Alternator swap
Posted: Mon Sep 04, 2006 10:36 pm
Did an alternator swap and wrote it up on another forum, thought it might be useful to somebody... Of course it's easier with the motor outside the engine bay...
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Well, today was Father's Day here in Oz, a bit of a Hallmark holiday but my old man came for a visit and we took him out for lunch. He has recently had some auto electrical trouble and, thanks to a bit of a saga, wound up with a good battery and alternator left over. Both are from his EA falcon, the alternator is an 85 amp unit.
Now I have been struggling for a while with this problem, which is that the 35A stock alternator is working fine, but I can't really bring myself to put the vehicle back together with such an obviously substandard item. It was probably an okay power rating once upon a time, but it is definitely below par these days.
Soooo...
My plan was to use the pulley from the old alternator, but the "new" one had an arrangement I haven't seen before - a two-part pulley. So all I had to do was space it out a little bit in the centre to suit the larger belt from the P motor.
Then I spaced the entire pulley forward a little. Basically all of this shimming was done by rearranging the existing washers.
Above image shows a test fit. Measured as carefully as I could and found that (including the spacing I had already done on the pulley, which moved the pulley 8mm forward), I needed ~ 4mm more spacing which I achieved with two flat washers.
Naturally Kurt assisted, what with it being Father's Day and all.
The brass spacer you can see at the back of the alternator is from my broken starter motor... it was a bush.
I used a 10mm (or maybe 3/8") bolt the full length of the alternator bracket setup, this gives me more confidence that the alternator is straight than if I had used the original arrangement of a short bolt at each end. The holes in the alternator bracket were around 9mm, so I drilled them out to 10mm. The bolt fits very snugly, which means there's very little play.
The new alternator is a 14V/85A internally regulated unit, so I will be able to ditch the stock regulator as well. As with most alternator swaps, this is pretty straightforward and easier than people seem to think. I'll worry about the wiring later, it won't be difficult though.
The alternator is from an Aussie EA/EB Falcon, some are 70A so if you are looking at them, try to grab the 85A one instead; they'll probably cost the same and they are identical other than the rating and presumably some internal parts. They are cheap at wrecking yards and are made locally by Bosch Australia. I also happen to think that the fan arrangement at the front, right behind the pulley, suits a 4WD well since it tends to repel water coming from the front and especially from the engine fan.
That's pretty much all I achieved for the weekend and it was only a 1 hour job really...
EDIT:
Just thought I'd add a bit about how you need to line up the pulleys.
The new pulley needs to be in line with the existing ones, this means (a) it can't be at an angle at all, and (b) it has to be spaced forward exactly the right amount.
In practice, you can avoid having anything at an angle if you use the existing bracket work the way I did - and this is usually possible if you choose the right alternator to swap in onto your bracket. Even if you make a completely new bracket you are okay if you are careful to keep it level and square. In other words it's just a case of care during fabrication and not measurement as such. When you drill holes, don't allow extra for the bolts, make them very tight around the bolts so that when you tighten the belt later, it cannot pull the alternator so that the bracket moves on the bolts at all. (You can use some rulers on the pulleys as below to check for angles but you shouldn't need to if you are careful with the brackets. If you do need to do it, just use a ruler on each pulley and make sure they are parallel, and remember to do it both "across" and "up and down".)
As for spacing the alternator forward or backward, the best way to do this is to test fit the alternator to get it pretty close, then add or remove your spacing washers until it's right. How do you know when it's right? Well, your main crank pulley is a nice and straight and square, so if you put a steel ruler against it, the ruler should be perfectly parallel with the belt on its way to the alternator. See:
This photo distorts things a bit, the belt and the ruler are actually parallel; you have to look at them straight on to be sure.
------------------------------------------------------------------------------------------------
Well, today was Father's Day here in Oz, a bit of a Hallmark holiday but my old man came for a visit and we took him out for lunch. He has recently had some auto electrical trouble and, thanks to a bit of a saga, wound up with a good battery and alternator left over. Both are from his EA falcon, the alternator is an 85 amp unit.
Now I have been struggling for a while with this problem, which is that the 35A stock alternator is working fine, but I can't really bring myself to put the vehicle back together with such an obviously substandard item. It was probably an okay power rating once upon a time, but it is definitely below par these days.
Soooo...
My plan was to use the pulley from the old alternator, but the "new" one had an arrangement I haven't seen before - a two-part pulley. So all I had to do was space it out a little bit in the centre to suit the larger belt from the P motor.
Then I spaced the entire pulley forward a little. Basically all of this shimming was done by rearranging the existing washers.
Above image shows a test fit. Measured as carefully as I could and found that (including the spacing I had already done on the pulley, which moved the pulley 8mm forward), I needed ~ 4mm more spacing which I achieved with two flat washers.
Naturally Kurt assisted, what with it being Father's Day and all.
The brass spacer you can see at the back of the alternator is from my broken starter motor... it was a bush.
I used a 10mm (or maybe 3/8") bolt the full length of the alternator bracket setup, this gives me more confidence that the alternator is straight than if I had used the original arrangement of a short bolt at each end. The holes in the alternator bracket were around 9mm, so I drilled them out to 10mm. The bolt fits very snugly, which means there's very little play.
The new alternator is a 14V/85A internally regulated unit, so I will be able to ditch the stock regulator as well. As with most alternator swaps, this is pretty straightforward and easier than people seem to think. I'll worry about the wiring later, it won't be difficult though.
The alternator is from an Aussie EA/EB Falcon, some are 70A so if you are looking at them, try to grab the 85A one instead; they'll probably cost the same and they are identical other than the rating and presumably some internal parts. They are cheap at wrecking yards and are made locally by Bosch Australia. I also happen to think that the fan arrangement at the front, right behind the pulley, suits a 4WD well since it tends to repel water coming from the front and especially from the engine fan.
That's pretty much all I achieved for the weekend and it was only a 1 hour job really...
EDIT:
Just thought I'd add a bit about how you need to line up the pulleys.
The new pulley needs to be in line with the existing ones, this means (a) it can't be at an angle at all, and (b) it has to be spaced forward exactly the right amount.
In practice, you can avoid having anything at an angle if you use the existing bracket work the way I did - and this is usually possible if you choose the right alternator to swap in onto your bracket. Even if you make a completely new bracket you are okay if you are careful to keep it level and square. In other words it's just a case of care during fabrication and not measurement as such. When you drill holes, don't allow extra for the bolts, make them very tight around the bolts so that when you tighten the belt later, it cannot pull the alternator so that the bracket moves on the bolts at all. (You can use some rulers on the pulleys as below to check for angles but you shouldn't need to if you are careful with the brackets. If you do need to do it, just use a ruler on each pulley and make sure they are parallel, and remember to do it both "across" and "up and down".)
As for spacing the alternator forward or backward, the best way to do this is to test fit the alternator to get it pretty close, then add or remove your spacing washers until it's right. How do you know when it's right? Well, your main crank pulley is a nice and straight and square, so if you put a steel ruler against it, the ruler should be perfectly parallel with the belt on its way to the alternator. See:
This photo distorts things a bit, the belt and the ruler are actually parallel; you have to look at them straight on to be sure.
