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Alternator belt and bracket issue

dbegeman

Member
I need a little help here. I had my prop pulled for a leak at the seal and while the prop was off it was recommended that I replace the belt. I went out and got the exact same belt (Gates 7360XL) that was on the airplane before the prop was pulled. Now the new belt is too big and the alternator adjusting bracket doesn't have any room left to adjust and put tension on the belt. My question is, is there a bigger (longer) bracket? Mine is boss mounted and the bracket in question has part number 99-1004 stamped on it, the alternator is a plane power alternator. I know I could pull the prop and put on a smaller belt but I would like to avoid pulling the prop. Thanks in advance!!
 
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Be aware that installing a longer belt will very likely cause the alternator to rub the cowling. There is not much lee-way here.

Remember; Every change usually necessitates other changes.
 
My B&C experience

Hmm, interesting Carl. The belt B&C sent me was a 7365 and that was too long - by about a half inch. It rubbed the cowl and dug a nice furrow into it. I went back to a 7360 like I had on my old Van's Nippon Densu alternator and it worked fine. I checked with Walt Aranow at my home field and he said he has a drawer full of B&C 7365. They're too long - he uses the the 7360 also.

Debegeman: Perhaps the "XL" in the Gates is the issue. Try a NAPA 7360 without the XL.

Chris
 
Hmm, interesting Carl. The belt B&C sent me was a 7365 and that was too long - by about a half inch. It rubbed the cowl and dug a nice furrow into it. I went back to a 7360 like I had on my old Van's Nippon Densu alternator and it worked fine. I checked with Walt Aranow at my home field and he said he has a drawer full of B&C 7365. They're too long - he uses the the 7360 also.

Debegeman: Perhaps the "XL" in the Gates is the issue. Try a NAPA 7360 without the XL.

Chris

The weird part is the original belt was a 7360XL also. I was hoping not to have to pull the prop to put on a smaller belt!!
 
7355

I too have found the 7355 belts work better. I never install the 7365 that comes with the alternators. The alternator pulley will put a hole in the cowling.
It is weird that your original one is different than the new-purchased one. Perhaps one of them is mis-marked.

Vic
 
The weird part is the original belt was a 7360XL also. I was hoping not to have to pull the prop to put on a smaller belt!!

After looking at the package today, I think the XL may be just a marketing term for Xtened Life or Extra Long Life as it was on my original as well. I removed my cowl today and saw no more cowling rub from the 7360. My alternator is the B&C 40 amp. The 7365 was the culprit for the cowl damage (repaired).

Not sure why the 7360 didn't work for you. Curious.

Chris
 
After looking at the package today, I think the XL may be just a marketing term for Xtened Life or Extra Long Life as it was on my original as well. I removed my cowl today and saw no more cowling rub from the 7360. My alternator is the B&C 40 amp. The 7365 was the culprit for the cowl damage (repaired)
Not sure why the 7360 didn't work for you. Curious.
Chris

Also be aware that positive "G" maneuvers have a big influence on alternator rubbing the cowling. If you intend to do much aerobatics, you will need more than the minimum clearance.
 
Found exactly the same thing yesterday. The replacement (new) 7360 was longer than the original 7360. Bought a 7355 on my way home and going to try again today. Suspect as Vic said, it'll be much better.
 
I had an issues with rubbing on the inside of my cowl and then finding the correct belt size but I have always used Dayco Top Cog V-belts. That was on the engine when I got it from AeroSport. Needed to replace belt due to wear at 500 hours. Replaced belt with same size and I ending up getting rubbing on cowl. Replaced with next size smaller and everything fine until I noticed a crack in the alternate attachment bracket during an oil change several hundred hours later. Replaced attachment bracket with different one (I think I bought from Vans) and had to buy a couple belts to get right length that worked with new/different alternator bracket.

Moral of the story is clearance to cowl of alternator, at least on an RV-6A, is close. You need to find the right size belt. I am now using the Dayco Top Cog 15360 and have had no issues but belt size is dependent on which alternator bracket you have. I also now have a nice selection of belts larger and smaller if I ever need one.
 
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