Is there a way to repair the threads on the alternator shaft?

[Evans, Marv]

I have heard of some who have had the shaft redone with a tap to a thread pitch they could get a nut for, although all of the threads weren't exactly complete after that but seemed to work OK. I've also heard of having the threads turned off of the shaft and then the shaft rethreaded. I just bought some m16x1.5 nuts from McMaster-Carr. I didn't think to look for an m16x1.0 at the time. I think they probably didn't have them either.

[SpeedracerIndy]

I looked on McMaster Carr and couldn't find one. That's the first place I thought of. As I said above, I already solved my dilemma by buying a rebuilt alternator off the classifieds since my bearings are shot also.

I wonder if this would work: http://www.amazon.com/Help-05186-Spn-T-Locknut-M16X1-0/dp/B000COB3YQ

I can't tell what grade it is, but for $6 it might be worth a try.

[David E. Clark]

Originally Posted by marlinaness

depending on the year, you will not be able to find a new nut. I had to pick up on in Stuttgart. for the older ones e.g. 70 or 71 they are 16mm x 1.0 mm pitch and for others 17 x 1.5 pitch. Nobody had the 16mm x 1.0. A nice german repair shop owner gave me one, it worked.

Marlin,

I picked up a KASTAR Master Spindle Rethreading Die set a few years ago. It contains a M16 x 1.0 rethreading die. I don't know if you can get that die individually but the set is not that expensive ($60.00 or so) and it's been pretty useful for several projects. The metric sizes included are: M16X1.0, M16X1.5, M18X1.5, M19X1.5, M20X1, M20X1.25, M20X1.5, M22X1, M22X1.5, M24X1.5, M24X2, M25X1.5 and M27X2. Interestingly, no M17x1.5.

[RWebb]

Lots of info for general use here, BUT note that on his setup it is the distal end of the shaft that effed up. You would need a split die that could be place on the good proximal part of the shaft, tightened and the run down to the end.

Personally, I'd try a sharp file (sometimes called a needle file, tho strictu sensu they are round and you don't want that) as one poster noted, and replace that nut like milt said.

[Porsche_monkey]

Chuck it and centre drill it. Then re-cut threads on a lathe.

Or cut it off and make a new thread, (something you can get a matching nut for) then join the two with a thread and grub screw.

[john walker's workshop]

use the rotor from your parts alternator. have a shop machine the commutator and throw in a set of brushes and bearings.

[burgundyben]

The nut is NLA from Porsche, I found a supplier in the UK of a similar nut, M16 by 1mm, grade 8 when I needed one, I bought ten, have sold five to other 911 owners.

Still got a few spares.

[tobluforu]

I did the same thing and thought I was F-ed! I used files and even thoug it took a while, it worked like a charm. I went down to local indie and they had a few extra nuts which they gave me. I would file some, place nut on and screw it on a little at a time. File more and so on and so forth. Screwing on the nut a little at a time would also cut the threads.
Good luck

[David E. Clark]

Originally Posted by burgundyben

The nut is NLA from Porsche...

Maryland Metrics has the M16 x 1.0 nut listed in their fastener catalog. You might want to give them a call.

[Nine9six]

Thread comb or thread file, as originally stated, working only the offending thds.
I doubt you could find a "special sized" split nut, but even if you could, try to refrain from running a die over the thds. A die will cut the buggered thds into shape, but in the process you will be loosing significant thd strength. The same applies to running a tap to straighten internal thds, as a thd chaser would be a better selection.
A 60 degree jewelers file would do the jpb but would take awhile to fix external buggered thds.
Currently, there are cut rate China crap thd files on fleabay, which should do the trick for a couple applications before they dull into worthlessness.
HTH