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Message started by och on 03/09/22 at 05:21:09

Title: Don't use stainless steel fasteners
Post by och on 03/09/22 at 05:21:09

Just something that I learned the hard way some time ago. They are very problematic, they suffer from what is called "galling", which is basically easily damaged threads, that easily lock up, especially when used in combination of both stainless steel bolts and nuts. Once you torque down a stainless bolt and nut, chances are the threads are locked up, and you won't be able to undo them. They should only be used in marine environments, or where the fasteners are exposed to a lot of salt.

Also, they are not as strong as grade 8 fasteners. I personally always try to use grade 8 fasteners, or class 10.9, which is the metric equivalent. These are the same bolts that are used in automotive suspensions, they are extremely durable, and come with various coatings that are corrosion resistant. I prefer zinc yellow chromate coating for maximum resistance.

Title: Re: Don't use stainless steel fasteners
Post by justin_o_guy2 on 03/09/22 at 06:03:49

Does it matter what they are screwed into? No nuts on the SS screws here, they are in aluminum.

Title: Re: Don't use stainless steel fasteners
Post by Gary_in_NJ on 03/09/22 at 06:08:58

Oh boy...this is not valid advice. It depends what you are using them for.

Title: Re: Don't use stainless steel fasteners
Post by justin_o_guy2 on 03/09/22 at 07:02:07

I've never seen a problem with the few I've used.

Title: Re: Don't use stainless steel fasteners
Post by TheSneeze on 03/09/22 at 08:07:58

If you use a stainless screw/bolt with a stainless nut, use anti-seize. Stainless fasteners in aluminum are not a problem, and stainless fasteners in steel (not stainless) are not a problem. Stainless on stainless will gall the threads and more than likely seize if used dry.

You are opening a huge can of worms if you want to talk strength of different materials!

Title: Re: Don't use stainless steel fasteners
Post by SoC on 03/09/22 at 08:08:39

There is some validity to this if over torqued, why measured torque (read use actual wrench) is important. One thing is stainless bolts in aluminum, it is particularly a problem as aluminum threads are much softer and more easily damaged, so things like header bolts are very susceptible. One way to minimize is to use of anti-seize. Anyone who works on salt water marine applications will tell how important anti-seize is on stainless fasteners in any other metal. Anti-seize does require some additional consideration of torque specs, but for most of our application it is nominal.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/09/22 at 08:27:39

332C090E040D01120B600 wrote:

Stainless steel into aluminum is not a problem, aluminum is too soft to damage stainless threads. However, stainless into steel often causes problems as well - torque it hard, and threads often lock up.

Stainless into stainless is almost always a problem, the finer the thread, the worse it gets. If you must use stainless, torque them slowly, and use anti seize compound.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/09/22 at 08:30:28

3A30343E353C38316F696D5D0 wrote:

Oh boy...this is not valid advice. It depends what you are using them for.

True, but in most common applications it may be tempting to use a stainless steel bolt and nut... don't! Unless you really have to due to corrosion concerns.

Especially if it is in an application when you have to periodically undo and redo the fasteners.

Title: Re: Don't use stainless steel fasteners
Post by Gary_in_NJ on 03/09/22 at 09:59:23

202C274F0 wrote:

Especially if it is in an application when you have to periodically undo and redo the fasteners.

If you need a grade 8, then you must use a grade 8 or equivalent. I wouldn't hesitate to use SS on items like covers (plastic covers, engine covers - things that are torqued to in-lbs) and brackets.

My rule: if I can see the fastener, and sheer or tension strength isn't critical, then SS is a good choice.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/09/22 at 10:37:35

Quote:
If you need a grade 8, then you must use a grade 8 or equivalent.

I tend to always use grade 8, even if they are not required. The price difference between grade 5 and 8 is negligible, but somehow the quality of the grade 8 is satisfying.

Quote:
I wouldn't hesitate to use SS on items like covers (plastic covers, engine covers - things that are torqued to in-lbs) and brackets.

My rule: if I can see the fastener, and sheer or tension strength isn't critical, then SS is a good choice.

Yep, that I can agree with. I should have been more clear in my initial post.

But no matter what you do, don't use bolts made with Chinesium. ;D

Title: Re: Don't use stainless steel fasteners
Post by Dave on 03/09/22 at 15:41:05

For years I have been using stainless button head screws for nearly all the places that hold on fenders, turn signals, side covers, etc. For the wheels, brakes, engine mounts, etc. I use the stock fasteners so that I have the correct strength fastener.

I agree that dry stainless on stainless can be a problem - but thread locker prevents the fastener from galling and also prevents them from coming loose!

Title: Re: Don't use stainless steel fasteners
Post by ohiomoto on 03/09/22 at 18:32:53

Metal War!!!!

Title: Re: Don't use stainless steel fasteners
Post by justin_o_guy2 on 03/09/22 at 19:06:23

My heart yet soars,that just makes me happy..
Just take the whole sheet, Dave.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/09/22 at 21:38:56

72757472707269721D0 wrote:

Metal War!!!!

Jihad, lol.

Title: Re: Don't use stainless steel fasteners
Post by Serowbot on 03/10/22 at 08:07:35

Life is soooo complicated,... now this. :-?

Title: Re: Don't use stainless steel fasteners
Post by Ruttly on 03/10/22 at 11:03:26

Blue Loctite , ok , definitely not my first choice
Neverseize , better
Uncolored candle wax , cheap

Stainless threads ALWAYS need something , even if it’s just a smear of grease or drop of oil

Title: Re: Don't use stainless steel fasteners
Post by och on 03/10/22 at 13:36:07

0A2D2C2C3421580 wrote:

Blue Loctite , ok , definitely not my first choice
Neverseize , better
Uncolored candle wax , cheap

Stainless threads ALWAYS need something , even if it’s just a smear of grease or drop of oil

Even with anti seize, once you torque them down hard, chances are the threads are locked. Not necessary a concern for something that is fastened down permanently, but for something that needs to be removable, stainless is to be avoided.

Speaking of thread lock. I personally like to use distorted thread locking nuts, I find they work a lot better than locking washers, nylon nuts, or threadlocker.

Title: Re: Don't use stainless steel fasteners
Post by TheSneeze on 03/10/22 at 16:14:25

Quote:

Even with anti seize, once you torque them down hard, chances are the threads are locked.

If you exceed the torque limit of a given fastener style/material/grade, it is always bad. SS fasteners using anti-seize, properly torqued, are not a problem to disassemble. I get it - you don't like stainless. It has it's place in the fastener world for sure, but it gets a bad rap when used improperly.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/10/22 at 19:42:09

https://youtu.be/HC4KiulYs68

Title: Re: Don't use stainless steel fasteners
Post by TheSneeze on 03/10/22 at 21:55:47

It has it's applications. I'm not saying it is better.

Title: Re: Don't use stainless steel fasteners
Post by Hiko on 03/11/22 at 00:01:51

If I wanted to make a stainless bolt and nut gall up I would do exactly what the chap in the video is doing Run it up and down dry at speed with an impact driver
Stainless steel has two characteristics that stand out that is not mentioned
It is a poor conductor of heat and has a high expansion rate when heated.
Stainless steel also wears out thread cutting tools quickly so poor manufacturing standards make for poor threads and also lead to galling
I have run my thumb and finger over some stainless threads and they are very rough Poor manufacture
Stainless steel fasteners of good manufacture and used correctly are fine in my experience Marine engineering and food factory maintenance

Title: Re: Don't use stainless steel fasteners
Post by SpamyToo on 03/13/22 at 05:32:03

Ive used stainless bolts for ages in aluminum and to other SS hardware. I always use anti seize and have never had a galling problem.

Ive had more problems with old rusty iron or supposedly zinc bolts on my bikes.

Anytime Ive ever encountered a galling problem is because some hammer hands over tightened or cross threaded a SS bolt.

I agree SS gals easier, but In my experience its almost always caused by user error.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/13/22 at 07:28:40

Threaded into aluminum and regular steel, stainless bolts are fine. Galling is mostly a problem stainless into stainless.

Also, it is important to buy fasteners from reputable vendors, not the chinesium junk from amazon, etc. My go to source for fasteners is mcmaster, they carry excellent quality products.

Title: Re: Don't use stainless steel fasteners
Post by TheSneeze on 03/13/22 at 08:18:32

I am a big fan of Mcmaster-Carr as well. Great quality, pricier than most, but their delivery is as good as their quality. Sometimes the next day, never more than 2 or 3 days.

Title: Re: Don't use stainless steel fasteners
Post by och on 03/13/22 at 08:34:06

091633343E373B28315A0 wrote:

I am a big fan of Mcmaster-Carr as well. Great quality, pricier than most, but their delivery is as good as their quality. Sometimes the next day, never more than 2 or 3 days.

Yep, and they have CAD files for most of their products, which is super convenient.

Title: Re: Don't use stainless steel fasteners
Post by noob on 03/15/22 at 12:06:24

I used thread locker grease to prevent screws from losing out, work well with outdoor stuff mounting, and it's waterproof too

Title: Re: Don't use stainless steel fasteners
Post by och on 07/15/22 at 19:02:19

Here is a real life example. Today I had my mechanic replace my stock brake system with the bike brake kit from RycaShawn. The mechanic said that OEM caliper bolts would not fit the treads in the new caliper, turns out they were stainless steel bolts, and the threads were damaged, so he had to buy new bolts.

Title: Re: Don't use stainless steel fasteners
Post by verslagen1 on 07/15/22 at 19:52:39

The stock bolts aren't SS, so there has to be more to it than that.

Title: Re: Don't use stainless steel fasteners
Post by och on 07/15/22 at 20:05:08

Interesting, he gave the stock bolts back to me, they are definitely stainless steel. Unless my previous mechanic put in stainless steel bolts when he was replacing my brake pads, for whatever reason.

Title: Re: Don't use stainless steel fasteners
Post by verslagen1 on 07/15/22 at 22:23:33

Stock are definitely chrome plated steel.

nickle plated steel looks like stainless.

maybe if stock ones were wire brushed, might look like stainless.

But, stainless has 80% the strength of steel.
I don't think the 'stainless' bolt would be damaging the threads of a steel plate.

Title: Re: Don't use stainless steel fasteners
Post by justin_o_guy2 on 07/15/22 at 22:29:56

thread locker grease?
Brand name?

Title: Re: Don't use stainless steel fasteners
Post by och on 07/16/22 at 05:48:41

It was getting dark last night, so at a glance these bolts looked like stainless, looking at them this morning they do look to be chrome or zinc plated. Did some searching, they are m10x1.25 38mm partially threaded bolts. In a pinch we got m10x1.25 fully threaded 40mm bolts yesterday at a hardware store. I wont find 38mm, but I'll order 40mm partially threaded bolts of the highest grade I can find to replace them.