Montego Blue E86 is Long Gone - Z4MC Diff Rebuild

1536Z4 · Post by **1536Z4** » Thu Jun 29, 2023 10:02 pm

Hi Lucas ,

Again sorry to hear about Rusty . I assumed that he had passed as you hadn`t mentioned anything for a while . Sounds like a great M you have there . Looking forward to see your updates .

lucasxdiniz · Post by **lucasxdiniz** » Sun Jul 16, 2023 10:33 pm

I thought I would wait until I did all the little jobs to make the Z4M feel like my car. I'm finally done with 'stage 1' - bringing the car to a reasonable standard (given my budget anyway...). In hindsight, I should have made shorter updates as I did things.

I bought this car privately. The ad had been on Autotrader for a long time and when I actually decided to go for an M, I realised it was still there and the price dropped significantly. I was surprised it hadn't gone and wondered if it looked like a dog in person but because it was my ideal spec, I arranged to see it.

I was a bit nervous about wasting my time as I had to get a day off, book trains etc. But as soon as I saw the car, I was mind boggled. The car looked stunning; basically new PS4s and brakes, recently refurbed wheels, and desirable optional extras that the ad did not mention. Basically, the guy made a low effort ad - low resolution photos (apparently a bug on AutoTrader if you upload directly from a mobile), not knowing details about the spec and how desirable some of the items are like the hi-fi, and he also kept telling the few people who called (judging by what he told me) that the car hadn't been serviced in forever. However, as I went through the history, I realised it had only been 3k miles since it had been serviced (he drove 800 miles in 2yrs of ownership - car mostly sat in storage) and this just hadn't been stamped in the book. At that point I knew I would be buying it, and after driving the car and feeling how solid and fresh it felt for the mileage, I paid the asking and loved the drive home even though I only dared reach 8k a few times as I was nervous about the rod bearings. First pic of the car, filling up for the trip:

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The only bad points about the car I could see was the wear on the driver's seat, but as this thread would prove, that would not put me off in the slightest. The front end had a respray, and against certain lights, one can see the clear has a sort of waviness to it around the bonnet creases. I don't know how to explain it, but I'm sure it isn't body filler as you can see the inside of the panel and it's perfectly straight. Front end respray in most Zs of this age is a must anyway, so I would have got it done regardless, so no loss there!

lucasxdiniz · Post by **lucasxdiniz** » Sun Jul 16, 2023 11:10 pm

Day #2 of ownership. After a quick drive in the morning in which I got to test the limits of the car a bit and made sure I really loved it, I parked it up and got to cleaning as you do. The only acceptable filth is your own I guess...

To start, I took all wheels off and cleaned the wheel wells and anything accessible. Good opportunity to check the suspension and the state of everything. I also painted the calipers. My intention is to put nice mono-block calipers in this car at some point, so no point in stripping calipers down and doing a perfectionist's job.

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This photos show the cured paint a few weeks later. When you first apply it, it basically looks like a toddler put it on. A few hours after application, it becomes touch dry and has a much smoother finish.

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Wheels got a nice detail as well - why do tyre places never remove old double sided tape properly? I hate removing those!!!

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Won't bore people with more cleaning photos but I did end up polishing the car to remove some car wash swirls and to revitalise the mirrors

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I am still not sold on having badges. The rear badge was removed as soon as I got to polishing the car - gotta be done for symmetry and to some extent because boot ///M badges are so diluted these days. But I am trying very hard to like the side badges, the O/S one is faded, so had a quick fix for it. I am developing new UV badge sticker sets for the Z4M since no one else is doing them anymore (more to come on this), so will try that before scrapping them.

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Plenty of interior tidy up jobs, but quite bored of talking about those. All I can say is that this is just a 'stage 1' repair, I will properly refurb the seats with a full re-dye at some point.

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lucasxdiniz · Post by **lucasxdiniz** » Sun Jul 16, 2023 11:40 pm

Engine bay went through a minor clean and the most eye-sore thing tackled - the SAS pump bracket. I also had a quick go at polishing the VANOS. Should not have done that, it made every thing else around it look old and corroded - will need to come up with a solution for it eventually (eg polish everything).

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Now to what really matters, rod bearings. As soon as I arranged to see the car, I made a preliminary booking with RBM as I know it takes a while to fit such jobs in and I knew I would be too neurotic to enjoy the car otherwise.

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The rod bearings looked bad to say the least. Definitely not the worst I've seen posted around here - seen worse at half the mileage. But I was told it was the worst ones they had seen in a little while. So now the car has new ACL Race bearings and engine mounts.

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lucasxdiniz · Post by **lucasxdiniz** » Mon Jul 17, 2023 12:00 am

With the main concern of S54s out of my mind, I managed to have a very fun drive home from RBM. Which happens to be a long way these days since I moved to Northamptonshire. But once I got back, I didn't wait around and started the inspection II process. I had spent weeks reading and ordering different parts, so I had it all here waiting for me. Oil had just been changed by RBM with 10w60 Castrol Supercar (which would have been my choice anyway), but here's the rest:

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Happy to share my thoughts about the fluids I used should anyone wonder. Very happy with the drive line fluids I chose. Gaskets and spark plugs were OEM.

Checking the valve clearances and shimming them was quite fun. A bit annoying that they are only available in 40µm increments, so couldn't get all to nominal, unfortunately. I measured all shims and then ordered what I thought was best - check summary sheet for details if interested.

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While there I had a good ol' look at the Vanos oil pump hub and timing guides, going as far as looking at the details with a borescope. All in good condition, so I will enjoy the car for this summer before doing some preventative maintenance on the VANOS and guides.

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Pressure bled all brake and clutch lines. All felt perfect before, so no change there, just getting it ready for Wales.

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lucasxdiniz · Post by **lucasxdiniz** » Mon Jul 17, 2023 12:55 am

For the short term (read until I feed the piggy bank), I did two 'significant' mods, changed the springs to Eibachs for better fitment and looks and modified the exhaust.

The stock suspension is pretty good, which genuinely surprised me. Since I had driven a friend's Z4M with Eibach springs and was impressed with the ride quality, I went for a set and can't say there are any drawbacks compared to the OE springs.

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How the car looks lowered. Bad photo to show that, but the only one I have.

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Got the geo set up with the E46 CSL specs. This worked really well for the open diff Z4s and even for my 3.0si with Wavetrac, but my first impression (in a rather wet day) is that it needs a bit more positive toe in the rear to make it more balanced (Z4M LSD is considerably more aggressive than the torsen types IMO). Having said that, I like how it is, rotation is great and I can manage the over eager rear end with a bit of right foot modulation in the wet weather (TC is only on if I forget to turn it off), and generally not afraid of the snappy chassis of the Z4s, very used to it by now.

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Now, the exhaust... A bit of a ~~f**k up~~ happy accident on my part. Decided to go for the usual backbox mod, which had worked wonderfully well in the 3.0si and 6er. Problem is, doing the same to the Z4M resulted in a muuuuch louder set up. When I first put it on, I felt pretty frustrated with myself as I couldn't justify spending another few £100s to get it re-done in a different way, so I sucked it up and went for a test drive after I let the idle drop inside a fully closed garage as cold start was beyond obnoxious... I ended up loving it in the end, especially now that is has matured and is less loud (cold starts are still an issue). I can potter around under 3k and not draw attention to myself in villages, so it's not too bad. But oh my does she scream above 3k!!! Usual boominess when under load and low revs, but no worse than I remember my 3.0si being.

Before, after, and the mod itself.

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Videos never do exhaust sound justice, but there's a clip below. I can only describe it as sounding like a vintage race car. Very raw and old school sound.

Ed Doe · Post by **Ed Doe** » Mon Jul 17, 2023 7:37 am

That's actually a decent sound imo, shame it's a bit loud for trackdays (certainly judging from that video anyway!) or I'd be rather tempted!

R60BBA · Post by **R60BBA** » Mon Jul 17, 2023 9:47 am

Ed Doe wrote: ↑Mon Jul 17, 2023 7:37 am That's actually a decent sound imo, shame it's a bit loud for trackdays (certainly judging from that video anyway!) or I'd be rather tempted!

I think it would be fine for track days (on the premise that it doesn’t sound as loud as mine).

Only way to really know though would be to do a db check.

Sounds pretty good btw.

N4LLY · Post by **N4LLY** » Mon Jul 17, 2023 4:06 pm

Most excellent work there buddy

Approved

Ed Doe · Post by **Ed Doe** » Mon Jul 17, 2023 4:16 pm

R60BBA wrote: ↑Mon Jul 17, 2023 9:47 am I think it would be fine for track days (on the premise that it doesn’t sound as loud as mine).

Only way to really know though would be to do a db check.

Sounds pretty good btw.

I'd be amazed if that got onto any sub 105dB days, it's got awfully strict recently....?

Obviously the only way to be sure would be to get it tested but its a bit late on the morning of a trackday when you're at the track getting noise tested to discover its over...!!! It's a good noise for sure, but I'd not want to run the risk of being chucked off track (or not making it on track in thefirst place!)

Plus I have 100cell race cats too, so it'd be significantly louder again than that!

lucasxdiniz · Post by **lucasxdiniz** » Mon Jul 17, 2023 6:23 pm

Ed Doe wrote: ↑Mon Jul 17, 2023 7:37 am That's actually a decent sound imo, shame it's a bit loud for trackdays (certainly judging from that video anyway!) or I'd be rather tempted!

Yeah, I would be surprised if it passed track day tests. When cold, it's definitely louder and boomier than when things get up to temps. I have a video of when I first put the backboxes on and feathered it up the road - it was insanely loud with the combo of cold everything and new pipework. Now that the exhaust matured, under 3k and light load and it's quiet enough that people don't look my way/notice me.

Some static revving:

And the chap who currently owns my old 3.0si filmed a few in-cabin clips:
https://www.instagram.com/p/CuwybmJOxWw/

Mr Tidy · Post by **Mr Tidy** » Mon Jul 17, 2023 8:39 pm

Some great progress already Lucas, but given your previous posts I didn't expect anything else!

A little more exhaust noise is a good thing - I was glad mine had Powerflow back boxes already fitted. And I think yours sounds fantastic.

I can understand the appeal of going back to blue and Champagne - it's a lovely colour combination. The first MC I looked at was Interlagos with Light Sepang leather and I thought it looked great, but by the time I had made my mind up it had gone.

Still the one I got was cheaper with less miles and better spec, including the Carver HiFi, so all good in the end.

lucasxdiniz · Post by **lucasxdiniz** » Mon Jul 17, 2023 10:57 pm

Mr Tidy wrote: ↑Mon Jul 17, 2023 8:39 pm Still the one I got was cheaper with less miles and better spec, including the Carver HiFi, so all good in the end.

Funny how things turn out sometimes.

I was an hour or so into my drive back home after walking away from a black Z4M when I decided that I should just stop at a services and call the guy who is now my car's previous owner.

R60BBA · Post by **R60BBA** » Tue Jul 18, 2023 1:22 am

Ed Doe wrote: ↑Mon Jul 17, 2023 4:16 pm
R60BBA wrote: ↑Mon Jul 17, 2023 9:47 am I think it would be fine for track days (on the premise that it doesn’t sound as loud as mine).

Only way to really know though would be to do a db check.

Sounds pretty good btw.
I'd be amazed if that got onto any sub 105dB days, it's got awfully strict recently....?

Obviously the only way to be sure would be to get it tested but its a bit late on the morning of a trackday when you're at the track getting noise tested to discover its over...!!! It's a good noise for sure, but I'd not want to run the risk of being chucked off track (or not making it on track in thefirst place!)

Plus I have 100cell race cats too, so it'd be significantly louder again than that!

No need for all of that. You can test it yourself at home with a db meter.

MrPT · Post by **MrPT** » Fri Jul 21, 2023 2:47 pm

I'm just back after a long break too. As usual, excellent work to be found in this thread.

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Montego Blue E86 is Long Gone - Z4MC Diff Rebuild

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction

Montego Blue E86 is Long Gone - Z4MC Introduction