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      12-05-2013, 03:09 PM   #243
oldmanstyle
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Originally Posted by klammer View Post
I just don't like people coming on here being sanctimonious pricks instead of providing actual content. And yeah, grammar and syntax is real important these days. I'm sure you're the type of guy that would shit on Einstein because he ended the sentence with a preposition and why add mass? It's a constant
Talk about condescending and lack of content, what exactly have you done here besides get all emo on me? I added mass because it is correct to include that when talking about force. Maybe you should pay more attention so you don't get tripped up when someone is being consistent with their terminology.

And again I ask, why are you being obtuse for no good reason? I advise you to get over it as nothing I've posted here was out of line until you came in crying because you're apparently ok with incomplete explanations and misinformation.

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Originally Posted by oldmanstyle View Post
There is more at play than this. There are also different spring rates, suspension geometry, available grip at each tire etc. And then there is an acceleration vector since one should be on the throttle throughout the turn in most cases if doing it right. It's nowhere near as simple as a rigid object experiencing uniform centrifugal force distribution.

That seems less out of line and condescending than your posts ITT, which are basically just whining at me for correctly elaborating on a misleading statement. So take a good look in the mirror before you continue this senseless derail that YOU started.
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      12-05-2013, 04:50 PM   #244
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Don't be so surrious.

He's just picking on you since you're coming in, telling someone they're wrong, and not providing any actual input as to a correct answer.

Frankly I buy the "it understeers because there's a couple hundred less pounds in the back" answer. Makes sense to me. Unless you want to tell us the correct answer...
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      12-05-2013, 06:51 PM   #245
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Originally Posted by Craigy View Post
Don't be so surrious.

He's just picking on you since you're coming in, telling someone they're wrong, and not providing any actual input as to a correct answer.

Frankly I buy the "it understeers because there's a couple hundred less pounds in the back" answer. Makes sense to me. Unless you want to tell us the correct answer...
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      12-12-2013, 04:59 PM   #246
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Originally Posted by Craigy View Post
Don't be so surrious.

He's just picking on you since you're coming in, telling someone they're wrong, and not providing any actual input as to a correct answer.

Frankly I buy the "it understeers because there's a couple hundred less pounds in the back" answer. Makes sense to me. Unless you want to tell us the correct answer...
I wouldn't say I didn't provide ANY actual input to a correct answer, but you're right I didn't completely spell it out. Of course we could have elaborated on that and had some discussion, but the conversation took a different turn...

So we have the car going around corner. The centrifugal force acts on the car, but it's the tires that provide traction for the car and determine where it's going (understeer/neutral/oversteer). Each tire has a limited amount of grip that can go to braking, accelerating, cornering, or a combination of those forces. These traction forces are developed by the friction between the tire and the pavement, and the magnitude of a friction force is dependent on the mass of the object pushing down on the friction surface (among other variables). For example, if you slid a small wooden block over a sheet of sandpaper by just pushing it from behind, then it will slide somewhat easily. If you put a 5 lb weight on the block, then it will take more force to slide it over the surface because the frictional force has increased due to the increase of the mass of the wooden block pushing down on the friction surface.

So getting back to the car, when mass is removed from the rear, it takes away from the magnitude of the traction force that the tire can provide through friction. With the rear tires having less traction available to them because of the loss of mass pushing down on them, they will lose traction earlier. This situation is made worse when entering a corner because the rear tire also has the acceleration force to deal with to go along with the cornering force (since we should be on the throttle through a corner). So it will exceed its available traction sooner than before, meaning the tail of the car has less grip and will swing out more easily, aka oversteer.

Aside from the technical explanation, I'm experiencing this exact problem in my track car that has had extensive lightweight mods in the back seat/trunk, but limited lightweight mods towards the front of the car.
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      12-13-2013, 04:57 PM   #247
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Quote:
Originally Posted by oldmanstyle View Post
I wouldn't say I didn't provide ANY actual input to a correct answer, but you're right I didn't completely spell it out. Of course we could have elaborated on that and had some discussion, but the conversation took a different turn...

So we have the car going around corner. The centrifugal force acts on the car, but it's the tires that provide traction for the car and determine where it's going (understeer/neutral/oversteer). Each tire has a limited amount of grip that can go to braking, accelerating, cornering, or a combination of those forces. These traction forces are developed by the friction between the tire and the pavement, and the magnitude of a friction force is dependent on the mass of the object pushing down on the friction surface (among other variables). For example, if you slid a small wooden block over a sheet of sandpaper by just pushing it from behind, then it will slide somewhat easily. If you put a 5 lb weight on the block, then it will take more force to slide it over the surface because the frictional force has increased due to the increase of the mass of the wooden block pushing down on the friction surface.

So getting back to the car, when mass is removed from the rear, it takes away from the magnitude of the traction force that the tire can provide through friction. With the rear tires having less traction available to them because of the loss of mass pushing down on them, they will lose traction earlier. This situation is made worse when entering a corner because the rear tire also has the acceleration force to deal with to go along with the cornering force (since we should be on the throttle through a corner). So it will exceed its available traction sooner than before, meaning the tail of the car has less grip and will swing out more easily, aka oversteer.

Aside from the technical explanation, I'm experiencing this exact problem in my track car that has had extensive lightweight mods in the back seat/trunk, but limited lightweight mods towards the front of the car.
Exactly and very well written. Hence in my first post where I couldn't understand why removing weight from the rear would increase understeer, quite the reverse. In my mind (rightly or wrongly) I used the simple analogy of downforce and running less rear wing. Less weight in effect pushing the rear into the tarmac and hence less grip. Less grip on the rear = more oversteer.
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      01-01-2014, 07:42 PM   #248
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Quote:
Originally Posted by oldmanstyle View Post
I wouldn't say I didn't provide ANY actual input to a correct answer, but you're right I didn't completely spell it out. Of course we could have elaborated on that and had some discussion, but the conversation took a different turn...

So we have the car going around corner. The centrifugal force acts on the car, but it's the tires that provide traction for the car and determine where it's going (understeer/neutral/oversteer). Each tire has a limited amount of grip that can go to braking, accelerating, cornering, or a combination of those forces. These traction forces are developed by the friction between the tire and the pavement, and the magnitude of a friction force is dependent on the mass of the object pushing down on the friction surface (among other variables). For example, if you slid a small wooden block over a sheet of sandpaper by just pushing it from behind, then it will slide somewhat easily. If you put a 5 lb weight on the block, then it will take more force to slide it over the surface because the frictional force has increased due to the increase of the mass of the wooden block pushing down on the friction surface.

So getting back to the car, when mass is removed from the rear, it takes away from the magnitude of the traction force that the tire can provide through friction. With the rear tires having less traction available to them because of the loss of mass pushing down on them, they will lose traction earlier. This situation is made worse when entering a corner because the rear tire also has the acceleration force to deal with to go along with the cornering force (since we should be on the throttle through a corner). So it will exceed its available traction sooner than before, meaning the tail of the car has less grip and will swing out more easily, aka oversteer.

Aside from the technical explanation, I'm experiencing this exact problem in my track car that has had extensive lightweight mods in the back seat/trunk, but limited lightweight mods towards the front of the car.


an actual explanation...and what kind of track car? and where do you run? btw, this conversation has gone exactly where I wanted
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      06-08-2014, 08:47 PM   #249
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The regular Stoptech stuff is in the first page, but I only see the ST60 non-Trophy setup listed so here's what I just did (finally):

Stoptech Trophy Sport 355mmx35mm ST40 front kit

Stock caliper/line/bracket with worn pads: 14lb
STR40 Trophy Sport caliper, bracket, pads, line: 10lb

Stock worn front rotor: 21.5lb (about 0.26lb of cast iron disappears from the rotor from new to used, based on 28.4mm minimum thickness, 30mm new thickness, 50mm swept area and a quick calculation of the mass of an annular cylinder, basically negligible change in mass from wear)
Stoptech 355x35mm front rotor/hat: 20lb

Total weight lost: approx. 5.5lb per corner, 11 total
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Last edited by Richbot; 06-16-2014 at 04:52 PM.
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