I first thought it maybe had something to do with the gear that is pulled into action by the solenoid but that was all fine.
It's always a consideration whether to take the orignal starter apart yourself and do the repair (10 quid) or to get a refurb one (75 quid or so).
On the one hand, taking it apart is doable (apart from 1 springclip on the centershaft which is a real pain), but takes work (maybe 2 hours if your comfortable with electric motors and are a competent mechanic/general tinkerer).
But on the other hand, if you take a refurb, it usually comes from a 3 or 5 series; those are not 100% the same but still fit (I don't know which one's better), but 3 and 5 series are usually not meticulously kept. So when refurbed they usually get a coat of paint and maybe the top part is beadblasted to get rid of the white oxidation, but there are of course a lot of Zeds that are garaged their whole life, pampered etc.
For those pampered cars I think it's better to repair the original starter.
You can also get general brushes, so separate brushes without the 'bridge' (part that holds them), but you can forget to solder them to the old bridge. The leads are like litze and suck full of solder before the joint is made. They are normally spotwelded, but maybe one can do that with a short strong blast from a tig torch if a spotwelder is not present. When I first started experimenting I couldnt find the part that included the bridge so that was what I tried but results were poor. That starter/those brushes lasted only 4 years, maybe due to less flexible leads because of the solder. Although the original/factory brushes lasted less than 7 years I think (my car is from 2004 and I did the first repair I think in 2011).
After it died the 2nd time the commutator was damaged so I got another used original starter from a z4 and swapped out the whole bridge. (By then I could find it on the interwebs)
It's always a consideration whether to take the orignal starter apart yourself and do the repair (10 quid) or to get a refurb one (75 quid or so).
On the one hand, taking it apart is doable (apart from 1 springclip on the centershaft which is a real pain), but takes work (maybe 2 hours if your comfortable with electric motors and are a competent mechanic/general tinkerer).
But on the other hand, if you take a refurb, it usually comes from a 3 or 5 series; those are not 100% the same but still fit (I don't know which one's better), but 3 and 5 series are usually not meticulously kept. So when refurbed they usually get a coat of paint and maybe the top part is beadblasted to get rid of the white oxidation, but there are of course a lot of Zeds that are garaged their whole life, pampered etc.
For those pampered cars I think it's better to repair the original starter.
You can also get general brushes, so separate brushes without the 'bridge' (part that holds them), but you can forget to solder them to the old bridge. The leads are like litze and suck full of solder before the joint is made. They are normally spotwelded, but maybe one can do that with a short strong blast from a tig torch if a spotwelder is not present. When I first started experimenting I couldnt find the part that included the bridge so that was what I tried but results were poor. That starter/those brushes lasted only 4 years, maybe due to less flexible leads because of the solder. Although the original/factory brushes lasted less than 7 years I think (my car is from 2004 and I did the first repair I think in 2011).
After it died the 2nd time the commutator was damaged so I got another used original starter from a z4 and swapped out the whole bridge. (By then I could find it on the interwebs)
