Belt for M25 with Alternator Bracket Upgrade Kit

Sep 29, 2018
28
Catalina 30 Annapolis
I recently did the alternator bracket upgrade on my '86 M25 (Not XP) which I purchased from CD. I used the smaller of the two belts that came with it, a Gates Super HC 3VX 400 (Universal Part 300817). That belt is too loose. I believe CD sent the wrong size and the exchange will take a while, have to send pictures, etc. Not sure if my alternator is original, but I'd guess so. Can anyone provide the make and model of the belt that's spec'd for this arrangement or recommend a different belt if there's a higher quality option?

Thanks.

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'86 Catalina 30 TRBSFK
M25
 
Feb 26, 2004
21,959
Catalina 34 224 Maple Bay, BC, Canada
I did the same thing eons ago, glad your old bracket lasted so long, be VERY glad. Congratulations for doing it.

Belts: Forget about what they sent, they have no idea what you have. Go to Napa and get Gates belts. I tried 7390s and 7400s finally found a 7395 that fit. Buy all three, return the two that don't fit and buy a few more of the ones that do. Then throw away ALL of the old other ones you have, because they will only confuse you later. The ONLY belts that should remain are the ones that actually do fit. :) Those worked for me, but you have a different alternator than I do. Point is there are in-between sizes, too. You have to experiment.

You also need to know these things about your new bracket:

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment 101 IMPORTANT

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment
and
Careful Engine Inspection & M25 Alternator Pivot Bolts Careful Engine Inspection & M25 Alternator Pivot Bolts & Tension Nuts


Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too :) This includes a link to the Critical Upgrades topic which has more engine information please read it too.

Diesel Engine - c34.org


These links come from my 101 Topics: "101" Series - Quick Links to "Popular" Topics includes "Electrical Systems 101"
 

Ward H

.
Nov 7, 2011
3,129
Catalina 30 Mk II Barnegat, NJ
A highly recommended belt is the Dayco TopCog belt. Recommended by Maine Sail AKA Rod Collins of Maine How To .com and contributor to the forums. I switched to the TopCog belt and drastically reduced any belt dusting/slippage.
Gates is another belt brand he recommended.
Then do as @Stu Jackson says for sizing and spares.
 
Feb 26, 2004
21,959
Catalina 34 224 Maple Bay, BC, Canada
I forgot to emphasize: forget about any further discussions with CD. It is NOT their problem and you'll only be wasting your time.

Spend the effort on aligning the new bracket and getting the right nuts&bolts, especially the pivot bolt.
 
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Sep 29, 2018
28
Catalina 30 Annapolis
Thanks for the belt recommendations and the other information. And, thanks for the critical upgrades posts which altered me to having the recalled old bracket. Between your posts and Maine Sails, I got the larger (10 mm?) pivot bolt, shimmed it with a washer, and backed the adjusting arm bolt with a nut, however my alignment is not perfect. Also, there is slop between the pivot bolt and the sleeve it slides through on the alternator. I wonder if an alternator shop could help with that and if not any ideas on who could? I'll need to revisit the alignment after resolving the sleeve issue.
 
Feb 26, 2004
21,959
Catalina 34 224 Maple Bay, BC, Canada
You're welcome, glad you found it & did it.
Maine Sail discussed that in one of his lengthy alternator topics. I'm not as conversant with the material on his website, but it might be in this one: First thing I thought of from your post was "bushings." Thing is without seeing what you have, shimmy doesn't help me to help you, since it seems you got the right pivot bolt, so it must be the alternator's foot, unless I'm missing something.
 

Ward H

.
Nov 7, 2011
3,129
Catalina 30 Mk II Barnegat, NJ
My alternator had an out-of-round hole the foot. I gave it to the marina owner along with the pivot bolt. The next day he handed it back with a pressed in bushing drilled out to fit the bolt. Did it in his own metal shop in about an hour or so.
 
Sep 29, 2018
28
Catalina 30 Annapolis
Yes, in looking at the info in the link, the proper term is foot. I will contact a good alternator shop and see if they can help me with a spacer to take up the room between the pivot bolt and the foot.
 
Sep 29, 2018
28
Catalina 30 Annapolis
Thanks, Ward and Stu. Now I understand the bushing concept. I might have a source or two for that. If can solve the foot issue, I'll get the piece of angle iron I bought and give another go at the alignment refinement.