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B&C alternator installation...

kbalch

Well Known Member
The time to install the backup alternator finally arrived this afternoon and, as expected, starting and torquing three of the four nuts was easy. Getting the fourth one started was a bear, but was eventually accomplished with a suggestion from Vic Syracuse (thanks!!) and some creative work by my wife with monofilament (don't ask).

The question is how to properly torque that tough nut. This is the nut on the lower left, of course. What's the secret?

I have the pictured wrench, but am not having any success with it. Is there another tool more suited to this particular situation?

IMG_0780-e1574539505158.jpg
 
I'm not sure if the issue you have is because of other items in the area that cause access issues, but I just did installs of 2 of these alternators over the last 2 weeks. One on an RV-10 and one on a 14. I didn't need any special tools. Both have standard horizontal oil filter mounts and had a filter installed when I did the alternator install. One seemed a little harder than the other to get the nut started. I was able to use a telescoping magnet to send in the washers and nuts. I then used a skinny long screwdriver to help nudge the nut around that was being held by my fingertip against the stud. I even used the screwdriver to start spinning the nut a tiny bit to get the threads moving. It took some hand contortioning, but it really only took 10-15 minutes of playing around on the first plane (the -14) to get that nut in place. Once it was on there, it was easily spun in by fingertip and I had good access on both planes with a standard open-ended gear wrench to get it tightened up. I considered buying some specialty wrench, but didn't need it. I did at first try an offset box end, and an S-shaped box end wrench to do the job, and the offset I think was the one that also worked. I can't remember for sure, because when it actually came time to tighten it down, the standard straight gear wrench worked fine. I was far more satisfied with how it went than I had stayed awake dreaming it would be when mentally preparing for the task. :D
 
I've gotten the nut started and spun down the stud against the washers, but despite being able to get a standard gear-wrench on the nut, it won't turn. Either I don't have enough swing for the wrench shaft to click the gear (and it only needs 5-degrees) or the nut isn't sufficiently tight to provide the necessary resistance for the gear-wrench to start clicking.

Either way, I can't afford to pull out any more hair, so I think I'll have to beg Vic's indulgence when he arrives for the inspection and let him show me the magic technique for this particular nut.
 
A 7/16" combo ignition wrench with the open end cut off (cut length of the box wrench remaining about 3") works great on that pesky nut.
 
One other trick for getting the nut to the point it can ratchet the wrench: Take a smaller sized flat blade screwdriver and hold it on the nut just on the flat near the peak so that when you whack it, it turns the night tighter. I know exactly what you mean about not being tight enough to ratchet the wrench, but if you can get it snugged up by rotating it with a screwdriver a couple flats, you may be able to use the wrench.

One other thing I've done over the years is go buy a couple sets of cheap harbor freight wrenches so I can cut them or bend them as necessary to reach tricky fasteners. You shouldn't have to do that, but, as was suggested in the last post, it may be worth sacrificing a wrench to get it to fit.
 
"Sacrificing a wrench"??
Nah, that's not a sacrifice - that's building a special-purpose tool that will serve your entire life, and likely be borrowed frequently by friends facing the same mechanical challenges. I have several of these custom-fabricated tools. They're not sacrifices at all, they're pure gold! :)

(If you ever want to see tools like this, go visit your friendly helicopter mechanic. That's where I learned to use a torch to make a wrench fit my purpose. Just that little skill set is a nice feather to have in one's cap!)
 
"Sacrificing a wrench"??
Nah, that's not a sacrifice - that's building a special-purpose tool that will serve your entire life, and likely be borrowed frequently by friends facing the same mechanical challenges. I have several of these custom-fabricated tools. They're not sacrifices at all, they're pure gold! :)

And you'll really appreciate that particular part when you start grinding on your high-dollar tungsten bucking bar to make it fit in some tight quarters.

I sacrificed a cheap wrench and a socket to make a custom bolt-torqueing device for my prop bolts, works great and I'll keep it as long as I have the airplane.
 
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A 7/16" combo ignition wrench with the open end cut off (cut length of the box wrench remaining about 3") works great on that pesky nut.

I've been trying to make that little wrench work without cutting it, but I may have to buy a Harbor Freight cheapo to modify. I'm afraid that, even if the modified wrench will fit, my hand is too large to extend the shortened tool up high enough to slip over the nut, let alone turn it.

One other trick for getting the nut to the point it can ratchet the wrench: Take a smaller sized flat blade screwdriver and hold it on the nut just on the flat near the peak so that when you whack it, it turns the night tighter. I know exactly what you mean about not being tight enough to ratchet the wrench, but if you can get it snugged up by rotating it with a screwdriver a couple flats, you may be able to use the wrench.

I've snugged it up some with the screwdriver technique, but have still been unable to tighten the nut past that point with any sort of wrench.

Frustrated doesn't come close. I?m about at my wit?s end with the silly thing. To be honest, if my panel and wiring design weren?t predicated on the presence of that backup alternator, I?d have already removed it and moved on.

If anybody with a proven tool/technique/touch is willing to come rescue me and my project from abject failure on this point, I'd be incredibly grateful.
 
Thanks, all, for the excellent suggestions. I'll get this thing licked, no doubt.

I've sent you an e-mail Ken

Sorry, but no email received as yet.

Snap-on makes a special crows foot, used with a wobble extension works very well.
https://shop.snapon.com/product/Aircraft-Vacuum-Fuel-Pump-Wrenches/Aircraft-Vacuum-Pump-Wrench/AVPW716

Thanks, Walt. I've ordered that special crowfoot and am hopeful that it'll be the answer. Much appreciated.
 
Ken,

If you're still out there, how did you end up getting this done? I've got the Snap-on crows foot and it fits on the nut nicely but there's not enough clearance for it to rotate. Have just about every tool in my shop out.

Using the B&C 90 degree adapter and 3/4" spacer but that's not the issue, no room for the crows foot to turn against left side of the case.

Could remove the right E-Mag, but hoping not to. Not sure if it would do any good anyway.

If anybody else has a solution, please post it.
 
Ken,

If you're still out there, how did you end up getting this done? I've got the Snap-on crows foot and it fits on the nut nicely but there's not enough clearance for it to rotate. Have just about every tool in my shop out.

Using the B&C 90 degree adapter and 3/4" spacer but that's not the issue, no room for the crows foot to turn against left side of the case.

Could remove the right E-Mag, but hoping not to. Not sure if it would do any good anyway.

If anybody else has a solution, please post it.

Hi Fred,

Yep, I'm still here. :)

That nut was one of the least accessible on the airplane and one of the worst I've encountered anywhere on multiple projects. Ugh.

In short, I had to remove the right E-mag for slightly better access and even that didn't do the trick entirely. I wound up using a combination of tools to turn the nut 1/16 of a turn (at most) at a time.

As you found, none of the advertised specialty tools worked effectively on this nut. I'm sure that a one-off tool could be fabricated, but it's probably only worth the trouble if you're going to be doing multiple installations. To do just the one, I'd do what I did.

Good luck!
 
Mark,

Many thanks for the follow-up. I too I ended up having to remove the right e-mag. Once removed, access to the nut was excellent, but it was still difficult to get a torque wrench in there to make a final measurement. Wanted it perfect as I hope to never access it again <crosses fingers>. Indeed the most difficult nut on the airplane (so far).

I ended up using an extension on the torque wrench making a careful calculation to make sure I was getting the right reading.

I'm a little surprised to see so few builders having this issue. However, I suppose with all the combinations of electrical systems, parts, and designs out there it's to be expected.

Thanks again for the follow-up.
 
I have a fellow hanger buddy who sold his beloved Bonanza and is now the proud owner of a new to him RV-9A. He is an old time retired AP/IA. He reminds me that his motto is, “If you can touch it, you can fix it”. I remind myself of that whenever I find myself in a tight spot.
 
I bought the tool that B&C sells. Of course I got to the point you are before realizing I needed it so it was a second order.

https://bandc.com/product/snap-on-wrench-vacuum-pump-for-aircraft-avpw716/

Then you need a longer 1/4" socket extension.

Walt's idea of the wobble extension might be helpful too, but that isn't what I did. Also, you might be able to use a regular crowsfoot wrench but the problem is you have very little room to rotate the wrench as I remember.
 
Ray,

Thanks for the response, however the tool from B&C wouldn't work in this application. I purchased it knowing the install would be a challenge.

For those of you reading this with an IO-390EXP50 (a.k.a. IO-390-A3B6), 90 degree oil filter adapter with spacer (spacer required for the oil line to go around the filter) it appears the only way to successfully install the back-up alternator on the vacuum pad and get it properly torqued is to remove the right mag (or p-mag).

The tool sold by B&C is a great idea, but you can't rotate it far enough to catch the next set of teeth on the tool (crows foot). FYI - the part B&C sells is a Snap-on AVPW716. A vacuum pump wrench also won't work as those wrenches max out at roughly 4 3/4" and the back-up alt is 6" from the pad to the end of the unit.

Had I removed the p-mag in the first place it would have been on hour or less to install the back-up alt and replace the p-mag. You're not going to find a "special tool" to make the job easier.

Short version: Ken has it right, remove the mag, install the back-up, alt and enjoy your day.

Best of Luck,

Fred
 
Thanks

Ray,

Thanks for the response, however the tool from B&C wouldn't work in this application. I purchased it knowing the install would be a challenge.

For those of you reading this with an IO-390EXP50 (a.k.a. IO-390-A3B6), 90 degree oil filter adapter with spacer (spacer required for the oil line to go around the filter) it appears the only way to successfully install the back-up alternator on the vacuum pad and get it properly torqued is to remove the right mag (or p-mag).

The tool sold by B&C is a great idea, but you can't rotate it far enough to catch the next set of teeth on the tool (crows foot). FYI - the part B&C sells is a Snap-on AVPW716. A vacuum pump wrench also won't work as those wrenches max out at roughly 4 3/4" and the back-up alt is 6" from the pad to the end of the unit.

Had I removed the p-mag in the first place it would have been on hour or less to install the back-up alt and replace the p-mag. You're not going to find a "special tool" to make the job easier.

Short version: Ken has it right, remove the mag, install the back-up, alt and enjoy your day.

Best of Luck,

Fred

Getting ready to do this install thanks Fred and others for posting the helpful hints , good read
 
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