Rear springs.

[Android 360]

Ok, heres the deal.
I want to lower the rear of my exa.
I have coilovers in the front which i will wind down to match.
I would like springs that are a closer match to the coilovers (firm)
I have monroe gt gas shocks in the rear which i am quite happy with for now..

I have heard rumors that some sort of supra front springs (MA70 or something?) fit well and are ideal for a firm ride. I need someone to confirm that this is the case, and what model supra it is.

It would also be awesome if i could see a picture of someone's car with the springs in place... need to see if it's low enough

If anyone could help that would be just lovely..
cheers

[Callumgw]

Check out this:

http://forum.n12turbo.com/viewtopic.php?t=4410

and if you get more options and more info post it up!

C

[shanec86]

http://www.industrialsprings.com.au/aurora.htm

they will make you what ever height, and what ever spring rate you want. easy

[Android 360]

thanks for the link shane, i've emailed them.

u 2 callum, that helped a bunch.. once i hear back from them i'll let everyone know the specs.

Cheers
Joel

[Android 360]

An update:

$307/pair for custom wound springs.

off the shelf springs are:
147Lb/In (front) and 218Lb/In (rear)

the ones im getting made are:
335Lb/In or 6kg like the coilovers.
(almost no movement)

I am going to send in my factory springs as a reference to double check everything.

I am looking at getting them made so that they are 2" lower than they are currently.

Ideally i'd like 3" lower, but 2" will take it down to 100mm +/- a few mm
As i'd still like to be able to drive it on the road, and the racing series i want to enter is for street-legal cars, this height would be ideal.

I'll keep posting updates

Details on manufacturing:
Aurora automotive coil springs are made of a specially developed micro alloyed spring steel developed by B.H.P. This material known as grade X4K92M61S has been designed to withstand higher operating stresses, with superior resistance to sag and with fatigue properties at least equivalent to conventional spring steels. To further ensure a long failure free life of Aurora springs we shot peen each spring before applying the required surface finish.

[ETONE]

correct me if im wrong, but wouldn't 6kgs be too much considering there's no engine in the back????

lots a wieght in the front, none in the back.

just a thought

Campbell

[Android 360]

When I was first thinking of it, i was thinking along the same line.....

but i've had a look at spring rates on aftermarket springs and they all either have the same sort of spring rate/front and back, or stronger weight in the back..
(check out callumgw's thread posted above - it has the same info)

what i'm thinking, is that it's to make up for the weight transfer under accelleration. When you accellerate, all the weight goes to the back which is why a lot of cars squat down.

[JETETT]

what i'm thinking, is that it's to make up for the weight transfer under accelleration. When you accellerate, all the weight goes to the back which is why a lot of cars squat down.

correct... i have alot of problem with weight transfer in mine to the back, but if u stiffen the back too much, would ya get too much wheel spin in the front?? or would it help put the rubber 2 the track for more traction? im also interested in this mod as i have been converted to circuit racing

[boost_truck_racer]

ive got 200 in the front and 350 int the rear

rears where custom from kings $200

[Callumgw]

Car balance is interesting. Normally (in a FWD) the rear is made stiffer than the front. It helps reduce understeer, not by improving front traction, but by reducing rear traction. Yep believe it or not, softer spring give more traction than hard springs.

Don't beleive me? look at how soft drag cars are on the rear.....when you think about how 'soft' it is you need to think about everything from the tread to the chassis. Back in the late 90's 30% of an F1 cars movement was due the tyre acting like a spring, the same in still probaly true. Lower profile tyre, more tyre pressure, stiffer springs stiffer shocks (shocks do have some spring in them!) nolathane bushes and chassis stiffness all contribute to increasing the stiffness of the chassis.

So why are race cars so stiff? because race tracks are so smooth. and they what to control the amount of wheel geometry change during cornering.

Going too stiff will take grip away and 'too stiff' depends where your driving and what the roads are like. So becareful.

ohh, effective stiffness does come into this as well. As mentioned before, the same spring will feel softer with a heavy mass than a light mass.

C

[JETETT]

if ya wanted 2 stiffen the springs in the back, iv seen in commo utes vr vs so on the have similar suspension to the ET's but bigger springs course they have an air bag which sits inside the spring that ya pump up with a tyre gauge for heavy loads or what ever could ya use that for a little more stiffness??

[Android 360]

I think a supplimentary air bag setup would cost more than stiffer springs wouldnt it?

wouldnt be near as reliable than just a spring either.

the way i see it, is less weight transfer to the back = more front traction = less understeer and more control.
we'll see how it goes on the track
I'm planning on having a go at a street sprint day at lakeside in a couple of months

[Callumgw]

I think a supplimentary air bag setup would cost more than stiffer springs wouldnt it?

wouldnt be near as reliable than just a spring either.

the way i see it, is less weight transfer to the back = more front traction = less understeer and more control.
we'll see how it goes on the track
I'm planning on having a go at a street sprint day at lakeside in a couple of months

unless you have GROSS suspension travel or body movement, weight transfer is not dictated by the spring stiffness, only a tiny portion comes from the springs. Its about physics of the centre of gravity relative to the contact patches. You want to change the weight transfer, move the C/G height (lower springs) or change the wheel contact patch spacings (deep dish rims, wide body suspension changes etc..)


C

[Android 360]

Well i'm going deep dish rims too.. getting them made to suit the car as soon as my amps are sold.. will be pumping the guards out like crazy, hopefully get a pretty decent width under there.

the car is going to be about 3" lower than factory.. so that should make centre of gravity a whole lot nicer.. plus on the convertible all the weight from the roof has been removed and there is more weight in bracing on the floorpan.

the n12 vert came with extra spongy suspension for comfort.. so stiff rear springs in my case should help a bunch. Atm it does a bit of a bum-wiggle which is just awful.

every time i've put stiff springs in a car i've noticed that there is less squatting under accelleration. Squatting is a result of weight transfer (weight moves to the back with compresses rear springs). best way to tell is in traffic, with your headlights on you will notice that the light travels up the back of the car in front when you accellerate. once you put stiff springs in there then there is virtually no movement.
So it must do something!

[Callumgw]

. plus on the convertible all the weight from the roof has been removed and there is more weight in bracing on the floorpan.

but convertibles have much softer chassis, even after the extra bracing. So stiffening the springs will make it stiffer, but you could quickly get to the point where the dominant component is the soft chassis. Most racer make the chassis as stiff as possible, so it doesn't need to be considered in the suspension tuning.

every time i've put stiff springs in a car i've noticed that there is less squatting under accelleration. Squatting is a result of weight transfer (weight moves to the back with compresses rear springs). best way to tell is in traffic, with your headlights on you will notice that the light travels up the back of the car in front when you accellerate. once you put stiff springs in there then there is virtually no movement.
So it must do something!

yep, it changes the amount of movement of the body relative to the wheels, NOT the amount of weight transfer between the wheels (unless the cg moves a lot). For example, go-karts have weight transfer too!

C