The rear brake upgrade to match the 6pot fronts has finally started.
I spent too many hours researching options, each solution resulted in far too much effort and money to justify even my own OCD, so I kind of gave up.
Our man
@damocell worked a solution using the 40mm piston version of the early m135i rear caliper and rotor.
Everything works with the wheel offsets and stock 160mm handbrake.
He documented the upgrade on his thread, also on a YT upload which details everything very well.
Using the spreadsheet of geekyness from
@B21 they worked out the upgrade path to achieve the correct braking forces. The much more common 44mm version could be an option if you run larger than 345mm front rotors.
They share the same part number as the 44mm calipers.
The only way to tell is to locate a stamped number on the inside between the mount holes, this is usually caked in brake dust so hard to see. P2.40 vs P2.44.
Painted BMW 445 Phoenix Yellow to match the fronts. I'm 90% happy with the DIY job.
Primer and paint is much thinner than I thought, it didn't fully fill the chips on the previous factory blue paint I was expecting it too, I should have flattened them down more.
I flattened some more and they're better but not perfect, they'll look absolutely fine when installed and inside the wheel, though.
Maybe I'll revisit the refurb one day.
I had some genuine stickers left over from the front project, nice.
Part numbers:
m*35i rear 345x24mm rotors: 34206797605
m*35i rear calipers (40mm): 34216860737, 34216860738 (P2.40)
m*35i rear pads: 34216887576
New bleed screws
Hoses from BTR:
https://www.brtmotorsport.co.uk/
Braided Brake Hose 720mm x2
M10x1 Male Swivel Nut 90 bend x2
M10x1 Square Swivel x2
Type 6 Hose Locator x2
Brake Hose Retaining Clip x2
I'm waiting on the bolts to arrive, then it's install time.!
Knocking out the bolt threads that the new eccentric bolts will replace.
Scuffed up, masked up, ready to go:
Fancy hoses:
They look great!: