Rebuild stock Alternator, or buy AL129X?

[BIMMERBOYZ]

I had the pleasure of removing my Alternator/PS bracket as one of the bolts sheared off inside. Causing the alternator to be at an angle.

Should I rebuild the stock alternator? Or just buy a AL129X and drop it in?

Anything I should look at with the PS pump, while it's out?

[Hit Man X]

Well, you know I am bias toward the AL129X 115A unit as a quick, no hassle, drop in upgrade for the stock 80A (AL46X?) or the late production 90A (AL49X). 25-35A gain for basically the same money. Toss on a smaller alternator pulley and gain a bit more ass at idle too. I just do not recall which belt I used when I upgraded it, either the 13x1040 with the smaller water pump pulley or the standard 13x1055 with the big water pump pulley.

Do a write up please.

NOW, the E32/34 came with larger alternators from the factory. 115A to 140A. AL143X and AL148X. These do fit the E23 bracket with some farting around with extra washers. Too much hassle for me, so that is why I recommend the AL129X for a no fuss upgrade and that thing with a 2.5" pulley can pretty much keep up with pretty everything you may have on the vehicle (HVAC on high, headlights, rear defroster, heated seats, etc)...unless you have a huge stereo or really high wattage lamps which will probably not be able to keep up at idle. Off idle at 1000-1500rpm should be able to keep up. I have that same 115A on my 560SEL and it is able to stay around 12.80 volts at hot idle with everything on (including all four seat heaters).

I am trying to force Kent to TIG a B35 upper bracket (the alternator portion) to a B34 lower bracket (hydraulic pump portion) for the ability to use the 140A from the E32 with no hassle.



Did that help?

[BIMMERBOYZ]

Yes, the Bosch units I've found for the AL129X are around 200$, a rebuild is about 80$. I will keep looking for a better price on a Bosch unit.

[JimmysE23]

What did the AL 129x come on?

[offroadkarter]

What did the AL 129x come on?

I believe a Saab

I did the AL129X swap, bought it from FCPEuro. All I had to do was transfer the noise filter over and tweak the fan a little since it rubbed,otherwise it bolted right on.

[Hit Man X]

Yes, a Saab. Late '80s 9000 model.

[1981320i]

I am trying to force Kent to TIG a B35 upper bracket (the alternator portion) to a B34 lower bracket (hydraulic pump portion) for the ability to use the 140A from the E32 with no hassle.

Let me first get my TIG machine and then become confident with it lol!

[750i]

You can always drop your stock alternator off at a shop and have them rebuild it to a higher spec. Odds are strong that you will end up with a better performing alternator with higher quality parts than the parts-house alternators. Local guy here does OE+ rebuilds for $100-ish and all new parts. Had the old 60amp Hitachi on my Datsun putting out 110 at ~1000rpms.

[BIMMERBOYZ]

I've had the one in my 535i rebuilt. As well as a few cars. I'll probably just do that.

[Hit Man X]

I never had good luck with over built small ones and idle output. For instance, I had a 200A large case 3G built for my F150 idle ouput was crap. 1000-1200rpm was fine, but in stop and go traffic the aftermarket volt meter would swing...and the HVAC fan would speed up and down along with headlights dimming and brightening. Two different brands, same results. Took it out and just tossed in a stock, large case 130A unit. Better output at idle and lost a bit of max output. Meh.

That is why I like that AL129X, it is physically larger so it makes more power with less effort (like driving a vehicle with a bigger engine, just easier to motor about). If you still want one rebuilt, I am sure you could squeeze that one to make 130-150A pretty easily.

[BIMMERBOYZ]

I haven't decided what I will do as of yet. I am waiting on a high pressure power steering hose I ordered. It won't arrive until Dec 10.

[offroadkarter]

Just get the AL129X, I agree with Eric on cramming higher amp internals in a small case. High amp alternators have bigger cases and better cooling properties to deal with the added heat. I had a 160A alt on my Marauder (stock is 130A) and it literally exploded inside after 5000 miles.

[Dirtboy Nay]

What's up Guy's and Gals. I Need a little help here. I'm want to Buy the Saab Alternator - Bosch AL129X for my 85 BMW E23 745i. I would like to add the 2.5/2.3 smaller pulley and I would also love to add the smaller water pump pulley for the additional cooling factor. THERE'S ONLY ON PROBLEM. I Have No Idea WHAT I'm looking FOR and WHERE DO I FIND IT. Part Numbers and Source would be very Helpful. HELP Thanks

[BONDOSPECIAL]

https://www.fcpeuro.com/products?utf...eywords=AL129X

Is your car stock? If so, I don't know why over driving the accessories would be necessary especially for the water pump and in your climate, where the cooling system is not going to be taxed. Over driving an accessory that doesn't need it is wasting hp.

[Hit Man X]

Biggest benefit of the 130mm water pump pulley is more distance between the pulley and the lower radiator hose.

Side benefits are more air through the condenser and radiator, plus a bit more coolant flow. That pulley was standard on all M30s starting around the 1988 model year from what I have seen. Hell, late E23s got the better crank pulley to overdrive the AC compressor a bit more at idle.

[BONDOSPECIAL]

It's so funny to me because performance builds are usually trying to underdrive accessories to free up hp. Look at all the billet underdrive accessory kits that exist for the popular domestic platforms.

[Hit Man X]

Agreed 100%.

The A/C one only hurts power with the A/C on, and there are probably 10 E23s in the US with working HVAC...including ours. I run the other on all vehicles I own and build.

[smitherz]

Agreed 100%. The A/C one only hurts power with the A/C on, and there are probably 10 E23s in the US with working HVAC...including ours. I run the other on all vehicles I own and build.

My HVAC works on my '79.

[espoe]

My A/c works too And I tell you, I'll take the small power reduction to have A/C any day of the week where I live. My A/C was working well and it's still nearly worthless in town so I'll take all the help I can get.

[Hit Man X]

My A/c works too And I tell you, I'll take the small power reduction to have A/C any day of the week where I live. My A/C was working well and it's still nearly worthless in town so I'll take all the help I can get.

86 evap, 86 condenser, 130mm water pump pulley, 86 crank pulley, A thermostat housing. Those all will help quite a bit.

S38 fan with three core radiator, B35 fan with two core radiator.

[espoe]

86 evap, 86 condenser, 130mm water pump pulley, 86 crank pulley, A thermostat housing. Those all will help quite a bit.

S38 fan with three core radiator, B35 fan with two core radiator.

Got the fan and at least one of the pulleys. Not sure about the crank. I've got the 3 row radiator. When I finally get the car back from the paint shop, (held up by windshield gasket issues and installer stupidity) It will be easier for me to investigate the crank pulley and condenser. The evaporator will also be easy since the whole interior is out. With all of that air flow is still not strong through the smallish vents. Ill do another thread on that when I get it back.

In the mean time I am going to swap out my alternator for sure. Something else to consider is after all this time the degradation of the wires, connectors and the actual build up on every connection. I am going through my whole car and cleaning up every connection I saw while the interior is out. A little extra oomph is needed just to stay even. If there is anything extra like audio or higher watt headlights, you'll notice the system struggle a little. Nothing bad for sure will come from the upgrade.