understeer

[driftmonkey]

Went to a trackday at hullavington airfield on friday, and my 325i has really bad understeer!
Koni adjustables, poo springs that came with the kit, yoko s drive 195 45 15 tyres on standard alloys.
Played about with tyre pressures and with 34psi on the fronts had less oversterr but still rubish, any advice?

[GeoffBob]

Understeer is commonly as a result of a reduction in tractive force (traction) at your front inside wheel while cornering caused by excessive body roll towards the outside of the corner. Due to this loss of traction the car will tend to "plough onwards", and be less responsive to the steering input.

The generally accepted solution is to fit stiffer front springs that help minimise the shift in weight towards the outside of the bend, thus improving the side-to-side weight distribution, allowing both front wheels to steer the car. Unfortunately the problem of understeer is exacerbated by the weight of your engine, its height relative to your front wheel axis, and how far forward it is mounted.

Since you state that you have "poo springs", I would suggest that you begin by changing them for something stiffer and lower. Later you might look at fitting coilovers and ways to adjust your camber in order to maintain optimal traction at your front wheels while braking and/or cornering.

[AlpineAde]

You don't say exactly where understeer was occurring but tired or mismatched springs won't help handling. Fiddling with tyre pressures was the right place to start, however.

This is from the late and very great Carroll Smith and might give you a few ideas:

"UNDERSTEER

Corner entry understeer: car initially points in and then washes out
”¢ Excessive toe-in or toe-out (car is usually ”˜darty’)
Ӣ Insufficient front droop travel (non droop limited cars only)
Ӣ Incorrectly adjusted packers (car rolls on to packers)
Ӣ Insufficient front damper bump resistance (similar to roll stiffness example)
”¢ Insufficient front roll stiffness ”“ car may feel like it is pointing in but may actually be falling over onto the outside front tyre due to insufficient front roll stiffness or diagonal load transfer under heavy trail braking. Initial understeer can often be cured by increasing front roll resistance, even though doing so may increase the amount of lateral load transfer.
Ӣ Non linear lateral load transfer due to spring and/or bar geometry. Or to non-optimal roll axis inclination

Corner entry understeer: car won’t point in and gets progressively worse
Ӣ Driver braking too hard, too late
Ӣ Relatively narrow front track width
Ӣ Excessive front tyre pressure
Ӣ Excessive front roll stiffness (spring or bar)
Ӣ Relative lack of front download (excessive rear download)
Ӣ Incorrectly adjusted packers or bump rubbers (car rolls onto packers)
Ӣ Insufficient front toe-in
Ӣ Insufficient Ackermann effect in steering geometry
Ӣ Front roll centre too high or too low
Ӣ Insufficient front damper bump force
Ӣ Insufficient front toe-out
Ӣ Insufficient front wheel droop travel (on non droop limited cars only)
”¢ Nose being ”˜sucked down’ due to ground effect
Ӣ Excessive Ackermann steering geometry
”¢ Can also be caused by unloading the front tyres due to rearward load transfer under acceleration ”“ cures include:
Ӣ Increasing front damper rebound force
Ӣ Increasing rear damper low speed damper rebound force
Ӣ Increasing rear anti-squat
Ӣ Droop limiting front suspension (will also make turn in more positive and will reduce overall understeer)

Mid-corner (mid-phase) understeer
Ӣ Excessive front tyre pressure
Ӣ Excessive relative front roll stiffness
Ӣ Excessive front toe (in or out)
Ӣ Excessive Ackermann steering geometry
Ӣ Insufficient front dynamic camber
Ӣ Relatively narrow front track width
Ӣ Insufficient front wheel travel (car rolls onto packers or bottomed shock)
Ӣ Insufficient droop travel (on non droop limited cars)

Corner exit understeer: slow corners
Ӣ Often a function of excessive corner entry and mid-phase understeer (whether driver induced or car induced) followed by throttle application whilst maintaining the understeer steering lock. The first step must be to cure the corner entry and mid-phase understeer. If this is impractical, then corner entry speed should be reduced slightly in order to allow earlier throttle application. Sometimes we have to be patient.

Corner exit understeer: fast corners
”¢ Relative lack of front download ”“ often caused by negative pitch angle (squat) due to rearward load transfer on acceleration. Can be helped by increasing rear anti-squat and/or by increasing rear low speed bump force, increasing front droop force and by limiting the front suspension droop travel.
Ӣ Relatively narrow front track width
Ӣ Excessive ramp angle or pre-load on clutch pack or plate type limited slip differentials.

Understeer stronger in one direction than in the other
Ӣ Uneven corner weights
Ӣ Uneven caster
Ӣ Uneven camber (especially front)"

HTH.

[e301988325i]

Went to a trackday at hullavington airfield on friday, and my 325i has really bad understeer!
Koni adjustables, poo springs that came with the kit, yoko s drive 195 45 15 tyres on standard alloys.
Played about with tyre pressures and with 34psi on the fronts had less oversterr but still rubish, any advice?

First step is to ditch the 195 yoko's unless they are slicks, but then you probably wouldn't have understeer, fit the 'standard' width tyres, in a slightly lower profile, 205/50 r15s Toyo T1r's would suit nicely.

34psi hot or cold? 34psi cold would be way too high IMO, although with narrower than stock tyres you're fighting a losing battle.

[driftmonkey]

bugger, got a set of 195 50 t1r's sat in the garage i was going to fit, guess i'll go for the 205 width, i was just being cheap!

[UweM3]

34psi hot or cold? 34psi cold would be way too high IMO, although with narrower than stock tyres you're fighting a losing battle.

are you talking road tyres?

[Brian28]

Not too sure about the tyres, 195/45 should be fine. Were there any situations that the car didn't understeer? No single right answer, try and work out where it was understeering and what you were doing with the brakes and the throttle at the time. Even an unweighted inside front wheel won't necessarily give understeer.

[GeoffBob]

Even an unweighted inside front wheel won't necessarily give understeer.

Sorry Brian28, but I have to disagree on this one. Tractive force at a tyre (and thus the ability to steer) is a direct function of the weight pushing down upon the tyre. Any reduction in weight upon the tyre will result in reduced tractive force, and thus effect the ability to steer. This is the underlying principle behind the analysis of understeer at the front (and similarly oversteer at the rear). The fundamental principle to be adhered to in an effort to minimise under and oversteer (if so desired), is to minimise the transfer of weight while manoeuvring the vehicle.

.... my 325i has really bad understeer ....
poo springs ....

[Brian28]

I can't argue the science with you Geoff, I'm not bright enough for a start . From a logical point of view though, if the outer front tyre is providing more grip than the rear of the car has regardless of what the inner front tyre is doing, then the car won't understeer? Not trying to provoke an argument, just trying to relate what I've experienced on track to the physics behind it all. In the photo the front inner wheel is off the ground so providing zero front end grip, but the car isn't understeering?

[aidanr]

Tyre pressure is way too high!

Take the front tyre pressure down to 20Psi cold. When they're hot (take about 2 laps of pushing it) they'll be at about 25ish. Leave rears at about 30Psi cold. If then too much oversteer then take them down accordingly until you're happy.

I've set my coilovers so that when you give a good push down on the front wing I can see about 3-4mm of travel. Stiff as a board basically. I'd have it stiffer if I could but can't go any lower without damaging arches upon visits to the gravel/grass.

I use the Toyo Proxes on the front and try my best to get understeer but can't. Rears tyres I'm not too bothered by, whatever I can get my hands on... I like to keeep the car sideways mostly.

You can see a video on youtube of mine if you type in 'e30 325i mondello' to get an idea of how mine handles and compare it to yours.. car is bog standard otherwise. 'camera is mounted on the roof just above the rear view mirror.

Hope this helps...

[GeoffBob]

I can't argue the science with you Geoff, I'm not bright enough for a start . From a logical point of view though, if the outer front tyre is providing more grip than the rear of the car has regardless of what the inner front tyre is doing, then the car won't understeer? Not trying to provoke an argument, just trying to relate what I've experienced on track to the physics behind it all. In the photo the front inner wheel is off the ground so providing zero front end grip, but the car isn't understeering?

Brian, I follow your logic, but should point out the following (and I'll do my best to leave the science stuff out): The issue isn't whether the front tyres have more or less traction than the rear tyres. The issue is more specifically whether any given wheel (wherever it may be located on the car) has sufficient weight down upon it to tolerate/support/handle the tractive (grip/bite) force applied at the interface between the contact patch and the road surface. A car can corner on three wheels (as in your pic) and still achieve neutral steering so long as the forces at the front tyre contact patch are below that required to break traction.

However, and this is the crux of the matter, the force upon that single front tyre required to break traction (and enter into understeer) will be far less than if the car were to go round the corner with both front wheels in contact with the road. Put another way, a car with drastic roll (picking up the front inside wheel say) will understeer at a lower cornering speed than a car with both front wheels on the ground. I'd be interested to hear from you what happens if you take that corner faster next time. Incidentally, any screetching from that wheel is already an indication of the fact that its direction of travel differs from the direction you are pointing it in.

Of course the faster you go round a corner the greater the body roll, and this is where other means must be relied upon to reduce that roll (as opposed to just driving slower ). This is why I say that DriftMonkey needs to sort out his "poo springs" first.

Also not arguing. Great discussion BTW

[Jhonno]

Enter the corner slower? Maybe a simple case of too fast an entry speed..

[Brian28]

I'm familiar with traction circle theory and some of the basics, but a lot of what I do is half guesswork and seeing how the car feels to drive more than anything else. Wouldn't go any faster on that corner (Quary at Combe) without running off the track at exit, that took it out to the track edge pretty much neutral handling and full throttle from the apex. Trying it faster in quali meant a bit more throttle balancing on the exit, and about 250 rpm worse off at braking point for the next chicane. No front tyre squealing, I'd guess mebbe a couple of degrees slip angle same at the back. The cars are limited in set up due to regs (which is no bad thing as I get confused if we are allowed to play with too many things) standard 318i front ARB no rear ARB, decent slap of front neg camber. Hadn't done any testing apart from qualifying sessions, the car was best balance I could come up with. Harder springs didn't give enough compliance at the front so it would push more rather than grip, softer was too much body roll.

As and when I have the time and money (likely never ) would like to try a load more stuff with a lap timer to see what is really faster and what just feels faster. Helpful discussion, good to have other peoples views/experiences.

[Brian28]

The issue isn't whether the front tyres have more or less traction than the rear tyres.

Actually that's the pretty simple way I've always thought about car balance. More grip at the back - understeer, more grip at the front - oversteer.
(Or more usually less grip at the front is understeer, less grip at the back is oversteer )

[hoshy]

Great thread

[GeoffBob]

Harder springs didn't give enough compliance at the front so it would push more rather than grip, softer was too much body roll.

If springs are stated as already sub-standard (as in DriftMonkey's case) then my first recommendation would be to improve them. Once you feel you have achieved the optimal spring rate (which sounds to be your case) then other mechanisms have to be called upon (provided regs permit) to minise weight transfer. One such mechanism (although I realise this does not apply to you) is to lower the engine down and pull it back (as in the picture of that V8 engined E30 track car that did the rounds somewhere on the zone). And not forgetting the usual adjustments to ARB's.

The issue isn't whether the front tyres have more or less traction than the rear tyres.

Actually that's the pretty simple way I've always thought about car balance. More grip at the back - understeer, more grip at the front - oversteer. (Or more usually less grip at the front is understeer, less grip at the back is oversteer )

I hear what you are saying Brian, but to put in a bit of detail: Less grip at the front than cornering force applied to the front tyres - understeer, less grip at the back than cornering force applied to the rear tyres - oversteer.

Not really about how the front compares to the rear, but whether (in absolute terms) the rear has enough grip to supply its tractive needs, and similarly whether the front has enough grip to supply its tractive needs. The instant one end puts more force (parallel to the road surface, but not necessarily in the direction of travel) on a tyre than it has traction (where the traction is according to how much weight is pushing down on the tyre) slip will commence. This is why my own car has 205's on the front, but 245's on the rear (not that I am saying this combination would work for anyone else as my weight distribution is very different to a standard E30).

[hazd31]

to avoid understeer, try using the brakes to slow the car down rather than the steering,
honestly it sounds stupid but all your doing is try too hard, slow in fast out!

[Brian28]

I see where you are coming from, thanks Geoff. Changing to a different series with free-er regs for next season, will also be using full coilovers and LSD, so lots of things to go wrong

Hazd31 you are spot on and that is usually the case, be interesting to find out where and how the understeer was happening though, and if it would be possible to balance it out a bit rather than just going slower in.

Moving slightly off topic driftmonkey, Hullavington is advertised with motorsport events as having a car control area off the actual track where you can just bugger about. Was this a big area that you could get a bit of speed up on? If so I'm fancying a day there myself mebbe in the new year some time, just to try a few different things out.

[hazd31]

I see where you are coming from, thanks Geoff. Changing to a different series with free-er regs for next season, will also be using full coilovers and LSD, so lots of things to go wrong

Hazd31 you are spot on and that is usually the case, be interesting to find out where and how the understeer was happening though, and if it would be possible to balance it out a bit rather than just going slower in.

Moving slightly off topic driftmonkey, Hullavington is advertised with motorsport events as having a car control area off the actual track where you can just bugger about. Was this a big area that you could get a bit of speed up on? If so I'm fancying a day there myself mebbe in the new year some time, just to try a few different things out.

Thats the driver coach getting out of me,
i see it with a lot of kids, on a test day they can be very fast, but the miniute pressure is put on them the try too hard usually ending up in pushing the kart too hard into a corner and scrubbing off speed,

dont know if this will really relate to an e30 but sometime if the front of the car is too stiff it would cause understeer, (best try removing that strutt brace)
or try removing grip from the rear of the car to stop it pushing the front!

[AlpineAde]

to avoid understeer, try using the brakes to slow the car down rather than the steering,
honestly it sounds stupid but all your doing is try too hard, slow in fast out!

Not bad advice at all.

And an addendum; I've seen a few cars at track days that have very stiff front suspension setups but they have forgotten the basic principles....balance. Suspension setup is always a balance between front and rear. These guys with very stiff front setups were getting stellar initial turn in but were washing out into understeer in a major way. Why? Front end too stiff.

[hoshy]

to avoid understeer, try using the brakes to slow the car down rather than the steering,
honestly it sounds stupid but all your doing is try too hard, slow in fast out!

Not bad advice at all.

And an addendum; I've seen a few cars at track days that have very stiff front suspension setups but they have forgotten the basic principles....balance. Suspension setup is always a balance between front and rear. These guys with very stiff front setups were getting stellar initial turn in but were washing out into understeer in a major way. Why? Front end too stiff.

Also turning in too violently will cause the same - stiff front exaggerates that.

[e301988325i]

34psi hot or cold? 34psi cold would be way too high IMO, although with narrower than stock tyres you're fighting a losing battle.

are you talking road tyres?

Yes road tyres on track.

I run mine cold at 32psi for road use.

[UweM3]

Tyre pressure is way too high!

Take the front tyre pressure down to 20Psi cold. When they're hot (take about 2 laps of pushing it) they'll be at about 25ish. Leave rears at about 30Psi cold. If then too much oversteer then take them down accordingly until you're happy.

I've set my coilovers so that when you give a good push down on the front wing I can see about 3-4mm of travel. Stiff as a board basically. I'd have it stiffer if I could but can't go any lower without damaging arches upon visits to the gravel/grass.

I use the Toyo Proxes on the front and try my best to get understeer but can't. Rears tyres I'm not too bothered by, whatever I can get my hands on... I like to keeep the car sideways mostly.

You can see a video on youtube of mine if you type in 'e30 325i mondello' to get an idea of how mine handles and compare it to yours.. car is bog standard otherwise. 'camera is mounted on the roof just above the rear view mirror.

Hope this helps...

20 psi cold??? You're having a laugh! We are talking road tyres, not racing slicks (even these are a bit low with 20 psi cold IMHO)
You folks do whatever you want, but I RAISE the pressure on a road tyre for track use. Reason is that the road tyre has a much softer sidewall ac compared with a track day tyre or slick and the excessive movements of tyre and sidewall on track will overheat the tyre sooner or later. Wit hth eincrease pressure you are avoiding this and the tyre lasts a lap or two more before overheating comes intl play.

Give it a try before you knock it. You wouldn't be the first one looking surprised afterwards

[hoshy]

...

Give it a try before you knock it. You wouldn't be the first one looking surprised afterwards

ditto this seriously. on track, a friend of mine was running 25psi in road tyres on his medium worked 200sx - I was dancing circles around him in my iS until I kindly suggested he upped the pressures to more like 35psi. After that he was flying.

[caneswell]

Understeer is commonly as a result of a reduction in tractive force (traction) at your front inside wheel while cornering caused by excessive body roll towards the outside of the corner. Due to this loss of traction the car will tend to "plough onwards", and be less responsive to the steering input.

The generally accepted solution is to fit stiffer front springs that help minimise the shift in weight towards the outside of the bend, thus improving the side-to-side weight distribution, allowing both front wheels to steer the car. Unfortunately the problem of understeer is exacerbated by the weight of your engine, its height relative to your front wheel axis, and how far forward it is mounted.

Not entirely correct there. Stiffer springs make no difference to weight transfer across the axle. Weight transfer is only a function of height of the centre of mass, lateral acceleration and track width. (Body roll will move the centre of mass slightly to the outside, but this is immeasurable compared to the weight transfer from the lateral acceleration.)

Two identical cars with massively different spring rates will have the same weight transfer (so long as the centre of mass is at the same height)

Stiffer springs offer an advantage because they allow the centre of mass to be lower, reducing weight transfer. Exactly as you say lowering the engine will achieve.

Altering roll stiffness can influence the weight transfer balance front to rear. A stiffer ARB/springs will increase the weight transfer at that end of the car compared to the other, giving either under/oversteer. As Brian is correctly saying its more about balance front to rear than outright grip (which is impossible to alter with stiffer springs/arbs).

Limiting body roll is also an advantage on most cars as they tend to have limited camber gain during bump so as the car rolls you move to having positive camber.

While we are on the subject of camber, this is probably the main cause of the OPs understeer. Get some negative camber top mounts!

[driftmonkey]

thats midway thru a chicane, after fighting to get it to go right and feeling bad rumblings, im guessing the tyres 'rolling' sideways i'm then trying to go left and hard over with the steering wheel and its still going right, one of the laps i took out those cones......

on another tight right, 100mph down the straight, hard on the brakes turn right, understeer off to the left, try to bring the back round with some more throttle, just provokes a slide off to the left, end up on the grass a couple of times.

even at low speeds the turn in was rubbish.

the 'poo' springs in question are just some tuv approved ones that came in the koni kit, i was pissed that they didnt come with koni springs, but was told by larkspeed that koni dont make springs for the e30 so supply the kits with 'sport' springs.

I'm collecting all the bits to make a set of coilovers, and i'm going to renew all my bushes.

[caneswell]

Get some adjustable top mounts first and adjust to full negative camber. As others have said try pressures of around 30-40psi on street tyres to stop them rolling off the side of the tread, as you can see in the picture (the camber helps this even more so).

Leave the springs at the moment.

[AlpineAde]

...

Give it a try before you knock it. You wouldn't be the first one looking surprised afterwards

ditto this seriously. on track, a friend of mine was running 25psi in road tyres on his medium worked 200sx - I was dancing circles around him in my iS until I kindly suggested he upped the pressures to more like 35psi. After that he was flying.

Good advice. Track tyres and road tyres are two entirely different beasties. I run road pressures on my street tyres when I track my car. I don't back the pressures off at all.

And as for camber...camber is your friend on track! I run -2.5 degrees all round, which is as much as I'd want for a car that is predominantly driven on the street.

[Brian28]

[ understeer off to the left, try to bring the back round with some more throttle, .

Will only work in a RWD car with a *lot* of power or else a surface with no grip ie skid pan. If the front is already pushing more juice just tends to make it push even more.

Some good ideas to try from people, the photo looks like just too quick in. (Picture a dog running across a laminated floor and trying to turn a corner ). For a bit of free extra neg camber, knock the three studs out of the top mounts. Ream the holes out to allow the strut tops to move towards the centre of the car, then either weld the studs in the new positions or replace with nuts/bolts (a lot more fiddly)

[GeoffBob]

Understeer is commonly as a result of a reduction in tractive force (traction) at your front inside wheel while cornering caused by excessive body roll towards the outside of the corner. Due to this loss of traction the car will tend to "plough onwards", and be less responsive to the steering input.

The generally accepted solution is to fit stiffer front springs that help minimise the shift in weight towards the outside of the bend, thus improving the side-to-side weight distribution, allowing both front wheels to steer the car. Unfortunately the problem of understeer is exacerbated by the weight of your engine, its height relative to your front wheel axis, and how far forward it is mounted.

Not entirely correct there. Stiffer springs make no difference to weight transfer across the axle. Weight transfer is only a function of height of the centre of mass, lateral acceleration and track width. (Body roll will move the centre of mass slightly to the outside, but this is immeasurable compared to the weight transfer from the lateral acceleration.)

Two identical cars with massively different spring rates will have the same weight transfer (so long as the centre of mass is at the same height)

Caneswell, while it is tempting to get into an argument and attempt to squirm my way out of this one in an effort to cover my arse, I have to admit (in the interests of supplying correct information to the OP) that you are quite correct on this one.

My intention, in the first paragraph of my post, was to illustrate the cause of the understeer and how it relates to a loss of traction at the inside front wheel.

The first sentence of my second paragraph, to quote yourself was "not entirely correct", but was, more specifically, a big load of bollocks

My statement should have read: The generally accepted solution is to stiffen up the rear ARB to help minimise the shift in weight at the front towards the outside by increasing the shift in weight at the rear. This will will direct the rear towards oversteer while reducing understeer at the front. It is, as you say, a case of balance.

DriftMonkey, I apologise for the misinformation. For the record though, I stand by my remaining posts with regard to the issue of traction and how the dynamic weight distributed over a wheel determines the level of traction at a wheel, and therefore dictates the the tendancy of a car towards oversteer or understeer.

[UweM3]

from my experience with the E30, that little bit of camber you can add by moving the top mount is not going to make a huge difference. It does help, but it doesn't solve it.

You need stiffer springs and shocks to stop the car rolling. Add some adjustable ARB's for fine tuning and Bob is your uncle. And tp put the icing on the cake buy some R-Compound tyres

Road tyres on a track will always underperform. Just a question of time. Every job needs the right tool. Even F1 Superstars look like learner drivers with the wrong tyres on the car.

Not entirely correct there. Stiffer springs make no difference to weight transfer across the axle. Weight transfer is only a function of height of the centre of mass, lateral acceleration and track width. (Body roll will move the centre of mass slightly to the outside, but this is immeasurable compared to the weight transfer from the lateral acceleration.)

I am not a qualified suspension expert but I am not sure if I want to agree with you on this. Stiffer springs will stop the body roll, hence less weight transfer to your outside wheel --> more grip.
Tried and tested by myself. Transformed my understeering M3 into a nicely neutral handling car with just springs, shocks and ARBs

Two identical cars with massively different spring rates will have the same weight transfer (so long as the centre of mass is at the same height)

I am very sure that I want to disagree with you on this
Isn't that the whole point of stiffer springs, reducing weight tranfer? Lowering at the same time is only maximising the effect, two birds with one stone thing.

[Jhonno]

I think there is confusion over definitions of terms..

For a given ride height, the same amount of force will be applied trying to compress the outside springs.. However, the stiffer set of springs will reduced the actual weight transfer compared to the softer set?

The stiffer springs and therefore reduced roll will maintain a larger contact patch (as in both tyres) with the road

E30's love some extra camber upfront..I run 1.5deg on the road and it is pretty good.. I ran marginally more on the 'Ring and for how hard I was able to push the car, I found it worked well!

[caneswell]

Geoff is now very correct!....... it's nice not have an argument, thanks!

The rest of you are still struggling! Uwe i thought you knew more than that!

Hmm, lets try this.... If you replaced your spring with infinitely stiff steel griders you would still have exactly the same lateral acceleration acting on the centre of gravity whcih has to be supported by the tyre contact patches, which are both (almost) in exactly the same position relative to the centre of gravity. So the respective loads on each is exactly as it was with soft wollowy springs!

Stiffer springs give the following advantages:
- Allow a lower ride height to reposition the centre of gravity to reduce weight transfer
- Improve camber control (as the car rolls the wheels and tyres lean out towards positive camber, reducing grip, see above pic!)
- Driver confidence (a softly sprung car has a delay between input and load transfer, which a squidgy human brain doesn't like when it wants things to react instantly)
- Stops bottoming out the suspension, which introduces a large shock loading through the contact patch, which could reduce grip)

Two tyres are better than one with double the load so minimising weight transfer is very important. but stiffer springs don't do that.

Camber control is almost as important too, stiffer springs and reduced body roll do help that significantly.

[caneswell]

Maybe these will help:

Article about weight transfer and body roll:
http://www.autozine.org/technical_schoo ... ling_3.htm

It does mention the small amount of weight transfer due to body roll I mentioned earlier, but the roll centre of an e30 is not on the ground as in that example, so for our cars it would be even less:

see here:
http://www.e30m3project.com/e30m3perfor ... ansfer.htm

[hoshy]

I think it's also interesting that when you lower the front of an E30 - the lower arm gets closer to horizontal, which is it's max neg camber position. As the spring compresses the lower arm effectively gets shorter and that starts to push the tyre in to positive camber.

I wonder sometimes if it might be better to have much stiffer front springs, but only slightly lower - so that when the spring is maximum compressed, the lower arm is horizontal and giving the max amount of neg camber. I guess it's a trade-off between small optimisation of dynamic camber and slightly(?) lower CoG.

Any thoughts on that point?

Oh and also on the side of stiffer spings affecting weight transfer - I would have thought that even though the net transfer is the same, the style is different - for stiffer springs the transfer is more immediate so you need to turn in smoother requiring a greater driver skill - rather than the the softer spring dampening the effect of sharp turn in?