Spot The Difference: Handling

[Greg]

I recently drove my friend's R32 gtst which has coilovers and a roll cage but is otherwise stock. It sits perfectly flat through corners without absolutley no body roll. I want this handling.

I'm currently running bilstein shocks with Apexi springs (which are a progressive rate spring). I've also have ARC swaybars and front and rear strut braces. Judging by pushing down on the corners of each car, my suspension is pretty much as stiff as his.

My issue is that when I put the car into a corner (on a racetrack of course), I initially get a small amount of body roll before the suspension stiffens up, which I find a bit unsettling. It makes it hard to judge where the car's limit is.

Do you think this is caused by:

a) lack of roll cage; or

b.) progressive rate springs; or

c) all of the above; or

d) other... please explain.

My current theory is that the "soft" coils of the springs are initially being compressed as I enter the corner, allowing the small amount of body roll, before load is placed onto the "harder" coils - will a linear rate springs be much of an improvement?

Cheers,

Greg

Edited August 28, 2005 by Greg

[Roy]

Rather then thinking about body roll etc, throw the same rubber on each car and look at corner speed. What feels quick isnt always, and sitting perfectly flat may not be the quickest way thru a corner?!?!?!

This is just conjecture but a darty pointy car with firm suspension could feel great and resposnive, but when you load the thing up through a quick corner with undulations like most australian roads and tracks for that matter, you may find the actual corner speed is down a little.

Then again it could be a lot higher...guess im just saying dont let the seat of the pants deceive you .

And it comes back to driver comfort as well, nand how you liek th ecar to feel. Im starting to lean towards liking a slightyl firmer setup then what i currently have, though odds are i wont be able to ride kerbs etc meaning that i will be wanting to make up a lot of time elsewhere, because at the moment my cars ability to really ride kerbs means i am able to make time on soem quicker cars then me.

[someonestolecc]

I've found from riding in peoples cars with roll cages it adds much more of a firm feel. But as Roy said what feels doesn't always mean faster (lap times). Are all your other stiffening bits the same? (struts/sway bars/bushes etc?)

Could it be your wheel/tyre setup too? (i.e. lower profile tyres on your mates car?) There have been a few people around that complain about having the tyre compress before their suspension does (when they have hard suspension but high profile tyres).

[Sydneykid]

As Roy posted, the feel is irrelevant, it's how much grip it has that determines how fast it is. Generally speaking a softer spring rate gives more grip. That said, we don't use progressive rate springs in the race cars. We do use tender/helper springs to keep the main coils trapped.

I have never seen progressive front springs in a Skyline, it is quite common in the rear though. But mostly to soak up the travel in the shock. The progression is there to keep the coil trapped, not to have an initial softer spring rate.

You should check this before you jump to the conclusion that it is the progressive rate that is causing the initial vagueness. Firstly check that you actually have progressive springs in the front (unlikely). Then have a look under the car (on ramps with the weight on the wheels) and see if there are any of the progressive coils not sitting on top of one another. That will tell you if there is in fact any progression at all in the dynamic spring rate.

cheers

[dangerous_daveo]

The roll cage will also add weight...

And the other thing, potentially your subconsous could make you think you can go round coners safer because you have a cage around you, like, even if you come off, you wont die kinda thing, strange how the mind works.

[Greg]

Thanks for the replies everyone

I am going purely off the in seat feel, not corner speed. In some ways the feel is more important to me as my car rarely sees the track.

The tyres I'm running are 205/60/15 so there is a distinct possibility that the sidewalls are flexing before the suspension. I'll borrow some lower profile rubber to test this theory.

My front springs are definitely progressive. I will check if any of the progressive coils aren't touching each other tomorrow in the light. Thanks for your help