about front suspension

[john.d]

i'm running my 340 on red koni's dampers in conjunction with springs from 360 from which i cut 1,5 coils. My front is standing on 345 mm. The combination works very well and gives a very good compromise between handling and comfort ride at any speed.

[john.d]

i think i need to lower i beat more the front to get i beat lower from the back wich is allready lowered about 50mm. the think is that i want more grip from the front. it looks like it has not much weight on the front

[jtbo]

You need to get more camber, that gives loads of more grip to front.

Getting more is just not so easy thing to do, you need longer lower suspension arms, 1-2cm should be enough.

But that is really worth of work.

Then you could get Toyo proxes r888 tyres to front and normal tires to back, those Toyos have bit negative camber build in.
However this might made tail bit too happy and unpredictable so first option is better.

[dalahare]

My 360 runs about 2 degrres of negative camber standard, road tyre cannot generate enough grip to require more camber than this so if you do start running more you will actually reduce your contact patch on the road and have lees grip overall, along with stuffing your tyres.

Try fitting a stiffer swaybar, i know whiteline do one, I haven't tried it yet though.

[john.d]

You need to get more camber, that gives loads of more grip to front.

Getting more is just not so easy thing to do, you need longer lower suspension arms, 1-2cm should be enough.

But that is really worth of work.

Then you could get Toyo proxes r888 tyres to front and normal tires to back, those Toyos have bit negative camber build in.
However this might made tail bit too happy and unpredictable so first option is better.

thanks jtbo . I have already got about 2 degrees by modyfying the strut. more camber might spoil its driveability on several conditions.
on the previous setup the coils were much stiffer and the front was about 20mm lower. the feeling and the grip was fantastic but only when cornering! the spring was too stif for daily use.
the think about the tyres looks intresting. Maybe experiment on it on the future

[john.d]

My 360 runs about 2 degrres of negative camber standard, road tyre cannot generate enough grip to require more camber than this so if you do start running more you will actually reduce your contact patch on the road and have lees grip overall, along with stuffing your tyres.

Try fitting a stiffer swaybar, i know whiteline do one, I haven't tried it yet though.

i have to look first what is swaybar

[Gulbrandsen_Racing]

its the bar that goes from one of your suspension arm, to the other one at the other side..

This bar will prevent the car from "rolling" over in corners. Like a boat do, when the boat take corners it "lays" in to the turn, cars "lays" outwards..

[john.d]

its the bar that goes from one of your suspension arm, to the other one at the other side..

This bar will prevent the car from "rolling" over in corners. Like a boat do, when the boat take corners it "lays" in to the turn, cars "lays" outwards..

I see, swaybar is what i know as antiroll bar. thanks gulbrandsen racing.
but the combination of springs and dampers on my front is stif enought to prevent the 'rolling'. I want grip the moment i turn just when i am entering the curve not while i am in the curve. Before a year i tried a pair of sorings at the front which was very very stif but they altered the front to 400 mm when the badck was lowered about 50 mm. So my front was nfacing upwards ! the result ; i had no grip from the front cause there was not enough load on the axle. that is way i believe now that the front must be lower than the back

[jtbo]

Stiffer antirollbar at front causes more understeer, adding ARB to rear causes more oversteer.

Stiffer rear springs will make again oversteer and stiffer front springs makes understeer.

Certainly car should stand so that rear is bit higher, 10mm is good already, that helps to keep some weight at front and at higher speed also aerodynamics come into play, but that is bit more complicated issue.

What kind of tire pressures you are using now?

I have unmodified 360 front suspension and there is not enough camber, with stock suspension there is only 0,2 degrees of negative camber which certainly is too little, tires will bend under when you take corner at speed that rear of car would handle.
2 degrees is perhaps cure for that at least

Another problem with stock setup is that when you are accelerating out of corner inside rear is spinning almost on air and thus not helping with acceleration, I believe stiffer front springs helps here.

But those sorted you will be left with too soft rear suspension and you need to stiffen rear springs by adding 2nd leaf to get car turn again or then you need to add rear ARB.

[dalahare]

Has there been changes over the years to the 300 series suspension? my car is standard and the front has visible negative camber, Definately more than the 0,2 that jtbo describes, i have measured the rear at 1.9 but haven't measured the front (mate works at a car tyre place, we were intrested to know what my car was running, only hooked up the rear as they are visibly more cambered than the front)
I presume it would be more than 1.0 degrees, about 1.5 by the looks of it.

Jtbo is fundementally right, though there is a bit more to it than he says, but generally if you take a standard car and stiffen the front without changing anything else it wil understeer more than it used to, stiffen the rear and it will oversteer more than it used to, my car is also like his in that you cannot get any usefull accalaration out of corners as the inside back wheel is almost off the ground coming into the turn and cannot provide the foward momentum needed to get weight back on it, however this is almost all in the front being to soft and rolling too much, the rear of my car is noticably stiffer over bumps than the front, so a stiffer antiroll bar might help here without it making the car understter alot more LSD would be great too

I am going to try finding some leafs to add to the rear from the wreckers on the cheap, only $7 a pop from a wreckers near home, it's just a matter of finding ones the right size. then the whiltline swaybar ($200 odd) and finally will be going for some stiffer springs on the front, I want to do this last as i have priced customs springs and compared to what is available off the shelf for the 300's in aus there isn't a huge price difference, (about $300 for a set of custom fronts) so i want to get the rest of the car to how it is going to be for a while before i spend the money.

[jtbo]

I did indeed left weight distribution and shocks out as those make thing quite complicated

I think that rear springs are softer than front, but as they are leaf springs they do feel stiffer on bumps as they don't react as well as coil springs.

-0,2 degrees is from factory specs, it really has not much camber at front to make it understeer and safe (That is unsafe from my opinion).

In race use they use 2-3 degrees of camber with 60mm lowered suspension and lot stiffer springs.

Front springs are rated approx 33,6kN/m and I believe they use something near 50kN/m on racing (V360Cup, Holland).
I have no data from rear springs, but only estimate that they are 28-30kN/m but I would need to find this data from somewhere, just is next to impossible to find this, same as damper ratios.

Stiffer springs are not more grip, but actually less, spring rate is usually compromise between grip and handling, if you could make car not to roll and still use very soft springs you would have much more grip around corners, but that is absolutely impossible to make

Spring rates at near 2,2 Hertz are considered good for racing, just I'm missing magic formula to calculate spring rate.
It can be checked when springs are installed to car and when there is no dampers, you push car down and check the rate at which it bounces. Not too high tech method but can help to determine if it is far off from that.

Well, suspension is science of its own, with our cars and possibilites there is not much we can do with science, just need to try find at least some part that will fit.

If you could find 360 leafs from wrecker that would be easiest, but I guess there is not too many of these at down there? Then other cars are typically so big that creates a problem I believe.

[john.d]

Here in Grecce the 360 was never been imported so it is very difficult to find spares. the tyres are 34 psi front and 30 psi back and the dimension is 185/60- 13. when i had the stiffer front springs a was running them at 30 psi both front and back.
about oversteering and understeering the issue is very complicated. My father had a renault 21 1.8 lt. the car had very soft springs for comfort ridding and the arb's at the front and the back was stiff enough to prevent excesive rolling on corners. it had good grip and was slightly understeering when pushed to the edge. Now, when i changed the rear dampers with a much more stif pair the balance was spoiled and the car became very understeered. the cure was the use of stiffer springs at the front. The car had now found again it's balance and the handling was better as it was more accurate and precise on sterring with more grip from the tyres.