Z4M Track Action

F

Fishy Dave

Active member
 Wiltshire, England
Yup, sorry, it's Castle Combe again!

Two months previously I'd had probably the most unenjoyable trackday in years, with a lack of power (traced to a TPS failure) and lots of understeer after I set the geometry to close to CSL settings http://www.z4-forum.com/forum/viewtopic.php?f=9&t=88181

On Monday Tom and I attended a BHP day at Combe. Since the last day I had changed the RTABs and fitted limiters and returned the rear toe out to about 2mm. What a difference the toe has made, the (lively) handling is back. You can see from the videos that it is quite tail happy and not exactly 'tidy' however, it is good fun and I can adjust the cornering angle by using the throttle. The Nankangs squeal like hell and their is a fair bit of them now smeared on the track but considering they've now survived a Spa and Ring trip plus 3 or 4 trackdays they still have plenty left.

The morning had a number of dramas for me as my driving got me a third and final warning from the circuit, having never been told off before in 150 to 200 trackdays (well except for a joint ticking off with Tom at Hullavington). I am always polite and have a lot of respect for authority but I did have to disagree with some of the accusations. I was accused of overtaking in braking zones, racing, driving too many laps and being out of control. Clearly these are edited videos but hopefully give you a flavour of how we respect other drivers when overtaking, whether following or driving alone. Yes, I could be accused of 'racing' but we only overtake each other by consent and indication and feel that we leave enough space between us; I certainly drive closer than this when actually racing. I did drive quite a few laps in one go but let the car cool for a lap or to before picking up the pace again. As for being out of control, well, others can judge but I didn't feel out of control once. I've had a good chat to the organiser who was very understanding and was happy from what he saw of me from the pit wall.

Video 1 was an experiment with my new phone and Harry's ap, quite pleased actually and will sort out a more rigid mount for next time. I think it captures the sound better than the camera in the 2nd clip that had an external stereo mic.

https://youtu.be/IQXCalSHSXg
[youtube]https://youtu.be/IQXCalSHSXg[/youtube]

Thank you to Tom for letting me drive his Coupe again, a really good comparison (part 2), with the following observations.

What is the same?
Nankang NS2R in 180 'street' compound, AP brakes all round with Pagid RS29, Eibach springs on standard dampers, strut brace.

What is different about Toms car (aside from having a roof!)?
Toms NS2R are wider and fresh for this trackday
Weight, Toms has a lighter battery, wheels, drivers seats and some trim removed
Power, with a CSL airbox, remap, Shrick cams and Supersprint exhaust Toms Coupe will make a touch more power (and a gorgeous noise)
Geometry set up, more neutral but also a bit more prone to understeer at Quarry and Tower. We agreed that a set up somewhere between the two cars is probably right. I wouldn't want to race my car with the set up it has now, but for trackdays I love it :driving:
The drivers seat and harness Tom has fitted make a huge difference. Really reassuring support and I could relax my grip on the steering wheel, this alone makes the two cars feel quite different.
Driving style, I think Tom is smoother and I certainly can't get away from him when driving my own car with exuberance, I should try to put in a cleaner lap really. I think I could drive his Coupe faster than my Roadster due to all of the above.

https://youtu.be/ew2kQuKoQ1k
[youtube]https://youtu.be/ew2kQuKoQ1k[/youtube]

The best bit of the day was the drift in Toms car at the end of clip no.2, I had a big grin from that! :D

That will be my last trackday now until Laguna Seca at the end of September, time to change my brakes too.

Long post over, phew, cheers, Dave
 
Great to see you guys giving using the capabilities of the car, great vids. I'll have to come down and watch at some point, Combe's not far from me :thumbsup:
 
that exgie couldnt get away could it..... still shocked how good this platform is with some choice mods.... Have you ever considered some power mods??
 
Great day again there at Combe dave, thanks for getting me down. Much as I'd love to be doing different circuits more often, Combe being so local makes the whole thing more acceptable (effort wise and financially!). The BHP guys do a really good day, generally high driving standards, and probably the fewest numbers signed up for each day compared to most 'normal' TDOs. It usually makes for a great day and I really enjoyed this one. Some cool cars there, and as Beedub says it's surprising how well these old lads go!
It was really interesting driving both cars, most notably to feel the difference in geo settings, which were quite apparent. Dave's car most certainly felt more 'fun' than mine, though not so much when you've hopped in it expecting it to be just like yours on a track! I'd like more time in it and really for it to be my own car, we've only just become friends!! I will definitely get mine realigned soon with some toe out, it seems to give you more adjustment options mid corner, the caveat being you have to be a little more careful.
Once again my video system/shambles was a bit annoying, however here's a little clip with some fairly decent noise
https://www.youtube.com/watch?v=qXGJEitEwjU

Looking forward to hearing about your trip, enjoy Laguna Seca :wub:
 
Beedub said:
Have you ever considered some power mods??
Click to expand...

Yes, every time I'm in Toms car, but for the cost involved I'm going to put it towards racing again next year. Much as I'd love to race a Z4M I couldn't take the risk of losing it in an accident so it will be something like my 325ti or an old E30 320i.
 
TomK said:
It was really interesting driving both cars, most notably to feel the difference in geo settings, which were quite apparent. Dave's car most certainly felt more 'fun' than mine, though not so much when you've hopped in it expecting it to be just like yours on a track! I'd like more time in it and really for it to be my own car, we've only just become friends!!
Click to expand...

Yes, I know what you mean, but I trust your driving mate. Take it out for a longer drive next time, I didn't mean to use our swapping as judgement of your driving (which was smooth and respectful of my car) 8) I'd probably made you more cautious by warning you how tail happy it was.
Clip does look and sound good, it must have been just before I caught the camera as it fell off :D
A trip up to Anglesey sounds good too, maybe early October?

@Andy Beech, yes, you're very welcome to come along and enjoy/hate as many passenger laps as you can stomach! :thumbsup:
 
This might not sound plausible but seeing these two cars go round Combe actually gives some weight to Gran Turismo 6's physics engine. I've had an extensive play around with geometry on the Z4MC in the game and I found that rear toe out was fun, to an extent. It made it very tail happy but also quite difficult to bring it back into line as it wouldn't bleed back straight smoothly, instead always requiring more corrective action like less throttle and steering. Closer to neutral or ever so slight toe in allowed power or weight transfer instigated oversteer but you could stay on the power and wind off smaller amounts of lock to come back straight again smoothly. All depends what you like but for me I'd prefer it closer to neutral so I'm more in control of what happens either end.

It's amazing how such small differences have a marked effect. For example on my old Integra DC2R going just one hole different on the rear ARB went from feeling like driving on rear tea trays to a perfect balance that was ultimately much faster round a bend. Similar results can be had with geometry.

Nice to see a few Z4's close to me, might have to venture onto Combe myself and bag a passenger ride in an M. :driving:
 
Fishy Dave said:
@Andy Beech, yes, you're very welcome to come along and enjoy/hate as many passenger laps as you can stomach! :thumbsup:
Click to expand...

Cheers Dave! May well have to take you up on that! Let us know when your next heading there :)
 
Argenta said:
So what's Tom's geom settings as it is?
Click to expand...

I'll have to check but I'm pretty sure it was set to CSL settings so basically zero toe on the rear, or maybe a smidge in.

Fishy Dave said:
I didn't mean to use our swapping as judgement of your driving
Click to expand...
No, not taken like that at all for sure. I was just surprised and slightly unnerved by the difference, certainly didn't want to bin it!
Do you think the extra camber you have at the front contributes to much of the differences also? What toe are you running at the front?

Fishy Dave said:
A trip up to Anglesey sounds good too, maybe early October?
Click to expand...
I've been to the javelin days there before, they have one on sun23rd Oct, which suits me....
 
Had a quick look and saw no dangerous driving there at all,they pulled over, you overtook and waved in acknowledgement. Good stuff mate.
 
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