Advice required please

[Kenhayes247]

Hello all and thank you for taking the time to have a look at this thread.

I bought my Z3 back in 2019 as a bit of a project car. Currently it is pretty much totally stripped (not the inside) as i work my way through a few repairs and maintenance. I removed the rear subframe yesterday as most of the bushes have failed and again I am part way through the dismantling process. I am looking to order some parts for the rear differential and the brake pipes fitted to the trailing arms.

Q1 - How do i identify the type of Diff i have (Z3 1.9L Built July 2001 M43 Typ CM12). It has a sticker on the top, i have attached a picture but everything else is covered in rust! there is no separate metal tab with a part number on. Real OEM has 2 part numbers listed for diff, with lock and no without lock. My car does have ASC if that helps.

Q2 - The brake pipes fitted to the trailing arms are looking quite tired. Would somebody please give me a steer as to where i might find the correct part numbers for replacing. I presume they are still available?

Q3 - If i were to change the drive shafts, other than BMW what would most people recommend as an alternative?

Q4 - What is the external and internal diameter of the rear wheel bearings, I have come across 2 different sizes which state they both fit my car, 75 ext and 42 inner and there is 72 ext and 39 inner. That's quite a difference.

For me, this website has been invaluable and i have really enjoyed working on my car. When finished i will probably be in around the £10000 - 15000 mark for a car that's worth 20% of that if I am lucky - That said its not about the money and it is fun, just don't tell my wife!

 

[Stevo7682]

Let's start with the brake pipe .
A lot of the time the rear metal pipe are re-made in either zinc coated or copper brake pipe cut to length and flared with new ends .

I put my zed into real oem as mine a 99 face lift m43 with asc.

I am relatively certain ( bmw dealer will be able to confirm) number 6 is the pipe along the rear beam ( it's the way the picture set out not looking like what on car )
Number 1 is the abs pump to rear flexi at the trailing arm mount point metal pipe
Number 5 is that flexi hose at that point .
Then you will see a dotted line on picture to indicate follow to next section.
Number 6 is the metal pipe along the trailing arm
Number 10 is the rear flexi hose that joins the metal pipe then goes into caliper.
The other bits are obviously the various clips etc .
Here is the part number list .

Stephen.

 

[Synclare]

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[Stevo7682]

Q1. The diff .
Being as its a 1.9 m43 unless specified by original buyer as an extra or your zed is a sport model not likely to have an lsd tend to be more common on 6cyl rather than the 4 cylinder .
Stephen

 

[Kenhayes247]

Thanks all, that's much appreciated.

I will measure the wheel bearing tomorrow to confirm the size. Brake pipe has been ordered.

Ken

 

[t-tony]

Thanks all, that's much appreciated.

I will measure the wheel bearing tomorrow to confirm the size. Brake pipe has been ordered.

Ken

A digital vernier calliper would be useful in measuring the old bearings Ken.

Tony.

 

[Synclare]

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[t-tony]

A bender, such as this,

Brake Pipe Bender Tool (Standard 5mm Pipe) LL | eBay

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www.ebay.co.uk

makes it easier to get tight bends in pipes. Practice makes perfect.

Tony.

 

[Stevo7682]

Brake pipe from BMW will presumably be straight, you will need to ensure you copy the same tight radius bends as on the original or you could end up with too short a pipe. Think Lee said they're about £15 each.

That's not so good me thinks Adrian.
We got 2 genuine pipes for a Ford for a customer with an mot fail and they came all pre formed you would think bmw would have at least gone to the effort of doing something similar.
Stephen.

 

[Kenhayes247]

I have a Set of verniers and even sourced a pipe bender as well. I kept the old pipe for exactly this reason. Thanks guys

 

[NZ00Z3]

Q1, Look at the top line on the bar code label. The part number is 1428412. This is not the full part number, you have to put the basic BMW diff code in front which is 3310 This gives you a full part number of 33101428412. The last part of the top row is the diff ratio of 3.38. You have a small case open diff with a 3.38:1 ratio. Easily checked by looking at the side of the diff. The flange holding the half shaft seals in will have 4 bolts. Medium case diffs have 6 bolts on that flange.

Q2, Buy some tube, a bender tool and flare tool and make your own. Far cheaper than going to BMW for straight pipes as you'll still need the bender tool. The new BMW pipes come straight. I purchased the first set I needed. Eye watering cost of straight pipes that I had to bend my self.

The correct tubing for the trailing arms is 4.75mm OD. It uses a 10mm by 1mm thread pitch nut with a 5mm ID, so 5mm tubing is fine to use. BMW use a DIN bubble flare, so get the correct flare tool for your tubing size. See bottom right in below picture.

Get the correct bender for your pipe. Don't use an imperial bender on metric pipe, it just ovals the pipe. Don't bend the pip around your knee or with your thumbs as it will flatten somewhat.

 

[Kenhayes247]

Thank you, really useful Information that's made things a lot clearer