Question re alternator mount

[Desert Rat]

Hey Guys-

In addition to the dogleg brace, the RV14 plans, show a brace going between a lug on the starter to the bolt common to the pivot point of the alternator. It's called out in the RV14 build manual section 43 with Vans part number V-1002.

I've got a B&C alternator and it didn't come with this brace, just the big U shaped boss mount and the dogleg. The area I'm talking about in circled in the picture below.

Is this something that I really need or is it 1/4 lb of dead weight I can live without?

 

[planenutz]

I recommend you install this brace as it spreads the load and reduces the chances of vibration loosening the bolts on the Alternator mount. Its an item that has been around a long time now and for me its one of those things that came about as a result of experience. Sometimes its best to use that experience to your advantage.

 

[Reflex]

Terry,

I'm building a -14 "up the road" from you and working on this very problem right now. I've got the same alternator/starter combo and can't seem to find out what is "right".

V-1002 is not a Van's part number....at least it didn't come with the kit, doesn't appear in the master list of parts, on the inventory sheet(s), and doesn't appear in the Van's store. I found posts on this site that say that it's not needed, and posts that say it IS needed. I've also found posts that say V-1002 doesn't fit between the B&C alternator and the starter.

Planning on calling Van's tech and B&C today to see what I can find out. If you find a solution, please post. I'll do the same.

 

[Reflex]

Here's what I found today when I spoke to (short version):

Van's - Not exactly sure why the bracket is there. They suspect that it is there to protect the alternator rather than the starter. The drawing was made by PlanePower and suggested I give them a call. They do not supply V-1002, it comes from PlanePower.

Lycoming - These are not parts furnished by Lycoming. It's suggested that you contact PlanePower and/or B&C and follow the manufacturer's recommendations.

PlanePower - The bracket helps with stabilization and vibration from the alternator. They recommend installation of the bracket to help with longevity for both the alternator and the primary bracket.

B&C - They were very familiar with the bracket state that their alternators are "precision balanced" and need no further stabilization. They haven't seen an increase in failures when not using a bracket between the starter and the alternator. With no issues found, they've seen no reason to include a bracket with their alternators.

 

[Desert Rat]

Hey thanks for following up on that. I used to work with one of the B&C guys at brand C back in the day. They are good people up there and if that's the word you got from them then thats what I'm going with.

ps. Where is "Up the road KS?" is that near Fredonia?

Shoot me a pm if you want connect and compare notes

 

[pilotkms]

FYI - converted from PP (finally) to B&C. Like u, PP had the bracket. B&C no bracket. That was about 400 hours ago. Have seen/felt NO negative effects. I tried keeping that PP going, but gave up and changed to B&C. Worry free since.

 

[Reflex]

Terry - Sent you a PM.

Keith - thanks for the follow-up, good to know!

 

[wcalvert]

The hour it took to build this part removed all questions in my mind. I can't tell if it helps since it's been on there since the first start.

 

[Malndi]

Not req for B&C alternator

When I converted from PP to B&C, the new alternator kit didn’t come with a brace, and the old brace from the PP installation didn’t fit the new installation. In fact the B&C pivot bolt wasn’t long enough to accommodate a brace. So I went looking for answers and I can’t remember where I read it, but somewhere in my research it said the B&C alternator is dynamically balanced and therefore doesn’t require the brace when used with a boss mount. I think the brace is required when the B&C alternator is used with an older-style case mount.

This helps:https://vansairforce.net/community/showpost.php?p=1084548&postcount=7

 

[fixnflyguy]

Not a -14, but pretty standard to have it.

I built a -4, O320 160hp,utilizing the old Vans catalogue Denso 35amp alt. As an APIA, I have seen the stabilizer link on many other applications certified and Exp. On my bracketry the stabilizer link is on the aft side of the lugs, just because alignment was better on the aft side. I made mine from a scrap piece of 4130..I like things that hang on the engine stabilized as best they can be.

 

[chrispratt]

My original alternator was a Van's rebuilt Nippon Densu and I made the supporting "jogged" bracket myself (not supplied by Van). It was a good learning exercise for a new builder, i.e. how to make a jog, how to allow for the bend, and how to drill the holes precisely where needed.

The reason the short bracket was necessary was 1) to give support the alternator because, 2) the long support arm provided was made of light aluminum and was prone to fatigue cracking.

After 750 hours, I switched to a B&C alternator and found that 1) the old jogged bracket no longer fit the geometry, and 2) realized that the B&C long bracket was made from much stronger material and did not need the support.

So if you're using B&C you don't need the short jogged bracket. If you buy a Plane Power, I believe the jogged bracket is included (I know I've seen pre-made ones somewhere) thus robbing you of the learning experience of how to make a short straight piece of thick aluminum into a jogged piece with the holes precisely drilled .

Chris

 

[Ironflight]

Old habits die hard….. back in the days of certified airplanes with monstrous American Automotive (MOPAR, AC DELCO, etc) alternators, trying to fly without that short bracket was sure to destroy the alternator and alternator bracket - lots of weight and vibrating mass.

Enter the world of homebuilding and the lightweight ND alternator cores (Autozone, PP, or B&C all use the same basic castings I think), and the amount of mass suspended off the bottom side of the motor is considerably less. Is the link even necessary now? Depends on how well you balance and line everything up I suppose. The link doesn’t hurt in my opinion, but necessary? I looked at pictures of my four Lycoming installations (no, I am not going to go pull cowls off….), and two have the link, two do not. Like I said, old habits.

Our Autozone ND’s just keep purring along…..

 

[gyoung]

FWIW, the old narrow deck Lycs had the alternator bracket attached to 2 case bolts. There was no lateral support other than a strap from the starter to the alternator. It was not optional. The boss mount on the wide decks is much more robust so it may be optional.

 

[jelliott]

My Two Cents

I live 10 miles from BandC and am a big fan of their products. My son actually machines many of their products at a local machine shop they contract with. I have had several conversations with TJ about this very question in person. Here is what I have learned.

Many alternators bearing fail because they are being pulled sideways and the vibration eventually deteriorates the bearings. I just saw this in my friends RV-8 with a plane power on it. The small brace between the starter and alternator helps reduce vibrations. BandC has worked very hard to precisely machine and dynamic balance their alternators. they do offer two braces they machine. The reason they offer these is because their starters are rotated differently. TJ explained this repositioning helped them get better torque on the starter.

With a BandC alternator you do not need this brace! You should make sure that your belt tension is correct.

A big thanks to BandC for the quality products they produce and the service they provide.

Fly Safe!!!