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Z4 3.0 Track car build

2003 - 2009, roadster, coupe, facelift
Artful-Bodger
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Z4 3.0 Track car build

Post by Artful-Bodger » Sat May 27, 2017 6:09 pm

If this car is for track use primarily, I would bin the ABS system and use braided lines front to back to eliminate as many joints as possible.

You can make or buy in a bias adjustable cylinder setup for the servo so you can dial the brakes in properly, ABS is fekin awful on the track.
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Z4 3.0 Track car build

Post by robjones888 » Sun May 28, 2017 7:38 am

Tyre wise if keeping it road legal and driving to and from track try the Yokohama AD08R 's as well priced and work really well wet or dry so no real need for two sets of wheels then to be taken.
Diff wise 3.9 or 4.1 ratios work well ,fit one of these and the car will feel like it's gained another 50 rwhp....quickens acceleration puts you in a nice usable rev range on track , getting good pull out of the corners top end will be reduced but you don't need top speed on track as you have already probably found out.
J C Racing are worth a call about building a diff as many of the BMWRDC use them in the e36 /e46 Kumho cup cars with excellent reliability.

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Z4 3.0 Track car build

Post by oalloyd1 » Sun May 28, 2017 9:18 am

Great stuff, cheers guys!

Anything else I should be looking out for?

o

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Steve84N
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Z4 3.0 Track car build

Post by Steve84N » Sun May 28, 2017 9:35 am

The Z4M offset front lower rear bushes are well worth it, they add castor so dynamic camber rather than static but it made a noticeable improvement to mid-corner grip for me. Makes me wonder if I should get camber plates after all as the grip has come from more camber.
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Z4 3.0 Track car build

Post by Artful-Bodger » Sun May 28, 2017 10:10 am

Steve84N wrote: Sun May 28, 2017 9:35 am The Z4M offset front lower rear bushes are well worth it, they add castor so dynamic camber rather than static but it made a noticeable improvement to mid-corner grip for me. Makes me wonder if I should get camber plates after all as the grip has come from more camber.
Only a tyre temperature gauge will tell you how much camber you need, it will be different for most cars and drivers and tracks come to that.

Either way it's important to consider the loads being applied to the top mounts, so if camber is to be increased spherical bearing top mounts may well be required.
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Z4 3.0 Track car build

Post by Scooba_Steve » Sun May 28, 2017 10:24 am

Sounding like a good plan so far. The only thing I would suggest for coilovers vs shocks and springs - you will get what you pay for, that doesn't mean the cheaper coilies are rubbish, just that, IMHO, if you're not going to adjust or don't have set up knowledge then B12 might be a better option.

Depending on what the E46 brakes (or 325mm from the 3.0si?) cost you may not get good value for money - not much more resistant to fade. You may get good results from putting in brake cooling ducts, perhaps taking out the fogs?

I'm not sure how much better the E46 ARBs may be, I'm not sure what's available but I'd be looking for something lighter and potentially also adjustable.

Don't neglect the front suspension, put some new lower arms on and poly the brake reaction bushings.

Definitely get some new engine mounts. See if you can get the E46 front strut brace to fit, the one from turret to turret (completing the triangle).
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Steve84N
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Z4 3.0 Track car build

Post by Steve84N » Sun May 28, 2017 10:57 am

Artful-Bodger wrote: Sun May 28, 2017 10:10 am
Steve84N wrote: Sun May 28, 2017 9:35 am The Z4M offset front lower rear bushes are well worth it, they add castor so dynamic camber rather than static but it made a noticeable improvement to mid-corner grip for me. Makes me wonder if I should get camber plates after all as the grip has come from more camber.
Only a tyre temperature gauge will tell you how much camber you need, it will be different for most cars and drivers and tracks come to that.

Either way it's important to consider the loads being applied to the top mounts, so if camber is to be increased spherical bearing top mounts may well be required.
Whilst a tyre temperature gauge would be enormously useful you can still feel with your hand which parts of the tyre are working. The fact I got more grip from more camber tells me more camber in my case was a good thing with no gauge required. :-)
I'm talking about getting closer to 2 degrees of camber not 3 plus where stresses are genuinely worth considering.
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Z4 3.0 Track car build

Post by Artful-Bodger » Sun May 28, 2017 12:14 pm

Steve84N wrote: Sun May 28, 2017 10:57 am
Artful-Bodger wrote: Sun May 28, 2017 10:10 am
Steve84N wrote: Sun May 28, 2017 9:35 am The Z4M offset front lower rear bushes are well worth it, they add castor so dynamic camber rather than static but it made a noticeable improvement to mid-corner grip for me. Makes me wonder if I should get camber plates after all as the grip has come from more camber.
Only a tyre temperature gauge will tell you how much camber you need, it will be different for most cars and drivers and tracks come to that.

Either way it's important to consider the loads being applied to the top mounts, so if camber is to be increased spherical bearing top mounts may well be required.
Whilst a tyre temperature gauge would be enormously useful you can still feel with your hand which parts of the tyre are working. The fact I got more grip from more camber tells me more camber in my case was a good thing with no gauge required. :-)
I'm talking about getting closer to 2 degrees of camber not 3 plus where stresses are genuinely worth considering.
It's down to what the individual is comfortable with so you make your choices and live with the results, so if your happy with that approach that's ok.

If you want the best out of your chassis everything starts with the tyre, the whole suspension and chassis is working to load the tyre and the guy who dials the car into the tyres requirements will achieve the highest grip and handling.

Increasing the camber can overheat the inner edges of the tyre during periods of low roll such as long straights fast corners, reduce grip under braking, cause premature wear and reduce grip in other parts of the envelope, so whilst you can feel more grip in some aspects it's advisable to know what the tyre is doing, especially as its a in combination with tyre pressure.

Your looking for an average spread of temperature across the tyre, the inner will be hotter than the outer so a rough guide is the centre of the tyre should be the average of the inner and outer temps, you juggle this in competition dependant on the track but for a track day car if you can achieve this with a combination of pressure and camber you will get the best out of your tyres.
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Steve84N
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Z4 3.0 Track car build

Post by Steve84N » Sun May 28, 2017 1:00 pm

Agreed.
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Z4 3.0 Track car build

Post by oalloyd1 » Tue May 30, 2017 10:57 pm

This is excellent guys, cheers!

I'm tempted by the B12 but would really like some coilovers - I need to make the decision this week either way as I need to get the build underway as not too long til this years' Nurburgring trip.

just got back from picking up the new lightweight wheels that are going on for the 4 square set-up - Its going to be an expensive month :headbang:

o :)

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Z4 3.0 Track car build

Post by oalloyd1 » Tue May 30, 2017 11:18 pm

So just bought this as it made such a difference to the shift quality of my E46 M3 - Here's hoping it'll do the same job here!

http://www.ebay.co.uk/itm/192098545555

o

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Z4 3.0 Track car build

Post by oalloyd1 » Wed May 31, 2017 11:02 pm

Hey all,

I'm about to buy the following - Can someone steer me to the best value place to get these from? Anyone got any special deals on right now?

Mfactory LSD fitted.

Coilover set that costs less than £650 but isn't totally rubbish

Uprated braided hoses and pads and race fluid at same time.

Uprated RTABS and any key other suspension components (Can't justify polybushing the whole car right now)

Cheers,

o

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Z4 3.0 Track car build

Post by oalloyd1 » Thu Jun 01, 2017 6:16 pm

UPDATE

So it;s had the hard top bolted in place and I must say I think it looks great. The car also felt noticeably stiffer to drive with no wobbles or shakes so it feels like a great base to work from. The colour is also growing on me more and more, especially as it's quite unusual.

[IMG]http://img.photobucket.com/albums/v705/ ... %202_1.jpg[/IMG]

[IMG]http://img.photobucket.com/albums/v705/ ... 4309_1.jpg[/IMG]

Straight after these pictures were taken I got it on the ramp for a close inspection of underside, bushes, hoses etc and was stunned at what great shape its in - I've seen 3 year old cars with more corrosion than this underneath! It's going to get a Dinitrol treatment once the suspension / bush work is done to make sure it stays like that for decades to come.

Whilst I was there I did a high quality oil and filter change as that's always first port of call when getting a new car for me.

Onwards with getting the modified parts purchased and fitted! Any advice appreciated - I've done E36's and E46's before but not a 'Z

Cheers all,

o

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Z4 3.0 Track car build

Post by Fishy Dave » Thu Jun 01, 2017 6:28 pm

In addition to the AD08R tyres recommended above I would also consider the Nankang NS2R as a possibly cheaper option again. A number of us use them with success on road and track. :)
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oalloyd1
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Z4 3.0 Track car build

Post by oalloyd1 » Thu Jun 01, 2017 6:35 pm

Cheers Dave that's exactly what I was thinking.

Am going to run a 17" square set-up (8.5J) - What tire size do you reckon is best considering i'll be dropping the car 30mm and need to avoid any scrubbage... I'd also like to fit some spacers but might that make the risk higher?

Thanks again,

o :)

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