"Alternator" 115 Amp Bosch AL129X works in 123s! - PeachParts Mercedes-Benz Forum

81Wagon · #1 05-05-2004, 08:20 PM

As previously discussed in this thread:
55 OR 65 AMP Alternator?

The Bosch AL129X (from a late eighties/early nineties Saab) appeared usable in 123's... Important to many of us because the stock 65 amps isn't always enough in this day and age. So, I bought one off Fastlane and installed it today.

Good news first:

It fits! It puts out a good 14.4 volts as opposed to the 13.8 of the old one. No noticeable extra drag on the engine (of course, I haven't added any more electrical load on it yet...). I'm very satisfied!

So-so news second:

The electrical connections, as you can see in the pics posted in the aforementioned thread, are different than the stock alternator. There is some rewiring involved. However, you'd certainly want to rewire it anyway with some heavier gauge wire thanks to the higher amps this thing can put out.

Also, when I say "it fits"... That's true, but the mount points are actually a good half inch or so farther apart than those of the stock alternator. This isn't much of a problem, because the mount adjuster for tightening the belts has enough adjustability in it to make up for the extra half inch. However, there is a limit to that - with the new alternator in, you can barely adjust it towards the engine enough to slip the belts on. Once the belts are on, though, you can adjust it back outwards to tighten them with no trouble.

And finally the bad news:

The electrical connectors on the new alternator are in a different place than on the stock alternator. A very, very bad place if you want to keep your AC compressor manifold hose in its stock location. It is all perfectly placed to block any access to the alternator connections.

Lucky for me, as I've mentioned in this AC thread, I'm getting rid of the manifold hose on that side anyway. So out it went... not a problem for me.

But before you get all disappointed, let me say it is probably (no guarantees) possible to work around the problem without removing that AC hose if you really try (it just wasn't worth my effort since I was doing away with the hose anyway). I would suggest grinding (or cutting) off 3/8 inch of the main electric connection bolt - that's mostly where the problem was, and all that extra length isn't really necessary anyway. Second, connect your new wiring to that bolt before you install the alternator all the way in and get blocked by the AC hose.

omegabenz · #2 05-05-2004, 11:10 PM

Nice job? Do you have euro lights? Thats a big alternator.

Are you finished with your A/C lines, post pics when you are done over on your AC thread. There are so many links from links, its like a circle of links. Oh well.

I will do this when mine fails.

81Wagon · #3 05-05-2004, 11:28 PM

My AC lines just came out today because they happened to be in the way, I wasn't actually ready to go to work on them. I guess I'd better get started though, before it gets hot again ;-).

I don't have the euro lights but I got rid of my sealed beams and put in a pair of 7 inch Cibies with 90/100w bulbs and a pair of 5.25 inch Cibies with 65/55w bulbs (for extra illumination when necessary :-). So the lights can consume a lot of juice just on their own.... one of the reasons I upgraded the alternator.

gsxr · #4 05-06-2004, 12:08 AM

Awesome! Thanks for the info & photos. And now for some better news to make you happy. You said the electrical connections on the new alternator aren't in the best place, right? Well you can unbolt the 2 halves of the alternator, rotate them 90, 180, or 270 degrees, and bolt it back up. At least I was able to do this with the larger 143A and 150A units, and they're not much different. This allows proper "clocking" so the wiring doesn't interfere with anything.

Also, with this upgrade, it's practically required to upgrade the wiring harness. Stock is a pair of 10ga wires, I think, which is way too small for 115A. I'd recommend a single 4ga which is easy to source wire and terminals for at local car stereo shops. Or at a minimum, run two 8ga wires.

omegabenz · #5 05-06-2004, 12:25 AM

Quote:

Originally posted by gsxr
Well you can unbolt the 2 halves of the alternator, rotate them 90, 180, or 270 degrees, and bolt it back up. At least I was able to do this with the larger 143A and 150A units, and they're not much different. This allows proper "clocking" so the wiring doesn't interfere with anything.

Wow, thats good to know. You should try that 81wagon.

81Wagon · #6 05-06-2004, 01:42 AM

Quote:

Originally posted by omegabenz
Wow, thats good to know. You should try that 81wagon.

That is very good to know; now there's nothing stopping anyone from using the AL129X in thier 123s if they want :-). There's no need for me to do it though; my AC hose is going to be out of the way anyway and everything is fine as installed now.

Unless you wanted me to try it to see if that really works... I was about to try it with my old alternator just out of curiosity. I'll post the results tonight or tomorrow.

81Wagon · #7 05-06-2004, 02:38 AM

I tried gsxr's suggestion on my old 65 amp alternator... Take out the four bolts and it can be rotated and bolted back together in 90 degree increments! This is still no guarantee you can rotate the AL129X (I'm not about to pull it out again just to try!), but I'm willing to bet it works exactly the same way.

So all you people looking for a more powerful alternator for your 123's have nothing standing in your way! :-)

#8 05-28-2004, 01:04 AM

Do you know of any reason it would not work on a 1979 300sd W116.
Dave S

81Wagon · #9 05-28-2004, 02:29 AM

I don't know anything about the 116. If the engine is a 617 (or I suppose more likely a 616) I'd imagine it would work fine though.

boneheaddoctor · #10 05-28-2004, 12:34 PM

Quote:

Originally posted by mattdave
Do you know of any reason it would not work on a 1979 300sd W116.
Dave S

I have a 1979 300SD, just went down to look and it has no A/C lines down the passenger side of the car when the Alternator is.

The A/C compressor is real low on the drivers side and the Alternator is real low on the Passenger side.

If it fits the brackets?????????? I don't know.

jdblann · #11 05-30-2004, 07:29 PM

I don't see why it won't work as the 116 has more room because of the AC hoses being on the drivers side. The braket on the engine is the same.

#12 06-02-2004, 01:41 AM

I am going to try to get one tomorrow at pick-n-pull. I am also going to check and see how available they are because I could get 10 or so rebuilt for free and if I had them turned so the wiring was not an issue I wonder, If I Also made a wiring harness for them. If I could not sell them and make a few bucks. What do you think is there a market for 10 at about $135 each professionally rebuilt with quality parts a wiring harness and a 90 day unconditional warranty?
Dave S San Jose

Jimmy Joe · #13 06-02-2004, 02:30 AM

Hey Mattdave,
I bet you would have a decent market with the veggy oil folks, you should put a post up at:http://biodiesel.infopop.cc/6/ubb.x?a=frm&s=447609751&f=159605551
Lots of conversions use electrical heating devices; the VegTherm draws something like 25A+.
With the 70A and 80A alternators going for $90 to $100, the high amp one should be real popular, especially with the wiring taken care of.

Heck, with all my alternator issues (used parts...) I should buy one from you.

(ps thanks for the pm, I will call tomorrow)

Mercedes Man · #14 06-02-2004, 09:11 AM

Which model of Saab should I be looking for?

pdxwaker · #15 06-02-2004, 11:57 AM

Quote:

Originally posted by Mercedes Man
Which model of Saab should I be looking for?

I found one in an '89 Saab 9000. I believe these are in '88 - '94 Sabb 9000s and '91-'93 Saab 900s. I noticed that some of the cars I scouted out had smaller alternators while some had the larger AL129x. Look for AL129X or 115A rating on a sticker on the part (hopefully still visible). I found that the easiest way to pull this was to remove a plastic panel under the passenger side fender. This provides good access to the passenger side of the engine and the alternator. I was able to pull the alternator without removing any other engine parts.

I'm still trying to figure out how to swap the flywheels (proper name?) between the original alternator and the Saab. There is a hex cutout on the shaft with a ~24mm nut holding the flywheel on. I can't quite fit my 24mm open end wrench on the nut due to clearance issues. I tried a 24mm deep socket with a hex wrench through the middle of the socket (vice grips turning the socket). This didn't work... any tips on removing this flywheel?