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Re-use or replace engine hardware?

H

Helmetfire

FRIEND
Caldwell, Texas
Overhauling my O-320 and wondering what to do with all the misc. hardware. I'm in the process of cleaning everything up while all the big $$$ parts are out for overhaul/inspection. Most of it looks like it will clean up nice and surely airworthy, but I want to put the case back together with only the alodine treatment and no paint, which means all the attaching hardware won't have any paint on it for corrosion protection. I'm mostly talking about all the 1/4"-20 attaching hardware for the case halves, sump and accessory....the one-off stuff i'll most likely replace

New hardware would have fresh cad plating right?
Can I get the old hardware cleaned and re-plated somewhere? Where's the best place?

If I go new, is there an alternative to Lycoming part number hardware ($$$)?

How about the Cylinder attach nuts for the narrow deck...Mine are fine and will re-use them but I'd like to have them plated if for no other reason than to have them look a little nicer and more consistent with the rest of the engine. Mechanic says plating them is not a good idea...I can't now remember his logic, something about changing the size or strength by removing material through the plating process... What do you guys say??
 
The precise answer is to check the Lycoming overhaul manual. It has a list of hardware that must be replaced at overhaul. If it were an engine that I had my hands on, the only hardware that I would consider keeping is the screws for the rocker covers.

The only Lycoming numbered hardware, I believe, is the coarse thread bolts/screws. All others should be AN- . It's an overhaul, don't get cheap over hardware.

Web
 
I would also recommend replacing the crankcase studs with new. Everytime a fastener is torqued it yields. Repeated overhauls will eventually cause failure of the cylinder base studs. Ask me how I know.
 
Whatever you do, DO NOT re-use connecting rod bolts. Seen that one a million times and the same amount of grief.
 
There was a place in Oregon or Washington the engine shop here would send the hardware or to be re CAD plated. You also can order a kit from caswellplatting.com ? Might be misspelled.


Sent from my iPhone using SuperCub.Org
 
Steve, do the parts have to be baked immediately after plating our can it be done at anytime before use? Thank's, Tim
 
There is a Lycoming SB that lists required replacement parts for an overhaul (SB240W). We all know that a Mandatory SB isn't really mandatory, but I'd hate to be on the witness stand having to explain how I signed off an overhaul and didn't comply with this SB.


Sent from my iPhone using Tapatalk
 
I didn't see anyone reference re-plating any mandatory parts. did I miss something?
 

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· Stressed bolts and fasteners, such as:
Stationary drive gear bolts (reduction gear)
Camshaft gear attaching bolts
Connecting rod bolts and nuts
Crankshaft flange bolts
Crankshaft gear bolt
 
not saying this is appropriate methods for this hardware... but I finally started taking time to learn plating and anodizing myself... thought I'd share some links.. I'm no expert, just my first attempts, seems easy... still waiting on some chemicals...

Was needing to find bakeout hydrogen time and remembered it was discussed on here and found this thread.

http://www.gomog.com/allmorgan/ZincPlatingAtHome.html zinc plating


http://www.anodizeworld.com/


Some of my first attempts
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Last edited:
Neat! I want to do some nickel plating.

I bet the AN-3s and 4s are cheaper new than it would be to plate and bake. Bolts do break, but a case bolt is sort of non critical. I think rod bolts, through studs, and gear bolts are the ones you do not want to mess with.

Some rod bolts are actually stretched. A second stretch is problematic.
 
Precision Metal Finishing in Oregon was excellent to deal with. Great prices for a bunch of pieces and an 8130 with every batch. They know what they're doing.. if a piece has phenolic in it and doesn't need baking, (think an water rudder attach bracket) then they can do it (the baking will melt phenolic, but the plating process doesn't exceed 80 degrees).. if a piece has bronze in it and doesn't need old-cad-removal (think a complex water rudder retract pully bracket) , then they will do it. (the cad removal step will melt bronze)... they also recognize highly stressed parts that must be relieved and will do them appropriately. (think a wire-pull clevis on a float assy). I found them this winter and they are great. Absolutely why not do your general engine hardware this way. About 40 years ago the guy supervising me for my cub engine overhaul had me send my hardware out for plating.. I had never even considered the idea.. it stuck with me and this winter while working on my floats I wondered about it again.. my mechanic gave the these guys' name from his dad's reference.. I could not be happier.. one of those places where I found excellent value for a great product. I only hope you won't make them too busy so I can still send them my stuff.
 
For fastners that will be torqued, does cadmium get in the threads of nuts and bolts during the plating process and screw up the torque values? Depending on the thickness of the plating I could see where a nut might not even screw onto its respective bolt after both were replated. I am thinking about cheap galvanized hardware but wondering if cad replated could be a problem too? Cleaning up the threads with taps and dies would defeat the purpose of the replating wouldn't it? I'm just asking. I'm trying to look at what might go wrong.
 
The threads are a legitimate concern, but they actually have 3 classes of thickness, and will apply it as-appropriate. I don't remember exactly but I think most AN hardware comes with Class 2 thickness.. at any rate, they will discuss this with you and help you know what will work. In my case, I separated parts.. On a bracket with no threads I asked for the thick plating (still pretty thin) and on hardware just the standard. It all came back looking like brand-new and fit with no problem. The hardest part was hiding those beautiful parts with epoxy.
 
N86250 said:
For fastners that will be torqued, does cadmium get in the threads of nuts and bolts during the plating process and screw up the torque values? Depending on the thickness of the plating I could see where a nut might not even screw onto its respective bolt after both were replated. I am thinking about cheap galvanized hardware but wondering if cad replated could be a problem too? Cleaning up the threads with taps and dies would defeat the purpose of the replating wouldn't it? I'm just asking. I'm trying to look at what might go wrong.
Click to expand...

thread size is divided into diffrent classes(sizes) the H value on a tap for example... I'm no expert, but you can look it up..

https://www.fastenal.com/content/feds/pdf/Article - Screw Threads Design.pdf
 
Actually, I think we are talking about two different types of classes.. The 1,2,3 to which I was referring is simply the method of defining how thick the cadmium plating is applied, not a reference to the hardware itself. I do remember asking for "double cad" the first time on my 0-235 overhaul (about 36 years ago) and I remember having trouble with exactly that - nuts not wanting to screw onto bolts. This time, (this winter - long gap for plating hardware) I asked them about that, and that's where learned that they control the thickness to avoid the problem. I think the spec. for thickness is "Class 2" for new AN hardware but couldn't quote that one. Remember they remove the original plating first, so it's not doubled up. If you ask for the standard, you'll not have any problem with plating interference. All that said, regular AN hardware is so cheap I really don't bother sending a regular bolt like say, an AN4-5A, but no reason you couldn't.. You can also specify silver or gold color. (I think that's defined as "type 1 and type 2" but not sure either.. I'm pretty sure "Class 2, Type 1" gets you a brand new looking standard gold piece of hardware.. but I dunno... I always ask them. BTW they are a Certified Repair Station with all the commensurate details.. drug testing, paperwork etc. The truly provide a great product for great value in my opinion.
 
And usually the overhaul manuals I'm familiar with specify for torque - clean 50 weight oil, or some mil spec anti-sieze, etc..
And the through bolts etc., usually specify that the torques are for nuts bearing down on cadmium plated washers. (Continental anyway - havent read a Lycoming one in a while) I don't know how much difference it really makes but they do specify the plating as part of the equation in the final torque value.
 
I bead blast the hardware prior to having it plated and baked at a prop shop. Never had any issues with the threads.
 
When I worked in the round engine overhaul shop, we did all but our chrome plating in house. Copper, tin, cad, lead, nickle.... I spent a few days on the plating bench, plating master rod bearings, link pins, etc....it was interesting work but took some patience, as it doesn't happen fast. The hardware wasn't too bad as we did it in vats and the tolerances were much less precise.
John
 
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