just curious about something...
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From: Cleburne, tx
just curious about something...
whats the point in getting a stiffer spring rate in the rear? wouldnt it cause the rear to spin out easier under heavy turning?
im about to buy some GC/koni's and was thinking about 450F/350R springs, but i keep seeing people ride 500F/600R, or 10kF/12kR, and just wanted to make sure my theory is right... for racing purpose anyway. (its a 93 hatch btw)
.. i've been experimenting on Forza2 on my 360, and my hatch handles better with stiffer springs out front, so its beyond me why guys grab stiff springs in the rear
Modified by fatpride111 at 8:56 PM 8/22/2008
im about to buy some GC/koni's and was thinking about 450F/350R springs, but i keep seeing people ride 500F/600R, or 10kF/12kR, and just wanted to make sure my theory is right... for racing purpose anyway. (its a 93 hatch btw)
.. i've been experimenting on Forza2 on my 360, and my hatch handles better with stiffer springs out front, so its beyond me why guys grab stiff springs in the rear
Modified by fatpride111 at 8:56 PM 8/22/2008
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Re: just curious about something... (fatpride111)
Stiffer springs allows the car to rotate better around a turn. Fwd cars is more prone to understeer than oversteering and adding stiffer rear will reduce the understeer a bit, but the car will still understeer.
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From: strathcedar, nsw, australia
Re: just curious about something... (fatpride111)
Because stiffer springs create higher roll stiffness at the axle line to which the stiffer springs are fitted, and higher roll stiffness creates more weight transfer. Stiffening the rear means you will have more weight transfer at the rear than you previously did, and less weight transfer at the front than previously.
This occurs even though you did nothing to the front roll stiffness, i.e. total front + rear weight transfer will equal X, but if you increase rear roll stiffness then a greater % of X will occur at the rear, so a lesser % of X must occur at the front. You would get the same affect by decreasing front roll stiffness, that + more body roll.
Increasing rear roll stiffness means that when cornering the front contact patches will carry the front weight more equally, and the rear contact patches will carry the rear weight less equally, which means that you will 'effectively' (i.e. not in reality, unless a wheel actually fully unloads, but in effect) have more rubber on the road at the front and less at the rear, so you will reduce understeer. A similar affect can be had by increasing rear anti roll bar stiffness (or reducing front ARB stiffness).
There are good reasons why you see so many FWD racing cars hoik the IR in the air so readily, to reduce understeer, and to reduce front weight transfer in order to get power to the ground at the IF. This happens because they typically run much more rear than front roll stiffness.
And, don't attempt to use Forza as a real world tuning guide, it's only a game, many of the adjustments have un-real-world affects (and some seem to have zero affect). Having said that, I've wasted a lot of time playing it, my best time at the Nordschliffe in the Audi R8 (with a wheel in manual mode and all aids other then anti lock brakes off) is just a tad over 6m21s, and I'm quite proud of that!
Modified by johnlear at 9:20 AM 8/23/2008
Modified by johnlear at 9:25 AM 8/23/2008
This occurs even though you did nothing to the front roll stiffness, i.e. total front + rear weight transfer will equal X, but if you increase rear roll stiffness then a greater % of X will occur at the rear, so a lesser % of X must occur at the front. You would get the same affect by decreasing front roll stiffness, that + more body roll.
Increasing rear roll stiffness means that when cornering the front contact patches will carry the front weight more equally, and the rear contact patches will carry the rear weight less equally, which means that you will 'effectively' (i.e. not in reality, unless a wheel actually fully unloads, but in effect) have more rubber on the road at the front and less at the rear, so you will reduce understeer. A similar affect can be had by increasing rear anti roll bar stiffness (or reducing front ARB stiffness).
There are good reasons why you see so many FWD racing cars hoik the IR in the air so readily, to reduce understeer, and to reduce front weight transfer in order to get power to the ground at the IF. This happens because they typically run much more rear than front roll stiffness.
And, don't attempt to use Forza as a real world tuning guide, it's only a game, many of the adjustments have un-real-world affects (and some seem to have zero affect). Having said that, I've wasted a lot of time playing it, my best time at the Nordschliffe in the Audi R8 (with a wheel in manual mode and all aids other then anti lock brakes off) is just a tad over 6m21s, and I'm quite proud of that!
Modified by johnlear at 9:20 AM 8/23/2008
Modified by johnlear at 9:25 AM 8/23/2008
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From: Cleburne, tx
so more weight transfer/stiffer springs in the rear would cause the back to spin out easier than the front since all tbe weight will go to the rear?
i believe on RWD's you almost have to have soft springs on the rear, since they loose traction much easier (also depends on driving ability) around corners since they cant go all out coming out of a corner without fish-tailing. i think my brothers car (its a rwd) he has like 500F/250R springs and it catches pretty decent.. idk if the same goes for FWD
what would you recommend for my hatch? im getting teggy LCA's and gsr swaybar, so if i grab some 350R, itll still be pretty stiff with the swaybar, right?
i believe on RWD's you almost have to have soft springs on the rear, since they loose traction much easier (also depends on driving ability) around corners since they cant go all out coming out of a corner without fish-tailing. i think my brothers car (its a rwd) he has like 500F/250R springs and it catches pretty decent.. idk if the same goes for FWD
what would you recommend for my hatch? im getting teggy LCA's and gsr swaybar, so if i grab some 350R, itll still be pretty stiff with the swaybar, right?
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Re: (fatpride111)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">oh okay, makes sense. So would 450/350 be good for road coursing between 60-100mph?</TD></TR></TABLE>
I'd recommend 550F/450R. And a bigger rear swaybar.
Dont worry about the rear spring bias. People run it because they think it gives them "rotation". This is an overly basic idea that only focuses on one aspect of the suspension, and when all is said and done the effects are quite minimal in terms of this "rotation". In fact the spring rates I recommend, when taken down to wheel rates, actually favor the rear so you could say they are rear biased as well, though they appear not to be.
I'd recommend 550F/450R. And a bigger rear swaybar.
Dont worry about the rear spring bias. People run it because they think it gives them "rotation". This is an overly basic idea that only focuses on one aspect of the suspension, and when all is said and done the effects are quite minimal in terms of this "rotation". In fact the spring rates I recommend, when taken down to wheel rates, actually favor the rear so you could say they are rear biased as well, though they appear not to be.
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From: strathcedar, nsw, australia
Re: (fatpride111)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">so more weight transfer/stiffer springs in the rear would cause the back to spin out easier than the front since all tbe weight will go to the rear? </TD></TR></TABLE>
Yes, up to a point (or beyond a point).
I think you might be a bit confused ("since all tbe weight will go to the rear"). The weight transfer that we are talking about occurs laterally, not longitudinally, i.e. unless there is also a longitudinal acceleration (i.e. 'G force'), IR weight transfers only to the OR and IF weight only transfers to the OF.
Anything you do to decrease understeer will bring you closer to possible oversteer, in some cases dangerously so. Car manufacturers typically set their cars up to understeer quite strongly because for an 'average' driver the instinctive reaction to the handling becoming 'strange' is to lift off the throttle, which is typically the right thing to do with understeer but very often the wrong thing with oversteer (spelled s.p.i.n. and c.r.a.s.h.).
They don't want to be sued because some court might consider the handling of their cars to be 'dangerous' for average drivers (e.g. GM vs Nadir). Even Porsche has gone to great lengths over the last few years to decrease the oversteery nature of the 911, an impressive feat considering all that weight hung out past the rear wheels...
You can of course go too far when trying to achieve a more neutral handling balance, an oversteering car requires constant driver attention which isn't always possible even for very skillful drivers (disaster can result from a moments inattention or in an unexpected emergency manouvre), so it's probably a good idea to err on the side of slight understeer for a street driven car...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">i believe on RWD's you almost have to have soft springs on the rear, since they loose traction much easier (also depends on driving ability) around corners since they cant go all out coming out of a corner without fish-tailing. i think my brothers car (its a rwd) he has like 500F/250R springs and it catches pretty decent.. idk if the same goes for FWD </TD></TR></TABLE>
RWD cars will typically have have softer springs rates in the rear (even racers) to keep rear roll stiffness lower than front roll stiffness in order to maximise rear traction. This tends to mean that understeer can be a real issue for RWD cars as much as for FWD, but then manufacturers mostly want an understeering balance. Stock FWD will typically have softer rear rates (i.e less rear roll stiffness) to induce understeer, which unfortunately also tends to decrease IF traction exiting corners. For racing cars it's a matter of finding the fastest compromise.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">ihat would you recommend for my hatch? im getting teggy LCA's and gsr swaybar, so if i grab some 350R, itll still be pretty stiff with the swaybar, right?</TD></TR></TABLE>
I can't really give you any specific recommendation, beyond to be cautious of going too stiff in the rear relative to the front. Personally, I'd firstly go with a stiffer rear ARB and see how that works out, before considering whether you want / need more rear roll stiffness from rear springs that have a higher than front stiffness.
Don't confuse steering response with under / over steer characteristics, you could have a car that turns in sharply yet still be an understeerer at / near the limit, or one that turns in lazily that oversteers at / near the limit. Steering response and handling balance are parts of what makes up 'good handling', but neither is the totality of it.
Yes, up to a point (or beyond a point).
I think you might be a bit confused ("since all tbe weight will go to the rear"). The weight transfer that we are talking about occurs laterally, not longitudinally, i.e. unless there is also a longitudinal acceleration (i.e. 'G force'), IR weight transfers only to the OR and IF weight only transfers to the OF.
Anything you do to decrease understeer will bring you closer to possible oversteer, in some cases dangerously so. Car manufacturers typically set their cars up to understeer quite strongly because for an 'average' driver the instinctive reaction to the handling becoming 'strange' is to lift off the throttle, which is typically the right thing to do with understeer but very often the wrong thing with oversteer (spelled s.p.i.n. and c.r.a.s.h.).
They don't want to be sued because some court might consider the handling of their cars to be 'dangerous' for average drivers (e.g. GM vs Nadir). Even Porsche has gone to great lengths over the last few years to decrease the oversteery nature of the 911, an impressive feat considering all that weight hung out past the rear wheels...
You can of course go too far when trying to achieve a more neutral handling balance, an oversteering car requires constant driver attention which isn't always possible even for very skillful drivers (disaster can result from a moments inattention or in an unexpected emergency manouvre), so it's probably a good idea to err on the side of slight understeer for a street driven car...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">i believe on RWD's you almost have to have soft springs on the rear, since they loose traction much easier (also depends on driving ability) around corners since they cant go all out coming out of a corner without fish-tailing. i think my brothers car (its a rwd) he has like 500F/250R springs and it catches pretty decent.. idk if the same goes for FWD </TD></TR></TABLE>
RWD cars will typically have have softer springs rates in the rear (even racers) to keep rear roll stiffness lower than front roll stiffness in order to maximise rear traction. This tends to mean that understeer can be a real issue for RWD cars as much as for FWD, but then manufacturers mostly want an understeering balance. Stock FWD will typically have softer rear rates (i.e less rear roll stiffness) to induce understeer, which unfortunately also tends to decrease IF traction exiting corners. For racing cars it's a matter of finding the fastest compromise.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fatpride111 »</TD></TR><TR><TD CLASS="quote">ihat would you recommend for my hatch? im getting teggy LCA's and gsr swaybar, so if i grab some 350R, itll still be pretty stiff with the swaybar, right?</TD></TR></TABLE>
I can't really give you any specific recommendation, beyond to be cautious of going too stiff in the rear relative to the front. Personally, I'd firstly go with a stiffer rear ARB and see how that works out, before considering whether you want / need more rear roll stiffness from rear springs that have a higher than front stiffness.
Don't confuse steering response with under / over steer characteristics, you could have a car that turns in sharply yet still be an understeerer at / near the limit, or one that turns in lazily that oversteers at / near the limit. Steering response and handling balance are parts of what makes up 'good handling', but neither is the totality of it.
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