dmj
Well-known member
How do I eliminate or at least reduce the amount of understeer in my Gvr4?How big of a front swaybar is recommended?
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Understeer
- Thread starter dmj
- Start date
DSMTurbo2
Well-known member
Well there are lots of ways.
You would not want to go with a larger ARB as that will actually make your problem worse.
What conditions are you experiencing understeer during?
Erik
You would not want to go with a larger ARB as that will actually make your problem worse.
What conditions are you experiencing understeer during?
Erik
dmj
Well-known member
Cornering,car leans excessively.Just put in H&R springs and new KYB GR2's.
thecman02
Well-known member
More details = better answer.
Ohh and Erik we need to meet up sometime.
Ohh and Erik we need to meet up sometime.
thecman02
Well-known member
If you put a huge sway bar in the back it'll help your car rotate better. Those shocks are going to disappoint you more then likely. The stiffer springs will help, but those shocks are more for just stock replacement. A bigger sway bar in the front will help with your lean, but not with your understeer.
Hertz
Staff member
Cannot forget the #1 handling element: tires.
dmj
Well-known member
Tires are Yokohamas 195/60/15.The handling on the car sucks though.I think I should upgrade to the Evo 8/9 set up.anyone with feedback on those?
belize1334
Well-known member
The first biggest thing you can do is tires, preferably on a 16" or 17" wheel. Then I'd do front camber and rear anti-sway bar together. Then I'd do stiffer springs/shocks. Then I'd do stiffer front sway bar, and then coil over suspension for even stiffer springs/shocks and more front camber.
Dialcaliper
Well-known member
Tires are the most important part of handling, but you can't really cure oversteer/understeer with street tires. A rear sway bar is the simplest and most cost effective solution.
Understeer is caused by the fact that the front loses grip before the rear. A rear sway bar will actually help the front grip better by causing weight transfer. If your familiar with corner weighing, "wedge" or diagonal weight, it works on the same principle - regardless of how you change the corner weights, you cannot change the actual front/rear or side/side weight balance of the car.
The sway bar stiffens the rear, and causes *more* weight to be transferred to the inside rear to the outside rear, essentially by "lifting" the inside rear a bit. If you think of a 4-legged stool that has mismatched legs, this will also cause the load on the outside front to decrease. In turn, the outside rear and inside front carry the weight that was lifted from the other pair.
The net result is that by twisting the chassis at the rear, you transfer unused "reserve" grip from the inside rear to the inside front, which is really not doing much work.
Note that in doing this, you end up with a net loss of available cornering force in the rear that is larger than the amount you gain in the front (because you also lost a bit on the outside front), so compared to other methods (changing tires and wheel alignment/camber, adjusting weight balance, using a suspension design in the front better than lousy mcpherson struts), your total "theoretical" traction is lower. But since you are adding grip on the axle that is traction-limited, you are actually cornering better than you were before.
Another alternative is to add negative camber and positive caster in the front. Whatever you do, don't fix it by reducing camber in the rear, as that will simply reduce overall grip without adding any in the front.
Another side-note is that you can achieve the same thing by using stiffer rear springs - the roll stiffness they add is functionally identical to a sway bar (but it will change the front/rear roll stiffness and ride quality, which can affect braking and acceleration)
Quoting Hertz:
Cannot forget the #1 handling element: tires.
Understeer is caused by the fact that the front loses grip before the rear. A rear sway bar will actually help the front grip better by causing weight transfer. If your familiar with corner weighing, "wedge" or diagonal weight, it works on the same principle - regardless of how you change the corner weights, you cannot change the actual front/rear or side/side weight balance of the car.
The sway bar stiffens the rear, and causes *more* weight to be transferred to the inside rear to the outside rear, essentially by "lifting" the inside rear a bit. If you think of a 4-legged stool that has mismatched legs, this will also cause the load on the outside front to decrease. In turn, the outside rear and inside front carry the weight that was lifted from the other pair.
The net result is that by twisting the chassis at the rear, you transfer unused "reserve" grip from the inside rear to the inside front, which is really not doing much work.
Note that in doing this, you end up with a net loss of available cornering force in the rear that is larger than the amount you gain in the front (because you also lost a bit on the outside front), so compared to other methods (changing tires and wheel alignment/camber, adjusting weight balance, using a suspension design in the front better than lousy mcpherson struts), your total "theoretical" traction is lower. But since you are adding grip on the axle that is traction-limited, you are actually cornering better than you were before.
Another alternative is to add negative camber and positive caster in the front. Whatever you do, don't fix it by reducing camber in the rear, as that will simply reduce overall grip without adding any in the front.
Another side-note is that you can achieve the same thing by using stiffer rear springs - the roll stiffness they add is functionally identical to a sway bar (but it will change the front/rear roll stiffness and ride quality, which can affect braking and acceleration)
Quoting Hertz:
Cannot forget the #1 handling element: tires.
DSMTurbo2
Well-known member
Ditto to Dial for the most part. Increasing wheel rate may not be the right way but will work.
We need a little more info though. The suspension geometry itself is very poor for neutral handling characteristics. The geometry itself is designed to under steer from the factory, as it is seen to be safer than oversteer. When I was asking "under what conditions", I was referring to high speed, low speed, braking, accelerating, transient, static loading, are you pulling into a parking space and smack the car next to you?? You need to give some more information if you want specifics. If you are just looking for an easy answer, we can give you one and you can go out and buy all the parts you want but it may not correct what you are experiencing.
Off topic:
thecman02, I am in the zoo from time to time, do you do any of the local meets or know any of the locals?
Erik
We need a little more info though. The suspension geometry itself is very poor for neutral handling characteristics. The geometry itself is designed to under steer from the factory, as it is seen to be safer than oversteer. When I was asking "under what conditions", I was referring to high speed, low speed, braking, accelerating, transient, static loading, are you pulling into a parking space and smack the car next to you?? You need to give some more information if you want specifics. If you are just looking for an easy answer, we can give you one and you can go out and buy all the parts you want but it may not correct what you are experiencing.
Off topic:
thecman02, I am in the zoo from time to time, do you do any of the local meets or know any of the locals?
Erik
Dial pretty much covered it. Note that there is some amount of tuning you can do with tire air pressure. With relatively narrow street tires you can gain a bit more grip in front by increasing air pressure, which stiffens the sidewall and helps keep the treadface planted at the road interface. Likewise, decreasing rear tire pressure will have the inverse effect. I would not recommend more than a 10 psig difference front to rear. This strategy does not increase the total amount of grip, just redistributes it between front and rear.
Also, the rear wheel steer function tends to exagerate the sense of understeering. Disconnecting it can give a more satisfying or at least more predictable steering sensation at turn in. You can just disconnect the links at the rear trailing arms, and the car will revert to the passive rear steer through the busings same as an Eclipse.
Mike R.
Also, the rear wheel steer function tends to exagerate the sense of understeering. Disconnecting it can give a more satisfying or at least more predictable steering sensation at turn in. You can just disconnect the links at the rear trailing arms, and the car will revert to the passive rear steer through the busings same as an Eclipse.
Mike R.
dmj
Well-known member
Glad for the insight and recommendations guys. I am going to disconnect the rear tie-rods first since it is a free mod,I got nothing to lose.
CP
Well-known member
Disconnect the rear tie rods...WTF?
Get a bigger rear swaybar, up the pressure in the rear tires and get an alignment from a tech that knows what he's doing (preferrably a race shop).
Get a bigger rear swaybar, up the pressure in the rear tires and get an alignment from a tech that knows what he's doing (preferrably a race shop).
Quote:
Disconnect the rear tie rods...WTF?
Yes, the rear-steer tie rods. The rear steer causes the rear end to tuck and delays rotation. You know that.
I was suggesting things that involve adding no new equipment.
Mike R.
Disconnect the rear tie rods...WTF?
Yes, the rear-steer tie rods. The rear steer causes the rear end to tuck and delays rotation. You know that.
I was suggesting things that involve adding no new equipment.
Mike R.
Last edited by a moderator:
Before you spend any money at all, try driving it differently.
If you try and drive the car the same way you would an FR (or FF) it will understeer - lots.
When you are off the gas, the car will understeer (as a function of the basic geometry), if the car is already understeering and you get on the gas, it will make it push more.
I've found when I'm rolling on the gas as I'm turning in the car prettymuch goes where I want it to.
If you find the car starting to push, or squealing the inside front tire, often reducing the steering lock (the opposite of what you instinctively want to do) will restore some front end grip.
Most importantly, be smooth with the steering, don't "throw" the car into the corner.
It's worth noting that modifications which will reduce the cars tendancy to understeer under neutral throttle will increase it's tendancy towards lift-off oversteer, particularly when you start braking over a crest.
If you try and drive the car the same way you would an FR (or FF) it will understeer - lots.
When you are off the gas, the car will understeer (as a function of the basic geometry), if the car is already understeering and you get on the gas, it will make it push more.
I've found when I'm rolling on the gas as I'm turning in the car prettymuch goes where I want it to.
If you find the car starting to push, or squealing the inside front tire, often reducing the steering lock (the opposite of what you instinctively want to do) will restore some front end grip.
Most importantly, be smooth with the steering, don't "throw" the car into the corner.
It's worth noting that modifications which will reduce the cars tendancy to understeer under neutral throttle will increase it's tendancy towards lift-off oversteer, particularly when you start braking over a crest.
markrieb
Well-known member
Quoting dmj:
How do I eliminate or at least reduce the amount of understeer in my Gvr4?How big of a front swaybar is recommended?
You may be too late as I think Whiteline quit making the GVR-4 parts, but what you need are the front Whiteline offset caster bushings, some front camber plates and some real shocks. Then step up to a good tire and wheel combination.
As old as these cars are now, if you really want to make it handle you are going to have to pretty much rebuild all of the suspension. All new bushings, get rid of the AWS, camber plates, sway bars, coilovers, etc.
I broke a lot of ground with that back when only Mofugas was selling Whiteline parts and there were no coilover kits available (even the DSM guys were just starting to go to true coilover). Now there are lots of good options and even better some 8" wide wheels that will fit.
Lots of discussion on the board if you'll search.
Mark
How do I eliminate or at least reduce the amount of understeer in my Gvr4?How big of a front swaybar is recommended?
You may be too late as I think Whiteline quit making the GVR-4 parts, but what you need are the front Whiteline offset caster bushings, some front camber plates and some real shocks. Then step up to a good tire and wheel combination.
As old as these cars are now, if you really want to make it handle you are going to have to pretty much rebuild all of the suspension. All new bushings, get rid of the AWS, camber plates, sway bars, coilovers, etc.
I broke a lot of ground with that back when only Mofugas was selling Whiteline parts and there were no coilover kits available (even the DSM guys were just starting to go to true coilover). Now there are lots of good options and even better some 8" wide wheels that will fit.
Lots of discussion on the board if you'll search.
Mark
Nice Topic. Saved.
I experience some understeer as well in Maine in a foot of snow. All the Roads are Off-Camber with a crown in the middle of it, causing a crab-walk like push of the front tires.
Luckily, its nothing a little power-oversteer doesn't fix. /ubbthreads/images/graemlins/smile.gif
I experience some understeer as well in Maine in a foot of snow. All the Roads are Off-Camber with a crown in the middle of it, causing a crab-walk like push of the front tires.
Luckily, its nothing a little power-oversteer doesn't fix. /ubbthreads/images/graemlins/smile.gif
Whiteline 26mm rear sway bar is the best cure for your understeer. They are being discontinued but for a short time I can still order them. There's none in the states but I've been ordering once a week and will continue to do so for the rest of the year. After that I'm not sure how long they'll keep taking the orders. PM me or call the shop if you want to get some while you still can.
RedTwo
Well-known member
Yeah, they've also scrapped their strut bars, all the smaller sway bars (front and rear) and a bunch of bushings (some are now in the new FlatOut catalogue though) /ubbthreads/images/graemlins/frown.gif
