Liam's Z4C race car project

[Jembo]

Some cut the plastic cone head off... especially if u decide to run adjustables on the rear top mounts that I assume you are also replacing.

From watching the guys adjust my rear tracking, seem to remember there’s a bolt directly underneath the hub that does the adjustment

 

[TomK]

Still haven't figured out how the rear wheel alignment is adjusted...

20190226_161050_HDR.jpg

To adjust the toe loosen the 3 18 mm bolts of the RTAB carrier and then move the wheel. There is a specific BMW tool for this but it's not necessary.
Camber is adjusted on the stock arms via an ecenctric bolt at the hub end of the lca. If you're lowering the car much you may find this range of adjustment is not enough in which case you'll need aftermarket adjustable arms.

 

[Liam22]

Whereabouts in Cambs are you? Happy to lend a hand if there's any two man jobs as I'm quite interested to see the end result!

As for bushes, I'd recommend the Millway Motorsports kit over anything poly - although poly arb bushes will have to do.

I'm just north of Royston (near Wimpole). Very much hoping that I won't come across two-person jobs, but you're welcome to pop round at any point.

Thanks for the pointer on the Millway Motorsport kit - very nice indeed. I'm on a budget (dictated by the sale of the RX8) so I'll stick the the Strongflex yellow bushes for now and see how I get on with them. The rear control arms will have spherical bearings at the inboard pivot.

Some cut the plastic cone head off...

What plastic cone? For what purpose? I'll wait and see what comes with the coilover/damper kit before deciding what to do with the rear damper top mounts.

To adjust the toe loosen the 3 18 mm bolts of the RTAB carrier and then move the wheel. There is a specific BMW tool for this but it's not necessary.

Ah, thanks - makes sense now.

I won't make any friends saying this, but the suspension design is disappointingly archaic. It's only half a step forwards from my 1989 E30. Especially when compared to the RX8, which has double, unequal length wishbones up front, and proper 5 link setup at the rear. All fully adjustable from the factory. Looks like it's going to be difficult to adjust the rear wheel alignment at home (without a ramp).

But the proof is in the driving, so I'll reserve judgement on that until I get it on track

 

[JDavis21]

I'm just north of Royston (near Wimpole). Very much hoping that I won't come across two-person jobs, but you're welcome to pop round at any point.

Thanks for the pointer on the Millway Motorsport kit - very nice indeed. I'm on a budget (dictated by the sale of the RX8) so I'll stick the the Strongflex yellow bushes for now and see how I get on with them. The rear control arms will have spherical bearings at the inboard pivot.

Only 10 miles away, I may have to pop over.

I'd prioritise a spherical on the trailing arm front bush, as the polybushes all tend to bind at this point.

I won't make any friends saying this, but the suspension design is disappointingly archaic. It's only half a step forwards from my 1989 E30. Especially when compared to the RX8, which has double, unequal length wishbones up front, and proper 5 link setup at the rear. All fully adjustable from the factory. Looks like it's going to be difficult to adjust the rear wheel alignment at home (without a ramp).

But the proof is in the driving, so I'll reserve judgement on that until I get it on track

You're not wrong, I ran an E36 Compact Cup car for two years which shares the rear axle with the E30's. I'd argue the rear is quite different, but the front is near identical. Certainly way behind the double wishbone setups on the likes of an S2000 or the RX8, but then it still works well!

The toe adjustment is the same as the Mini, which is manageable on the floor with some strings and turn plates

 

[Beedub]

oh yes... best thead ive seen in a while!! this will be a corker!

 

[Liam22]

Lots of deliveries today:

Water pump
Thermostat
Front brake discs (Brembo Max grooved)
Big box of bushes!

 

[Jembo]

Lots of deliveries today:

Water pump
Thermostat
Front brake discs (Brembo Max grooved)
Big box of bushes!
20190227_193405_HDR.jpg

You could have run a competition of ‘guess the bits’... u never know there could be a market for some of the old parts you’re throwing away

 

[Liam22]

Made my first purchasing mistake and bought an E46 M3 rear ARB (21mm) not realising that it won't fit. Ho, hum - it'll go straight back on eBay...

I already purchased 21mm rear ARB bushes so thankfully the Ultra Racing rear ARB is the same size. Ordered!

BTW, this will match the E46 M3 cab front ARB (27mm) that I have ready to go on. Shame that BMW has skimped on the ARBs and used solid instead of lighter/stiffer hollow tube.

 

[TomK]

Shame that BMW has skimped on the ARBs and used solid instead of lighter/stiffer hollow tube.

Indeed. The front e46m3CSL arb is hollow and 31mm or so I think, not sure they fit on a standard Z4 chassis though? Otherwise there's a bunch of hollow aftermarket stuff I'm sure.
What are the restrictions placed for things like this on the series you're entering?

 

[Liam22]

On the whole, suspension tends to be "free" so long as you are using the factory mounting points. In general I'll start with as much OEM stuff as possible and then optimize it once I get to know the car, how competitive it is, and where to focus my energy (and budget).

Speaking of which…

Got the front control arm bushes removed last night, and prep'd the lollipops for the new control arms.

Pressing out the old arms:


This 1 13/16" socket (bought from Halfords clearance shelf for 99p) has come in handy more times than I can remember. Turns out it's just about perfect for pressing out 66mm bushes. Still hard work, though - needed 8t of pressure to move them.


Eccentric aluminium shells for the Poweflex black series bushes. This will push the outboard ball joint further forward in the wheelarch, adding more castor for better braking feel (and quicker self-centre steering).

 

[Liam22]

Forgot to mention... new control arm bushes have saved 100g

Winning!

 

[Liam22]

Got a few more hours on the car today.

Removed the bracing at the rear of the car, heat shields, exhaust, and propshaft. Then set about the rear-left corner: brakes, damper, ARB, inboard wishbone bolts, and driveshaft. Unlike the rear-right wishbones, the inboard bolts cannot be removed with the diff in-situ.


The handbrake system is a complete pain in the arse. Is it possible to disconnect the handbrake from inside the car? I'm very tempted to delete the whole thing, but still planning to drive it to the Nurburgring, so that may be unwise.

With the handbrake cables finally detached, the subframe came away surprisingly easily. I kept the diff attached, lowered the whole thing on a jack, and separated the diff once on the floor.


So now I've just got the job of replacing all of the rear bushes before putting it back together again!

 

[Jembo]

Keep going fella, don’t forget the GoPro mount(s)

 

[Liam22]

Got started on bush extraction this afternoon. Quickly realised that my hydraulic press won't be much use.

This is my technique. Cut out the rubber centre, then cut 2 slots in the outer shell with a hacksaw. Drift out the slot and the rest falls out wirhout much effort.

Rear trailing arm front bush:


Upper wishbbone inboard bush:

 

[Davz]

I won't make any friends saying this, but the suspension design is disappointingly archaic. It's only half a step forwards from my 1989 E30. Especially when compared to the RX8, which has double, unequal length wishbones up front, and proper 5 link setup at the rear. All fully adjustable from the factory. Looks like it's going to be difficult to adjust the rear wheel alignment at home (without a ramp).

You will also miss the torque sensing LSD and light Carbon propshaft of the RX8.
I will be amazed if you get a Zed to handle as well as an RX8, the ride and handling is the most disappointing element of a Zed. Couldn't you have upped the power of the RX8 or was that not allowed in the race series?

Interested to know when you lower it on coilovers, how low you are taking it and what effect this has on the ARB's and if you will need to fit shortened ARB links.

Keep adding pics, this is most interesting.

 

[Liam22]

Good points Davz. In reality the BMW thin aluminium tube propshaft doesn't feel much heavier than the Mazda carbon fibre resin item. I'm going to see how I get on with the open diff but plan to put a Kaaz 1.5-way LSD in the case sooner rather than later.

I'll keep an eye on the front control arm angle as I lower the car and try to stay close to parallel with the road. I'll only buy new drop links when it's all fitted up.

Just bought a set of pullers for removing the rear subframe/diff bushes. The subframe is in decent condition but it'll get a couple of coats of POR15 before going back on the car.

What I could really do with is a guide on assembling the handbrake shoes. I used to be a master on the E30 drum brakes but these little handbrake shoes are fiddly!

 

[JDavis21]

I'm going to see how I get on with the open diff but plan to put a Kaaz 1.5-way LSD in the case sooner rather than later.

I was already getting frustrated by the open diff after the one track day in mine! Have you looked at the option of getting an E36 LSD built for it with a shorter final drive? From my experience, that or a Gripper will be the most available and serviceable option

 

[Liam22]

Kaaz DBW3020 should drop straight in with the 3.46 FD. That seems reasonably short and should see 145mph at the redline in 5th. Are shorter FDs available?

 

[JDavis21]

Kaaz DBW3020 should drop straight in with the 3.46 FD. That seems reasonably short and should see 145mph at the redline in 5th. Are shorter FDs available?

There's quite a range available, 3.64, 3.85, 3.91 and 4.10 all seem quite common. Lots of E46 M3's run them built by JC Racing, with varying numbers of friction plates built to the specific use. All 188 sized (E36 EVO) so they fit in our diff casings too.

I'll be at Snetterton on 30th March with two M3's, one with a 4 plate 3.91, the other with a 6 plate 3.85, feel free to pop along for a few passenger laps so you can feel how they behave if you want! The guys I'm with know a thing or two about setting up BMW's, so may be worthwhile your time even for a chat

A 3.85 would take you to 156 at 7000rpm in 6th, which even at Spa you may struggle to hit. The E46 M3's can get away with 4.10's due to the extra RPM's available.

Would you not also be stung with import tax on the Kaaz? I'd personally rather have something that I know spares are available in the country for etc.

 

[MrPT]

Please keep disassembling stuff and taking photos. Enjoying this. opcorn:

What's the thinking behind improved braking feel and the eccentric lollipops? Or did you mean that switching to poly will give you less deflection under braking?