Centre cap problem on 15" BBS Rz's

[minesapint]

Built-up centre cap


Four components of centre cap
Basket weave metal disc. Part no 09.24.028
Hex cap. Part no 09.23.114
Black locking ring. Part no 09.23.117
Badge+centre disc. Part no 09.24.030


Image showing expanding lugs on the black locking ring


The hex cap, locking ring & badge are new.
The metal disc was refurbed along with the rims at Lepsons.

THE PROBLEM
The assembled cap when presented to the rim does not lock in position, the expanding lugs on the locking ring should engage behind a machined shoulder in the rim centre hole, mine is about 4mm short.
Can anybody tell me what's wrong & could anyone kindly provide the various part numbers for me to cross reference with mine.
BMW sell the centre cap as a complete unit....(except the badge), so cannot get the individual part numbers from them.

Many thanks

[cmsslee]

My metal outer part (cap locks fine ) is 09.24.029 and I'm also on 15" RZs - no idea if it has different dimensions to your part ending 028 though

edit: other part numbers are the same as mine

[minesapint]

Thanks for that.
Can anybody else help, as at the minute I can't fit my beautifully restored & newly rubber shod rims.