Liam's Z4C race car project

[enuff_zed]

Just watched the video.

'Probably the most successful club racer'
'Brilliant tactician'

Well done God!

[thornad]

Hi Liam,

Killer thread, a joy to read.
How are you getting along with the GAZ Mono coilovers?
Some Z-Cars racers said they are terrible and that the spring values seem to be completely off.

I bought a 2004 E85 Z4 (M54 engine) race car built for the Z-Carts series (but never raced) using the GAZ Mono kit, and it has almost no rear compliance. I do have a 3.73 diff with LSD, but still...
I can go into oversteer way too easy with a bit of lock and just 1/3rd throttle in 4th gear in the dry (on MTF ZTR tyres 215/45/17). The rear also seems very rigid when pressing down on it, even on the softest settings.
My rake seems to be pretty high too, the rear being about 25-30mm higher than the front.
Alignment is Camber 3 degrees front, 2 degrees rear, and toe 0.2 degrees (or 12 minutes, or 2mm) toe-out in front, and same amount but toe-in in the rear (for each wheel). Stock roll-bars.

So I was really wondering how did you manage to do so well on them? Or did you have any issues not mentioned in the thread? Did you have to make changes to the setup?

Thank you,

Adi

[Liam22]

AFAIK, the ZCars series ran the GAZ Gold dampers (not the monos).

I very quickly changed the spring rates so I'm not using the ZCars setup at all. Whoever spec'd the ZCars spring rates didn't know what they were doing. I went stiffer, but also changed the front/rear delta. I run the damping at about half-way on the front and 3/4 on the rear.

My ARBs are M3 CSL front and M3 cabriolet rear.

Rake is about 5-10mm higher at the rear.

Alignment is parallel front (+0.5mm, -0mm) and as much toe out as I can get at the rear.

Camber is similar to you, but I don't have my setup book to hand.

Tyres are 225 front and 255 rear (17") Nangkang AR-1 at ~21-22psi cold.

[thornad]

Many thanks for the prompt answer Liam, I really appreciate all the info.
I'm pretty sure it's the Monos, at least this is what I have on my car, but not sure about the spring rates.

http://www.dropbox.com/scl/fi/n2pea4lz4 ... jrn8k&dl=0

What do you mean you changed the front/rear delta ?

And if you don't mind, what springs rates (and length) are you using? Do you have the GAZ product number ?

[Andrew J]

I was travelling down south for a holiday back in March and completely forgotten I'd taken this picture. If I remember rightly we were on the A43 so potentially a Silverstone day? Anyway, car looked ace, proper mean!

[1536Z4]

Found this on You Tube . You have another admirer Liam . Any updates for us ?

[thornad]

Sorry to be a pain Liam, can you please tell me the actual values you went for the spring rates in the end ?

Thank you,