GSF 'OEM' Alternator - does not fit?

[George]

Had a few issues with battery drain of late (see other thread), however I did feel that a new alternator was in order, since according to the test values it was only working on the very lower edges of normal.

GSF - Part number: 903BM0170. According to the guy there, apparently OEM.

£65 (ex VAT) + surcharge (need to return old one).

Came in this box (not an OEM brand I was aware of).


Side by side to the OE Bosch, not a huge amount of difference, however one fundamental issue:

The mounting holes on the Bosch (nice and tight around the bolt):


The mounting holes around the replacement (at least 3mm to big, bolt is loose!):


How is this supposed to fit? It can't sit there loose with all that play? Can't be right...any ideas (apart from going to ECP and gettting the proper Bosch item for over twice the price)?

TIA

[e30topless]

the casting on the new alternater looks a bit crappy ?

you should be able to remove the rubber mounts on you old one and use them on the new one in place of the one's they supplied !

carefully drift them out of the old housing ,

failing that just use the new resister/bush pack from the new alternator in your old one !

[bpowell555]

Because the brush pack is probably all it needed

[rmt]

There are two ways that alternators are bolted to an e30. One has the bolts going through rubber bushes (thus the larger holes in your new alternator). This system has to have a wire to earth the alternator. The other system uses bolts straight into the body of the alternator and it earths throught the bolts (your old alternator).

[George]

the casting on the new alternater looks a bit crappy ?

you should be able to remove the rubber mounts on you old one and use them on the new one in place of the one's they supplied !

carefully drift them out of the old housing ,

failing that just use the new resister/bush pack from the new alternator in your old one !

Yes, doesn't looks top quality does it.

Will check regarding the rubber mounts.

Because the brush pack is probably all it needed

Hopefully, am going to try the old alternator with the new bush pack and see.

There are two ways that alternators are bolted to an e30. One has the bolts going through rubber bushes (thus the larger holes in your new alternator). This system has to have a wire to earth the alternator. The other system uses bolts straight into the body of the alternator and it earths throught the bolts (your old alternator).

Ah right - I didn't know this! I'm not sure if I remember rubber mounts (it was a while since I removed it, not had that much chance to refir owing to the bad weather). Thanks for the info.

If mine was originally the latter, can it be converted to the former for the new alternator?

[badassyas]

Get your original one rebuilt. GSF are simply selling the item that gains them the larger profit. If it was oe quality it would come in a Bosch/Lucas/denso/magnetti marrelli. The item you have there is equivalent to ECP's rtx brand and I wouldn't ever touch either...

[George]

Checked the box (thrice!) and there were no rubber mounts included.

Decided it was worth refitting the original Bosch but with the new bush pack/regulator to see if that actually made a difference.

This is what the old one looked like:


Old alternator in situ with new voltage regulator:


Voltage at idle (just under 14.5V):


Dropped to 13.5 with high beams/heater but then back up to >14 with a little throttle. Massive difference to how it was previously!

Took the car on a fair motorway drive, the test will be whether it starts in the next couple of days. Here's hoping!

As such, I'll be taking back the (crap non OEM) alternator but tell the guy I want the regulator (they sell them seperately for around a tenner).

[Brianmoooore]

If you gave that inner brush a gentle pull, to straighten out the wire braid holding it in place a little, it would work again happily for months.
I once watched an RAC man spend most of a Sunday afternoon discovering this.

[bpowell555]

My pas was causing the lights to dim at full lock parking, was well chuffed to trace it back to the brush pack

[George]

If you gave that inner brush a gentle pull, to straighten out the wire braid holding it in place a little, it would work again happily for months.

Double checked this. The brushes are actually worn asymmetrically (!), no amount of pulling would get the shorter one out.

[Brianmoooore]

If you gave that inner brush a gentle pull, to straighten out the wire braid holding it in place a little, it would work again happily for months.

Double checked this. The brushes are actually worn asymmetrically (!), no amount of pulling would get the shorter one out.

They usually do wear asymmetrically because the speed of one brush on the commutator is much higher on the one furthest from the centre shaft.
You don't need to pull the most worn brush out to match the other one - just a fraction of a millimetre further out will give a few months extra life.

[George]

If you gave that inner brush a gentle pull, to straighten out the wire braid holding it in place a little, it would work again happily for months.

Double checked this. The brushes are actually worn asymmetrically (!), no amount of pulling would get the shorter one out.

They usually do wear asymmetrically because the speed of one brush on the commutator is much higher on the one furthest from the centre shaft.
You don't need to pull the most worn brush out to match the other one - just a fraction of a millimetre further out will give a few months extra life.

Ah right, I thought I'd be looking at the shorter one puling out to the same length as the longer one.

Either way, the new voltage regulator is on and seems to be working well.