Subframe refurb on my 06 Z4 M Roadster

Gazhyde · Post by **Gazhyde** » Thu Oct 21, 2021 5:27 pm

Here's some pics to show the progress so far, a project between myself and Joycey (from here and other places

) and another mate called Trev

2006 Z4 M roadie on 123k miles with seemingly original everything underneath (except for BC Racing coilovers)! Initially replacing the 17 subframe bushes and to deal with the leak on the input seal of the diff. Now we are underneath scope creep is setting in and may be dropping the gearbox as there may be a slight weep on the output seal (or it's coming from the engine, so probably gonna poke around that for a while).

Everything coming off is being grit blasted and either powder coated or painted with black Hammerite. Got some exposed areas under the boot floor needing a good wire wheeling and rust proofing.

Just gonna throw some pics here, have a full write up elsewhere - not sure if I'm allowed to link

Into the garage she goes.

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Up on the axle stands

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Subframe down on the floor. Took about 3 hours to get to this stage removing the under braces, panels, exhaust, prop shaft and all the other things in the way!

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Failed RTAB on both sides

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New rear discs and pads on order

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Diff going off for full rebuild including all bearings and seals and possibly clutch packs if needed.

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General crustiness

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Handbrake assembly and cables

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Pulling bearings

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Gazhyde · Post by **Gazhyde** » Thu Oct 21, 2021 5:32 pm

New drop links...

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Naked trailing arm

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Bush removal with a bit of gentle heat, can't go mad as the wishbones are cast aluminium.

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Subframe bushes get all the heat before being pushed out in a 10t standing press.

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Front diff bush

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Some bits back from powder coating

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Gazhyde · Post by **Gazhyde** » Thu Oct 21, 2021 5:36 pm

Some more random pics

Diff oil plastered over the petrol tank

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Things to wire wheel and rust proof

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Handbrake mechanism - shows why you need to remove the prop to get at it, 6 nuts and it comes out the bottom of the car. Also, don't forget to unclip the sensor cable like I did...

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My shaft

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Supersprint Racing with x-pipe

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RvsBmw · Post by **RvsBmw** » Thu Oct 21, 2021 5:56 pm

Gazhyde wrote: ↑Thu Oct 21, 2021 5:36 pm Some more random pics

Nice job, looks better now and curious to see the pics from the process and when finished

.

Gazhyde · Post by **Gazhyde** » Thu Oct 21, 2021 6:00 pm

A bit about parts... It's an M, they are all expensive. Don't even think about asking for a running total

My parts spreadsheet has 25 lines, covering bushes, ball joints, wheel bearings, discs, pads, handbrake cables, diff & gearbox oil, friction modifier, braided brake lines, caliper seal rebuild kits and other sundries like nuts/bolts/clips.

Where I can I've aimed for best quality I can find, and at minimum OEM quality. Nothing unbranded or a brand I've not heard of. For example discs are BMW and the pads are EBC Yellowstuff. HEL for braided brake lines.

The 17 subframe bushes are either BMW OEM or Meyle HD (drop links are Lemforder which are OE equivalent). The diff is getting Powerflex Black, they should have been Purple but they sent the wrong ones in the right packaging. The reasoning being Powerflex on the diff is that you have seem to have to replace the rear diff cover to change the bushes, they aren't listed as separate parts. PowerFlex make replacement bushes for the back plate, so that was that.

RedUn · Post by **RedUn** » Thu Oct 21, 2021 6:07 pm

Love it what a great bit of resto so far! Look forward to further updates!

bigwinn · Post by **bigwinn** » Thu Oct 21, 2021 6:11 pm

Great pics and resto matey

Fills me with dread as I know at some point I need to do a handbrake mech!

buzyg · Post by **buzyg** » Thu Oct 21, 2021 7:35 pm

Nice job.

Beedub · Post by **Beedub** » Thu Oct 21, 2021 7:55 pm

i have to say underneath has really weathered well..... the bits you took off needed some love but im really impressed with the underside condition.

Well done OP. excellent work.

Gazhyde · Post by **Gazhyde** » Thu Oct 21, 2021 8:25 pm

Thanks all, we’ve done this on over 50 Z3 & Z3Ms now so a Z4 makes a nice change. Z3 subframes are very different, and a lot of them are starting to deteriorate badly.

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Vanne · Post by **Vanne** » Fri Oct 22, 2021 5:32 am

Holy s**t!!! That z4 been parked under salt water?? Nice job on the refurb, but I've never seen it as bad as that.

Gazhyde · Post by **Gazhyde** » Fri Oct 22, 2021 7:38 am

Vanne wrote: ↑Fri Oct 22, 2021 5:32 am Holy s**t!!! That z4 been parked under salt water??

We like our roads well flavoured in the UK. Standard UK car, looks mint on the top but underneath...

Nothing more than surface rust, unlike the Z3's which are developing holes!

Martyn · Post by **Martyn** » Fri Oct 22, 2021 8:15 am

Great job!

Whilst you're there you should consider pulling the rear bumper and checking the rear bumper carrier as the rear bumper seems to trap alot of moisture.

Gazhyde · Post by **Gazhyde** » Fri Oct 22, 2021 9:45 am

Martyn wrote: ↑Fri Oct 22, 2021 8:15 am rear bumper seems to trap alot of moisture.

That makes sense as to why I struggled trying the new towing eye I bought, the internal thread on it was a mess with corrosion. Took me ages to clean up the thread so the eye would go in far enough. Just kept winding the eye in and out with a large bar and plenty of grease! Good tip, thanks!

Justino · Post by **Justino** » Fri Oct 22, 2021 1:16 pm

Good work. Don't forget to clean off the diff oil from the tank. When I had my output shaft seals done, it wasn't cleaned off, and I am now wondering if the oil I have recently noticed is historic, or form a new leak!

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