InTurbo

iTrader: (3)

After spending quite a few months researching about suspension dynamics and speaking to a lot of highly regarded people in suspension set up, It's clear to me that there a major difference in so called optimum ride heights.

A few examples on a Hawkeye Sti.

Chevron say
Front 345-350 Rear 335-340 hub to arch.

Scoobynet members
Front 380 rear 360 hub to arch due to roll centre being affected.


PCA dynamics
Say the front should be lower than back as seen on P1 and RB320. This helps lower roll centre at front reducing under steer and helping turn in.


I have played around with my cars ride heights and I have noticed less roll at slightly higher ride height but also noticed less responsive turn in and under steer.

sivo

iTrader: (30)

350 fnt 335 rear
Centre of wheel to arch

This was set up by simon at chevron, see my spec in my garage for details.

Simon does all the testing for the whiteline Impreza and is highly regarded with anything Subaru.

Hence why I had him build my engine

Siv

P555SBR

iTrader: (1)

Trust in what simon at chevron says the guy knows suspension he set my car up for every sprint last year his cars won 2012 2013 2014 in s2 2014 overall winner 2014 s1 and had a lot more on the podium in each class

sivo

iTrader: (30)

I only realised how well my car was set up when simon took me out for a test drive in it and scared the **** out of me with how much corner speed it can carry

I've had all kinds of cars back off in the bends and mine just stays as flat as a pankake no matter how much you push.

Go and and have a chat with chevron, you may have to wait your turn and it may seem like it takes ages to get the job done but I can assure you it's well worth waiting for.

Siv

2pot

iTrader: (3)

This is going to be interesting.

Just to say; hub to arch distance is a good datum - it doesn't mean it directly indicates the suspension heights.
ie. Because the front hub to arch distance is, say 20mm greater at the front, than the rear: doesn't mean the front suspension is 20mm higher.

InTurbo

iTrader: (3)

I did speak to Simon. I was going with his custom B14 kit until we got on to the subject of RB320 Bilstein's.
I asked how his B14 would compare and he said the Bilstein's fitted to the Rb320 are the best damper for fast road use.
He even mentioned about trying to get his B14's made with a softer low speed bump and more bump travel to try and get the same level of compliance.

So this has ended up in me buying the Rb Bilstein's and springs.

Will measure the ride height and compare once fitted.

2pot

iTrader: (3)

Well, I'm interested

InTurbo

iTrader: (3)

Rb kit ride height is 355 front 365 rear centre of wheel to arch.

2pot

iTrader: (3)

Thanks.
Looking forward your handling analysis. Particularly the bar sizing you prefer. The RB320 was 20/21mm(rear-2 way adjustable), but, it was, intentionally, a bit hard core.
Maybe less bar would still suit?

fpan

iTrader: (11)

I played with ride heights a little when I had my custom made B14s from Jamsport and found that in a Forester STi it handled the best (better turn in, rolled less and would power steer progressively and predictably out of bends) when the front was ~0.8-1cm lower than the OEM height and the rear around 0.5cm lower than the OEM height.

When the car was 2cm lower than OEM height (alround) using STi pink springs it rolled more but the car was still progressive and predictable at the limit.

InTurbo

iTrader: (3)

Still waiting for it to be set up. I had to cancel my appointment due to work.

fpan

iTrader: (11)

21.6mm (rear-2 way adjustable) to be precise

2pot

iTrader: (3)

Does that include the powder coating?

InTurbo

iTrader: (3)

I'm going to keep the oem bars on for now. The car corners very level as it is.
I've also noticed the at the current ride height it feels like I have a stiffer rear bar. I think by having the back higher it makes the front turn in better and gives less understeer but with out the extra harshness of having a thicker bar.

At first I didn't like the ride height compared to where I had my BCs but has grown on me now.
Hopefully be getting the alignment done Saturday morning.

Hear is a pic of the ride height as it is now.

2pot

iTrader: (3)

[QUOTE=InTurbo;11687170]I've also noticed the at the current ride height it feels like I have a stiffer rear bar. I think by having the back higher it makes the front turn in better and gives less understeer but with out the extra harshness of having a thicker bar.(/QUOTE)

100% agree.

I'll have a go:
The positive rake induces greater load transfer at the rear, reducing rear grip.
All done without a big rear bar, restricting the independence of the rear suspension - fast and comfy; perfect.
And, you can still fill it full of people, fuel and things.

Ratbag

iTrader: (1)

What you using now?
I've got some jap coils on my fozzy sti and the springs are goosed, I'd want to go back to shocks and springs. Probably going to go for impreza sti shocks and springs, not sure to go for oem stuff or aftermarket

rickya

iTrader: (18)

"Chevron say
Front 345-350 Rear 335-340 hub to arch."

Perfect for Hawkeye & almost same as what Tein recommend.

2pot

iTrader: (3)

Read post 6: Chevron told 'InTurbo' to buy the rb320 set up - as it's the optimum fast road set-up.

d.kenny

does anyone have any info on what a classic should be?

my car is far to low and handles terrible

i want to get it sorted...going to add more castor this weekend and raise up a bit i think

InTurbo

iTrader: (3)

When speaking to Simon from chevron I explained to him that I wanted a compliant ride that can handle bumpy fast road use. He said the b14s are good with excellent handling, but even with him customising them with more bump travel and softer low speed bump they won't be as comfortable as the rb320 Bilsteins and for a fast road use there hard to beat.

Chevron also set there cars with a slightly higher ride height in the front to help reduce dive under braking as the Sti has a high front brake bias.

Prodrive solved the same problem by having a well designed front spring assister (bump stop) to reduce the cars pitching under braking.

Two different ways of solving the same problem. But two different ride heights
Chevron front higher Pridrive front lower.

Prodrive like the front lower as this adds more resistance to roll at the rear and lowers roll centre at the front, helping to reduce understeer and help turn in response.

Chevron use a roll bars and extra caster/camber to do the same affect so again two different ways of going about things.

2pot

iTrader: (3)

So, when Chevron say, for a Hawk:
Front 345-350 - They can't be referring to optimum, bumpy, B-road, heights?
As the front, Prodrive rb320 road height, is 355mm; and 363mm for the 'normal' Prodrive Hawk.
I assume, the Chevron front B-road height, is more like the 'normal' Prodrive Hawk?

2pot

iTrader: (3)

Classic:
335-345 front - you might want to look at whiteline kit kca313, if under 340mm front.
340-345 rear.

Ensure you're not constantly engaging the stiff part of the bump stops, by running too low. Or change your bump stops.

Don't over do the bar size.
Roll-rock:
If the spring rate is relatively low and the sta bar is too stiff, a suspension movement, initially, occurring on only one side of the vehicle, will be transmitted to the other side, inducing an unsettling 'roll-rock' motion.

HTH

InTurbo

iTrader: (3)

The ride heights I was given by chevron was between 345 to 350 on the front and between 335 to 340 on the rear

2pot

iTrader: (3)

How did it go?

InTurbo

iTrader: (3)

Lol I've got my weeks mixed up. Sat the 6th I'm booked in. Lucky I emailed him before I left!

fpan

iTrader: (11)

Yes it does. Have you measured it bare?

fpan

iTrader: (11)

The car (sold now) in its latest setup had a custom made Jamsport suspension

You will ruin the handling by putting Impreza STi shocks and springs on the FSTi, the car will be too low.

2pot

iTrader: (3)

That joke obviously lost something, when I wrote it down

2pot

iTrader: (3)

2pot

iTrader: (3)

Aligned?