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Alternator bracket /alternator help - H2AD + B&C

rjcthree

Well Known Member
I started with the PP to B&C conversion on my H2AD today. It didn’t go well. The mounting bracket used with the PP is 07a21516 and with a thin washer aligned the PP well. The B&C bracket provided does not fit the engine, as the case bolt hole spacing isn’t correct, and belt alignment is way off. This is just a quick shot in the dark to see if anyone else has already been down this road and figured it out?

Picture: PP 07A21516 on the left, B&C on the right, up is forward ( at least for the PP).

The fact that the tension arm is in a different place on the alt case is a problem for another day, maybe. It’s looking like a shorter belt will be required, so I guess the prop is coming off regardless. Big sigh.
 

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I started with the PP to B&C conversion on my H2AD today. It didn’t go well. The mounting bracket used with the PP is 07a21516 and with a thin washer aligned the PP well. The B&C bracket provided does not fit the engine, as the case bolt hole spacing isn’t correct, and belt alignment is way off. This is just a quick shot in the dark to see if anyone else has already been down this road and figured it out?

Picture: PP 07A21516 on the left, B&C on the right, up is forward ( at least for the PP).

The fact that the tension arm is in a different place on the alt case is a problem for another day, maybe. It’s looking like a shorter belt will be required, so I guess the prop is coming off regardless. Big sigh.

I had a bracket similar to the one on the right, but it had one hole and one slot to accomodate variable spacing. I definately neeeded spacers to get the belt alignment correct, but was not really difficult to do. Also needed washer to shim out the top arm as well. Might look for a different version to buy with a slot.

If you send me that bracket, I could mill one of the holes into a slot.

Larry
 
B&C fixed for me

I too had an issue with the bracket supplied by B&C. I took detailed measurements and photos, and after discussing with B&C, they sent me a different bracket. Perfect fit.
 
My B&C alternator and bracket bolted right up with no issues.
 
I spoke with B&C today

I spoke with TJ today at B&C, and none of the brackets they have have the case bolt spacing I need for the H2AD. Normal case bolt spacing is about 1.16”oc, the 07A21516 lyc bracket for the H2 that worked for the PP is 2.06”oc (scaled from pictures, parts at the hanger). There is no way to make the B&C bracket work, simply not enough material there, but I appreciate the offer immensely. The lyc 07A21516 bracket doesn’t align the belt by a fair amount, the through bolt hole has no real play fore and aft, both brackets nailed that at 3” as stamped, additionally, the lyc bracket and the PP use a 7/16” pivot bolt, the B&C 3/8” pivot bolt. The vertical offset is also different by about an inch. I’m likely in fab land. I’ll know more when I get the parts home and measure.
 
Better picture.

This may help clarify. B&C on the left, lyc 07A21516 on the right. Forward is up, at least for the lyc bracket.
 

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If you need to fab something, drop me a line. I would be willing to fab a part to your specifications inexpensively. I have been doing more fabrication work in retirement. I made a custom bracket for my old 320 that didn't have the boss mount on the case.

Larry
 
H2AD Bracket

I have an H2AD on my -4,but I don't remember who I bought it from. It has a link to the starter also that I believe I fabricated.
 

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Plane Power H2AD

I've forgotten exactly how I fixed this, but it was an issue as you've found. I think I ended up with a 1/4" steel plate that would bolt to the case, and that plate then bolted to the PP bracket. As I recall I had to use a countersunk allen bolt as one of the bolts --- so that the adapter plate could lay flush against the h2ad case. It's all really snug. And you can't let the alternator droop much or the pulley interferes with the lower cowl.
 
I had similar issues with B&C that they were going to fix for me but it's been over a year now with no fix.

I had an IO-540 narrow deck and a new IO-390, and had plane power 70A and 60A respectively.

I then bought brand new B&C BC460-H alternators and tried to upgrade.

First of all, for builders that haven't taken the time to actually look CLOSELY and measure these alternators, you're doing yourself a big disservice in alternator belt wear, and I can see how someone may say "Mine fit fine". This isn't something you should just eyeball, but you need to really measure.


On my planes, of them fit fine, the other did not, and was off by a lot.
I had a lot of back and forth with B&C about it, and ordered their other bracket, and that shifted it too far the other way. I gave them the proper measurements, and months later, when I thought they had actually listened to me and understood the situation, with them saying they would send a fixed bracket, I found out they indeed had not been listening. They DID have other complaints on the IO-390 with aligment, so it wasn't just me.

Their fix was to send out new alternators, believe it or not. They didn't do the simple thing of modifying the bracket and making one with the right hole spacings, they modified the alternator body, specifically the mounting swingarm lug dimensions, to machine it differently to make it fit.

I was very skeptical, but when I mounted it on the first plane, it fit perfectly.

But guess what? If you fix it on that plane, that means the other plane will now NOT be perfect. Sure enough, that was the case. Now the other airplane was misaligned.

The only thing I could do was, pick one of the 2 alternator styles, and oblong the holes in one of the brackets, so that it would work. I did that in early 2020, waiting to hear back from them on a fixed bracket. Then COVID hit, and I figured they may take a while.

Then, last summer I bought a brand new wide deck IO-540 and swapped out my old engine. Guess what. Yeah, my brand new IO-540 was now poorly aligned just like my brand new IO-390. And, neither bracket they sell made it fit properly.

If you have not checked your B&C 460 series alternator, I'd suggest you take the time to check it out. You may think it's aligned but if you have any new lycoming, it probably isn't.


As for B&C, they never contacted me again about it, and at this point I have both planes with doctored brackets. I don't like the fix because it was almost impossible to hand file the holes perfectly and now I have slop in the alignment and have the worry that things may not stay aligned if there is any movement of the bracket. I would love to have them just make correct brackets, for either alternator (they produced BC460-H an BC460-1 variants with different dimensions)

At this point, it's been about a year since they dealt with it and I'm still waiting today for a fix. My PlanePower alternators were aligned just great. It may well be that some day I go back to PlanePower. It's hard to pick a vendor when you don't have confidence that they are listening when you tell them things don't line up. My theory is that most people just slap the alternator in and don't look at it...and there are tons of these out there that aren't lined up properly.

If you measure it, on mine you find that the center of the drive belt hits about .093" or so off from the center of the pulley if I remember correctly. And that puts the V of the belt not at all aligned with the V of the pulley

I have another RV friend who put one of them on one of his planes with an IO-540 in it as well, and his suffered the same misalignment. He didn't believe me at first. I told him my alignment was off, and he claimed his fit perfectly. He thought I was crazy. Then when he finally had the cowl off one day, he measured it and found indeed his was off by about the same amount as mine.
 
Taking measurements

So as I try to understand the fit issues, I have to separate two topics. The first is the H2AD. The second is the differences between the B&C and PP dimensionally. On the first, the H2 is just its own thing. Two bolt mount, widely spaced at 2”oc to the case.

The second gets sticky. Starting with bolts, the pivot and tension arm bolts on the PP are AN7 and AN5 respectively. On the B&C both are AN6. The 07A21516 bracket for the H2 has a 7/16 pivot hole. Rhuh-rho.

The PP on the 07A21516 bracket aligns to the flywheel pulley.

Taking measurements of both alternators to the pivot face puts the center line of the B&C pulley groove 0.071” forward versus the PP. working from only the drawing provided by B&C suggests it should only be about 0.020”, but both eyeball and measurement says the 0.071” is more correct. Still, manageable with slotting of the bracket to case joint and a washer here and there, or by taking some of the rear pivot bolt boss down and using washers forward. The difference in diameter of the pivot bolt can be managed with 4130 bushings.

The tension arm may be a little tougher. The alternators are different in design here. The PP has an offset tension arm - as in the pivot to alt pulley cl to tension bolt are not in a line. The tension arm is offset/rotated around, resulting in the bolt being about 1 1/4” higher than the B&C, which is a straight line across. Bottom line is I will need a shorter belt to get the B&C on the slot of the tension bracket. And I thought I could get the job done without pulling the prop....

Anyway, the fore/aft position of the alt tension arm is also different between the two, with the PP being forward of the B&C by 0.407”. It may be close enough that the arm I have, when used on the back side of the PP, will work on the front side of the B&C, but it requires the belt alignment to be correct before making any decisions on that. Removal of that bracket requires baffle surgery.

Measurement note: I’m not working with a CMM here, but I’m using two or three measurement methods, each measured a couple times to work through the lack of precision of the meat servo. I will amend this as things become more clear.
 

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I can't tell from the pictures if the pulley has enough clearance from the alt case to do so, but have you considered modifying the pulley? That could be easier than changing the alternator case.
 
Pulley

Mark, no I haven’t thought about modifying the pulley. Your comment brings another idea though, maybe I should look at swapping pulleys. No tools here at the apartment though. TBD...

Update/Edit: alternator shafts are significantly different at the pulley end, pulleys are not interchangeable.
 
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Interestingly, I noticed that the pulley on my B&C 60A alternator sits about 1/8" forward of where it should to align with the flywheel on my narrow deck 540. If it was off in the other direction, I'd guess I had the flywheel mis-indexed, but that's not the case.

Has B&C come back to any of you with a solution?
 
Not me. Between the 2 versions of alternators with the 2 versions of brackets, I haven't found a way to use the current model of BC460 with my 2 Wide deck engines, both new, IO-390 and IO-540, without slotting the holes which is a messy process if you don't get them straight. And, the old narrow deck IO-540 either. There are combinations that can work, but not where you can interchange them. Personally I think they need to just come up with an in-between model of their bracket and everything would be fine, but I just don't think they believe us when we tell them they're mis-aligned. If enough people like you call them, maybe we can get resolution.
 
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