Suspension

[Bles 32]

Hi

I am looking to change my suspension to coil overs. Having done a bit of reading I have decided to go for the Tein Street Flex with EDFC active pro.

These coil overs come standard with 7KG front and 7KG rear springs. However from my reading it is suggested this is too stiff and it is better with 5 or 6KG front and 6KG back. This is where I am having problems as I am having trouble finding somewhere to supply these. Any Ideas ?

Also should I have the GPS with the EDFC active Pro.

Thanks in advance for any help

[rob275 1817]

Speak to Fensport, they can ask TEIN UK to swap the springs for different rates Something Yukiko is happy to do

 

also yes if you're going for the EDFC then you may aswell get the GPS it's an add-on part I think, or is that the G Sensor. Can't remember now. Fensport have supplied plenty now though so they know what you need

[Bles 32]

Thanks Rob will ask Fensport then. What springs are you using.

[Lauren 2259]

He's using 5/6kg same as me. This was a rate I asked for Tein to do for me, which was checked with Tein Japan and then air freighted over. The usual choice outside the stock 7/7kg setup which is a bit much on our roads is 6/6kg because when you lower the car it affects the spring rate and so pretty much everyone runs a 6/6kg or setup or equal front and rear. 

 

However I wanted the car to be able to transfer weight and particularly to load the front. I must admit compared to other cars with the 6/6kg setup I've tried the 5/6kg seems to help me alleviate understeer more. So driving say Spec K's car with 6/6kg I did notice more understeer. Depends what you like though of course. 

 

You will need offset bushes for the rear lower wishbones to get the camber right. 

[Bles 32]

Lauren

Thanks for the advice will contact Fensport and see if they can do the work as well as supply.

[rob275 1817]

Expect a bit of labour as its a lengthy process installing the edfc. But ultimately i'd say worth it

[Ade 517]

20% staggar will get you a nice setup

[Church 209]

Stagger as in staggered tyre setup? Why, to loose tyre rotation capability & to make handling worse just for looks (that rarely someone may notice) sake?

[Ade 517]

Sorry I meant stagger as in spring rates. so 20% stager would be, for example, 5kg front and 6kg rear.

 

Stock car is 60% firmer in the rear. With a Mcpherson strut you have to firm up the front and bit more than the back when lowering to compensate for the changes in roll centre, front to back. So 20% is a good starting point.

[rob275 1817]

Sorry I meant stagger as in spring rates. so 20% stager would be, for example, 5kg front and 6kg rear.

 

Stock car is 60% firmer in the rear. With a Mcpherson strut you have to firm up the front and bit more than the back when lowering to compensate for the changes in roll centre, front to back. So 20% is a good starting point.

 

So what you are saying 6kg front 5kg rear? I'm confused, perhaps i've misunderstood.

[Deacon 1357]

I would think 5kg front 6kg rear. The front has an almost 1 motion ratio where as the rear is 0.75 so it effectively reduces the rear spring rate.

[Church 209]

Stock spring rate IIRC was staggered.

Front OE Spring Rate: Subaru BRZ 27 N/mm (153 lbs/in)
                                    Scion FR-S 23 N/mm (131 lbs/in)

Rear OE Spring Rate: Subaru BRZ 34 N/mm (195 lbs/in)
                                   Scion FR-S 37 N/mm (211 lbs/in)

EUDM GT86 somewhere in-between, with front springs like FR-S's, and rear rate between FR-S's & BRZ. But also stiffer then front.

 

link #1, link #2.

 

So i guess, that maybe there is sense to go for staggered aftermarket spring rates too to keep it more tailhappy as stock is, not neutral/understeerish.

[Ade 517]

So what you are saying 6kg front 5kg rear? I'm confused, perhaps i've misunderstood.

 

20% stagger as in 20% firmer rates in the rear.

 

As decon has pointed out, motion ration at he front is 1 but at the back it is 0.75. What this means is that to have equal wheel rate (as in the effective rate of the wheel rather than the spring) front and back, the rear spring rate have ot be 78% firmer than the front!

 

Our car has a forward biased weight distritbution which is why the stock car only has 60% firmer rear rates.

[Deacon 1357]

I noticed the trd coilovers have a 3.5 front spring but a 5.75 rear.

[Lauren 2259]

I have run a 5/6kg spring rate for the last 30K miles with a lot of road driving, sprinting and trackday stuff as well. 

 

I would say that my car is one of the better handling cars out there, though it is of course down to what the driver can do. I'm pretty happy with my spring rates. Rob went for the same when he got his car sorted. 

 

It's a personal choice, but I prefer the 5/6kg over a 6/6kg as tried in Keith's car. I don't run any additional bracing as I'm yet to be convinced it's necessary. For me, I wanted the weight transfer under braking so I can transfer the weight effectively. It was for this reason I didn't uprate the roll bars either. It seems to work very well and I can pedal the car pretty quickly when I'm minded to. 

[Ade 517]

I noticed the trd coilovers have a 3.5 front spring but a 5.75 rear.

 

Thats good to know, where did you find that info?

 

They offer 5, 6.2 and 7.5kg fronts and 7.2, 7.9 and 8.7Kg/mm rear as options for their coilovers.

 

http://www.trdparts.jp/english/86_performanceline/parts_suspension.html

[Deacon 1357]

Thats good to know, where did you find that info?

They offer 5, 6.2 and 7.5kg fronts and 7.2, 7.9 and 8.7Kg/mm rear as options for their coilovers.

http://www.trdparts.jp/english/86_performanceline/parts_suspension.html

It's in one of the Japanese parts catalogues I've got.

[Deacon 1357]

Theoretically an even spring rate should give a stiffer front end and softer rear so making the car more likely to understeer. A softer front spring should help keep the car more 'balanced' front to rear and so the handling more neutral. Obviously other settings would effect this such as damper valving, arb rates, etc.

[Keethos 842]

What does it say about having 9kg and the front and 7kg at the rears then?

[Bles 32]

This all sounds really good but what I don't understand is why they then come with 7kg front and rear as standard and so far this is all anybody wants to sell me ???

[Ade 517]

Square setup is safe.

 

If you look at the higher end track orientated teins they are staggered:

 

Monosport: 8kg front, 9kg rear

Tein SRC: 10kg front, 12kg rear

 

Ohlins are 6kg square and very safe. But they can accept 25% firmer springs on the back without needing to send them off to be shimmed. Many of the higher end coilovers have a much bigger usable range of adjustment which makes it easier to mess with spring rates.

[Lauren 2259]

Yep, I do think that's it, i.e. it's a safer setup, understeer is easier to deal with compared to oversteer. I must say my car does not understeer like the stock car, nor does it understeer like the 6/6kg setup I've tried. 

 

So, it is as other's have said a matter of preference. Bles you can easily get the same setup as I have if you desire, just speak to Fensport and they will speak to Yukiko. I can also contact Yukiko on your behalf if you give me an email address she can reply to, but Adrian knows the score, so I'm sure he can sort it. 

[Bles 32]

Hi

Have booked my car in for the Suspension change as requested, waiting for 6kg springs to come into the country. However i have been recommended to fit SuperPro Rear Lower Adjustable Control Arm and Adjustable Toe Arms at the same time so that the camber can be set up.

 

Have those of you with coilovers fitted needed to go down this route ?

 

Many Thanks

[Deacon 1357]

I had the whiteline upper camber bushes fitted instead. A bit more of a pain to fit but fairl easy to set up and cheaper than lca's. Allows me to run 2 degrees negative camber at the rear.

[Bles 32]

Hi Deacon

 

Did look at this but the garage fitting the suspension was only £50 pounds different for the bushes to the control arms due to the extra labour required with the Bushes.