E85 Track Ready Discussion

2003 - 2009, roadster, coupe, facelift
casadefadi
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E85 Track Ready Discussion

Post by casadefadi » Mon Jan 18, 2021 9:20 pm

Hi all,

I just recently started attending track days and driving schools.
I wanted to start this discussion to see what modifications fellow z4 enthusiasts are doing to increase performance.

I am driving an E85 2004 2.5l manual.
Screenshot 2021-01-18 121814.png
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The first modification I thought I was going to start with was my radiator, but surprisingly the car runs normal even during hot desert California days (Chuckwalla Race Way, and Streets of Willows).

After maybe a 3rd track session, I started to notice that my brakes were getting mushy, obvious signs indicate brake fluid getting hot.
Doing some research, I will be flushing my system with Motul DOT4 RBF 600 brake fluid. Does anyone have any recommendations on brake pads? Also has anyone replaced brake lines with SS? P.S I am still running stock rotors.

love to hear back any comments.

thanks,
FG

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E85 Track Ready Discussion

Post by PDJ » Mon Jan 18, 2021 9:51 pm

casadefadi wrote: Mon Jan 18, 2021 9:20 pm track days and driving schools.
That is the BIGGEST IMPROVEMENT UPGRADE you can do and you are doing it

Brake fluid change is a good thing to do and possibly after a track day if you can do it your self as it is not too expensive
Change your pads to something more suited to track use
Change the other fluids gearbox diff coolant engine oil

Enjoy learning how to drive on track it’s different to on the road, too many people feather the brakes it is better described as brakes on brakes off they also last longer before over heating.

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E85 Track Ready Discussion

Post by Jamie25 » Mon Jan 18, 2021 9:52 pm

I think it's generally accepted that the brakes are usually the weak spot on most BMWs for track days including our Z4s. Updated brake fluid, brake cooling by ducting air in and larger brakes seem to be the most common first upgrades.
I've only done one trackday in mine but went through a set of pads in that one day.
E85 3.0 M54 Titanium Silver. 88k. Cotteswolds.

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E85 Track Ready Discussion

Post by brillomaster » Mon Jan 18, 2021 10:17 pm

Brakes are relatively easy to sort. Fresh fluid, and decent pads. Over here the go to brands are performance friction (PF), carbon lorraine (CL) and pagid race compounds. Personally i had great success with PF08 compound.

No need for stainless lines or bigger rotors imo, pads and fluids are 90% of braking performance.

I also found taking the front fogs out helps duct the front brakes, cant imagine you get many foggy days!

Other than brakes, tyres are next up for track performance. With a warm climate, you could run them year round. I liked federal 595 rsrs, but youll have different brands stateside.

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E85 Track Ready Discussion

Post by ScoobyR1 » Tue Jan 19, 2021 1:02 am

In response to your call for track upgrades, I've consulted with guys way more experienced than I and here's what I've done based on this info.
(1) E46 330d front brake calipers/ carriers/ Discs MTECH - allows 325 mm front brake discs
(2) Combined with above EBC Blue stuff pads
(3) Stainless steel brake hoses
(4) Refreshed all fluids - Diff/Gearbox/Transmission/engine oil and coolant and brake fluid DOT5
(5) Polybushed the RTAB's front control arms(lollipops) and ARB bushes.
(6) Uprated H&R adjustable ARB
(7) Stock suspension with new dampers all stock, Previously had lowered Eibach springs but got sick of grounding out so went back to stock as car is almost exclusively used on road.
(8) All round wheel alignment.
(9) New Drop links front and rear
(10) Nanking NS2R tyres- Not too expensive but grippy and will withstand track abuse better than more road oriented tyres.
Hope this helps :driving:
'03 Titan Silver 3.0 auto. Hand controls, CC, MFSW,aero front, aero sideskirts CSL reps, strut brace, H&R ARB's,E46 BB upgrade :thumbsup:

Now sold '03 Sterling grey 2.5 E85 :(

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E85 Track Ready Discussion

Post by ScoobyR1 » Tue Jan 19, 2021 1:08 am

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Here's my car with the road tyres and wheels, I have it fitted with stock 108's and the Nankings for the track, although these are really quite surprisingly good road tyres. :thumbsup:
'03 Titan Silver 3.0 auto. Hand controls, CC, MFSW,aero front, aero sideskirts CSL reps, strut brace, H&R ARB's,E46 BB upgrade :thumbsup:

Now sold '03 Sterling grey 2.5 E85 :(

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E85 Track Ready Discussion

Post by HU51A_FU » Tue Jan 19, 2021 12:22 pm

Holy body roll! Lowering the centre of gravity will help massively too :)
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E85 Track Ready Discussion

Post by brillomaster » Tue Jan 19, 2021 12:52 pm

need to watch out with this statement, as if you lower the car, the suspension geometry may move the roll centre further away from the CoG, in which case you'll get more body roll, not less...
ie if by lowering the car 10mm, you move the roll centre by 30mm, in which case the lever length is increased by 20mm, and you're more likely to get body roll. the top diagram is standard height, the bottom is lowered, but because length A2 is longer than A1, the car in the lower diagram will roll more, everything else being equal.

Image

https://www.e30sport.net/myths/Weight_T ... nsfer2.htm

personally, id look to reduce body roll with the use of sway bars and stiffer springs, rather than necessarily just lowering the car. suspension and vehicly dynamics is a very complex system!

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E85 Track Ready Discussion

Post by casadefadi » Thu Jan 21, 2021 7:04 pm

This is beautiful, thank you all for your responses!!! I seldom see any Z4 on the track days I have gone to and I am glad that I am not the only one tracking.

To add on, I have about 130k miles on the car now. I got under the car at 127k and replaced the oil pan gasket, dipstick o ring (still can't get rid of oil leaks), rear main seal, flywheel, clutch assembly, and fresh transmission and rear dif fluids. All parts were purchased from FCP Euro.

Based on the answers from above, I decided to do a front brake update based on
ScoobyR1 wrote: Tue Jan 19, 2021 1:02 am (1) E46 330d front brake calipers/ carriers/ Discs MTECH - allows 325 mm front brake discs
(2) Combined with above EBC Blue stuff pads
(3) Stainless steel brake hoses
After this brake update, I will dive a little bit more into suspension set up to reduce body roll from that image.
HU51A_FU wrote: Tue Jan 19, 2021 12:22 pm Holy body roll! Lowering the centre of gravity will help massively too
HU51A_FU, out of curiosity what, suspension system are you running and how much have your lowered your CG?
brillomaster wrote: Tue Jan 19, 2021 12:52 pm ie if by lowering the car 10mm, you move the roll centre by 30mm, in which case the lever length is increased by 20mm, and you're more likely to get body roll. the top diagram is standard height, the bottom is lowered, but because length A2 is longer than A1, the car in the lower diagram will roll more, everything else being equal.
brillomaster, you're absolutely right, my senior design project as a mechanical engineering student was developing an active anti-roll bar system for an Electric FSAE vehicle. I relied heavily on Race Car Vehicle Dynamics by Milliken for suspension design.

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HU51A_FU
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E85 Track Ready Discussion

Post by HU51A_FU » Thu Jan 21, 2021 9:13 pm

I'm on Stance+ coilovers.

Not sure what I'm lowrted by but I can go more on the front a few inches and I'm maxed with helpers out on the rear. :)
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E85 Track Ready Discussion

Post by breezyloco » Fri Jan 22, 2021 7:50 am

ScoobyR1 wrote: Tue Jan 19, 2021 1:08 am IMG_0378.JPGIMG_0367.JPG
Here's my car with the road tyres and wheels, I have it fitted with stock 108's and the Nankings for the track, although these are really quite surprisingly good road tyres. :thumbsup:
Thanks all for the responses! Really informative for a new Z4 owner like me. Also hey Scooby, might be a dumb question here, but do you just run 17"s? Any recommended offset? Also, any reason to not run 18"s with smaller tire walls for the speedo?

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E85 Track Ready Discussion

Post by PDJ » Fri Jan 22, 2021 11:33 am

Something else to consider is to add a bit of rake to the car

This was suggested by John at J C Racing I achieved this my adding around 8mm under the rear spring pad between the chassis and the pad.

As I don’t do back to back testing on a race track I have just accepted his judgment a few people who have been in my car have said how nice it appears to handle.

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E85 Track Ready Discussion

Post by brillomaster » Fri Jan 22, 2021 1:04 pm

this makes sense, bit more rake would put a bit more load through the front tyres, which will benefit your ability to turn.

despite being RWD, most BMWs are set up to understeer, but you want a more neutral balance.

i also reduced the staggered sizes in tyres - a lot of track day goers run a square setup, with equal tyre widths front and rear. personally i moved up to 18" diameter wheels, purely so they could fit a wider tyre. On standard suspension, and standard BMW slightly staggered wheel size, i was running 245/35/R18 fronts, and 255/35/R18 rears, and the car had a lovely balance.

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E85 Track Ready Discussion

Post by TheDan » Fri Jan 22, 2021 2:58 pm

I too run with different tyres than the standard 18" staggered setup. Standard is usually 225/40/18 front and 255/35/18 rear. I am running 225/40/18 fronts and 245/35/18 rear. This helps with the default BMW understeer setup that brillomaster mentioned.

You can go a step further to create an even more neutral setup (or oversteer biased if you prefer that) by adjusting from the standard Z4 (non-m) alignment settings. More oversteer is typically achieved by running near zero toe and less camber on the rear as well as making sure camber on the front is more than on the rear.

It all depends if you are happy with how the car turns in and feels through the corners.

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E85 Track Ready Discussion

Post by Wursle » Fri Jan 22, 2021 3:58 pm

Pretty common one is E46 M3 Convertible front sway bar. Pretty cheap to do and makes the front end sharper.

As for ride height and geometry settings you ultimately want to start with a proper corner weighted wheel alignment if you have coilovers. Do not worry about sway bars and springs until you have done the geometry and ride heights properly, geometry/ride heights and corner weighting have a bigger impact on how the car brakes, turns and over/understeers where as springs and sways allow you to make finer adjustments for specific corners on the track. Bigger brakes arent needed if you have the 3.0si/ 330i brakes, just get some disgustingly harsh pads, Motul RPF600 and stainless lines thatll be all the braking you need and it keeps consumables cheap. A good rule of thumb for a starting point is to have 1 degree less camber in the rear than the front, its not perfect but for someone that does a few trackdays a year its more than fine 💪

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