Alternator Mounting Holes Larger Than Necessary

[Captain Obvious]

I took my alternator off and in the process, I noticed that the lower bolt holes are significantly larger in diameter than they need to be. In other words, the bolts fit through the holes and there's still a lot of wiggle room. The lower bolts could be larger in diameter and still fit.

I've seen this done on other cars where they pressed in a tight fitting bushing into the holes that slide a little bit as the bolts are tightened. These bushings account for the fact that they can't hold the tolerance on the distance between the alternator mounting holes.

But, I don't have any of these bushings on my alternator and I'm wondering if this is normal, or if I'm missing pieces. I'm wondering if my PO got this rebuild and was supposed to move something over from the old one to this one?

Here's the alternator:

And here's the lower bolt holes in question:

[Arne]

Some of the later alternators had these larger holes. I saw this on the ZX alternator that came in my yellow 240Z. While you can use it as is in a pinch, ideally you'll want some sleeves of some sort in the holes to locate things better. In this case, any sleeve you use should be slightly shorter than the thickness of the mounting ear.

[Captain Obvious]

Thanks Arne. Out of curiosity, any ideas as to what constitutes a "later" alternator?

The reason I ask is that I compared my alternator (the one in the pictures above) to another alternator which I believe to be original from 74, and the holes on both were all the same size (bigger than necessary).

I guess it's academic though, because the answer to my original question is "No, there were no spacers or bushings used", right?

I'll make some bushings for mine. I'll make one of them shorter than the ear is wide (like you suggested), but I'm thinking I'll include some feature on the other ear to make it a more snug fit on the mounting bracket. It's loose enough now that I'm concerned I'll crack an ear off if I torque that sucker down without some kind of spacer in there. My PO used a washer, and if I'm going to make bushings, I can do better than that.

[MotoManMike]

There are Two Versions Here - The Standard Stator (204-130) With a "Step" on the Rear Housing Just Above the Mounting Hole, and the Wider Stator (204-130A) With No

Short Note

NISSAN MAXIMA 1981-84 1-V PULLEY, 74MM OD, 17MM ID NOTE: RAISED REAR HOUSING SEE: 204-130A (SAME)

"Step" on the Rear. This Unit Has Special "P"-Terminal On the Rear of the Alternator. Use 14185 If No "P"-Terminal is Needed. A 14303 (With the Large 139mm Diameter Stator Stack) Looks Very Similar to This, Except the Bottom Mounting Holes are 10mm (14303) Instead of 8mm (14592), and the 14303 Has No "P" Terminal.

It would appear you have the 14303 with the 10mm mounting holes.

This info is from our internal alternator and starter cross reference database at work.

NISSAN Car & Lt Trk 280Z, 280ZX 2.8L 1981-1983

MAXIMA 2.4L 1981-1984

Edited October 18, 2012 by MotoManMike

[Captain Obvious]

Thanks for the info Mike. The terminals on my alternators are labeled F, N, E, and A. There is no "P" on either one.

Does that tell you anything?

[Jeff G 78]

The last alternator I bought came with sleeves wire-tied to the mounting ear.

[Captain Obvious]

Thanks Jeff. My alternator was installed by my PO, so I have no idea what happened... Maybe there were sleeves included and he didn't use them, or maybe there wasn't anything like that included at all.

In any event, making a pair or spacer sleeves sounds like the best plan at this point. Thanks again for the data point.

[MotoManMike]

I'm pretty sure the P terminal is a tach output. Some alternators have an output for an electronic tach that puts out about half the charging voltage or so. You definitely have the 10mm bolt hole version.

[Captain Obvious]

Thanks again Mike.

Do you have any insight into the timeline for those two alternators? In other words, was one of them the first version and then then they switched to a different version, or were those two varieties both available at the same time on different cars?