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Thread: Anyone using a 90A Alternator?

  1. #1
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    Anyone using a 90A Alternator?

    Just pulled out the alternator so I could remove the support bracket that was cracked in half.......

    Time to upgrade! Anyone have info on what alternators are a direct swap?

    I have heard of people saying the S14 90A unit would work, but i don't remember if there was fabrication involved to do so.

    Post up!

    - M

  2. #2
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    I have a 90 amp one on mine but its mounted where the a/c used to go, so not a direct swap as you say. I think its from a 325, but it's the same size and shape as the 318i 80 amp one that is so popular, which means one of the mounting ears is not in the same position as the 80-83 e21 one, but you can probably make it work. I don't know anything about an s14 one.

  3. #3
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    I just bought one from Josh, and we believe it to be a close fit requiring minor grinding to the support bracket to fit.

  4. #4
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    I'm running a 90 amp alternator. I have heard of guys swapping the front cover from the e21 65 amp alternator onto the front of the early '80s 80 amp alternator so that it is a direct bolt on swap. I tried to do this with the 90 amp unit and the bolt pattern is totally different and the case is larger, so the 90 amp unit is not the same as the 80 amp unit.

    Update:
    The 65 amp alternator is Bosch part# AL44X (stock e21)
    The 80 amp alternator is Bosch part# AL46X (e30 318i and other early 80's bmw's)
    The 90 amp alternator is Bosch part# AL49X (e30 325i and many other late 80's bmw's)

    There are several options for installation. Basically the mounting ears are more centrally located on the 90 amp alternator, so the alternator body mounts too far toward the motor and interferes with the mount bracket. You can grind down the alternator mount bracket just above the lower mount and/or grind the bolt hump on the alternator body just above the lower mount ear to flatten it some. This is just a test fit/grind operation until it fits nicely. The other option which I haven't tested is to buy a longer belt so the alternator can swing out farther. This may still require some clearance grinding as you can't go very far until it hits the frame rail. I'll try to pull my alternator and get some pics sometime. Mine needs cleaned up anyway, I just slapped it on dirty in an emergency which is not my style.
    Last edited by jrcook320; 11-10-2010 at 09:10 PM.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  5. #5
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    I'm using a 90A from a 535i, I'll show you the mount I made when I can get some pics. Same deal as Josh, I put it on there with out painting the bracket so I'll remove it and paint and get some pics.

  6. #6
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    Update:

    Alternator arrived. Any tips on testing clearance or do I have to take the bracket and the alternator on and off a few times?

    I might try a trip to the parts store and pick up a longer belt and see how that works.
    Last edited by MattE21; 01-31-2009 at 06:58 PM.

  7. #7
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    This thread sparked my interest the other day, so I borrowed a GM AC Delco alternator from a buddy. I'll be now swapping one of these in to my car, especially now that I am completly rewiring it. I'll go with the simple single wire alternator.

    Anyways, all you need to do is grind down a little bit of the alternator mount bracket as it is a little long between where the bolt is and the alternator is. (I'll grab a picture when I get a moment.) And then just put a washer on each side of the alternator arm. (The BMW arm is a wee bit wider). This will give for a cheap high output alternator, that is cheaply and easily replaced.

  8. #8
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    I'll be out in my shop today. I'll post up pics of my setup this evening.

    bfc was down last night when I tried to post this. To mount the 90 amp alternator you'll need to crimp a new fitting on the end of the D+ terminal as it bolts on rather than pushing onto a spade terminal. You'll also need a longer bolt for the top mount ear. From the pics you can see where I ground the lower mount and also the raised portion of the alternator body. If I had to do it again I would grind much more material out of the lower mount and leave the body alone. I would also consider buying a belt that is the next size up so the alternator can swing away from the motor slightly.







    I while I had teh alternator out I took it apart, ground the casting lines off and wire brushed things to clean it up, then shot it with a coat of hi-temp engine primer, aluminum, then clear coat which is what the rest of my engine hardware painted with.











    Last edited by jrcook320; 02-02-2009 at 09:45 AM. Reason: Automerged Doublepost

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  9. #9
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    stupid automerge....

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  10. #10
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    thanks for the pic, josh. it's the only clear photo of a 90A alternator that i've seen.

  11. #11
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    That amount of grind is the same that would be need to occur to make a GM AC Delco unit fit. Why did you grind the alternator casing rather than the bracket, asides from that the alternator was already out?

    Like this, which is what I'll do to my bracket:
    '82 320i M10 Turbo with VEMS
    '95 525i with VEMS M50 PnP
    '99 528 Wagon

  12. #12
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    Quote Originally Posted by vtgti View Post
    That amount of grind is the same that would be need to occur to make a GM AC Delco unit fit. Why did you grind the alternator casing rather than the bracket, asides from that the alternator was already out?
    Because you have had to cut into the bracket by about 1/4" to get the clearance needed, and you have to grind right where a gusset ties in to the lower mount so you also have to shave the gusset down by the same amount. At the time I thought it might be an issue, plus I didn't want to remove the bracket since I had just had the oil filter flange and bracket off a few months before that. I've since determined that it's not a big issue and would grind solely on the bracket so swapping alternators won't requre repeat work.

    The area that you have outlined in red has no effect on structural integrity, grinding where I had to does.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  13. #13
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    Whoops, didn't read your thread close enough, I now see that you stated that you would have ground the bracket. Yeah, if you grind just the red areas in my pic, it won't affect the bracket at all, and will allow for more upgrades in the future (hint hint, for anyone who has that bracket out of their car at any point in time).
    '82 320i M10 Turbo with VEMS
    '95 525i with VEMS M50 PnP
    '99 528 Wagon

  14. #14
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    Thanks for the writeup Josh. I am going to try a longer belt and try to avoid grinding.

    CAN ANYONE TELL ME IF THESE BOLTS WERE ON THEIR CAR?


    Bolts #3,4

    Mine were missing, and i need to know what size they are so I can match something up at Ace when i go over to get longer bolts for the alternator.

  15. #15
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    Real OEM lists #3 & #4 as an M8x80mm, which would be m8 x 1.25 x 3" long.

    The stock lower alternator mount will work fine, it's an m8 x 85mm (3.25")

    The upper bolt should be something like m8 x 3" as well. I can measure mine this evening or you can measure the alternator ear and add 1/2".

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  16. #16
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    Thanks Josh. ACE Hardware had the bolts.

    I am experimenting with a longer belt. AutoZone has one that is 1m that I picked up. (The stock size is 980mm) A 990mm would be ideal, but the clowns at the parts store don't know shit and wouldn't let me rip thru the hoses on the shelf. All i asked them to do was pull me out every hose starting at stock size and go up one size. They couldn't do it.

  17. #17
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    Useing an e30 318i 80amp with e30 alternator-bracket/hardware, very simple install just use everything e30 even the belt, unless you changed your crank-pulley. Hope this helps ya' out. vibrant.

  18. #18
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    Updates: (these will also be PM'd to Josh for the DIY sticky thread)

    Thank you to Boomer for shipping me out the bracket in record time!
    Thank you to Josh for shipping out the alternator for a great price.

    -----------

    You do not need to grind anything to do this mod. The only changes:

    - Purchasing longer hardware to bolt the alternator to the bracket
    - Purchasing a longer belt
    - Changing the size of the connection on the D- wire to fit.

  19. #19
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    i'm running a 90a chevy alternator on mine. i had to do some creative grinding on the stock bracket and lengthen the adjuster arm, but it uses the stock bmw belt. also i had to make a spacer for where it pivots because the bmw bolt was a smaller diameter than the chevy one. i could have also drilled out the bracket, but i didn't want to take it off the engine. also this way i could swap a bmw alt back on if i wanted to. i used a 3 wire alt so i could hook up the gauge light too.

  20. #20
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    greaaaaaaaaaat work

  21. #21
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    Will be my next upgrade if I keep my US model 320. Then I can add a small sub amp and some BIG fog lights.

    brute

  22. #22
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    This goes out to matt especially- what is the part number for these 90 amp alternators you guys are using? AC Delco makes all kinds of different alternators for GM. either that or could you guys specify the vehicle the alternator is from?

    thanks!
    trev

  23. #23
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    I too will try and determine the alt I have. It's a later model Bosche without the rubber mount bs. I had to drill a hole and use different hardware on the adjuster bracket, and possibly grind abit, and a different length belt - I forget, it's been a few years. Nice alt though, the the Boshe regs are less than half the price of the older AC Delco regs too..


    If you're trying to make me feel better about this scenario, give it up....

  24. #24
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    So i picked up a 80 amp alternator from a 85' 318. (new they are $200, used was $70 at double 02 in hayward) I initially cut some metal from the bracket where you guys talked about. i fit it on, but it turns out that there is interference between the back of the alternator and the oil filter while using the original belt.

    since i don't feel like building an oil filter relocation quite this moment, I bought the next size up of fan belt (about 1-1/2" longer) and it fit great. it turns out that i never had to cut much (if any) from the bracket with that belt. i also have to figure out how to now fix the new alternator ear because it has the same soft rubber problems as the original alternator.

    also, the pulley is a little wider on the new alternator. it helped that the new belt i got was a little wider- so its a bit thick for the water pump and crankshaft pulleys, and a little thin for the alternator pulley. a good compromise. it works great. big difference from the little 65 amp guy.

    thanks for the help! i will take some pics if it ever stops raining....

    trev

  25. #25
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    Quote Originally Posted by jrcook320 View Post
    I would also consider buying a belt that is the next size up so the alternator can swing away from the motor slightly.
    Hey Josh,
    By that did you mean to say *all* griding would be unnecessary had you sourced a right-size belt?
    Thanks,
    Eric P.

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