuss. I'll also show you the courtesy of using the known qualifier, "IMO". I could quote a number of more notable expert sources for my position, rather then Wiki, such as "Race Car Engineering and Mechanics" by Paul Van Valkenburgh, page 34, "Chassis Engineering" by Herb Adams, page 15, "Tune to Win" by Carroll Smith, page 68, or "Competition Car Suspension" by Allan Staniforth, page 45, but you likely need to review them for yourself, as we seem to have reached an understanding impasse.


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PostPosted: Fri Jun 09, 2017 10:58 pm 
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The OP just wants to go around corners without the car flopping over uncomfortably. If he wants to go faster around corners then yes, we would need to consider additional cornering forces, but if the lateral acceleration is constant then my statement remains true; the weight transfer will stay the same regardless of what's done with springs or anti-sway bars if the roll couple is also held constant. If the weight transfer stays the same then the tire loading stays the same. I believe that you contradicted that, and yourself in this statement:

jcc wrote:
I agree the weight on the front axle doesn't change, the amount a corner transfers is consistent based on the parameters you mentioned, BUT the loading L/R of the tire contact patches is dependent on the swaybar rate in this example. The inside tire sees less loading, because the bar lifts that wheel, the outer tire patch sees more loading...


If the CG height, roll center height, track width and cornering force are fixed then the weight transferred from the inside wheels to the outside wheels will also be fixed. You can find this on page 14 of Herb Adams' Chassis Engineering, page 39 of Fred Puhn's How to Make Your Car Handle, and page 36 of Carroll Smith's Tune to Win. On page 38 Smith writes "If the amount of roll generated by a given lateral acceleration has no real effect on load transfer, then why worry about it?" He then addresses why.

Once we get past what causes lateral load transfer and body roll then we have the basis for a discussion on resisting body roll.

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Joshua Skinner, formerly SrA US Air Force


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 Post subject:
PostPosted: Sat Jun 10, 2017 5:46 am 
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Joshie225 wrote:
The OP just wants to go around corners without the car flopping over uncomfortably. If he wants to go faster around corners then yes, we would need to consider additional cornering forces, but if the lateral acceleration is constant then my statement remains true; the weight transfer will stay the same regardless of what's done with springs or anti-sway bars if the roll couple is also held constant. If the weight transfer stays the same then the tire loading stays the same. I believe that you contradicted that, and yourself in this statement:

jcc wrote:
I agree the weight on the front axle doesn't change, the amount a corner transfers is consistent based on the parameters you mentioned, BUT the loading L/R of the tire contact patches is dependent on the swaybar rate in this example. The inside tire sees less loading, because the bar lifts that wheel, the outer tire patch sees more loading...


If the CG height, roll center height, track width and cornering force are fixed then the weight transferred from the inside wheels to the outside wheels will also be fixed. You can find this on page 14 of Herb Adams' Chassis Engineering, page 39 of Fred Puhn's How to Make Your Car Handle, and page 36 of Carroll Smith's Tune to Win. On page 38 Smith writes "If the amount of roll generated by a given lateral acceleration has no real effect on load transfer, then why worry about it?" He then addresses why.

Once we get past what causes lateral load transfer and body roll then we have the basis for a discussion on resisting body roll.


One more time, on bold above:
1. The Op has stated he is worried about roll, and using a swaybar to reduce it
2. The likely already pointed out fact the OP does care what causes roll, only what reduces it, should color this thread from the get go
2. Reducing that roll with a swaybar DOES have an effect on load transfer, as I have discussed with you numerous times here and you don't seem to accept that, and repeatedly return to causes, roll centers, COG, track width, etc
3. And I breaking my own personal rule of repeating myself, which should not be necessary in an informed discussion.


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 Post subject:
PostPosted: Sat Jun 10, 2017 5:28 pm 
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I disagree that a sway bar increases load transfer from the inside tires to the outside which is why I keep repeating what causes load transfer.

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Joshua Skinner, formerly SrA US Air Force


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 Post subject: Re:
PostPosted: Wed May 30, 2018 2:21 pm 
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TBI Slant 6

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Car Model*: '65 Valiant 170 T5
Matt Cramer wrote:
Some tuners like to use springs to set both wheel rate and roll stiffness, but I personally prefer the school of tuning where one sets the springs to be as soft as they can to avoid bottoming out at your preferred ride height, then use sway bars to dial in body roll and oversteer / understeer balance.

^^^^^^
This.

Assuming no other change a stiffer sway-bar changes the effective wheel rates due to the weight transfer since that is what it is acting against. A stiffer bar increases the wheel rate of the outer corner at the expense of decreasing the rate of the inner corner. That may or may not be good. If the car under-steers then clearly a stiffer front bar is the wrong answer.

I learned to drive corners in a Saab 96. Those things heal over like a sail boat in a corner. As a result I've never had much sympathy for those who whine about a car that doesn't corner absolutely flat. If that healing over takes the car out of it's ideal camber curve range, then clearly there's work to be done, but if they're simply not comfortable with a car in a lean don't talk to me about it.

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 Post subject: Re: Front-End Body Roll
PostPosted: Thu May 31, 2018 3:38 am 
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I agree that lean in itself is probably/usually less of a problem than people think.

Lou

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