EA to EJ alternator on EA81 - How to

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El_Freddo
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EA to EJ alternator on EA81 - How to

Post by El_Freddo » Mon Oct 12, 2020 10:23 pm

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How to swap your EA81 alternator to an EJ alternator:


Image


Basic details:

- use pulley from EA81 alternator
- make a 7mm thick bush (cut down the bush on the EA alternator shaft behind the pulley)
- shave the front face of the EJ alternator to clear the EA pulley
- EJ alternators will bolt in place of the EA alternators without any mods or changes to bolt/mounting hardware.
- get the alternator wiring cut as close to the donor’s fuse box as possible - this applies more if going with an EJ conversion later (you want the length in the EJ alternator wiring)
- can be wired in so this conversion is completely reversible. I added a fuse box in “just in case”

Tools needed:

- 12mm socket or spanner to remove and install the alternators
- 8mm ring spanner to remove the charge wire from the back of the EA alternator
- spanner for whatever size battery terminal nut you’re using (mine is a 13mm).

Impact driver/wrench (handy, makes the job easy) with:
- 19mm and 22mm socket to remove and install pulley bolt

- some way of shaving the bush down - or get a machine shop to do it for you - they will have pinpoint accuracy too

- angle grinder with cutting disc and grinding disc - could get away with just a grinding disc.

- wiring tools - side cutters, crimpers and wire strippers

Other things needed:

- alternator wiring from donor EJ vehicle - as long as possible
- two spade connectors (blue ones)
- ~1m six gauge wiring
- ring terminals for 6 gauge wiring
- midi fuse holder and two 80amp fuses
- cable ties

How to do it:

- remove the EA alternator (ensure the battery is disconnected first!)
- remove the nut on the EA alternator shaft, put the two piece pulley aside. Bin the finned part. Pull the bush off the shaft.
- mod this bush to a 7mm thick bush
- EJ alternator - remove the nut and bin/put the flat ribbed belt aside if needing to use it again later.
- using the angle grinder with the cutting disc (or the grinding disc if you want), remove the snout piece that protrudes out from the front of the alternator around the shaft. It needs to be flat with the face of the alternator.
- fit the 7mm bush and one of the purely pieces. Mark a line around the pulley where it connects on the alternator casing. You want to shave this are down to clear the pulley. It should look something like this:

Image

^ my 7mm bush is fitted in this pic - I used the inside of a bearing to create my 7mm bush from - then I found the spacer bush on the EA alternator. Note that you need to shave down the screw heads too.

- on the charge wire mount, cut out a section of the black plastic around the stud the wire connects to. You want this to be opposite where the factory cutout section is. This is done because the charge cable will move away from the alternator in the opposite direction compared to stock.

- fit your spacer bush and the EA pulley to the EJ alternator, do the retainer nut up nice and tight. I used my electric impact wrench/driver tool (don’t keep the spring washer like I did below. It was removed later)

Image

Now is where you dummy fit the alternator to the engine and work out where to lay out your wiring. My cut section of EJ alternator wiring was not cut down any further and I added a six gauge ring end terminal to the two charge wires from the alternator and a blue spade connector on the L and the S wires. These plugged directly into the EA plug - but be sure to check out your wiring needs with your EJ alternator.

- once you have your EJ alt wiring length correct fit the end terminals. I squashed mine in a bench vice. Worked a treat.
- fit the EJ alternator wiring to the alternator and fit the alternator to the engine, put the belt on etc and tighten accordingly
- on the end of your EJ alternator wiring you can install the fuse box. I used a twin midi fuse panel/box. One fuse goes to the factory charge wire. No mods needed to this wire, it will bolt straight on.
- second fuse will be connected to a wire that taps into positive power at the starter - this is what the length of six gauge wiring is for. Crimp appropriate sized end terminals on to the wire, cover/protect with conduit and fit.

Cable tie the wiring neatly to things so it doesn’t move or rub on anything. You can find a spot or make a bracket to secure fuse panel. I used the cable ties as I’ll make something up later.

Here’s my fuse panel:
Image

^ you can see the wiring for the EJ AC - this can be stripped out if you’re keeping the EA. I’ll be looking at using the AC with a future EJ conversion, so kept this wiring.

That’s about it. It’s quiet, replacements are easy to come by and the later model alternators are quite stable. I’m looking forward to not hunting alternators for a while now!

Shout out and thanks to Subarino of Subarino Auto Electrics in WA - without his R&D knowledge I’d be stuck working it out with too much down time on the vehicle. That 7mm bush is essentially the key to this mod!

I used a Gen3 “square plug” alternator. This 7mm spacer bush will work on all EJ alternators.

Cheers

Bennie
"The lounge room is not a workshop..."
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henpecked
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Re: EA to EJ alternator on EA81 - How to

Post by henpecked » Sun Mar 28, 2021 6:07 pm

Thanks, as i have an ej20 'waiting" - I may as well look to use its alternator if i have to. Great write up.

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El_Freddo
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Re: EA to EJ alternator on EA81 - How to

Post by El_Freddo » Mon Mar 29, 2021 5:42 pm

Thanks mate.

Good to see you back on the forum! It’s been some time since your last post!

Cheers

Bennie
"The lounge room is not a workshop..."
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