Sorting Out an e89 Z4

[z4_hyperorange_fan]

ZPost community,

I recently bought a 2015 Z4 sDrive35is and it's awesome: beautiful, fun, and fast.

BUT, it's a loud and rough-riding example, even for a "sports" car. I really want to sort it out to make it a comfortable daily driver. Does the community have any advice for the following issues?

Rough ride:

19” wheels and 30-series tires with M-sport suspension mean the ride is rough. I replaced the run-flat tires with non-run-flats which was an improvement, but is there anything else I can do to improve the ride? Are new struts or softer suspension bushings an option?

Rough engine idle:

BMW inline-six engines are famously smooth, but this car idles roughly. I had it tuned up, but it didn't help much. Do the engine mounts need replacement? Any other tips?

Noisy ride and squeaky interior panels:

I lubricated the interior panels with silicon lubricant, which solved some but not all of the squeaks. Do I need to remove the interior panels and reattach them? Would adding sound deadening materials behind the panels improve the noisy ride? Would a sound-deadening undercoating help?

Thanks in advance for any advice.

[Marcoose]

Hi. IRT to ride hardness, it’s possible your adaptive shocks, arms, bushings, etc are done for. Not uncommon. I’ve replaced my AS with KWV3. It’s tits! But not more comfortable. Rather shaper. I’ll never go back to AS. Switching to 18” would also help.

But for sure, the 35is isn’t a Cadillac. It’s a sporty-ish car. The ride will be a bit hard.

Oh, good looking car !

[KennyP]

Z4 35is has different stiffer engine mounts than 35i. Its considered an upgrade for us 35i owners. So its maybe possible to change them out with softer? 35i engine mounts. I thnk 1 mount was actually different.
19inch wheels have a very thin tyre sidewall. To make it comfortable maybe get smaller 18 inch wheels with tires that have thicker sidewalls... my car is way more comfortable on smaller winter wheels than on 19" summers.
Getting rid of runflats was a right move.
Ruff idle may be an engine issue. Have coilpacks been replaced? If not maybe replace those.. they arent that expensive.


My car has an a-pillar squeak on the passenger side on some ruffer roads with the roof up. With the roof down its quiet. Also sometimes rear part of the roof makes noise. but after a proper wash and going over the seals it dissapears.
I have taken apart a pillar trim and used some foam pads etc trying to fix it. Well, its still there. Bmw even has a repair manual page for fixing that rattle which is hilarious.

All in all it is a sporty roadster/ convertible and theres only so much you can do.

[B21]

Welcome, you don't state the mileage of the car?

On the ride..

There are several options..

You can increase the profle of the tyres and go for 40 front and 35 rear in stock widths with no issue..

You can go with slightly wider profiles 235 front 265 rear

Different tyres ride differently, the new Continental Sports Contact 7s suit the E89 much better than the Michelin MP4(S)

Suspension wise the springs and adaptive dampers tend to wear prematurely on a heavy and powerful version of the E89. One option is to buy new M Sport springs from say Supplex and ally those with Bilsteain B8 dampers..I used this very successfully on my first E89. A more expensive option is to go for the Ohlins Road and Track replacements, which offer a comfortable ride with excellent handling and are easily adjustable to your tastes whilst preserving standard ride height.

Noise wise the 35is has a noiser exhaust than the 35i..

Idle wise as was suggested plugs, coils but probably your inlets are badly coked up, a very common problem on N54s with direct injection..needs a chemical clean or walnut blast!

[MRCW]

What were your expectations with a low roadster sports car with the most powerful drive train?

I get that people want to modify their cars...I do that with all of them... but it's to improve on their basic fundamentals, not to make them worse...

Perhaps you should look at a 2 series convertible? Otherwise you'll be putting $1,000's into a car to make it perform like it wasn't intended to do.

[z4_hyperorange_fan]

Originally Posted by B21

Welcome, you don't state the mileage of the car?

On the ride..

There are several options..

You can increase the profle of the tyres and go for 40 front and 35 rear in stock widths with no issue..

You can go with slightly wider profiles 235 front 265 rear

Different tyres ride differently, the new Continental Sports Contact 7s suit the E89 much better than the Michelin MP4(S)

Suspension wise the springs and adaptive dampers tend to wear prematurely on a heavy and powerful version of the E89. One option is to buy new M Sport springs from say Supplex and ally those with Bilsteain B8 dampers..I used this very successfully on my first E89. A more expensive option is to go for the Ohlins Road and Track replacements, which offer a comfortable ride with excellent handling and are easily adjustable to your tastes whilst preserving standard ride height.

Noise wise the 35is has a noiser exhaust than the 35i..

Idle wise as was suggested plugs, coils but probably your inlets are badly coked up, a very common problem on N54s with direct injection..needs a chemical clean or walnut blast!

B21, I appreciate your thoughtful reply.

In response to your question, my Z4 has 34K miles -- which is part of my conundrum: It squeaks and rides like a much higher mileage car.

You're quite right about the non-run-flat Continental Sport tires. They are much smoother and quieter than the Michelin run-flats.

I'll look into the springs, dampers, and coils!

P.S. You're right about Scotland.

[z4_hyperorange_fan]

Originally Posted by KennyP

Z4 35is has different stiffer engine mounts than 35i. Its considered an upgrade for us 35i owners. So its maybe possible to change them out with softer? 35i engine mounts. I thnk 1 mount was actually different.
19inch wheels have a very thin tyre sidewall. To make it comfortable maybe get smaller 18 inch wheels with tires that have thicker sidewalls... my car is way more comfortable on smaller winter wheels than on 19" summers.
Getting rid of runflats was a right move.
Ruff idle may be an engine issue. Have coilpacks been replaced? If not maybe replace those.. they arent that expensive.


My car has an a-pillar squeak on the passenger side on some ruffer roads with the roof up. With the roof down its quiet. Also sometimes rear part of the roof makes noise. but after a proper wash and going over the seals it dissapears.
I have taken apart a pillar trim and used some foam pads etc trying to fix it. Well, its still there. Bmw even has a repair manual page for fixing that rattle which is hilarious.

All in all it is a sporty roadster/ convertible and theres only so much you can do.

KennyP, great feedback. Much appreciated.

I'll look into the engine mounts and coil packs. And yeah, the A-pillar squick is ridiculous. I solved it with a shot of silicone lubricant.

> All in all it is a sporty roadster/ convertible and theres only so much you can do.

Yep, I'm not trying to turn it into a Lincoln Town Car. Just trying to make it a little more livable as a daily driver. The best part is that most of the problems I noted are solved when the top is down : )

[B21]

Some cars just seem to rattle and squeak more…my friends 23i had 130k miles on it, when you close your eyes and ride in the car it feels like a 20k mile 3 year old car..

I found using high density thin foam strips were a good way of silencing various rattles..

FWIW the sun visors often generate an inordinate amount of noise but ‘throw’ the sound in the cabin…try holding a visor when you hear a rattle and see if it disappears..

On the poor idle the further thoughts are poorly gapped plugs..people ‘tune’ these N54 engines by closing the gap..the downside is poor idle.

Otherwise my money is on coked up inlets..

Coils more often break down under high load.

[z4_hyperorange_fan]

B21, you're my Z4 Yoda. I'm sharing your notes with my mechanic now.

With your help, I'll get this thing to drive as beautifully as it looks.

[B21]

Originally Posted by z4_hyperorange_fan

B21, you're my Z4 Yoda. I'm sharing your notes with my mechanic now.

With your help, I'll get this thing to drive as beautifully as it looks.

May the force be with you

[z4_hyperorange_fan]

Hahaha!

[golfguy]

On my 35is my adaptive suspension shocks and struts were leaking and needed replacement. One adaptive strut was about the same price as a 4 piece set of the Bilstein B6. They did make the ride nicer, but you'll need to have your shop do some coding or the car will constantly warn you that your adaptive suspension isn't working. I really don't notice any handling difference.