Pugtk

I'm running BC coilovers in my classic with the softer 4/3 spring setup with longer travel dampers with valving to suit springs on my classic type r.

What is the optimum ride hide for bumpy b-road tarmac? I was trying to find the standard ride height of the P1 but ive had no luck.

2pot

iTrader: (3)

P1 - f340-345mm r345-350mm

Markyscoob

Good choice sir. The longer travel damper and softer spring and divergent damping is a very usable and flexible setup. It enables you to run higher than standard if you want. Do you have longer springs or standard ones and helpers fitted? Ideally, you want to set them on the length initially to be no longer than the O.E. strut to avoid "necking" and ball joints and straining hoses and ABS cables.

With stiffer springs you would sit above O.E. ride height at that point. So can lower to suit from there.

Now, the really crutial thing you need to take into account now is Roll Centre. Your car pivots about a mystical line that connects front and rear roll centre and on a McPherson strut setup, that roll centre is determined by the 90' angle in from your strut top and drawing a line through the bottom ball joint through the inner lower arm pivot and continue till it crosses the top mount line. From this point go back till you reach the centre of the tyre's contact patch. Where this last line crosses the centre of the car, (the opposing side's line if symmetrical) is your instantaneous roll centre.

Typically, drop the car 1", and the roll centre drops 3"-4".

Hence, lowering makes the car roll a lot more, and why stiffer springs are needed to counter the roll.

What are you looking for? Loks or handling? Often they are not in harmony...

O.E. the cars have about more arch showing in front than back, this produces a tendency to roll into the rear quarter, lifting the inside front and producing progressive understeer.

Here's your ACE. With the BC, you can lower 5mm at a time and feel the change until it feels right to you.

Best of luck.

Pugtk

Some good info there lads!

Springs are the one piece items from memory.

Whats the main difference between the two?

Ive had the struts set at -40mm from scoobyworld

But it has an **** up face down stance.

The rear looks standard and if not higher than oem

The front has around one finger gap

So I'll set it p1 height and adjust from there

Markyscoob

Definitely too low at the front! The car geometry works best on the road with a similar gap front to rear. Too low and the roll centre is far too low for the road. This causes the car to dip into the front corner and lift the inner rear tyre- bit like those iconic Golf GTi cornering photos.

BC are notorious for not making the springs long enough- they fit the 50mm helpers to compensate, but the result is you sit too low in the travel. I'm making do on mine for now but plan on getting longer springs made for me this coming summer.

fpan

iTrader: (11)

Alleluia! Some proper questions and answers unlike the majority who lower their car to "improve handling"

bonesetter

iTrader: (9)

Great advice. I would just add, the front wheelarch usually has a bigger gap, making it appear higher, so that needs to be factored in

Here's a classic too low



Here's the same about right

Markyscoob

The ride height on all cars is a balance of factors. Initially, once the height is set the stylists will alter the arches to give the right look to the car. Then it enters production engineering and the resultant ride height will change. Often messing the original look up. The New Age Impreza is a great example of this.

On a McPherson strut design, the primary change of geometry when you lower is to roll centre, this then affects balance, squat, dive and bump-steer. amongst others. It's a minefield, so if the Engineers do their stuff right to start with, you can't go far wrong with O.E. ride height. I learned that the hard way on my Mk4 Ford Escort. Several sets of springs later, I ended up with a great handling car- at O.E. height!

On my Impreza, the coilovers mean I can play much more and change things independently. It's a learning experience again.

My impression is that the front was lifted to generate more understeer by engineers for safety. It really does sit into the back corner under acceleration when cornering and on wet roads with cheap tyres you can feel it slide and provoke it easily. Ditchfinders are great for learning balance and feel. The O.E. Bridgestones are not.

As I work away from home a lot now, I don't get to play a lot. Poor car just sits in the airport car park most of the time. Shame.