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Compass Marine How To | all galleries >> Welcome To MarineHowTo.com >> Universal M-18 & M-25 Alternator Bracket Upgrade > Sloppy Factory Bolt Fit
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Sloppy Factory Bolt Fit
11-JAN-2012

Sloppy Factory Bolt Fit




Oh no trouble in Paradise! Caveat emptor or DO NOT always trust that the manufacturer has taken the time to do things right. This is an utter embarrassment to the folks at Westerbeke and is plain and simply SLOPPY, especially when this "upgrade" is supposed to address deficiencies in design and installation.


I spoke with Bob B. at Westerbeke about this at the 2013 Annapolis Sailboat Show and HOPEFULLY they have now addressed this issue. Still be on the look out for sloppy fitting pivot bolts. The Devil is always in the details.


Many owners of the M-25's have alternators as large as 100A or more on these engines. Install an alternator with a sloppy fitting pivot bolt like this and you are asking for trouble. The alternator will have chronic alignment issues and will eventually oblong the pivot hole in the alternator thus potentially ruining the case.. SHAME ON Westerbeke!


The bolt passing through the alternator ear AND the bracket MUST be a proper fit. This is NOT a proper fit..



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Guest 21-Apr-2017 01:22
Last November (2010) I installed the upgraded Alternator mounting bracket, with the kit available through Torrensen Marine, and while I was at it I installed a new Leece-Nevile / Prestolite 90 amp alternator on my Universal M25. If you are reading this far, you probably know that the new alternator uses EXACTLY the same housing as the old 55 amp Motorola. BTW the kit is now ~$180.00 When I opened the box containing the kit, I was happy to see that it included all the parts, including the Alternator mounting bolts. I did the installation using the new bolts, but noticed that they did not seem to fit perfectly. The SAE Grade 5 pivot bolt allowed "a little" play of the alternator, and the tension bolt never seemed to fit "right." At the time I assumed that the alternator was machined so that the bolt would jam, thus preventing the bolt from loosening. The real reason is embarrassing....

I thought it strange that both of these bolts, and the nut were SAE. 031555 - 5/16NC x 1 031615 - 3/8NC x 3-1/2 031762 - Nut 3/8-16 Hex Steel Zinc

However, EVERY other fastener is Metric. I assumed that Torrensen would know and include the correct bolts, however the extra play was because the bolts did not fit... you know what happens when you ass-u-me... The Pivot bolt SHOULD BE a Metric M10 fastener. The tension bolt (connects the tension arm and the alternator) SHOULD BE a Metric M8 coarse thread. I realized this because I was getting a little belt dust on the engine. After only 50 hours this summer, I thought that was unusual, or I would need to buy a lot of belts. In October of this year (2011), I checked the alternator tension, and the "little" play seemed a "little" worse than it should have...

Because by now I had stripped some of the threads with the bolt that was included with the kit, I purchased a slightly longer bolt, a nut, and lock washer to use as a tension bolt. I also replaced the pivot bolt with a slightly longer M10 Fine thread bolt. It fit perfectly (no play at all). I used 2 nuts and a spring washer to jam the pivot bolt, so that it will not vibrate loose. I can't speak to the kit available through Catalina Direct, but the Torrensen kit has the wrong bolts!

Lesson 1: If the components in the "kit" don't seem right to you, they are not. Lesson 2: DO NOT USE THE ALTERNATOR MOUNTING BOLTS INCLUDED IN THE TORRENSEN KIT if they are SAE, and you have a Leece-Neville or Motorola Alternator.