Tires
#16
09-22-2004, 10:31 AM
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#17
09-22-2004, 10:57 AM
Re: Tires
Go to rear medium first and see if you like the feel.
Not much detail on Stillen site 7% > 70%.
It's a summation game! two [both] 70% doesn't change the understeer ratio. front at 35% [middle ?] rear at 70% would shift ratio by 35%/2=10-18% more rearward.
Really need to know the spring and bar effectve rates to zero in on the exact numbers.
I am guessing that the Stllen rear Gbar is probably 70-80 lbs per inch at the 70% position and the oem rear bar is 40-45 lbs per inch.
Obviously the +7% rear would not be noticeable, the mid [+35%?] or the stiffest +70% are the two desirable positions.
The factory bars are pretty close for average driver on average streets..............you might like +7% front +35% rear if your city has lots of bumps/bad roads........you might go back to oem front bar.
On my Q45 I use a minus 3.5% front bar [29>28mm]and a plus 33% rear bar [20mm] which shifts the ratio 36.5/2=18% rear ward.........18% less understeer roughly.
Have a 70% [24mm] rear bar [non adjustable] which is just too rough over some of the highways I travel.........and a little scarey in the wet. After 5 years of experimentation mixing matching 4 different bars and stock vs Eibach springs with 3 different grade shock absorbers.............just like Goldilocks I've finally got it just right FOR ME.........everyone is different.
The rear stillen bar appears to be 22mm is the oem rear bar 20-21mm.......don't have one to measure?
Nissan uses standard equations on their cars so it is valid to compare a heavier Q45 to a G35 suspension --- correcting for weight.......the errors won't be more than 10% why I gave ranges in the above!
Remember the bars act in parallel with the springs and the bars are 25-80% of the spring wheel rate so changing the bar is always less than half the total roll stiffness.
A 70% stffer bar only increase the total rear roll resistance by < 35% probably 30%...........so don't expect sway bars to actually reduce body sway that much!
Not much detail on Stillen site 7% > 70%.
It's a summation game! two [both] 70% doesn't change the understeer ratio. front at 35% [middle ?] rear at 70% would shift ratio by 35%/2=10-18% more rearward.
Really need to know the spring and bar effectve rates to zero in on the exact numbers.
I am guessing that the Stllen rear Gbar is probably 70-80 lbs per inch at the 70% position and the oem rear bar is 40-45 lbs per inch.
Obviously the +7% rear would not be noticeable, the mid [+35%?] or the stiffest +70% are the two desirable positions.
The factory bars are pretty close for average driver on average streets..............you might like +7% front +35% rear if your city has lots of bumps/bad roads........you might go back to oem front bar.
On my Q45 I use a minus 3.5% front bar [29>28mm]and a plus 33% rear bar [20mm] which shifts the ratio 36.5/2=18% rear ward.........18% less understeer roughly.
Have a 70% [24mm] rear bar [non adjustable] which is just too rough over some of the highways I travel.........and a little scarey in the wet. After 5 years of experimentation mixing matching 4 different bars and stock vs Eibach springs with 3 different grade shock absorbers.............just like Goldilocks I've finally got it just right FOR ME.........everyone is different.
The rear stillen bar appears to be 22mm is the oem rear bar 20-21mm.......don't have one to measure?
Nissan uses standard equations on their cars so it is valid to compare a heavier Q45 to a G35 suspension --- correcting for weight.......the errors won't be more than 10% why I gave ranges in the above!
Remember the bars act in parallel with the springs and the bars are 25-80% of the spring wheel rate so changing the bar is always less than half the total roll stiffness.
A 70% stffer bar only increase the total rear roll resistance by < 35% probably 30%...........so don't expect sway bars to actually reduce body sway that much!
#18
09-22-2004, 11:03 AM
#19
09-22-2004, 11:29 AM
Re: Tires
I think for the sake of sanity and reason - it's safe to say that when dealing with cato, one can assume that he is not dumb enough to suggest that his new tires should perform better than worn old ones - any moron knows that.
What textbook have you been overreading that says consumers don't know how to tell if thier own tires are better?? Burn it and stop teaching school when the bell has already rung. Anyone who is on this board and knows their windshield from the wind remembers the crappy traction these things have at 10, 1,000, and 10,000 miles. And I'd also bet that his EL 42's are just as crappy as mine and vice versa. Did infiniti allow for 6 different sets of tires that were that different to come out of the factory...sounds inconsistent with some other things you have said the factory is very concerned about for magazine performance??? I'd also bet I could **** out on broad street right now and hit a car with better tires than mine - anything would be an imrovement.
2003.5 DP 5AT Sedan
14.2 @ 97.18
Z-Tube
K&N Drop In & Airbox Mod
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Hotchkis Sways (M/M)
Polk EX-3500 Tweeters/Shock Sensor/H-Liner
What textbook have you been overreading that says consumers don't know how to tell if thier own tires are better?? Burn it and stop teaching school when the bell has already rung. Anyone who is on this board and knows their windshield from the wind remembers the crappy traction these things have at 10, 1,000, and 10,000 miles. And I'd also bet that his EL 42's are just as crappy as mine and vice versa. Did infiniti allow for 6 different sets of tires that were that different to come out of the factory...sounds inconsistent with some other things you have said the factory is very concerned about for magazine performance??? I'd also bet I could **** out on broad street right now and hit a car with better tires than mine - anything would be an imrovement.
2003.5 DP 5AT Sedan
14.2 @ 97.18
Z-Tube
K&N Drop In & Airbox Mod
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Hotchkis Sways (M/M)
Polk EX-3500 Tweeters/Shock Sensor/H-Liner
#20
09-22-2004, 12:14 PM
Re: Tires
You can use the bar setting of others as a starting point. Adjustable sway bars are ment to fine tune the car, to make it offer up at the limit behavior that suits you. As such if you are to make the most of them you must test various settings and be willing to make changes until you find the settings that allow you to become one with machine. What may be right on one car, it's driver, and all the other parts that may have been added, may not be right for you. Your goal it to shape the cars behavior so it is a finely tuned weapon that allow's you to extract the best performance as your talents allow. Sway bar's are NOT ment to correct poor set up choices. Use this meathod, posed by Loren04Coupe. https://g35driver.com/forums/showfla...t=1#Post175209
Front motion rates on the G and Z are .79, rear .36. So, with a 314lbs spring rate your front wheel rate is 248lbs. And with a rear spring rate of 342 your rear wheel rate is 123lbs. The OEM torsional deflection rate on the front sway bar is
1100 lbs./ in. The OEM torsional deflection rate on the rear bar is 380 lbs/in
So, if I read what Qtech is saying right, front wheel rate plus half of sway bar rate would equal a oem setup as follow's
Front 248lbs+550lbs= 794lbs
Rear, 123lbs+190= 313lbs
Looking at my Cusco sway bar setup,
Front 248lbs+754lbs= 1002lbs
Rear 123lbs+329= 452lbs
Hotchkis set at med/med
Front 248+726= 974lbs
Rear 123+365= 488lbs
Hotchkis set soft/med
Front 248+600= 848lbs
Rear 123+365= 488lbs
***!! If you have aftermarket springs or coilovers, the above numbers DO NOT APPLY!*** Several G35 lowering springs and coilover systems use weak rear spring rates and transfer roll stiffness to the front, sometime A LOT!
In any event, we should not be in the business of picking bar settings based on numbers, set sway bars on trial and error, going with the settings that make the car the way you need it, you shape the car, not the other way around.
"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke
G35 6mt
Front motion rates on the G and Z are .79, rear .36. So, with a 314lbs spring rate your front wheel rate is 248lbs. And with a rear spring rate of 342 your rear wheel rate is 123lbs. The OEM torsional deflection rate on the front sway bar is
1100 lbs./ in. The OEM torsional deflection rate on the rear bar is 380 lbs/in
So, if I read what Qtech is saying right, front wheel rate plus half of sway bar rate would equal a oem setup as follow's
Front 248lbs+550lbs= 794lbs
Rear, 123lbs+190= 313lbs
Looking at my Cusco sway bar setup,
Front 248lbs+754lbs= 1002lbs
Rear 123lbs+329= 452lbs
Hotchkis set at med/med
Front 248+726= 974lbs
Rear 123+365= 488lbs
Hotchkis set soft/med
Front 248+600= 848lbs
Rear 123+365= 488lbs
***!! If you have aftermarket springs or coilovers, the above numbers DO NOT APPLY!*** Several G35 lowering springs and coilover systems use weak rear spring rates and transfer roll stiffness to the front, sometime A LOT!
In any event, we should not be in the business of picking bar settings based on numbers, set sway bars on trial and error, going with the settings that make the car the way you need it, you shape the car, not the other way around.
"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke
G35 6mt
#21
09-22-2004, 02:17 PM
Re: Tires
Thank you very much SixFive!
The first time I checked, my EL 42s were a piece of crap.
The last time I checked, my EL 42s were a piece of crap.
03 5AT Sedan, sunroof, splashguards, HKS muffler,
14 wire Grounding kit, Z Duct, Stillen HF/AB
Underbody rear diffusers, Drilled alum pedals,
Stillen sway bars H/H
The first time I checked, my EL 42s were a piece of crap.
The last time I checked, my EL 42s were a piece of crap.
03 5AT Sedan, sunroof, splashguards, HKS muffler,
14 wire Grounding kit, Z Duct, Stillen HF/AB
Underbody rear diffusers, Drilled alum pedals,
Stillen sway bars H/H
#22
09-26-2004, 10:37 AM
Re: Tires
This is because you replaced the GS-D's w/ probably EL42's. Those are Standard All-Season Touring tires. They are not made to glue you to the road. They were designed to be a quiet and comfortable tire in everything from dry pavement to light snow.
This has nothing to do with not going through dealer channels w/ Nissan using Ultra Ultra performance tires than what is available anywhere else (that was actually quite funny to read though). I don't care much for the GS-D's anyway, I just wish we weren't so limited due to tire size.
As for Kumho's, my experience (I've heard the same from many others) are that they are great tires for the money initially, but after about 5k-10k, they start getting really noisy, and the ride goes to He**. If I could get some DS-D3's or SO-3's on the care, I'd be one happy camper!
This has nothing to do with not going through dealer channels w/ Nissan using Ultra Ultra performance tires than what is available anywhere else (that was actually quite funny to read though). I don't care much for the GS-D's anyway, I just wish we weren't so limited due to tire size.
As for Kumho's, my experience (I've heard the same from many others) are that they are great tires for the money initially, but after about 5k-10k, they start getting really noisy, and the ride goes to He**. If I could get some DS-D3's or SO-3's on the care, I'd be one happy camper!
#23
09-26-2004, 01:09 PM
Re: Tires
"Front motion rates on the G and Z are .79, rear .36. So, with a 314lbs spring rate your front wheel rate is 248lbs. And with a rear spring rate of 342 your rear wheel rate is 123lbs. The OEM torsional deflection rate on the front sway bar is
1100 lbs./ in. The OEM torsional deflection rate on the rear bar is 380 lbs/in "
I agree with the ~~123 lb/inches for the rear wheel rate [corrected for motion and angle] from springs
248 lb/inches for the front Wheel rate seems grossly excessive as usually [98% of the time] to optimize highway ride based on spacing and undulations from the asphalt and concrete seams, the front wheel rate matches the ratio of the weight balance.......now in a performance car you can and some do increase the ratio [stiffen the front] [which raises the tuned critical speed for highway fore aft pitching]. I would expect something on the order of <150 lb/inches [springs alone] if tuned for 60 mph or <175 lb/inches if tuned for 80 mph.
Both front and rear sway bar attach inward of the midpoint of the approtriate suspension arm so they are reduced [by the trig/geo-metrictric function] of their real motion: the fronts actual wheel stiffness would be divided by greater than 5 probably 6 [1100/6= ~~185 lb/ft] [just guessing from a blown up diagram measured with a ruler].
The rears 380 lb/in for the bar alone [looks again from a picture] more like a 5-4.5 motion ratio so ~~75-85 lb/inches at the wheel hub.
123 +75 or 85= ~~ 200-210 lb/inches Total rear roll stiffness combined would be aggressive for an Oem design.
My Q has 163>181>200 lb/inch rear roll stiffness with progreesive rear Eibach and a 40 lb/in wheel rate rear bar.
[Nether of us has calculated the series sidewall stiffness of the tire spring action] which usually reduces the roll stiffness by another 2-7%!]
How did you derive the front spring motion ratio"? I get closer to 0.5 [not actually measured on the G].
1100 lbs./ in. The OEM torsional deflection rate on the rear bar is 380 lbs/in "
I agree with the ~~123 lb/inches for the rear wheel rate [corrected for motion and angle] from springs
248 lb/inches for the front Wheel rate seems grossly excessive as usually [98% of the time] to optimize highway ride based on spacing and undulations from the asphalt and concrete seams, the front wheel rate matches the ratio of the weight balance.......now in a performance car you can and some do increase the ratio [stiffen the front] [which raises the tuned critical speed for highway fore aft pitching]. I would expect something on the order of <150 lb/inches [springs alone] if tuned for 60 mph or <175 lb/inches if tuned for 80 mph.
Both front and rear sway bar attach inward of the midpoint of the approtriate suspension arm so they are reduced [by the trig/geo-metrictric function] of their real motion: the fronts actual wheel stiffness would be divided by greater than 5 probably 6 [1100/6= ~~185 lb/ft] [just guessing from a blown up diagram measured with a ruler].
The rears 380 lb/in for the bar alone [looks again from a picture] more like a 5-4.5 motion ratio so ~~75-85 lb/inches at the wheel hub.
123 +75 or 85= ~~ 200-210 lb/inches Total rear roll stiffness combined would be aggressive for an Oem design.
My Q has 163>181>200 lb/inch rear roll stiffness with progreesive rear Eibach and a 40 lb/in wheel rate rear bar.
[Nether of us has calculated the series sidewall stiffness of the tire spring action] which usually reduces the roll stiffness by another 2-7%!]
How did you derive the front spring motion ratio"? I get closer to 0.5 [not actually measured on the G].
#24
09-26-2004, 01:35 PM
Re: Tires
Most dealers buy tires locally [the same tires you can buy from Tirerack and others],
My point was the oem tires that come on the car are built to a different spec at a different Japan factory for Nissan than the same make model US made brand tires you buy in the US replacement aftermarket.
They make look the same externally [same tread pattern because the mold design and initials cost so much] but the compound and tread/sidewall material thickness may be grossly different between Japanese made and US made.
Some times they are mostly identical sometimes quite different.
The EL42 comes in T, H, V and W speed ratings with a tread wear index of 170-400 with single and double ply and 2.5 ply sidewalls. There are nylon full cap, half edge caps, and spiral wrap nylon, not counting the 7 versions in the tread carcass.
Can't just say EL42 must be very specific and the date and which factory produced.......all coded on the sidewall.
My point was the oem tires that come on the car are built to a different spec at a different Japan factory for Nissan than the same make model US made brand tires you buy in the US replacement aftermarket.
They make look the same externally [same tread pattern because the mold design and initials cost so much] but the compound and tread/sidewall material thickness may be grossly different between Japanese made and US made.
Some times they are mostly identical sometimes quite different.
The EL42 comes in T, H, V and W speed ratings with a tread wear index of 170-400 with single and double ply and 2.5 ply sidewalls. There are nylon full cap, half edge caps, and spiral wrap nylon, not counting the 7 versions in the tread carcass.
Can't just say EL42 must be very specific and the date and which factory produced.......all coded on the sidewall.
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