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MN Lady Bug
Samba Member
Joined: May 29, 2014
Posts: 33
Location: Minnetonka, MN
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 Posted: Sat Jul 12, 2014 4:17 am Post subject: Stripped Alternator Pulley Threading |
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Running a 1978 Super Beetle Convertible.
So....weird problem. When I was driving the other day, I heard a
'flapping' sound when at idle at a traffic light. It almost sounded like when a car has too much bass and the panel rattles, and at first, I thought that it must have been a surrounding car
Anyway, I got home and opened the engine compartment to check that everything was okay. What I found was not okay.
My belt had gotten really loose, including the pulley (and probably because the pulley was loose). One of the shims on the outside of the pulley had sheared off partially, and the other outside shims were no longer centered behind the disc that is behind the nut.
I backed off the nut so that I could get everything taken care of and it was hard to turn (I have had it off before and knew there was no reason it would be hard to turn once loosened). By the time I got the nut off, the end of the threading on the shaft was totally screwed up, stripped, whatever. It seemed that some of the metal for the shim had gotten in the nut or something and I destroyed the threading as I backed off the nut.
Questions - has anyone ever heard of this? Any idea what I did wrong? I had my belt tightened to spec and it wasn't squealing at all before I discovered the problem (just the flapping noise).
I think that I am stuck with doing a new alternator now as this threading is not coming back. Any thoughts on if I did something wrong?
One other piece of information. I do think that I am running a little warmer than I should, but not a ton. I would expect the belt to be able to stay the right tightness, I am not OVERheating. When I had the engine out last, I had to do a new generator stand, and the stock belt size was too loose even with no shims, so I am running one belt size smaller than stock. |
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MN Lady Bug
Samba Member
Joined: May 29, 2014
Posts: 33
Location: Minnetonka, MN
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| Posted: Sat Jul 12, 2014 4:22 am Post subject: |
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| One more piece of information. There was no washer between the nut and the 'rounded disc/plate' that sandwiches the extra shims between the pulley and the rounded disc. Please tell me that i didn't forget to put it on when I put this back together, causing this problem of loosening up. |
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jlex
Samba Member
Joined: January 23, 2009
Posts: 2902
Location: NW Pennsylvania
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| Posted: Sat Jul 12, 2014 5:54 am Post subject: |
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I haven't done it, but why couldn't you just re-tread that shaft using a tap & die set?
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jlex.
'70 std. "Elsie"
'88 Carrera |
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jlex
Samba Member
Joined: January 23, 2009
Posts: 2902
Location: NW Pennsylvania
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| Posted: Sat Jul 12, 2014 5:58 am Post subject: |
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| MN Lady Bug wrote: |
| One more piece of information. There was no washer between the nut and the 'rounded disc/plate' that sandwiches the extra shims between the pulley and the rounded disc. Please tell me that i didn't forget to put it on when I put this back together, causing this problem of loosening up. |
On my generator, I have the nut, a cone-shaped metal piece, shims, then the outer half of they pulley.... I have no washer between the nut and the cone-shaped shim holder...
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jlex.
'70 std. "Elsie"
'88 Carrera |
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Harleyelf
Samba Member
Joined: April 23, 2009
Posts: 1572
Location: Appleton, WI
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| Posted: Sat Jul 12, 2014 6:11 am Post subject: |
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Are there good threads near the tip of the shaft? At least three or four of them?
Just get another nut and use the old nut as a spacer. I did this five years ago to my bus and it hasn't given me any trouble. |
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 31378
Location: Hot Arizona
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| Posted: Sat Jul 12, 2014 7:59 am Post subject: |
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| jlex wrote: |
| I haven't done it, but why couldn't you just re-tread that shaft using a tap & die set? |
I've done this on my generator, about 8 years ago, fine.
Since you'd be "deviating" from what the purists may think, don't overlook that cutting SAE threads on that shaft may be possible too. I'd cut to the next smallest size regardless. For example: if such threads are 10mm, next smaller size would be 3/8 inch (about 9.5mm).
Anyway, using a die would probably work better than trying to do similar with a new nut; but a stainless steel nut would be stronger than the shaft steel.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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