E89 Z4 Track-ready Sleeper Build

[Asbjorn]

So if anyone ever wondered how the rear damper mounts look like after 11yrs/150kkm, the are quite fine actually. Same for the inner upper control arm bushings. The damper rubber stoppers however not so much...







Also bought some used HR springs and compared them to eibach and oem. Definitely lower. Should also be stiffer as the wire diameter isn't variable, and the progressive coils (those with shorter distance) close first, and then the stiffer rate kicks in.

I will try to run these together with a height adjuster to get the height back to eibach-level rear. Front I will just keep the stock springs.

 

[Asbjorn]

Had these made

And did the @fmorelli - inspired mod to the rear upper arms. Unfortunately we misunderstood each other and they made them so they cant be adjusted inwards. They are redoing them today and I should have them back early next week.

,

Probably going to regret the open bearing design but lets see.

The same shop is looking into the cost of making custom uprights. However I don't expect that to be cost effective at all.

 

[Lurcher]

Soon you could start offering limited production on some of these items. Those rear strut mounts - hmmm...

 

[Asbjorn]

Soon you could start offering limited production on some of these items. Those rear strut mounts - hmmm...

Haha just say the word. Buuut the price would be unreasonable. I think revshift sells an e46 kit (that wont fit) for $99, and these would be like double. Also since the stock mounts looked OK I think the market for such a product would be between the size of zero and none.

 

[doublespaces]

Awesome, wonderful work in here as usual.

 

[fmorelli]

According to @barry@3DM there's really no reason to change the rear shock mounts. he says they add a noise vibration and harshness without really any gain.

In the case of my upcoming rear suspension, the rear shocks are eyelet mounts, so it's a completely different setup and unfortunately we cannot use the factory mount.

Filippo

 

[Asbjorn]

According to @barry@3DM there's really no reason to change the rear shock mounts. he says they add a noise vibration and harshness without really any gain.

In the case of my upcoming rear suspension, the rear shocks are eyelet mounts, so it's a completely different setup and unfortunately we cannot use the factory mount.

Filippo

I can confirm Barry is right. The NVH is horrible. Not "poly engine mounts"-bad, but definitely a good step above the NVH you get form running camber plates up front. Must be because they are so close to the cabin in a Z4 - you hear the klocking even with the top down. Usually top down solves everything, but not this. Going back to stock asap.

Super happy with the all bearing setup rear though. That made a larger difference than I had expected. The inner bushings are rather small on the Z4, but you can definitely feel that they are both gone. More road feel, more responsiveness to steering and accelerator pedal inputs.

 

[Asbjorn]

The new camber plates allowed us to dial in more camber and caster up front. In combination with the OEM springs and extended length dampers, the ride height is still somewhere slightly above stock. This means the static camber is "only" -3 deg. With the old camber plates I also had -3 deg, because the ride height was lower with the stock length dampers. Alright then... the overall result should be a better performance-to-comfort ratio.

Before (drivers side), maxed out ground control plates:

After (passenger side), custom made camber plates:

We raised the rear by around 8mm, and dialed in rear camber to -2 deg. Rear is still running Eibach pro-kit springs (Progressive: 65.6N/mm (initial) - 131.6N/mm (final)). Here's how we raised the rear:

We adjusted the "new" rear upper control arms so that when the lower control arms are in the middle position, I have -2 deg camber. Before I had to max out the eccentric bolt to get close to -2deg - even at lowered ride height. And we were still able to dial in some toe-in. The raised ride height, which is now closer to stock, probably helped toe as well.

Here's how the square 275 ET35 setup with a 3mm spacer up front looks now.

I might want to lower the front ever so slightly, and increase the rear sway bar stiffness, but otherwise pretty happy with the balance.

For reference, nelow is how it looked before with the lower rear ride height, old camber plates front as well as old rear control arms.

 

[fmorelli]

For any Z4 owners reading the thread and thinking about their upper rear control arm bushings: on the Z4, which runs a E46-derived upper rear control arm, one can move from the rubber-sleeved inner bushing to a spherical bearing courtesy of Ben Liaw @ Rogue Engineering - https://www.rogueengineering.com/Ro...per-Inner-Control-Arm-Bearing-Pair_p_258.html. There are $180/set. Until we fabricated different rear arms on my car, I ran these bushing quite happily. They work well and I would recommend them.

Filippo

 

[derekgates]

Incredible updates in this thread, like always @Asbjorn ... I enjoy this thread every time.

 

[sancho78rus]

What fuel pump are you using?

 

[Asbjorn]

What fuel pump are you using?

My fuel system is all stock Z4, except for WI. Running chinese RON98 + WI mostly.

 

[sancho78rus]

Dont you have a problem with a lack of fuel when driving with half tank or less?

 

[Asbjorn]

With the Z4 fuel starvation happens below 50% tank in long right hand turns only. I have only ever experienced it at Ningbo International Circuit. They have a 270 deg right hander where you accelerate through the last 180 degs as it opens up. I know a car like the Audi S3 is much worse in this regard, while the M4 basically don't have problems until you are very low on fuel.

 

[sancho78rus]

Apparently I have a problem with the fuel pump, because it is impossible to track when the tank is half or less.

 

[Asbjorn]

Apparently I have a problem with the fuel pump, because it is impossible to track when the tank is half or less.

What error code are you getting?

 

[F87Source]

Apparently I have a problem with the fuel pump, because it is impossible to track when the tank is half or less.

The m2 suffers from the same condition. Dinan sells a modification to the passive jet pump which enhances the fuel transferring ability from the left side of the tank to the right side of the tank so you won't experience fuel starvation even under really low fuel conditions. You can check it out and likely make a cheaper version diy for your car if you cannot buy one from dinan.

Dinan R420-0001 Dinan F-Series Fuel Pump Upgrade Kit - 2012-2018 BMW 228i/328i/335i/428i/435i/M2/M235i

With increased power comes increased demand on the fueling system to satiate that demand. The stock fuel pump is incapable of delivering consistent fuel flow at low fuel tank levels for high output applications under heavy load resulting in the possibility of inconsistent power delivery when the...

www.dinancars.com

 

[sancho78rus]

What error code are you getting?

A couple of times there was an error 29F1 DME: Fuel Pressure, Plausibility
Other time just lack of power.
And its ok when I race on full tank.

The m2 suffers from the same condition. Dinan sells a modification to the passive jet pump which enhances the fuel transferring ability from the left side of the tank to the right side of the tank so you won't experience fuel starvation even under really low fuel conditions. You can check it out and likely make a cheaper version diy for your car if you cannot buy one from dinan.

Dinan R420-0001 Dinan F-Series Fuel Pump Upgrade Kit - 2012-2018 BMW 228i/328i/335i/428i/435i/M2/M235i

With increased power comes increased demand on the fueling system to satiate that demand. The stock fuel pump is incapable of delivering consistent fuel flow at low fuel tank levels for high output applications under heavy load resulting in the possibility of inconsistent power delivery when the...

www.dinancars.com

Thanks, I'll think about it.

 

[F87Source]

A couple of times there was an error 29F1 DME: Fuel Pressure, Plausibility
Other time just lack of power.
And its ok when I race on full tank.



Thanks, I'll think about it.

No problem! I really hope this helps you out, because I know this issue sucks.

Also no hard feelings about earlier if I sounded rude, I know that is how I sound sometime because I can be really blunt, but I just had no other way of explaining how the oil pick up goes dry under high G forces.

 

[Asbjorn]

A couple of times there was an error 29F1 DME: Fuel Pressure, Plausibility
Other time just lack of power.
And its ok when I race on full tank.



Thanks, I'll think about it.

Actually in my experience that doesn't sound like fuel starvation. Fuel starvation should produce a code that says something about injector cut out. And it is quite violent. There will also be a check engine light, and you'll have to turn the engine off and on again before continuing if I remember correctly.

If you do a normal 3rd WOT log, what does the hpfp curve look like? Does it drop way below say 2000psi?