Reduce Oversteer? - geo set-up question
#31
bonesetter,
The 24mm on the rear is fine (on the softest setting for the road), with a standard ARB on the front. I run this on my Spec C and it is absolutely fine, even with -2.5degs front and -2.0degs rear camber. I even open the diff up on the road (2nd position from fully open) and it's great fun!
The 24mm on the rear is fine (on the softest setting for the road), with a standard ARB on the front. I run this on my Spec C and it is absolutely fine, even with -2.5degs front and -2.0degs rear camber. I even open the diff up on the road (2nd position from fully open) and it's great fun!
With the back being a little shaky on occasion (hint of the start of a possible tank slapper the other day), I'm going to fettle some to reduce that, and for more grip!
#32
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To keep the balance, the rear will probably need to go back to the middle setting once the front bar is on. Mine is a 22mm on stiffest setting @ the rear.
dunx
dunx
#33
Scooby Regular
At the end of the day the car set-up is personal to each driver. I don't want a neutral car, I want a car that has sharp turn in, pointy with the back end coming round to ensure I don't understeer (and also to have some fun) to keep the line. I certainly don't want a load of grip at the back!
Horses for courses really and life would be so boring if we all wanted the same!
Hope you get it all sorted as you want it.
Horses for courses really and life would be so boring if we all wanted the same!
Hope you get it all sorted as you want it.
#35
At the end of the day the car set-up is personal to each driver. I don't want a neutral car, I want a car that has sharp turn in, pointy with the back end coming round to ensure I don't understeer (and also to have some fun) to keep the line. I certainly don't want a load of grip at the back!
Horses for courses really and life would be so boring if we all wanted the same!
Hope you get it all sorted as you want it.
Horses for courses really and life would be so boring if we all wanted the same!
Hope you get it all sorted as you want it.
What I am hoping to correct is lift-off and snap oversteer as well as increasing overall grip.
Last edited by bonesetter; 08 September 2009 at 05:32 PM.
#36
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On VERY tight corners too much power can just leave you understeering, BUT....
yes front bar on stiff & rear (both 22mm) , and yes rear end slides under full power, at Blyton as the revs increase so does the slip angle.... NICE !
Mine is still mainly a road car, with some trackday fun added. So I tend to want a stable car, not something "edgy" and nervous.
LOL
dunx
P.S. I don't push the car as hard on the road, as I'm old and slow now....
yes front bar on stiff & rear (both 22mm) , and yes rear end slides under full power, at Blyton as the revs increase so does the slip angle.... NICE !
Mine is still mainly a road car, with some trackday fun added. So I tend to want a stable car, not something "edgy" and nervous.
LOL
dunx
P.S. I don't push the car as hard on the road, as I'm old and slow now....
Last edited by dunx; 08 September 2009 at 10:11 PM.
#37
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dunx,
I suspect it all comes down to what you are used to and what you specifically want. I wouldn't say mine was nervous.... it has been though with different set-ups.
I suspect it all comes down to what you are used to and what you specifically want. I wouldn't say mine was nervous.... it has been though with different set-ups.
#38
Semi-sucess
Fitted the Roll Centre Correction Kit today.
Should have read the fitting instructions supplied before hand and then I would have known there was alloy arm insert which fits onto the ball joint taper for the alloy bottom arms, instead of thinking I had the wrong kit Couple of phone calls later and I was on the way again - big thanks to Kevin at Whiteline
Height adjustment:
Here's the semi-success bit. One of the adjusting screw collars on the rear has become too stiff to turn anymore, even with a pair of stillson's! I have achieved level heights each side (was ~8mm out on the rear before) and height has ended up as front 350 and rear 335. I hope this enough and OK. I think I remember hearing Tein recommend F355/R340 so 15mm difference would seem OK looking at that, and hopefully I'll end up with the car about level
Next is alignment which I'll get done tomorrow. Drove down the road to get some fuel (30mph) and car felt like it was on ice
Should have read the fitting instructions supplied before hand and then I would have known there was alloy arm insert which fits onto the ball joint taper for the alloy bottom arms, instead of thinking I had the wrong kit Couple of phone calls later and I was on the way again - big thanks to Kevin at Whiteline
Height adjustment:
Here's the semi-success bit. One of the adjusting screw collars on the rear has become too stiff to turn anymore, even with a pair of stillson's! I have achieved level heights each side (was ~8mm out on the rear before) and height has ended up as front 350 and rear 335. I hope this enough and OK. I think I remember hearing Tein recommend F355/R340 so 15mm difference would seem OK looking at that, and hopefully I'll end up with the car about level
Next is alignment which I'll get done tomorrow. Drove down the road to get some fuel (30mph) and car felt like it was on ice
#39
Current state of play...
Front feels razor sharp now. Turn-in has improved and the whole 'front end' just feels well sorted, not sure what else I can say.
The rear however has deteriorated. Feels like the back end is lurching and listing heavily as if the front and rear are out of balance.
Is the next step to fit the front arb and change the rear to the middle setting at the same time?.
How detrimental to the front will just altering the rear arb setting be?
Current geo settings. The front camber (left) is 1' 45' and the the units are in 60. So 45' is three quarters of one degree. So left camber is one and three quarter degrees negative.
I asked for the toe to be increased from previous settings, along with front caber slightly
The rear however has deteriorated. Feels like the back end is lurching and listing heavily as if the front and rear are out of balance.
Is the next step to fit the front arb and change the rear to the middle setting at the same time?.
How detrimental to the front will just altering the rear arb setting be?
Current geo settings. The front camber (left) is 1' 45' and the the units are in 60. So 45' is three quarters of one degree. So left camber is one and three quarter degrees negative.
I asked for the toe to be increased from previous settings, along with front caber slightly
#40
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As you stiffen the rear bar the front should be more "pointy" because the car rolls less as you turn in to a corner.
I'm not sure but is the rear toe setting right ? is it +ve or -ve ?
dunx
I'm not sure but is the rear toe setting right ? is it +ve or -ve ?
dunx
#42
Hi,
Alignment looks good. With the handling you indicated earlier, I would fit the front ARB, and leave the rear ARB at the softest setting to begin with and see if the balance is more towards your goal. As long as your rear dampers are ok and have enough efficiency to control, I suspect that you are getting close...........
After that you can always turn up the rear ARB to try, it only take a few minutes.
Alignment looks good. With the handling you indicated earlier, I would fit the front ARB, and leave the rear ARB at the softest setting to begin with and see if the balance is more towards your goal. As long as your rear dampers are ok and have enough efficiency to control, I suspect that you are getting close...........
After that you can always turn up the rear ARB to try, it only take a few minutes.
Last edited by lookout; 16 September 2009 at 07:22 AM.
#45
The longer the ARB, the softer, so the holes closest to the end of the ARB are softest setting.
I would start with the softest setting and work your way up. So when the car gets too much oversteer for driving style and taste, go back to the softer setting.
I would start with the softest setting and work your way up. So when the car gets too much oversteer for driving style and taste, go back to the softer setting.
Last edited by lookout; 16 September 2009 at 05:06 PM.
#46
Oh My God!
Massive leap forward today after front arb fitment
In fact I'm staggered. Going from what there was yesterday (back feeling like a sofa) to today where the whole car is transformed. Very little roll front or rear. Takes corners like a dream.
Didn't have too much time for a prolonged drive, but will post back when I've got some more time with it.
For the moment though, I'm well happy. Big thanks Lookout, and others who have input. I was totally in the dark until asking here.
In fact I'm staggered. Going from what there was yesterday (back feeling like a sofa) to today where the whole car is transformed. Very little roll front or rear. Takes corners like a dream.
Didn't have too much time for a prolonged drive, but will post back when I've got some more time with it.
For the moment though, I'm well happy. Big thanks Lookout, and others who have input. I was totally in the dark until asking here.
#49
Haven't been able to get out much in the car recently, but today went on a ~100 miler of decent open, fast/slow & tight cornering, off camber, quick switching bends
If I had to sum up what the car is like now, I would say it is about balanced front to rear as far as under/oversteer and roll is concerned with a slight bias to rear oversteer and roll.
However, it still has too much roll overall.
I'm really not sure whether to try stiffening the rear first or the front or both together. I think I should try just one thing at a time though.
Like I said I was amazed at how stiffening the front by upgrading the front arb had such an impact on overall car feel. But I'm not sure if changing the front to a stiffer setting would work as much magic this time...?
If I had to sum up what the car is like now, I would say it is about balanced front to rear as far as under/oversteer and roll is concerned with a slight bias to rear oversteer and roll.
However, it still has too much roll overall.
I'm really not sure whether to try stiffening the rear first or the front or both together. I think I should try just one thing at a time though.
Like I said I was amazed at how stiffening the front by upgrading the front arb had such an impact on overall car feel. But I'm not sure if changing the front to a stiffer setting would work as much magic this time...?
#50
I would stiffen the front bar to increase front roll resistance. This will increase the rear grip and traction at the same time. I suspect that in reality you don't have quite enough low-speed bump damping, to hold the car up on initial turn-in. But stiifening the front bar will mask that quite nicely. You could increase the coil spring rate slightly, but that will have a negative effect on the compliance.
If you find that increasing the front bar stiffness has created a bit more push-on understeer because of the increased rear traction, you can trim the rear bar a click stiffer to compensate..........
Great, developing the handling bit by bit, isn't it?
If you find that increasing the front bar stiffness has created a bit more push-on understeer because of the increased rear traction, you can trim the rear bar a click stiffer to compensate..........
Great, developing the handling bit by bit, isn't it?
#51
The handling has come a long way since acquiring the car a couple of months ago, that's for sure
It's also nice to be able to change the suspension to a preference, that certainly is a great feature of the adjustable arbs. I suppose one could dial the settings for use too? Track or road?
On a similar theme I have an imported MY96 Sti Wagon. This behaves in a similar way to the JDM of this thread in that it feels soft and wallows in the rear (and i suppose all over, but especially the rear). As I have decided to keep the car for a while I am keen to dial as much of the roll out as I can, but given the age and value of the car, keeping within a sensible budget.
So, without going to the extent I have with the JDM what should I looking at doing? It seems alot of roll can be taken out with just a front arb upgrade? Would the front arb I took off the JDM be of any use?
Cheers
It's also nice to be able to change the suspension to a preference, that certainly is a great feature of the adjustable arbs. I suppose one could dial the settings for use too? Track or road?
On a similar theme I have an imported MY96 Sti Wagon. This behaves in a similar way to the JDM of this thread in that it feels soft and wallows in the rear (and i suppose all over, but especially the rear). As I have decided to keep the car for a while I am keen to dial as much of the roll out as I can, but given the age and value of the car, keeping within a sensible budget.
So, without going to the extent I have with the JDM what should I looking at doing? It seems alot of roll can be taken out with just a front arb upgrade? Would the front arb I took off the JDM be of any use?
Cheers
#53
If your wagon is predominantly rear wheel drive, more front roll resistance will work very well, but on most Imprezas, the rear roll resistance is fairly low as well, so a bigger rear ARB will also be needed to trim the car. Best to have a look what the diameters are of the bars that are currently on the car.
Dunx is right about the rear bar, as the normal standard set-up lacks rear roll stiffness more than the front. You might find that adding a rear 20 or 22mm adjustable ARB will just balance the car nicely.
Mind you, it won't give you the directness and grip that your other one now has.
Don't forget the WALK though, as the front wishbone, rear bush will most likely allow too much caster loss, even though it will look like new.........
Dunx is right about the rear bar, as the normal standard set-up lacks rear roll stiffness more than the front. You might find that adding a rear 20 or 22mm adjustable ARB will just balance the car nicely.
Mind you, it won't give you the directness and grip that your other one now has.
Don't forget the WALK though, as the front wishbone, rear bush will most likely allow too much caster loss, even though it will look like new.........
#56
With a 19mm front and 22mm rear ARB you should be able to get to a nice balance. But next to your other Sti it will still feel a bit loose. But for fast dog transport and go-anywhere ability, it should be great :-)
#58
Strewth!
Have now adjusted the front arb to the stiffer of the two settings. Again, I'm shocked by the difference this has made, and I think I'm fairly close now to achieving what I was initially after
Although I haven't completed enough testing I feel it is okay to post some initial conclusions as the differences are obvious.
The performance of the car is now quite devastating. To think it has come from being scary and threatening to swap ends at any moment, to now reassuringly inviting you to explore a safe & predictable limit is a real joy
Although I haven't completed enough testing I feel it is okay to post some initial conclusions as the differences are obvious.
- Turn-In - MUCH sharper turn-in was the first thing I noticed from the off. As the wheel is turned, because there is little roll, there is little delay in response. It's as if the car does not have to 'drop' (roll) into its attitude and once firmed into the suspension can settle and negotiate the bend. This of course becomes more plain with quick changes.
- Roll - Next noticeable change was overall less roll, closely linked to the above of course, and I am tempted to say the roll is no longer an issue, but again that's a first impression.
- Grip - Overall grip has become more confidently exploitable. It seems easier now to 'feel' the grip of the tyres and know where their limits are. This is a very nice feeling and allows for big confidence in cornering and 'floating' it round on the limit is quite easy
The performance of the car is now quite devastating. To think it has come from being scary and threatening to swap ends at any moment, to now reassuringly inviting you to explore a safe & predictable limit is a real joy
Last edited by bonesetter; 27 September 2009 at 04:15 PM.
#59
I am glad that you have your car more the way you want it. It's great when a car gives enough confidence to allow the chauffeur to exploit the limits of grip.
On the Wagon, start with the rear ARB on the softest setting and work your way up. You'll know when you've gone too far...........
By the way, my greyhound is pushed against the rear window quite often after kissing the side windows..........
On the Wagon, start with the rear ARB on the softest setting and work your way up. You'll know when you've gone too far...........
By the way, my greyhound is pushed against the rear window quite often after kissing the side windows..........
#60
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Did all that and then fitted R888's, raises the bar another notch....
Then I have the problem that it still feels a touch too soft on track
LOL
dunx
Then I have the problem that it still feels a touch too soft on track
LOL
dunx