stainless steel fasteners really a problem?

[Graflex45]

I'm trying to get a definitive answer to the issue of using stainless fasteners on attachments, particularly mower decks.
I've restored 3 over the past 4 years, disassembled a 4th for parts to use and stripped down and restored a tiller. I have become set on using stainless steel bolts where I can, and modifying the sheet metal to use carrige bolts where possible on the decks to keep cluppings and crud from building up. And I'm now restoring a non-cub deck and doing the same on another tractor.
Is using lower grade stainless fasteners with carbon steel really a bad idea? I smear anti-sieze under the fasteners and then on the thread. I have even disassembled a deck i replaced the fasteners on 3 years ago to get painted and the area doesnt show any pitting underneath and plenty of compound was still under it. same with cleaning up one of the decks for my 70 before it gets used this year.

[green407]

If you're worried about dis-similar metal corrosion, stainless hardware is the way to go. However stainless hardware is more prone to galling then standard carbon steel hardware.

[Graflex45]

Originally Posted by green407

If you're worried about dis-similar metal corrosion, stainless hardware is the way to go. However stainless hardware is more prone to galling then standard carbon steel hardware.

Perhaps in writing the post I didn't phrase it clearly. is using stainless 304 bolts with the mild carbon steel of cub mower decks, snowblower, tiller etc, cause a problem with rotting the steel around the bolt holes?
I was making a post on another group about rebuilding another tractors deck and replacing all the rusted up bolts with stainless carriage bolts so the clipping won't build up and the bolts won't rust and become unremoveable. Guy confidently replies to me and other person that I shouldn't do that and it will rot out the holes.
I understand how galvanic corrosion works, but these aren't immersed in water because it's not a boat or plumbing.

[Grandpa53]

You might want to look into using a sacrificial anode like is used on boat motors.

[finsruskw]

It's the acid & moisture in the grass clippings that rot stuff out when left not cleaned out.
Or left sitting in the yard where it ran out of gas or whatever.
One sees them sitting out wherever one goes it seems.
Makes one wonder...What's next??..... Decks made from plastic???!!

[Frank1541]

I stopped using Stainless to replace any bolt that is grade 5 or higher. While high strength stainless bolts are out there, they are pretty expensive. (I used to have access to high strength SS bolts where I worked).
I didn't want the stainless bolts to break or shear off in critical situations.
I never had it happen, but I have become more conservative about safety in my old age.

[Graflex45]

Originally Posted by Frank1541

I stopped using Stainless to replace any bolt that is grade 5 or higher. While high strength stainless bolts are out there, they are pretty expensive. (I used to have access to high strength SS bolts where I worked).
I didn't want the stainless bolts to break or shear off in critical situations.
I never had it happen, but I have become more conservative about safety in my old age.

I know stainless bolts are less strong, but I don't think that's really a concern with bolts holding together the attachments. The sheet metal of the deck would deform before a 3/8 bolt would shear. you have multiple bolts holding brackets together that hang the deck off the mule drive so they don't swivel or twist.

[green407]

Originally Posted by Graflex45

Perhaps in writing the post I didn't phrase it clearly. is using stainless 304 bolts with the mild carbon steel of cub mower decks, snowblower, tiller etc, cause a problem with rotting the steel around the bolt holes?
I was making a post on another group about rebuilding another tractors deck and replacing all the rusted up bolts with stainless carriage bolts so the clipping won't build up and the bolts won't rust and become unremoveable. Guy confidently replies to me and other person that I shouldn't do that and it will rot out the holes.
I understand how galvanic corrosion works, but these aren't immersed in water because it's not a boat or plumbing.

I get what you're saying, I've never really seen stainless hardware cause carbon steel to corroded. Ive seen lots of aluminum oxide cling to stainless hardware, but as far as carbon steel goes i think you're safe.

BTW, I'm a shop foreman at an International and Isuzu dealership in the rust belt.

[CC_HDS_2185_JB]

imho : Safe to use if under 1/4" diameter on any application that has a 1/4" grade 8 or 12.8 metric bolt because what it is holding together will usually shear or pull out before the stainless steel fastener gives up.

That being said, I stock and use everything from #10-28 to 3/8" stainless repairing OPE and trucks. Mostly bought off Amazon.

No, I am not going to use a 3/8" or 1/2" stainless to remount a spring hanger, TTB radius arm on a truck, or a shock mount. I AM going to use it on cutting decks, consoles, stake holders, roll bars (aka light bars) etc.

I lost a 4x8 trailer into a big hole when a tree uprooted, the bolts (3/8 stainless) and frame held, what gave out? Not the pressure treated 2x4, not the 3/8" stainless bolts, it was the stake holders that twisted.

When I worked for Ryder truck (tractor trailer) part of my job as a mechanic was removing all unmarked or grade 5 fasteners and replacing them with grade 8 for the mudflaps in boxes at that location while I was testing for my federal license.

I would never use stainless in that situation, thousands of constant high load shock and vibration where a loss means a potential accident or fatality ... to a bus load of nuns.

In my much younger days, I worked on and off doing engine work to boats a few times (old school V-8s). Binimi tops are secured with stainless to many times plain steel or aluminium , but, you would be hard pressed to find stainless in the engine compartment of a cruiser.

Nope, cast steel (or iron?) exhaust fastened with carbon steel grade 5 or grade 8 bolts. Even with water running through them. Not even the water pump impellers were held on with stainless steel.

So, it comes down to common sense and location, location, location



Today I was changing wheels (bought on Amazon) attached to hubs I bought from Amazon:

DRIVE UP EZGO TXT Front Hubs, Golf Cart Front Wheel Hub with Wheel Bearings Assembly Fits EZGO TXT Medalist 2001-2013 Gas and Electric Golf Carts, 70895G01

https://www.amazon.com/dp/B08DKTTGK3

Aluminium hub, stainless steel bolts, with steel acorn nuts.

Someone correct me if I am wrong, but, I think these are standard clone replacements and if stainless steel with aluminium and steel was a death sentence, would Club Car and E-Z-Go be using that combo?

If you need an upgrade in anti-seize beyond the grey stuff, marine might be a good pick.

https://boltdepot.com/MRO_solutions_...ade_anti-seize

Yes, in an industrial setting having stainless with steel or aluminium while being exposed to chlorine might be a bad idea. But, the engineer that earns over $150 per hour is going to have all that figured out before you come along.

It is a used, under $2000, lawn or garden tractor, I would not over think it. Use what makes you happiest, especially if you might have to repair it again in the future.

Aluminium rivets on a steel deck might be a problem, but, might the fix to a neighbour's cutting deck using license plates (aluminium plates, aluminium rivets, steel deck, no anti-seize) far out lasted the Kawasaki 22 HP engine he blew up by running it out of oil.

[PBIjim]

Stainless fasteners in aluminum will corrode & lock up over time in a salt water environment. I don't know how corrosive wet grass clippings are.

Stainless is more susceptible to metal fatigue from vibration compared to carbon steel.

Stainless is also more prone to galling, if not lubricated. When I worked in a boat yard, I used green marine grease on everything that didn't get hot like an engine head and I had good results. NASA uses something called tefgel. It's not quite as messy as anti-seize, but it's a runner up in that department and it's expensive. For hot applications, like spark plug threads, I use a small amount of Never Seize and just deal with the mess.

Regardless if a bolt is stainless or carbon steel, if it scrapes the paint off of the carbon steel sheet metal that it is fastened to, then the sheet metal will rot. Rubber washers may be worth considering here.

304 & 18-8 are two different names for the same grade of stainless. 316 is more expensive, stronger and more corrosion resistant. Grades above that get more expensive fast.

If you want to look up actual strengths of different bolt materials, Google is your friend. KSI, KPSI, or thousands of pounds per square inch, is generally the unit of measurement for shear, and tensile strength charts. That's 3 different ways of writing the same unit of measurement. Look up shear ratings if the load on the bolt is sideways. Look up tensile ratings if the load is pulling the nut away from the bolt. You may be surprised to see just how strong a crummy little 1/4" bolt can be.

I mostly use grade 5 for general purpose applications on tractors. I generally use Grade 8 or high alloy fasteners for motor to frame bolts and stress critical bolts (like suspension or drive-line). I've used 304 bolts here & there on tractors and never noticed any issues. Stainless can be nice in areas where the paint and/or plating is likely to get rubbed off of the bolt.

If you want to avoid the extra work of modifying the sheet metal to use carriage bolts, you may wish to consider button head Allen bolts.