Anti roll bars...

Depends where the link arm connects to the wishbone/arm and hence the motion ratio leverage at the wheel.

Many cars connect arb to the Mcperherson strut such that you get a 1:1 ratio in terms of wheel and roll bar movement. Others on the wisbone will need a thicker bar to offer the same roll resistance to the wheel.
 
An update on this. I bought the bars and fitted them.
I did nothing else to the setup of the car, initially they were set on hard rear and soft front.
Drove it on a dry road not too hard and it seemed ok but the front didn't feel much different.
Set the front to hard and this made a dramatic difference to the feel, initial steering response was much more immediate and direct. Like it a lot.

Took it up to shoes house, a winding road I drive regularly and know well, a bit damp. Holy **** balls the car is unstable in the rear, can't get in the throttle at all whereas before I could go full throttle, feels like it wants me dead.

With this in mind, I soften the rear bar. I go to a medium setting, I couldn't be bothered to switch both sides because it's getting late, night before the trackday, and it's a nightmare job to do.

Feels decidedly more forgiving on the way home anyway, doesn't want to kill me nearly as much.


So, trackday, now we have hard front, medium rear. Couple of laps warmup and then I go for it, full throttle attack down craners. I should state that with the stock bars in the car, this posed no problem at all and I was doing it every lap. It was a disaster, the car nearly understeered clean off the track, same story piling it into the old hairpin. Utterly horrendous, so I decided to soften the front bar down to a medium setting also, now it matched the rear.
Back out and now the car feels better, but it still has a mild understeer which was not there on the previous day.
Fortunately, the previous day I had been down to a-line and we'd played around with the camber in the front and marked out some settings on the top mounts. With this in mind, I increased the front camber by around 30 mins, so now at -3 deg, with a side order of toe out.

Back out there, the car is feeling better now, has a reasonable balance. I was seeing a little push on entry to coppice that I didn't have on the last day. However, I also now have fuel starvation in coppice with as much as half a tank in. I didn't have this before, so I'm presumably creating more lateral G despite it feeling slower.

Overall, I'm not convinced by this modification.
On the road, I loved the feel of it when I had the front bar on the stiff setting, but it is useless on track. However it's worth noting that I turned the damping up on track. On the road, with the softer bars and firmer damping, it feels not too different to stiffer bars and softer damping, the problem is that the ride quality is abysmal and I can't put up with it being so crashy on a daily basis.

On the track, it sort of works. However, I had to soften the bars to make the car drive properly, kind of defeating the object of them a bit. I also don't understand why even after doing this, I still had to run more static camber in order to make it turn the same as before.

I still had notable body roll even after all this.
I wonder, if I were to go back to stock ARBs, and increase the coil spring rates, would I see the same loss of grip, be it real or perceived?
 
Yes, higher is definitely better in the case of damping. I didn't take them all the way to max though, I also didn't try stiff damping and bars, maybe I missed a trick, I doubt it though.
 
The problem with stiffer ARBS is the fact they are making the suspension less independant.

Does your car need roll centre adjustors now you have lowered it. Increasing stiffness may have no impact if you are getting excessive roll due to this. The camber increase is just a band aid, how is bump steer?

What rear toe you running?

Im running 1.5 front and 2 deg rear and its very balanced because Im still on OEM ride height
 
Simon said:
The problem with stiffer ARBS is the fact they are making the suspension less independant.

Does your car need roll centre adjustors now you have lowered it. Increasing stiffness may have no impact if you are getting excessive roll due to this. The camber increase is just a band aid, how is bump steer?

What rear toe you running?

Im running 1.5 front and 2 deg rear and its very balanced because Im still on OEM ride height
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You also have a double wishbone front suspension with presumably a much nicer camber curve. Within E36 circles, it's pretty much accepted that -3.5F and -2 to -2.5R is a good setup for track use, with 0 toe front and 20mins rear toe in.
I was running -3 and -2, about 18min toe out front (due to the trackside camber move, usually it's -2.5 with 0 toe), and 20min rear toe in.

Going way back to the original point, I was concerned by the feeling that the car was rolling over into oversteer. That behaviour seems to have been eradicated for the most part, there is a definite improvement in exit traction. I'm pretty happy with the way the rear works now, shifting it's shortcomings to the front isn't what I had in mind though.

Roll centre adjustment would be nice, but I've never seen products out there to achieve this. Typically an extended bottom ball joint is the ideal band-aid for this problem, right? With regards to bump steer, there is none.
I was interested in this actually, and wondered how the old touring cars could run so low. I found a bunch of pics under the front end of a works super touring E36, it is massively modified, doesn't share any parts whatsoever with the road car, the roll centre is very much adjusted though.
 
The fact an S2000 is double wishbone means it already is less sensitive to roll centre deviation as the upright has a tighter camber to bump control. Every mm your suspension compresses you are losing spring rate due to the wheel resistance (spring) moving closer to your wishbone bush.

The ball joint spacer is fine, as it puts the arm back where it should be. Seems common with EP3 / DC5 and MINI. I would junk off the stiffness from ARB and go for the 'purer' stiffer spring to manage what's happening at the wheel rather than axle. We don't have magneride or air suspension so compromise is required to suit your preferences.
 
Jonnycoupe said:
The fact an S2000 is double wishbone means it already is less sensitive to roll centre deviation as the upright has a tighter camber to bump control. Every mm your suspension compresses you are losing spring rate due to the wheel resistance (spring) moving closer to your wishbone bush.

The ball joint spacer is fine, as it puts the arm back where it should be. Seems common with EP3 / DC5 and MINI. I would junk off the stiffness from ARB and go for the 'purer' stiffer spring to manage what's happening at the wheel rather than axle. We don't have magneride or air suspension so compromise is required to suit your preferences.
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Compromise seems to be the name of the game with it now, meh :/ Seems I've reached a point where out of having a comfortable ride, good handling, and darty feeling steering, I can only pick two at once. If upping the spring rate is likely to be a better compromise of the above then I'll totally give it a go. My only reservation about this is that changing out the front springs track side is a bit of a chore, should it not work out.

The Running Man said:
What tyres are you using, how stiff arfe the sidewalls?
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Not sure how this is relevant since they were the same in both cases, but they're Advan Neova AD08, sidewall about as stiff as you can get.
 
The Golf doesn`t have independant rear, so its not a like-for-like, but after speaking to someone who knows about these things, I kept the stock ARB and upped the spring rates, to try and keep the independance across the axle. Too stiff and the ARB can cause issues as mentioned earlier in the thread with the loaded / unloaded wheel.

I can`t compare it with softer springs and uprated ARB`s, but I found the balance of the car was very similar from the softer rates, less body roll and damping kept around medium.
 
Hi there

From messing with ARBs on my car and from speaking to others it seems basically softer within reason means more grip. Yet going too stiff can result in less grip.

Problem I had with my car is I fitted gen2 997 GT3 front and rears ARBs. On the gen2 997 GT3 they cured the gen1 GT3's tendency to understeer by introducing a slightly thinner front bar but went with the GT2 rear bar which was much stiffer, infact the GT2 bar is 30% stiffer in its softest setting compared to the gen1 GT3 bar in its stiffest setting.

What this meant for me is the front-end feels absolutely sublime on track in the soft or stiff holes and is a little bit bouncy over bad roads on the front due to stiffer front end.

But the GT2 rear bar was to stiff for the mechanical grip my car had available, remember a GT3 has 305-325 rear section tyres along with a mechanical LSD, wheras my Carrera has no LSD and has 295 rear section tyres. This meant that the GT2 rear bar just made the rear-end too stiff for the mechanical grip available making the rear-end basically loose.

In fact for a hot dry track day the gen2 GT3 bars made the car pretty much perfect with a very neutral balanced car that had progressive oversteer, with this setup I put in a sub 1:24 round Donnington. But cold weather hits, drive the car on the road, in the wet and its got plenty of oversteer at both corner entry and exit, killing my confidence in the car for road use and just making it a handful and not so enjoyable to drive on the road.

So now I am running the front gen2 GT3 bar on its softest setting and without a doubt over bad road surfaces front-end grip and bite is far better and body roll seems no less as afterall its just one notch softer on the settings.

Obviously with the stock C2S bar in the back the car still has understeer even in the wet on the road which to be frank is nice because its managable and confidence inspiring.

So for rear bar I need to try either a C4S bar which were 1mm thicker than C2S I believe because the C4S want to understeer a lot being 4WD so Porsche put a thicker bar in the rear to reduce understeer on the 4WD models. So this is an option or I hunt down a gen1 GT3 bar and install it on the middle or stiffest setting and see how I get on.

Either way car is driving great now even if with a bit of understeer, though its less understeer than it previously had and its managable. :)
 
Keeping it back on the subject of BMWs...

I think the massive camber is a band-aid for too much 'real' camber loss during compression as the chassis roll is making the static camber ineffective.

You need to look at this. Raising the coil overs to the standard ride height would be a good start. I gave you my figures purely as an example of a car that doesn't need loads of camber for it work. When you lower them you need to raise the steering rack, increase hub to lower arm clearance to keep the lower arm horizontal and also for anti bumpsteer rear arms.

This is why mine is at the stock height on soft springs still
 
Something I found.

The roll moment arm is the lever centrifugal force uses to roll the chassis when cornering. Shortening the roll moment arm by raising the roll center reduces chassis roll, effectively "stiffening" the roll axis. You can do the same thing using anti-roll (sway) bars but that reduces wheel independence--the two wheels are coupled through the anti-roll bar. Hitting a bump with one wheel will transmit energy through the anti-roll bar to the other wheel's suspension causing unwanted chassis movement.
 
Gibbo said:
Hi there

From messing with ARBs on my car and from speaking to others it seems basically softer within reason means more grip. Yet going too stiff can result in less grip.
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I assume all these Porsche variants have the same suspension arms with the same connection point for the ARB links? Otherwise it kinda makes comparison a very confusing affair!

The wheel width also moves the centre point of the wheel actions an hence influences the lever resistance offered by the anti roll bar.
 
Bumps aren't a problem on track. Running the bar on stiff does make it more bumpy on the street though but not enough to make it unsettled IMO.
 
Jonnycoupe said:
I assume all these Porsche variants have the same suspension arms with the same connection point for the ARB links? Otherwise it kinda makes comparison a very confusing affair!

The wheel width also moves the centre point of the wheel actions an hence influences the lever resistance offered by the anti roll bar.
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Nope different arms, which mine now also has too, only way to get the extra front camber which was desired.

I'm happy with the car just need to fine tune the balance of the car with the swaybars, aim is just to remove a little more understeer by finding the correct sized anti-roll bar. Being a Carrera most just stick after market parts on, but I'm doing it with O.E. parts so going through the Porsche catalogue. :D
 
Clarkey said:
Bumps aren't a problem on track. Running the bar on stiff does make it more bumpy on the street though but not enough to make it unsettled IMO.
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The point was about chasing more stiffness thinking it will help when infact roll centre adjustment would have the same effect without making the suspension two torsion bars.
 
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