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Bill Dicus

Well Known Member
Have been looking for 1/4 x 20 bolts, AN quality, to mount my angled oil filter adapter and spacer(necessary to clear the RV-8 motor mount) and after a few months have nothing but hardware store bolts. Have tried Vans, Spruce, General Aircraft Hardware and many other suppliers found thru Google - no luck. What I need are 1/4 x 20 (not 1/4 x 28, as in AN4 hardware) with grip length of 1.75 to 1.825 inches and at least 3/4 inch thread. Anybody know where to find these? Thanks for any advice. Bill
 
Also the nuts

Also, there are niffty AN coarse-thread nuts that have a flat mating face on one side - I'd love to find a reasonable source for those. So far the only option I've found is ordering from Lycon using the lycoming part numbers. pretty pricey that way.
 
Grade 8 will work just fine.. You can always look into getting some $$$$$$$ bolts from AERO... but I don't think they're any "better"
 
Bolts

Thanks Steve. Will contact Lycon - they built up my engine. Not sure how to get Lyc part #'s, but I hope they can do that. Have a good weekend. How far along are you? Bill
 
I did a quick check on AN bolts and found that AN standard is now obsolete and has been superseded by NASM. A search for NASM bolts found this:

http://www.thomasnet.com/products/bolts-6214803-1.html Numerous suppliers.

There are so many standards out there. There is SAE for Automotive and then there is ASME for structural bolts, NASM for aircraft the list goes on and on and is duplicated in metric. All these bolts standards are pretty much the same, strength is pretty much the same, alloys are very similar so as the others have stated use a Grade 8 bolt from any automotive / industrial supplier and you will be more than OK.

Putting a 1/4" Grade 8 bolt through a sheet metal bracket and a sheet metal firewall is over kill. The bolt is so much stronger than any of the other materials it will be the last thing to fail. The threads may loosen but a Grade 8 bolt will not fail in this application.

Bob Parry
 
Bolts

What an amazing resource this VAF is! Should have checked earlier. Thanks to all who responded and will let you know when and if I get the bolts. Bill
 
SAE Grade 8

...is essentially an alloy & heat-treat specifications. the spec tells you what strength you should have if the bolt is made right. Unfortunately, Grade 8 is NOT a quality assurance spec. For example, there is no requirement for post heat treating for hydrogen embrittlement of plated bolts or x-ray for inclusions and/or voids. In all the years I raced cars, every critical fastener was AN or a specialty fastener with QA standards & company reputation.

This is just not my opinion, but it is in print in every book published by Carroll Shelby, the individual responsible for the Ford GT finally lasting the entire 24 Hrs at LeMans. The cars had been fast enough for years, but always broke.

His books included "Prepare to Win", "Tune to Win", and a Fastener/Hardware Handbook the name of which I can't rememeber because we all called it Sc**w to Win," a title apparently vetoed by his publisher.

Larry
 
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Be careful using grade 8 bolts in structural situations. They tend to be brittle and have cut threads. AN bolts have rolled threads and are not as brittle.
Do not present an aircraft to me for inspection with grade 8 bolts installed.
 
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AN vs Grade X

Mel:

I should think that grade 3 or 5 Hardware Bolts should be sufficient to hold a 2pound oil cooler filled with oil. I would think that the aluminum would fail first. I don't think that this aplication would warrent X-rays or special NDI inspections. ???????????????????????:confused:
 
Primarily I'm talking about structural issues. But why would you want hardware store bolts to hold your oil cooler instead of AN bolts? If you are talking fine thread vs coarse threads, fine threads are almost always preferred except when going into a casting.
 
I was wondering Mel. What do you do in the case of an automotive engine that may or may not have bolts even as good as grade eight bolts? I get for structural but what about stainless for holding things on the firewall or even brass in some electrical apps?
 
Depends on where...

mannanj said:
Mel:

I should think that grade 3 or 5 Hardware Bolts should be sufficient to hold a 2pound oil cooler filled with oil. I would think that the aluminum would fail first. I don't think that this aplication would warrent X-rays or special NDI inspections. ???????????????????????:confused:
Click to expand...

If I read the original posting correctly, this is an add-on oil filter with a spacer.

The bolts in question would go into tapped holes in the Lycoming accesory case.

High vibration, an overhanging weight, tapped holes in a expen$ive Lycoming part....

Good bolts are certainly called for in this application... and Lycoming's standards have already defined a coarse thread....:)
 
How about a bolt cutter?

I bought a bolt cutter from Cleaveland tools - tried it out, and it works great.
Maybe you could cut down the 28-length to 20 with it. The cutter works like a guillotine - you thread the bolt into the face plate, then shear the bolt with the blade. I thought it sounded a little crude, but I was impressed when I tried it.
Anyway - just a suggestion for you, Bill.
Pete
 
Let me rephrase...

Jim, Certainly I use logic when inspecting. If you have a valid reason for using non-AN hardware then it may be acceptable. My point was not to use hardware store bolts just because you have them. AN hardware should be used unless you have a specific reason to deviate.
Pete, The 20 vs 28 is threads/inch, not length.
 
I agree that Grade 8 bolts tend to be brittle, I have always preferred Grade 5 for most applications.

Automotive OEM bolts are as tightly controlled as aircraft after all the automotive industry has as many people trying to sue them as the aircraft industry.

Those AN bolts for ECi I hope that price was per 100 as $7.50 for a 1/4" x 1" long bolt is a bit excessive.

SS bolts are very weak and should not be used in any application where structural strength is required. SS bolts are around Grade 2 and should only be used for corrosion resistance.

A good source for your fasteners is a must as there have been a number of instances of counterfeit bolts being passed along. This has been an issue in both the aircraft and automotive industries. I would stay away from hardware and discount house for my fasteners and go to proper suppliers for the application.

Bob Parry
 
1/4 20 bolts

I tried multiple sources suggested and found no AN bolts available at reasonable prices. Finally a local Fastenal Store came up with grade 8 2.25" 1/4 20 bolts for $13/50 bolts. Thanks for all the help. Now I have another question. That is, how deeply should the threaded end of bolt extend into the accessory case blind hole? The Standard Aircraft Handbook says at least the thickness of the item being bolted in place. The angled oil filter adaptor has a flange 1/4" thick, and the spacer is 1 3/8". The holes in accessory case can take almost an inch of bolt. I currently have 1/2" of bolt extension into the hole; is this enough or should I get longer bolts? Does anyone feel the grade 8 bolts are too brittle for this application? Thanks in advance for any insights. Bill
 
Bolt length

You've got a 1/4" bolt, buried 1/2" deep, so you've got a 2 to 1 ratio, which is double the minimum. Add a bit of medium Loctite and you're good to go.
 
aeroinstock.com

Aeroinstock.com is another option for engine bolts.

I overtorqued a bolt and needed a replacement. I was able to get my engine supplier (aerosport power) to send me the bolt, but I also discovered this site as another option. They had no minimums, and I was able to get a few spares.

Don
 
Lycoming uses Grade 8

All the course-thread bolts on a Lycoming are Grade 8, not AN. Lycoming has told me to use "good quality Grade 8 bolts" for engine assembly.
 
LarryT said:
...is essentially an alloy & heat-treat specifications. the spec tells you what strength you should have if the bolt is made right. Unfortunately, Grade 8 is NOT a quality assurance spec. For example, there is no requirement for post heat treating for hydrogen embrittlement of plated bolts or x-ray for inclusions and/or voids. In all the years I raced cars, every critical fastener was AN or a specialty fastener with QA standards & company reputation.

This is just not my opinion, but it is in print in every book published by Carroll Shelby, the individual responsible for the Ford GT finally lasting the entire 24 Hrs at LeMans. The cars had been fast enough for years, but always broke.

His books included "Prepare to Win", "Tune to Win", and a Fastener/Hardware Handbook the name of which I can't rememeber because we all called it Sc**w to Win," a title apparently vetoed by his publisher.

Larry
Click to expand...

Mel said:
Be careful using grade 8 bolts in structural situations. They tend to be brittle and have cut threads. AN bolts have rolled threads and are not as brittle.
Do not present an aircraft to me for inspection with grade 8 bolts installed.
Click to expand...

This, and the above quotes, is why I will never install hardware-store hardware on ANY aircraft I own or maintain.
 
I guess I'm still confused

I also need 1/4 x 20 Bolts..Need 1 1/2 inch length, with 3/4 threads..but they must be drilled heads...for the injector..went on thomas.net and had no luck..the GAHCO site is apparently down.. don't really want the gr 8, as most are chinese made, and I don't trust 'em anyway..any other suggestions? thanks in advance.
 
Bolts

This has been an incredibly frustrating process. We now have replies about brittle #8 bolts with voids, completely unsafe and unable to pass an inspection with Mel to one suggesting that Lycoming uses these same bolts on their engines. Thanks to Fastenall my oil filter adaptor is now installed and seems solid. I've tried for 4 months to get AN 1/4 20 bolts with no luck. Now I have several more feelers out there, some suggested on this thread. Thanks to all who took time to reply. I'm still confused and waiting to get the ideal bolts. Bill
 
Bolts

Tried aeroinstock.com and they can't supply them either. This makes 15 vendors I've tried. Think I'll stick with the #8's. Mel - are you still as opposed to these? Bill
 
Try NAS1352 Socket Head Cap Screws

We have issue finding aerospace quality UNC fasteners at work, too. In those applications where we are forced to use UNC threads, we generally use NAS1352. Readily available and excellent quality. They are available in 3 basic flavors - alloy steel (155ksi yield), CRES (stainless steel - 30 ksi yield), and Heat resistant steel (A286 - 120 ksi yield)
We rarely use CRES due to its low yield strength. Most often we use A286 as it has excellent corrosion resistance without plating. In very high load situations, we specify alloy steel.

Good luck,

Dean Pichon
Bolton, MA
 
One thing not mentioned much in the information overload above, is that using a coarse thread fastener (particularly in a cast aluminum part) is to not let it become loose. Make sure you use thread locking compound (my preference) or locking washers to make sure it doesn't loosen. This is much more of a concern in the application originally brought up than the fastener material itself.
 
Bolts

Thanks to Dean and Low Pass! Have some possibility of obtaining thru ECI and otherwise will try your suggestions. Will use thread locker and internal tooth lock washer. Bill
 
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