How to: Replacing Alternator Bearings

Discussion in 'Z32 Technical' started by bRACKET, May 9, 2013.

  1. bRACKET

    bRACKET Do Right Dean

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    This is a how to on replacing your Alternator bearings. Excuse the phone pictures, I really need a decent camera :(

    Please note, these bearings were a direct replacement for me 90A TT alternator, I'm unsure if these bearings will fit a 80A NA alternator.

    Tools/Materials Required:
    -8mm Socket
    -22mm Socket
    -Philips Head Screwdriver
    -Bearing Puller (Makeshift or Proper)
    -Press or Hammer :p
    -Contact Cleaner
    -New Bearings (B15-86ATIXDDG3W-G01 & B8-85T12DDNCXMCBE)

    These are the two bearings you need. The brand is NTN, when I called up the bearing wholesaler I use and quoted him the sizes, he gave me the above numbers for ordering. Both bearings cost me a grand total of $14, so this isn't exactly expensive. The bigger one is the one we'll be replacing first.
    [​IMG]

    This is what your starting with. (Not mine, got this image from Google :eek:)
    [​IMG]

    Use the 22mm socket to remove the large nut on the shaft holding the pulley in place. It isn't reverse thread, just standard lefty loosey type thread.

    There are four bolts holding the "face" of the alternator onto the main body of it. Use the 8mm socket to remove the four bolts. Then you get this

    [​IMG]

    The first step to removing the bearing in the face is to remove the plate on the inside of the face. Using a Philips head screwdriver, undo the four screws on the face. Picture of the plate you will be removing.
    [​IMG]

    PRO TIP; These screws are mega tight, and I rounded two of them off whilst trying to undo them. I replaced them with flat head screws to make removal next time easier.
    [​IMG]

    Clean the face as best as possible. Don't worry about wetting the bearing as you'll be replacing it anyway.

    Once the plate is off, get a bit of pipe that's just smaller than the alternator face. This will be used as a pin punch type tool to knock the bearing out of its housing in the face. The pipe I used can be seen a few pictures up.

    Knock the bearing out and clean the bearing housing. Rest the new bearing in its spot and push it in as much as you can with your hands. Mine went in about half way before I had to use a soft hammer and knock it down the rest of the way. You'll be left with this.
    [​IMG]

    Replace the plate and that's the face done!

    Next up, you have to pull the armature out of the main body of the alternator. The armature is the middle bit that spins inside the body. To remove it, there are NO bolts or anything holding it back, just use some force and pull upwards and it will come out of the housing.

    This is the armature once out of the housing.
    [​IMG]

    The second bearing that needs replacing is on the bottom of the shaft. There are a few ways to remove this. The first is the legit way, by using a bearing puller. This kit is around $150 (for quality) and will get the job done with zero damage to the shaft. While this is the best way to do it, it's also the most expensive assuming you don't have the kit already. Another way to do this is to support the bearing from underneath with some metal, then hammer the shaft out with a pin punch. This is how I did it, then I went and got a bearing puller to make life easier.
    [​IMG]

    Once this second bearing is off, give the commutator (The part that makes contact with the brushes inside the alternator, looks like a bearing but doesn't move) a quick rub down with some 1000grit wet and dry sand paper, just to clean it up.
    [​IMG]
    All cleaned up!

    Luckily for me I have access to a press. This is needed to press the new bearing onto the shaft. If you can't get your hands on a press, a hammer will do the job, but it'd be a last resort type thing for me.

    Put the bearing on the shaft and press it down.
    [​IMG]

    Make sure that the dust cover is on before you press the bearing on, no way to get it on if you forget (Unless you pull the bearing off again)! When pressing the bearing on, make sure it isn't all the way down the shaft, or it will contact the dust boot and make noise when reassembled. Press it down most of the way, the pull it back up until the desired result is reached. You can test if it will hit by putting the armature back into the housing and putting the face on and spinning the armature. If you can hear noise or it doesn't spin freely, you've put the bearing on too far down.

    Now that all the bearings are replaced, hit the alternator with contact cleaner. Don't be afraid to get into the cleaning with contact cleaner, as it is proper electrical cleaner and will evaporate and leftover, whilst not harming and electrics, perfect! This was mine before cleaning.
    [​IMG]

    Once it's all clean, you're ready to put the armature back into the housing. To do this, you must hold the brushes back with a small piece of wire, so that the shaft with bearing can sit all the way back in the housing, as per THIS THREAD.

    Will look like this when you're done.
    [​IMG]

    Before bolting the face back to the main body, make sure to put the spacer on the shaft. Can be seen in this photo.
    [​IMG]

    Once the spacer is on, put the face over the top and secure down using the 8mm bolts that you took out at the start. Don't over tighten these as they snap easily, don't ask how I know :rolleyes:

    Then you're done!
    [​IMG]

    Nice and clean, with brand new bearings, your alternator should be noise free for years to come :) Note there is no pulley installed on mine as I'm waiting for my lightweight pulley to come from CZP.

    :zlove:
     
  2. tassuperkart

    tassuperkart Its a lie I tell you!

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    Just a bit of a different approach here.
    The front pulley nuts are large and if the alternator is unmolested, bloody hell tight and often the pully gets damaged by either grabbing it in a vise or with large multigrips...not good.
    To make life easy, AND to avoid damaging the front pulley by grabbing it, is to undo and remove the housing screws and drop the bottom housing off FIRST.
    Then you can securely grab the armature in a vise and heave or even rattle the pulley nut off which are often hell tight.
    Do the reverse on assembly and your grinning.

    E
     
  3. bRACKET

    bRACKET Do Right Dean

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    Great advice, never even thought of that.
     
  4. Anti

    Anti 14.7 x 14.7 = 44.1

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    Wow, great write up man! This really simplifies it. Food for thought!
     
  5. rob260

    rob260 Moderator Staff Member

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    Nice work
     
  6. z-alot

    z-alot Member

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    Great write up! Please PDF it up with pictures and send to Tech Section :)

    This will be on my list of things to do :D
     
  7. badxtc

    badxtc kirby's bitch

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    yeah whatever , its ok , pppffffff ;)
     
  8. stevearm77

    stevearm77 NA Compression + TT Boost

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    great write-up mate!

    I don't seem to be having much luck with those bearing numbers though through my local supplier, do you have another number for them like 6302 or similar? or bearing sizes?

    Cheers!
     
  9. bRACKET

    bRACKET Do Right Dean

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    I had them, will try get the information for you tomorrow :)
     
  10. strange zed

    strange zed Member

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    big thanks to you braket, helped me out greatly. numbers worked for me :)
     
  11. bRACKET

    bRACKET Do Right Dean

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    Glad I could help :)
     
  12. Mitch

    Mitch Has one gear: GO

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    5.5yrs later, bearing numbers still current at my local bearing supply. Current cost about 18 clams for 1off each bearing (2 total).
    Front housing bearing came out without a fight. Rear bearing on the armature needed some coaxing with a strategic cut with a 1mm grinder cutoff wheel, and a blow with the cold chisel.
    Reassembly was simple- scuff all faces with some very fine emery paper - I had 1500grit on hand. Heat up the front casing and bearing drops straight in (I used sparing heat from a MAPP gas torch).
    Rear armature bearing a booty-fabbed in with my ghetto-press - a 12T bottle jack, a socket, all perched inside an old steel car rim.

    For clean up I can recommend CRC electra-clean. Bronze brush to scuff all the crud up, and a few sprays on to a paper towel to wipe it all down. When it's fully disassembled, easy to go the extra mile with paint, sandblasting, or chroming if you wished.
    For reassembly, refer to the paperclip trick in this thread: https://aus300zx.com/xenforo/index.php?threads/replacing-alternator-bearings.324640/

    NB... if you've fully pulled it apart, and it's a bit crunchy when it goes back together, check the heavy wires from the windings are not interfering with the rear fan blades. they may need to be pressed in or pushed back down (I used a few gentle taps with a pin punch).

    Thanks for the write-up Dean.
    I rate this as a 6-beer job.
     
  13. Sanouske

    Sanouske Retired Moderator

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    wow, haven't been on the forum in a long while and I see familiar users popping up all over again.

    Is the band getting back together.

    Furthermore, good write up! Albeit 5 years back
     

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