Balance Motorsport and gaz have been developing a coilover kit for the 20vt (as posted in the group buy section).

A prototype kit was installed on my car yesterday – followed by a trip to Elite in Essex to get the tracking setup.

The day involved a fair bit of driving back to SW London afterwards so I could have a bit of a play – luckily the roads were also dry. The initial setup was with the damping set at 6 on the front and 9 on the back (rears can be adjusted up to 20 for max damping, and I think the fronts go up to either 10 or 20 – will check later).

Driving out of Gaz it was obvious the tracking was a bit out with the steering had a very light feel. At elite they found a fair bit of positive camber and toe out on the front, and therefore put camber bolts in – even with these they could only get –0.3 on the front (will post tracking printouts when I have a chance), so I think that there is some more work needed on the top mount, or perhaps a slightly shorter spring?

The ride height of the car is pretty much standard, which is allowing the correct wishbone angle on the front (horizontal) and should really benefit handling – though I’ll need to get the car on track to find out just how good. I think I may need a shorter spring on the front though as the dampers are currently adjusted to full drop, and it would be nice to have the option of dropping the car down a bit.

So how does the car feel? The damping is very good, and the ride is less crashy than with my Koni adjustables with Eibach springs (35mm drop), handling also feels tight, and the back lively (23mm rear ARB on the car as well).

Bad bits (bearing in mind this is a prototype kit):

1. The bracket on the strut does not appear to be quite right – so I have a few bits and bobs held in place with cable ties.
2. The camber as mentioned cant be adjusted to any more than –0.3 degrees even with bolts.
3. Either my car has gained another 50bhp (it’s cold – but not that cold!) or I’ve lost some traction. On high boost as soon as I hit 5,000 rpm (peak torque) on a dry road with full beans I get a nice lump of torque steer and wheelspin in second gear – which I did not with my old setup. I’m going to try winding down the fronts a few clicks and seeing if this gets back the traction.

Any thoughts chaps?

Bad tracking would easily cause torque steer, followed very quickly by a loss of traction as you try to stop the wheels going where the power wants to take them

Sounds like the mounting holes are in the wrong place if the default setup caused positive camber - the maximum of -0.3 would support this theory

If the coilover is narrower than the standard spring (which I assume it would be) then adjustable top mounts may be an easier (and more accurate) way of setting camber.

Be careful with top mounts though - a small change in the fore/aft position will muck up the castor and trail, which will play havoc with the steering weight and the self-centring effect

Finally, I guess they've used the same type of camber bolt as DrFrag used (slimmer bolt, with cams) - remember what happened to Joe?

PS - how easy is the damping adjustment on the rears? - I would LOVE a set of rears with remote-adjustable damping, instead of having to take the shock off to adjust it

Are bump and rebound damping independently adjustable or is it just one adjustment that changes both in a set ratio?

I’ve got a table somewhere that tells you what you should do when different things happen. I think Jimbo did a really good few posts on how to set it all up back when pistole got his kit fitted (easy to find on a search ‘+adjustable’ and ‘pistole’ as name of poster) which might help you out.

Also bear in mind that the ride height and everything else will probably take a while to settle/bed in.

Did Gaz go for a slotted top hub mounting hole Si, even a standard coupe should be running more camber than that so they've got something wrong ?

What spring rates have they gone for and what sort of springs, I tried all sorts of springs before being happy with the ones Im using now, it takes time and some tinkering to get it all sorted so stick with it

Oh and the springs won't get any shorter as they settle, coilover springs should be guaranteed to keep their length.

Dont worry about lowering it more, having the wish bones in a position where the kinematic roll centre is below ground means nothing. It must be the most incorrectly stated bit of suspension knowldge ever, esp on a Mc Strut. The kinetic situation is vastly different where the wishbones will not have symettrical position. The kinematic situation only accounts for symetrical wishbone positons, and you dont have to be a genius to realise that in cornering where the you are actually interested in the roll center can no longer be predicted but the Kinematics. Lower it down.

Rich

I think Gaz or at least BMS were more concerned with the geometry of the wheel as the wishbone went passed the horizontal.
Have a look at Eibachs ERS line of springs and have a play around, the beauty of Leda was they would do this exchanging of springs for free until we found a good one. Ask if Gaz/BMS will do the same ?

doesnt matter Jim its the biggest myth about roll centres, ignore it. Its a poor comparison for performance suspension and was widely used in deciding what happens with soft passenger vehicles. Be concerned with force application points in the kinetic situation. Those who cite such stuff should explain what the situation is in cornering when one side is in droop and the other in bump - that completely rubbishes the kinematic situation and forces a kinetic analysis.

rich

Interesting reading Rich. I never did see the issue with the wishbone position, its a single pivot point on a Mcphearson strut wishbone so the geometry shift shouldn't really be that radical if its set up correctly at the required ride height ?

Thanks for the feedback guys - I'll write more when I can.

Another quick question - how much front negative camber does the coupe run as standard?

Between 0.5' to 1' negative is standard, you want at least 1' negative though even on a road car, a track car should be looking at around 1.4 depending on how stiff the car is in roll. Too much camber on a fwd car will ruin it.

Anyone know what the distance from the arch to the rim is on a standard car front and rear?

Rich you are correct about the roll centre moving when under load through a corner but it is a known fact that with macstrut suspension starting out with the roll centre way below ground (generally indicated by a wishbone above paralell)is wrong especially on a fwd car. i have practical experience of this with customers cars and my own with laptimes. drop to far and you just end up with loads of understeer. An elegant solution is to move the balljoint pivot point (works brilliantly on Mitsubishi Evos) however nothing available on the coop short of a custom wishbone or moving pick up points.

Whiteline suspension explain the point well here
http://suspensionparts.info/showthread.php?t=294&highlight=roll+center+height

There's a dial that you can turn on the shock - very easy, and no need to remove the wheel etc.

I went straight to elite to get the tracking done after fitting - they suggested the camber bolts, and said that they only use top quality ones... the chap I spoke to really knew his stuff.

The tracking is spot on.

One adustment that changes both as far as I know.

the top hole is not slotted. I dont know the spring rate Jim - Julian did not want it disclosed until the kit is done - but any knowledge you could provide would help...I know how much time you have spent with suspension setups!

Pants - looks like I'm running more than standard positive camber at the moment then.

Julian I will email the article from race car engineeing, its made interesting but difficult reading.

Rich

please do! i may well have read it already as they keep sending me free copies !

Here are the printouts from Elite - one shows the readings before the camber bolts were added, the other after:

http://i11.photobucket.com/albums/a198/suba11/alignment2.jpg

http://i11.photobucket.com/albums/a198/suba11/alignment.jpg

Any comments are appreciated. I'm thinking that a shorter spring on the front will sort out the camber issue...

I think one of your rear trailing arms is starting to fail, hence the .11 you have on the rear left

Looks like they've screwed up the caster measurements Si, the original measurements look spot on but the after ones are miles off. This would be ok if the caster was adjustable but its not. They measure it by rocking the alignment rig to be in line with the strut and in your case it looks like they didn't do it right for some reason ?

Begbie is spot on with the rear arm bearing though, replacing that will tighten things up at the rear.

Let me check your toe settings against mine, it looks like its almost set up as wheels nearly straight instead of running some toe ?

Yes. Sorting both rear arms has been on the to do list for a while...

How would they sort out the caster then? I don't want to spend a lot of time and money making adjustments and getting it all alligned continuously...

Thanks for the help Jim.

I dont think you need to sort the caster, I think there's some sort of error in their measurements the second time around.

Yeah like Matt said, they've just cocked up the second reading, they can't adjust anything with the caster so the first reading will be the correct one.
When they measure it its just a case of rotating the alignment device on the wheel so it lines up with the angle of the damper strut, that gives you the caster angle.
They must have got it slightly out or forgot to do it the second time ?

I can't find my print out from Leda but I'm sure it was running a total toe of around 0.8' ? Your is set to almost wheels straight and that will give you some torque steer.

Not sure what toe is in terms of degrees and minutes, but I know it's 2mm toe'd in as the standard setting.

Also, I dont remember writing that previous post in the early hours of this morning. Suprised it makes sense.

All except that your talking about castor and not caster Matt, aren't they the wheels you get on shopping trolleys ?

Drunken bum