What's wrong with my nut? (alternator)

[lateapex911]

OK, the issue: New alternator nut from Pelican...Porsche, part #: 90160390501 doesn't fit. It is listed on the site as 16 x1mm

My alternator (from originally a 1973 911E is, I believe, a Motorola. I *think* I had it rebuilt in 1996 in Glendale CA...and it has a brown rectangle inset in the upper part, with a tab marked DF, and 5 bolts arrayed from 9 o'clock to 3. The bottom 3 are on a raised semi circle that's red (has fins on the back (interior to the alt) side. it's marked "D+/61" at the 8 o'clock position and "B+" at the 6 o'clock position. On the alt body, the bolt at 9 has no markings the one at 3 says "D"

And the shaft....is: (Outside diam) 15.9mm x 1mm thread pitch as measured. The inside (deep part) of the thread is 15.54mm.

I describe all that as it might be a clue to somebody who knows old alts!

So, the Porsche nut bag matches the art number ordered. But the nut won't thread on. It measures 14.92mm inside diameter. (I can't measure into the threads) But the thread npitch is correct at 1mm. The face to face of the exterior is 21.98mm, which is odd because the web lists all 16mm nuts as 24mm face to face (where the wrench goes). Which might be a custom Porsche thing,? It's 8.02mm thick.

So, the matching numbers (to my mind) should be the inside nut diameter and the deepest part of the thread diameter of the shaft. Seems to me the nut has to be a tad bigger than the shafts deepest diameter. But I'm the opposite: Shaft minimum is 15.54mm. the nut minimum is 14.92mm.... nut needs to grow by .62mm

Whats going on???


More random info...my not exhaustive digging shows this is the largest of alternator shafts, others are 14mm

What to do??

Sadly I don't happen to have a 16mm x 1 thread tap.
is this just a plating build up Seems like thats a LOT.

Or am I some idiot here?

(I lost the OE one after getting it plated ...the tensioning washer too! Arrrg. )

What say the Pelican experts??

[manbridge 74]

The old alt nut has 22mm between faces and is 1.00mm thread pitch. The 24mm nut won’t thread on because it is 1.25mm pitch. (The part about the pitch is from memory - I’m not at work, but I know the two nuts are different threads)

Edit: I see you received a 22mm nut…. Let me know if you still need one Monday and I’ll see what I have in the old bin and measure….

[Dpmulvan]

Kastar spindle retread part#2599

[Dpmulvan]

Trouble locating a new fan pulley nut

[Dpmulvan]

Try this https://www.fvd.net/us-en/90160390501EQ/alternator-pulley-nut-911-930-1965-81-m-16-x-1.html
High-quality replacement, designed to perform like the original. We source this part in Germany to ensure quality, reliability and precise fitment.

Sold Individually. 1 Necessary Per Car.

Please Note: Please check the model fitment tab to ensure accurate fitment. Motorola Alternator Only

[JimmyT]

FS: 911 Alternator Shaft Nut, M16, 901.603.905.00, $5.07

[lateapex911]

Originally Posted by manbridge 74

The old alt nut has 22mm between faces and is 1.00mm thread pitch. The 24mm nut won’t thread on because it is 1.25mm pitch. (The part about the pitch is from memory - I’m not at work, but I know the two nuts are different threads)

Edit: I see you received a 22mm nut…. Let me know if you still need one Monday and I’ll see what I have in the old bin and measure….

Yea. I don't know exactly what I got! I DO know it's 1.0mm pitch. Matched my pitch gauge perfectly. But at 14.9mm nut ID, it's not screwing on a 16mm shaft.

So, I think I can safely conclude that Pelican has mis marked that. It's a Porsche OE part... but it is NOT 16mm x 1mm jamb nut.

I think I found them on McMaster Carr:


Steel Thin Hex Nut
Fine-Thread, Low-Strength, Zinc-Plated, M16 x 1 mm Thread
90326A203

[lateapex911]

Originally Posted by Dpmulvan

Try this https://www.fvd.net/us-en/90160390501EQ/alternator-pulley-nut-911-930-1965-81-m-16-x-1.html
High-quality replacement, designed to perform like the original. We source this part in Germany to ensure quality, reliability and precise fitment.

Sold Individually. 1 Necessary Per Car.

Please Note: Please check the model fitment tab to ensure accurate fitment. Motorola Alternator Only

Thanks..
minimum order is $50. (Plus it says it comes form German warehouse, soooo....)

I chased down the links in the other thread, but that was 2009, and the Scacremento company didn't show any results in their search bar for that part #. And the other link was dead.
We'll see how the McMaster Carr ones work.

[lateapex911]

Originally Posted by JimmyT

FS: 911 Alternator Shaft Nut, M16, 901.603.905.00, $5.07

Yea....not sure how I'd order that..is that an individual selling them??

I think I found a 5 pack...and they say it's going to be here Tuesday.

crossed fingers
Have to call pelican and tell them the part doesn't match the description. grrrrr

[smadsen]

This is easy, quick, & cheap. Go to a competent hardware store, Ace, Home Depot, Lowes. They all have a large selection of metric nuts & bolts. Buy a metric thread pitch measuring gauge and a tool with a bunch of holes in it to measure bolt & stud diameter. Go home & determine the diameter of the threaded part of the alternator shaft (don't pay any attention to the hex part you put the wrench on, it's irrelevant). Then determine the thread pitch with your new tool. Then go back to the store and buy one nut to fit your shaft. The nut description will be express as the diameter X thread pitch.

[lateapex911]

thanks...but I already did that... I already own the pitch gauge. Bolt (alt shaft) is 16mm, thread pitch is 1mm.

No local hardware store has a jam nut in 16mm x 1 mm, it's very rare.

[Shaun @ Tru6]

Is this what you are looking for Jake? I've got a lot of various alternator nuts if you can't find one.

M16 x 1.0 jam nut

[Dpmulvan]

Originally Posted by smadsen

This is easy, quick, & cheap. Go to a competent hardware store, Ace, Home Depot, Lowes. They all have a large selection of metric nuts & bolts. Buy a metric thread pitch measuring gauge and a tool with a bunch of holes in it to measure bolt & stud diameter. Go home & determine the diameter of the threaded part of the alternator shaft (don't pay any attention to the hex part you put the wrench on, it's irrelevant). Then determine the thread pitch with your new tool. Then go back to the store and buy one nut to fit your shaft. The nut description will be express as the diameter X thread pitch.

You try it.

[Dpmulvan]

This doesn’t pertain to OP but thought it might be useful to others.

[lateapex911]

Originally Posted by Shaun @ Tru6

Is this what you are looking for Jake? I've got a lot of various alternator nuts if you can't find one.

M16 x 1.0 jam nut

Hey Shaun!
So ironic that you responded...it's the nut and tension washer I had you replate for me...and I can't find them! Arrrrrggggg. SOOOOOOoooo mad at myself!

The strap you did looks great on my Cerakoted fan housing.

I've ordered a few of those from McMaster Carr and they should be here tomorrow, if they don't show up or are wrong, I'll let you know, thanks!!!!!!
(The downside is the McMCarr one lacks the nice plated appearance of the one you did for me...sigh. It will probably show up at some point)

[Locker537]

McMaster is awesome.

After ordering a bunch of things from there, you end up with your own hardware store. That's a pro or a con depending on your perspective.

You need 3 bolts and end up with 25.

[lateapex911]

True, and I LOVE when I'm making something and I go to my organized compartments and find stock in what I need (Oh, say M5 button head allen screws, in stainless) I feel like the boss LOL.

But the key is being able to go where they should be and put your fingers on them in 3 minutes. That's the hard part, organization!