Broken Alternator Bracket

[Bob_A]

Upon getting into the engine area of our new to us C350 I noticed right away the misaligned belt and the resulting belt dust all over the front of the
engine. it took only a moment to discover the alternator bracket was broken. I thought just a poor alignment as this was not readily visible or detectable. I had half thought the alternator log had hogged out and might require bushing. we'll never know if this was a case of age, over tightening or the thrust from the Balmar 100A alternator. Not impressed this essential hardworking part was cast aluminum I gave it to a machinist to make me a structural aluminum one. Doing some machining myself I went away knowing this would be expensive. To the fellows credit he ordered a stock bracket and suggested he machine per my original and beef up the resulting narrower leg. What I am talking about here is the ear to ear measurements on the bracket. Bracket to engine was 1 3/4" and bracket to alternator was 2" and my bracket had been machined out to this 2" per picture attached.

Here's where it got interesting. The only major Universal part supplier in our area (who stocks very little) actually has the original bracket per correct part number, in stock! When I asked how this could be he said that they receive calls every year from owners who have a broken one while out in Desolation Sound. When the stock part arrived we were very surprised to find that it had the exact ear to ear (or leg to leg) measurements I required which means that a stock original part per correct part number is in fact stock ... so what was mine? I had thought it was modified to suit the larger Balmar. Anyway I took the win and my part away and did the minor modifications myself as the bottom of the ears need some material removed to clear.
The fit, bracket to engine and the M10 bolt, was very good, no play. The bracket to alternator and the 3/8"NC bolt have enough slope to pass a piece of ham through. What I did was measure this play with inexpensive feeler gauges (20 thou!) and then I make a washer from the feeler gauge. This is a inexpensive way to have many shim stock thicknesses available. The slope in the alternator bolt log to 3/8" NC bolt is unacceptable and I see that one can buy a reducer from Marineknowhow.com for about five dollars US. I made one from 5 thou shim stock by rolling a 2" wide piece cut so it wont overlap when rolling it around the bolt, then inserting the bolt with the reducer into the log. It springs against the sides of the log and the bolt pulls out for installation later. Installing everything once again I half expected further pulley shimming but the alternator aligned perfectly to the other pulleys. a nice win there too. I adjust to the widest part of the belt. a bit of belt dressing sprayed on while running and adjust again after running the engine 10 minutes or so. This past weekend of a fair bit of motoring due to little wind revealed zero belt dust.