8 replies to this topic

[Stu-7]

Check you this pic, taken at Bedford on Saturday.
I am running Nitron 3-ways. FR and Rear compression was 4 clicks from full hard. Rebound was 7 clicks from full hard, with the rear set 2 clicks softer than the front.

What do you think about this pic?



Body roll is rather pronounced for a geo-d, "Nitron'd" car don't you think?
Time to stiffen up the preload on my spring settings?
My initial thoughts were thicker ARB's actually.....
Thoughts...?

Edited by Stu-7, 20 February 2007 - 03:18 AM.

[GruFF]

surly thats helping you get round the corner? if it was to stiff, surly it would give you more understeer? atleast thats what i thought

[Stu-7]

surly thats helping you get round the corner? if it was to stiff, surly it would give you more understeer? atleast thats what i thought

Body roll only has a relationship to understeer if the front compression is stiffer than the rear (*i tink*)

Edited by Stu-7, 20 February 2007 - 03:16 AM.

[GruFF]

surly thats helping you get round the corner? if it was to stiff, surly it would give you more understeer? atleast thats what i thought

Body roll only has a relationship to understeer if the front compression is stiffer than the rear.

i see, so providing you have an even compression on front and rear, or more compression at the rear, your OK ?

Edited by GruFF, 20 February 2007 - 03:13 AM.

[Stu-7]

surly thats helping you get round the corner? if it was to stiff, surly it would give you more understeer? atleast thats what i thought

Body roll only has a relationship to understeer if the front compression is stiffer than the rear.

i see, so providing you have an even compression on front and rear, or more compression at the rear, your OK ?

Erm....<hooo!> this is a massive topic! people have written books on this stuff

What I have learned so far about the VX is, as far as Compression is concerned (ie: how quickly the damper firms up when you lean on it (whether over a bump or compressing into a corner) you need to keep the balance of compression stiffness from front to rear as close as you can.
To improve turn-in, you can soften up the front compression but, only to a point. As the more you do this, the more you start to compromise overall grip.
I've found I've had to completely change my driving style (massively for the better btw) to overcome what_I_originally_felt_was_understeer and, have gone from a soft front-end to a much harder setting (more in-line with the rear) and as a result, I can carry more corner entry speed, as the front of the car can be loaded up more on turn-in without stepping out (as it used to do when the rear was harder than the front).

What felt clear over this kerb (pictured) was my rebound is a little too hard still, as the car didn't recover well from each bump, it skipped across the tarmac after mullering the kerb; i've still some work to do on the rebound.

My concern from the above picture was body-roll: I never thought the VX would roll that much. Maybe it's a small optical illusion, as the shot in this pic (from a different day) shows much less pronounced roll.....

Edited by Stu-7, 20 February 2007 - 04:21 AM.

[Arno]

Time to stiffen up the preload on my spring settings?

Roll doesn't look too bad.

Increasing the spring preload just raises that ride height of the car, but does nothing for body roll. (actually can give very bad effects if you raise it enough to run out of droop travel on the inside when cornering!)

Getting stiffer springs and/or stronger ARB would be my idea.

Bye, Arno.

[clipping_point]

The roll looks OK. What kind of tyres do you use, roll is speed-dependant? Adjusting the springs wont help, instead a Plans adjustable ARB could be used to reduce roll, or stiffer springs.

[Stu-7]

The roll looks OK. What kind of tyres do you use, roll is speed-dependant?

Adjusting the springs wont help, instead a Plans adjustable ARB could be used to reduce roll, or stiffer springs.

Thanks, I've discovered increasing the preload on the springs won't help.
I discussed the roll issue with several, shall we say "alumni" from the university of suspension, and the general consensus is I need stiffer spring rates as opposed to ARB's which on the VXT are supposed to be more than ample.

So, I called Nitron this afternoon. Apparently, the standard spring rates for the VXT on the 3-ways are:
375 lbs FRONT
475 lbs REAR

So, the basis recommendation is to swap the existing rear springs to the front, then acquire x2 new springs for the rear, making:
475lbs FRONT
575lbs REAR

[Arno]

So, the basis recommendation is to swap the existing rear springs to the front, then acquire x2 new springs for the rear, making:
475lbs FRONT
575lbs REAR

That sort of spring rate is OK.

I personally run 400/500lbs springs on my Elise with a Honda engine in the back, but I did have my nitrons re-valved for these rates when I had them serviced/refurbished.

But I don't think you can move the rear springs to the front. Rear ones are longer and probably don't fit on the fronts length-wise.

Not a biggie though. Springs are not very expensive.

Bye, Arno.