From what I understand, cornerweighting is putting each wheel on its own scale and adjusting ride height until each wheel has even weight over it.
Does cornerweighting actually affect weight distribution? Say I were to raise a car in the front, would that put more weight on the rear or would it simply just raise the center of gravity of that weight....
The benefits of cornerweighting...
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IveBeenBad
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Cornerweighting does not affect weight distribution from a mass standpoint. But it does affect how each wheel will "see" this weight. Basically, if you have a mismatch on the weight on each tire, the wheel with less weight on it will provide less grip when it is the outside wheel. The tires have to throw around the same mass, but one of them is providing less grip due to not having as much weight on it.
Think of it as affecting the dynamic weight transfer of the car by altering the ride height if that helps.
So if I'm reading your question right, then yes, if you raise the front up, the rears will gain more normal force(weight they "see"). This will affect their grip, but NOT the weight distribution of the car.
Think of it as affecting the dynamic weight transfer of the car by altering the ride height if that helps.
So if I'm reading your question right, then yes, if you raise the front up, the rears will gain more normal force(weight they "see"). This will affect their grip, but NOT the weight distribution of the car.
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IveBeenBad
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Def wrote:Cornerweighting does not affect weight distribution from a mass standpoint. But it does affect how each wheel will "see" this weight. Basically, if you have a mismatch on the weight on each tire, the wheel with less weight on it will provide less grip when it is the outside wheel. The tires have to throw around the same mass, but one of them is providing less grip due to not having as much weight on it.
Think of it as affecting the dynamic weight transfer of the car by altering the ride height if that helps.
So if I'm reading your question right, then yes, if you raise the front up, the rears will gain more normal force(weight they "see"). This will affect their grip, but NOT the weight distribution of the car.
So what you are saying is that corner balancing is used to modify the amount of effective weight over a tire to provide more grip to that tire?
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Just remember that tires translate weight on them to friction in a linear , THEN NON LINEAR way as the threshold is reached.
Some where between 73% and 78% of the load index rating, each pound of extra weight does not result in an extra pound of friction.
This is the CRITICAL ERROR that most make when downgrading oem load index with Plus Size Tires.
Factories just size tires to meet 73-78% FRONT WEIGHT under static conditions. A 4300 pound loaded Q may have 1160-1180 pounds on each front tire; 1180/1521= 77.58% Sitting Still leaving only 341 pounds to overload in any turning or max braking manuever!
EXACTLY enough to cover a 0.79G TURN EXCEPT the inflation pressure [normaly used is not 44 psi] so the tire is momentarily overloaded.
In the Q the front load index capacity set the ultimate ability [LIMIT] to achieve higher G in manuever.
A simple increase in front tire load index [comparing same tire] will do more than almost anything you do to suspension other than somehow REDUCING the weight on the front tires.
A 100 pound increase in load index is almost like reducing the front weight by 60 pounds x 2 tires! Yielding at least 0.03G [probably more like 0.05 G] improvement. More than any spring or sway bar or shock can possible do! More than relocating the battery to the trunk.
Setting the weight equal STATICALLY [sitting still] is not the real world situation in turning.
Some where between 73% and 78% of the load index rating, each pound of extra weight does not result in an extra pound of friction.
This is the CRITICAL ERROR that most make when downgrading oem load index with Plus Size Tires.
Factories just size tires to meet 73-78% FRONT WEIGHT under static conditions. A 4300 pound loaded Q may have 1160-1180 pounds on each front tire; 1180/1521= 77.58% Sitting Still leaving only 341 pounds to overload in any turning or max braking manuever!
EXACTLY enough to cover a 0.79G TURN EXCEPT the inflation pressure [normaly used is not 44 psi] so the tire is momentarily overloaded.
In the Q the front load index capacity set the ultimate ability [LIMIT] to achieve higher G in manuever.
A simple increase in front tire load index [comparing same tire] will do more than almost anything you do to suspension other than somehow REDUCING the weight on the front tires.
A 100 pound increase in load index is almost like reducing the front weight by 60 pounds x 2 tires! Yielding at least 0.03G [probably more like 0.05 G] improvement. More than any spring or sway bar or shock can possible do! More than relocating the battery to the trunk.
Setting the weight equal STATICALLY [sitting still] is not the real world situation in turning.
Of course if you're wanting wieght for a ballast it is best to put it as close to the center of gravity as possible so the car can theoretically rotate around it instead of carrying it semi randomly and effecting wieght transfer on corner entry.
Which makes me wonder if it would be possible to mount the amps closer to the CG. Maybe under the seat. To me, it seems like this may help some but I don't know how noticable it would be nor am I sure how this would apply to what Q45tech just said.
Enlighten me further please.
Which makes me wonder if it would be possible to mount the amps closer to the CG. Maybe under the seat. To me, it seems like this may help some but I don't know how noticable it would be nor am I sure how this would apply to what Q45tech just said.
Enlighten me further please.
Q45Tech - I'm not exactly sure how the logarithmic relationship between normal force and grip of a tire relates to trying to slightly optimize the existing grip of the tires.
Corner balancing is just trying to get all the tires to "start off on the same foot" within reason, since more weight on a tire does achieve less grip in most cases(and it is logarithmic, so it falls off fast). In a corner you have dynamic weight transfer that will change things, but when turning left and right, you obviously want to get things as equal as you can on both sides. It would stink to drive a car that can do 1G in left hand turns and only .9G in right hand turns due to a gross mismatch of the crossweights.
I personally think people who ADD weight to balance things out are missing the big picture and are letting details make them do stupid things. I do think it is worthwhile to move things around a bit if you find a poor weight distribution picture. This is a relatively minor thing though, only adding up to hundredths or tenths of a second per lap of the racetrack. But hey, all it takes is a nanosecond lead to win.
Corner balancing is just trying to get all the tires to "start off on the same foot" within reason, since more weight on a tire does achieve less grip in most cases(and it is logarithmic, so it falls off fast). In a corner you have dynamic weight transfer that will change things, but when turning left and right, you obviously want to get things as equal as you can on both sides. It would stink to drive a car that can do 1G in left hand turns and only .9G in right hand turns due to a gross mismatch of the crossweights.
I personally think people who ADD weight to balance things out are missing the big picture and are letting details make them do stupid things. I do think it is worthwhile to move things around a bit if you find a poor weight distribution picture. This is a relatively minor thing though, only adding up to hundredths or tenths of a second per lap of the racetrack. But hey, all it takes is a nanosecond lead to win.
wow---very good info here--you guys are passing around great info here!
How would you correct tire overloading in a turn radius turn? If the car turns left and puts an overload on the front passenger tire, then, by what you are saying is to compensate by calculating the correction needed to overcome this overload and bring a more equal load on the fron tires, however(and i HOPE i am readin all of this correctly) it would then place a heavier bias on the driver front tire/wheel. The only way to properly ditribute weight frequently is from a standstill, the way DEF said it, and have the car be on level ground to start with---"start off on the same foot". It makes more sense to have the car perfectly weighted at all four corners to have the front/rear, and side/side bias as equal as possible in relation to one another.
Did i get all of that right?
-Josh
How would you correct tire overloading in a turn radius turn? If the car turns left and puts an overload on the front passenger tire, then, by what you are saying is to compensate by calculating the correction needed to overcome this overload and bring a more equal load on the fron tires, however(and i HOPE i am readin all of this correctly) it would then place a heavier bias on the driver front tire/wheel. The only way to properly ditribute weight frequently is from a standstill, the way DEF said it, and have the car be on level ground to start with---"start off on the same foot". It makes more sense to have the car perfectly weighted at all four corners to have the front/rear, and side/side bias as equal as possible in relation to one another.
Did i get all of that right?
-Josh
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Q45tech
- Moderator
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The problem is the drivers weight left [right] of the CG, even in a perfectly balanced unloaded car.
Just like alignments need to be done with driver in place.
The weight change in the rear as gasoline burns [up to 140 pounds] can be significant.
Many are missing the point that the front tires are overloaded and this limits the G forces more than the rear tires.
If oem is 91,92,93 find a tire that is at least 100 pounds stronger say a 95 if already a oem 95 try a 98.
I agree the wheel/tire loads should be equal at least on front and rear why oem has battery and ABS on passenger side.
Limit drivers weight [healthy also], measure and match individual spring and shock stiffness........not unusual to see 5-10% variations from nominal. Tires also vary in exact sidewall stiffness.
Just like alignments need to be done with driver in place.
The weight change in the rear as gasoline burns [up to 140 pounds] can be significant.
Many are missing the point that the front tires are overloaded and this limits the G forces more than the rear tires.
If oem is 91,92,93 find a tire that is at least 100 pounds stronger say a 95 if already a oem 95 try a 98.
I agree the wheel/tire loads should be equal at least on front and rear why oem has battery and ABS on passenger side.
Limit drivers weight [healthy also], measure and match individual spring and shock stiffness........not unusual to see 5-10% variations from nominal. Tires also vary in exact sidewall stiffness.
Projex240 wrote:wow---very good info here--you guys are passing around great info here!
How would you correct tire overloading in a turn radius turn? If the car turns left and puts an overload on the front passenger tire, then, by what you are saying is to compensate by calculating the correction needed to overcome this overload and bring a more equal load on the fron tires, however(and i HOPE i am readin all of this correctly) it would then place a heavier bias on the driver front tire/wheel. The only way to properly ditribute weight frequently is from a standstill, the way DEF said it, and have the car be on level ground to start with---"start off on the same foot". It makes more sense to have the car perfectly weighted at all four corners to have the front/rear, and side/side bias as equal as possible in relation to one another.
Did i get all of that right?
-Josh
Yep, you've basically got it. You can *slightly* adjust ride height on individual corners to get the cross weight to change(it gets pretty complicated if you want it dead even, it's not just a left to right, front to back relationship).
Moving around heavy components like batteries and even shifting the passenger seat a bit(if the floorboard allows) can help out a bit. Really though, if the car is horribly unbalanced, cornerweighting is only going to take the bad situation and make it "not quite as bad."
Luckily S13's and S14's seem to be pretty well balanced from the factory for a LHD configuration.
Man - I wish they taught stuff like this in school(although my Internal Combustion Engines class is badass...).
The little bit of stuff I know about this is hanging out with racers(amateur, and I do mean amateur) and reading anything I can get my hands on.
Check out Carrol Smith's Tune to Win if you want a decent book on setup(although much of it is only related to open wheeled/Prototype racers). It's old, but the man truly had an insane amount of knowledge. Read Engineer to Win if you want a more comprehensive outlook on practical metallurgy than any Mechanical Engineering ciriculum can provide. Very VERY heavy reading, but lots of good info.
But I digress, I'm rambling. The books are good tho'!
).The little bit of stuff I know about this is hanging out with racers(amateur, and I do mean amateur) and reading anything I can get my hands on.
Check out Carrol Smith's Tune to Win if you want a decent book on setup(although much of it is only related to open wheeled/Prototype racers). It's old, but the man truly had an insane amount of knowledge. Read Engineer to Win if you want a more comprehensive outlook on practical metallurgy than any Mechanical Engineering ciriculum can provide. Very VERY heavy reading, but lots of good info.
But I digress, I'm rambling. The books are good tho'!