Z4 coupe road and track build - upgrades advice

Jpt23

New member
Hey all, recently picked up a 2008 e86 z4 3.0si as a fun weekend car and occasional track use. Been wanting to get into track for a long time and after a day at palmersport in August I finally bit the bullet and bought a car to build out for next season.

Looking for some advice for upgrades I plan to make. Some will go on over winter before getting out on track in spring, some after I get started - I don't want to entirely pre-prep the car because I want to experience the shortfalls I'm trying to remedy so I better understand what benefit they have for the car when they do go on. I feel this will make me a better driver and give me a stronger understanding of how cars perform on track.

Been digging through historic threads and have gotten some ideas already, but would be great to get some feedback, comparison, or suggestions I've not come across.

Suspension
So far it looks like popular options for mixed use on the e86 are:

Kw v3 - £2-2.3k

Bilstein b16 pss10 - £1.5-1.7k

Bc racing br series - approx 1k

Ohlins are likely to be out of budget unless heavily discounted for black friday.

Bc are most budget friendly but I don't want to end out swapping later to upgrade again, leaning toward kw or bilstein - any thoughts?

Brakes
I know less here, how are the si brakes on track? I know they got a bigger set than the 3.0i, and that cooling and pads are key.

Upgrade wise, to begin with I'm hoping to focus on cheaper upgrades, thinking:

Braided lines

EBC bluestuff track pads

Brake cooling ducts to replace the fog lights (already had these made).

Further down the line, I'd like to upgrade to floating calipers, 4 or 6 pot. I've heard 130i/135i bmw performance brakes with e46 m3 discs can fit, and there are some dedicated bbks out there, some using renault calipers, but really not sure what's best for my application, and most cost effective. I've also heard the 130/135 calipers have ceramic pistons which can crack under track temps.

Any tried and tested approaches, kits, or swaps from other models for brake upgrades? And when upgrading discs and calipers, is it best off doing all 4 corners? Seems like it's easier and cheaper to just upgrade the fronts, but concerned this might mess with brake bias?

Limited slip diff

Fairly certain i'll go with a Quaife helical ATB fitted at birds. Seems to have solid in the field feedback and birds are well regarded.

I know the wavetrack won't spin a wheel if it lifts, but from what I've heard more is made of this than is really an issue, and it's a bit of a gimmick. For the extra money, I suspect I'll notice little difference.

Aero

Lowest priority on my list, definitely wrll into next year, but I do currently have a fairly large gt wing on the car (came with it) seems like a cheap ebay special, looks ok, but is aluminium and the mounts look weak. Considering replacing this

Almost purely on looks, I'm also considering a fancywide rear diffuser.

I'd like a front splitter, again largely for looks but any performance gains are welcome. Have had trouble finding one I like.

For areo in general i don't like the maxton design stuff, AP and varis are nice but very expensive. Any suggestions are welcome.

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Thanks for any advice you can give, or if I've missed anything. I know I don't need everything here to get out on track, but would love to slowly build it up into a street/track weapon - comfortable with the compromise dual use brings
 
I’d say chat to Scooby who did a recent track build (very well imo)

I can’t recall his user name on here but someone will post it up
 
Might be worth reading this thread too:- https://z4-forum.com/forum/viewtopic.php?t=112593
 
Cheers guys, will do - any of you run any of the suspension set ups above? Probably going to be my first purchase and hoping to get lucky on black friday

Leaning towards the kw v3s but quite a price tag on them
 
As a 'veteran' of multiple track car builds, the only advice I'd give you would be to think hard about how much track use the car is actually going to get.

There's little to no benefit to building a stripped, noisy, uncomfortable, crashy car with zero ground clearance if you're only doing a couple of trackdays a year with it.

I had a Mini that I turned into an absolute weapon on track, to the point where it could easily keep pace with much more exotic and expensive kit. Then I took it on a trip to the NC500 with some mates, and realised that I'd basically ruined it for British roads.

Choose things like spring rates, suspension bushes and brake setups very carefully if this is going to get more use on the road than the track. For example, do you need a noisy helical diff, or would an ATB diff be a better compromise?

How much track experience do you have? Are you a veteran who will be able to feel the difference between entry level BC Racing coilovers and something that costs 2-3x as much?

Far too many people (me included) who do 2-3 trackdays a year fall into the trap of trying to build a pretend race car.
 
Wise words by [ref]DaveP[/ref], I have done a similar thing with my previous Mini. With the Z4 taking a much more sensible approach as it mainly will be a car to go on trips and hit the track maybe 2-3 times a year.
 
Micke said:
Wise words by [ref]DaveP[/ref], I have done a similar thing with my previous Mini. With the Z4 taking a much more sensible approach as it mainly will be a car to go on trips and hit the track maybe 2-3 times a year.
Indeed.

I find it funny to see how many "Clubsport" track builds are on sale at any given time, with people citing "not getting enough use" as the reason. These people are all taking a massive bath on the sale because they got carried away with building a pretend race car.

I could have easily predicted that your M3 with bucket seats, no sound deadening, no Aircon and solid mounts everywhere would barely turn a wheel between trackdays.
 
Thanks guys, sound advice - I will definitely be building with that in mind, it will very much be a mixed use car so won't be going for the absolute firmest ride, and definitely with an atb diff rather than plated. I won't be stripping the car it's too nice for that lol, won't even be taking out the heated sports seats, can save a lot of weight there, but not worth the spinal realignment on day to day road use. I've put it on michelin pilot sport 4s, still staggered.

Track day wise I'm just starting out, plenty of sim time, and I've done a day out at Bedford in august but I've bought this car to get into track - whether or not I'll enjoy it isn't in question, been a gearhead all my life, the only reason I've not gotten out before is money but I'm earning better now. I also do a lot of my own spannering so significant savings there. Really the main things I want to chnage at the moment are brakes, suspension, diff, with track days stock, then with each upgrade in between so I can see the differences step by step on track and road. Probably looking at least 4 to 5 days this year.

Brakes wise I've seen the brembo 4 pots from a megane rs are a fairly straightforward upgrade with m3 csl discs, anyone used them?

These guys do a kit, but you can also pick them up used
https://k-system.pro/en/product/bmw-e36-e46-z3-z4-brembo-4-pot-conversion-kit-megane-3-rs-calipers-345x28/

The suspension set ups I've been considering, I'm trying to have a range of adjustability that let's me switch between suitable road and track set ups, that will mean a degree of compromise on both but I'm comfortable with that to make sure I'm not too far in one direction or the other. V3s fit that bill, I'd heard bcs can knock/be a little crashy, and I liked 2 way adjustability, street/track focused, and corrosion protection of the v3. Plus if it did ever go more track focused, It's relatively straightforward to upgrade to clubsport, springs and revalving I think. They are expensive though.
 
My advice?

Go and drive your car on track. You've somehow already decided that you need 2-way adjustable coilovers, 4-pot brakes and an LSD without driving a single mile on track in it.

I recently did 40 laps of the Ring in two days without any of those things, and I had an absolute blast. I say that because enjoying yourself should be the goal here, not chasing laptimes.

Change your fluids, check your brakes and tyres have plenty of life left, and just book a trackday. I can promise you that your car is already much more capable than you are on track. It will be a while before you find the ceiling of the current setup and figure out what your upgrade priorities are.

This isn't meant to sound dismissive, but ask yourself why you're doing this. You're better off spending money on trackdays and Ring trips than having a car with loads of shiny parts sitting outside your house.
 
Jpt23 said:
Brakes wise I've seen the brembo 4 pots from a megane rs are a fairly straightforward upgrade with m3 csl discs, anyone used them?

These guys do a kit, but you can also pick them up used
https://k-system.pro/en/product/bmw-e36 ... rs-345x28/

I picked up this kit from k-system. They're a good, responsive company, but are registered in Poland, so you will have to pay import tax as they'll be over £135.

In terms of braking performance, these calipers and M3 discs (I have 325mm but will be switching to 345mm CSL discs soon), combined with Carbotech XP8/10 pads, braided lines and RBF660 is absolutely all you'll need on track. Braking power hurts my face sometimes!
 
Jpt23 said:
The suspension set ups I've been considering, I'm trying to have a range of adjustability that let's me switch between suitable road and track set ups, that will mean a degree of compromise on both but I'm comfortable with that to make sure I'm not too far in one direction or the other. V3s fit that bill, I'd heard bcs can knock/be a little crashy, and I liked 2 way adjustability, street/track focused, and corrosion protection of the v3. Plus if it did ever go more track focused, It's relatively straightforward to upgrade to clubsport, springs and revalving I think. They are expensive though.

Take a look at ST XTAs. Basically KW V2s without the inox coating, but they come with club sport fully adjustable solid topmounts and linear (rather than progressive) springs. I have set up with lots more castor (7 degrees vs 5 and a bit standard) and just under 2 degrees of camber. Behaves much better on the road like this with the castor taking out a lot of the inherent twitchiness of z4 steering and making it easier to place. It is a stiffer ride but it eats bumps well and is a massive improvement vs my old sport springs and B6 dampers approach. I soften off to 11 clicks rebound for the road, and stiffen up for the track. It’s a great value package - really made by those adjustable top mounts. Also I haven’t had any corrosion (but I do garage it).
 
I'm currently setting mine up for track (link in signature) having had an M3 track car on KW Clubsports with stiffer custom springs and AP brakes off a touring car. Why have I mentioned this? Because its had a knock on effect to the mods I've made to the Z4.

You are doing exactly what I did when I first went on track, overthinking it and believing you need to get all mods done before you go on track. I'm not trying to sounds condescending, more explaining that I've been there. one thing you can't beat is seat time and I wish I'd worried less and got on track sooner. Half the stuff I thought I'd need, I didn't, especially on the first few days.

So, to answer your points above in the first post.

Suspension
For me, KW's are brilliant, but the Z4 ones are too soft for track work, same with ST plus with them setup for those spring rates you can't run stiffer springs. I ended up going for Yellowspeed instead of BC as they have a better warranty and better damping adjustment. 8kg front and 10kg rear springs. Its perfectly acceptable on the road and no worse than the B12 Bilstein kit that came on the car. I am probably going to go to a 12kg rear spring though to aid rotation. My Clubsports on the M3 has 2 way adjustment for damping and I got myself in a right mess and set the car up wrong. Too much adjustment can be as bad as too little. The Yellowspeed adjust compression and rebound in one so less chance of messing it up.

Brakes
The 325mm are a good setup with the right components. Wexmoto hoses, bluestuff pads and ATE or RBF600 fluid are a great setup
4 pot brembos are probably unnecessary. I brake hard and late, good pads with lines and fluid are doing me just fine, especially with the brake ducts I've fitted. Plus, if its your first time on track you won't be pushing as hard as you think you are going to be.

LSD
Depends how quick you are and how aggressive you are plus which tyres/sizes you go for. I'm experiencing some slip in second but not a lot in the dry, however, wet running is a different matter. Personally I wouldn't get a Quaife. I know people swear by them but a 1.5 way plated diff is a better option for the track. My ZF plated is being built at the moment with custom setting to allow me to turn the car more effectively on the brakes and throttle. I've got a grat contact who can build them into a Z4 diff casing for a very reasonable amount. LSD makes a wet trackday mega fun.

Aero
Not necessary at this stage I'd say.

Personally, if I were you, I'd spend £1000ish on coilovers (if you really wan them, but they are unnecessary for now), polybush as much as possible (again, unnecessary but if your heart is set on it), do the lines, fluid and pads, add some good road tyres (don't just jump to semi-slicks as you'll learn track craft quicker on road tyres) and get some quality seat time.

Oh, and join the Z4 facebook track group

https://www.facebook.com/groups/520863040768702/

So coming back to the having owned a track M3 with £3500 suspension and £3000 brakes, you can see I'm not going the same way. Why? Because II've realised you don't have to spend big money to get on track. It's more important to just get on track and learn to lap!
 
DaveP said:
My advice?

Go and drive your car on track. You've somehow already decided that you need 2-way adjustable coilovers, 4-pot brakes and an LSD without driving a single mile on track in it.

I recently did 40 laps of the Ring in two days without any of those things, and I had an absolute blast. I say that because enjoying yourself should be the goal here, not chasing laptimes.

Change your fluids, check your brakes and tyres have plenty of life left, and just book a trackday. I can promise you that your car is already much more capable than you are on track. It will be a while before you find the ceiling of the current setup and figure out what your upgrade priorities are.

This isn't meant to sound dismissive, but ask yourself why you're doing this. You're better off spending money on trackdays and Ring trips than having a car with loads of shiny parts sitting outside your house.

This is bang on advice tbf, plus part of the fun is fitting a new part and then finding out how it affects the car on the next trackday. If you do everything in one go, you won't have a base to start from.
 
I did a dozen trackdays in my e85 z4, the only mods I did were decent brake pads, front brake cooling ducts and budget oriented track tyres. That was it.

Personally, never felt the need to bother with suspension or big brake kit, or an lsd. Just do as many trackdays as possible.

Once you've done a year of trackdays and learnt the car, then you'll know what you want to upgrade. But for the first few days, I'd do absolutely zero mods, just make sure it's got fresh oil and brake fluid, and some brake pad material.

My highlight in the z4 was keeping up with various porsche gt products round a damp spa francorchamps. With stock power, stock suspension and just brake pads and tyres. Oh and driving experience of 40 odd trackdays...
 
Thanks everyone, some really helpful advice in this thread. I definitely plan to get out on track more or less stock, and add as I go/see fit, but also wanted to do some research in advance and possibly look out for any significant savings come black friday even if I don't fit those parts right away. Keeps me entertained til the sun comes back but first priority for sure is track time and instruction. Part of the reason I bought a z4 coupe was the 'out of the box' element.

I should probably have mentioned that some bits here (brakes and suspension in particular) will come due on this car in the reasonably near future, so they're likely going to be a 'while I'm there' job - discs are a bit lipped, nsf caliper bleed is seized, and front top mounts are worn. Had the car in for a health check with RBM and sorted some of the common oil leaks and refreshed some fluids, but these I left to wear down then upgrade. They'll be OK for a bit of track use but when the time comes, I'm not going to bother replacing oem only to upgrade 6 months to a year down the line.

On the topic of brake pads, what's the reccomendation here for mixed use without too much squeal or brake dust?
 
Good mixed use pad are EBC Bluestuff. Work from cold on the road, stable friction profile up to high temps and no squealing. You’ll struggle to find a pad that copes with the track and gives low levels of dust though.
 
damocell said:
DaveP said:
My advice?

Go and drive your car on track. You've somehow already decided that you need 2-way adjustable coilovers, 4-pot brakes and an LSD without driving a single mile on track in it.

I recently did 40 laps of the Ring in two days without any of those things, and I had an absolute blast. I say that because enjoying yourself should be the goal here, not chasing laptimes.

Change your fluids, check your brakes and tyres have plenty of life left, and just book a trackday. I can promise you that your car is already much more capable than you are on track. It will be a while before you find the ceiling of the current setup and figure out what your upgrade priorities are.

This isn't meant to sound dismissive, but ask yourself why you're doing this. You're better off spending money on trackdays and Ring trips than having a car with loads of shiny parts sitting outside your house.

This is bang on advice tbf, plus part of the fun is fitting a new part and then finding out how it affects the car on the next trackday. If you do everything in one go, you won't have a base to start from.
There's a big 'scene' vibe about trackday cars of late.

It's more about the car of choice (it has to be a modern M-car) and making sure you've got the right parts fitted ("if it's not X, it's not worth having") than just getting out and driving.

Personally, I do trackdays because I like driving my car on track. My car is never going to have its own Instagram account.
 
Jpt23 said:
Thanks everyone, some really helpful advice in this thread. I definitely plan to get out on track more or less stock, and add as I go/see fit, but also wanted to do some research in advance and possibly look out for any significant savings come black friday even if I don't fit those parts right away. Keeps me entertained til the sun comes back but first priority for sure is track time and instruction. Part of the reason I bought a z4 coupe was the 'out of the box' element.

I should probably have mentioned that some bits here (brakes and suspension in particular) will come due on this car in the reasonably near future, so they're likely going to be a 'while I'm there' job - discs are a bit lipped, nsf caliper bleed is seized, and front top mounts are worn. Had the car in for a health check with RBM and sorted some of the common oil leaks and refreshed some fluids, but these I left to wear down then upgrade. They'll be OK for a bit of track use but when the time comes, I'm not going to bother replacing oem only to upgrade 6 months to a year down the line.

On the topic of brake pads, what's the reccomendation here for mixed use without too much squeal or brake dust?
Nobody can tell you how to spend your money, but the point people in this thread keep making is that you have no idea whether you'll even need these upgrades.

A set of good quality discs can be had for £90 (https://www.ebay.co.uk/itm/335440300312) and changed over in an hour or two on your driveway. Avoiding swapping out lipped discs because you "know" you'll be replacing them before you've even done a single mile on track feels like a bad compromise. You could get a whole year of enjoyable trackdays out of £90 of discs and a set of pads, which is valuable time to figure out whether you even like the way the Z4 drives on track.
 
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