Stainless steel or grade 8?

[lazylightnin717]

So I was browsing some sites today, looking for some parts and I came across stainless steel bolt kits. Stainless definitely looks good and it will withstand a lot more than zinc, but it looks like my S4 is already held tight by grade 8. And correct me if I am wrong, but grade 8 is the big cheese. Outside of aesthetic purpose, is there any good reason to switch over to stainless? Or am I just crazy for pondering about the bolts on my machine... What do you guys think??

[Speeddog]

For the vast majority of bolts on a Monster, stainless bolts are fine.

Most of the OEM bolts are metric grade 8.8, which is roughly equivalent to SAE Grade 5.

More info here:
http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx

[battlecry]

Using grade 8 on anything threaded into aluminum is a waste of money.  Stainless is not as strong, but plenty strong to hold aluminum.  Be sure to use anti-seize compound.

[victor441]

from what I've read SS fasteners can be brittle so it is NOT a good idea to use them in critical locations i.e. suspension, brakes, motor mounts, etc...

[Raux]

ok this brings up a good question.
can anyone give a breakdown of the different bolt materials and they pros/cons?
I know there's
Stock metric 8.8
Stainless Steel
Titanium
Aluminum
Ergal

[He Man]

Raux, the specs are posted in speeddogs link. for 8.8 10.9 and stainless
8.8 and 10.9 are both carbon steel. 12.9 is an alloy steel.

you can look up the uses of carbon and alloy steel, and i think there is a difference in the annealing and tempering specs, but im not sure on that.

Titanium is pound for pound twice as strong as steel. This means you can get the same strength of a steel bolt, in half the weight.

ALuminum is soft, needs to be polished and coated. It corrodes and develops a milky layer very quickly.

Dont know what ergal is.

Using grade 8 on anything threaded into aluminum is a waste of money.  Stainless is not as strong, but plenty strong to hold aluminum.  Be sure to use anti-seize compound.

It isnt a waste of money if there is a reason behind it. On your engine, I think stainless is the way to go. noncorrosive, and the torque required is very low.

On your rotors though... 12.9 is the way to go. End of story Try taking a impact gun to the stock bolts or stainless steel bolts. they will strip in a heartbeat.

[Speeddog]

Beyond the carbon steel bolts, IE OEM bolts, 8.8, 10.9, 12.9....

Stainless bolts aren't as strong, but for most applications on a duc, that's not an issue.
They look nice, and stay looking nice.

Titanium bolts are about 2/3 the weight of steel.
They are gall-prone, probably not much of an issue when threaded into aluminum, but moreso if threaded into steel or a Ti nut.
I've never had any, couldn't justify the weight savings vs. cost.

Aluminum and Ergal are the same, Ergal is just a trade-name for aluminum.
They are roughly 1/3 the weight of steel.
I wouldn't use them for any load-bearing application, but for a handful of non-critical spots they'd be fine.
Never had any of them either, same reason as the Ti bolts.

[Raux]

ok, on my bike, the horizontal exhaust port stud and nuts are corroded. what would you recommend for replacement. and is there even a replacement for the stud?

[LowThudd]

ok, on my bike, the horizontal exhaust port stud and nuts are corroded. what would you recommend for replacement. and is there even a replacement for the stud?

Probably stainless, since it won't corrode with heat. Don't know if they are available or not.

[He Man]

they are copper cladded steel. most companies use it. i just looked it up right, they say its because the steel is strong and the copper has a high resistance to corrosion.

i always thought it was pretty dumb becuase the thing turns green and then black from all the grime sticing onto the oxidation.  but i guess they have their reasons

[lazylightnin717]

Good information guys! I am having an issue with one of my turn signals at the moment. I'm trying to do tail chop and removed everything except for one turn signal. The bolt is rusted. It looks like there is a coupling nut on the inside of the turn signal and when I try to work the bolt loose, the nut spins inside the turn signal. I've tried clamping it and that didn't help. I've also tried pulling the coupling nut out of the signal but it won't budge. It must have a flange to keep it from working it's way out. Any suggestions of what I can do to get the signal off?

[Cider]

from what I've read SS fasteners can be brittle so it is NOT a good idea to use them in critical locations i.e. suspension, brakes, motor mounts, etc...

Paging Chris @ CA Cycleworks...

There was a big "discussion" about this a couple years ago (can't remember which board exactly).  IIRC, they were talking specifically about caliper bolts.

[hcomp]

Yes,

Stainless Steel is more brittle than carbon steel.  It is what is called a very "Dry" metal.  I would not use stainless bolts on braking systems period.  On brakes, you should only use metric grade 10.9 or higher, or SAE grade 8 or higher.  If you are using titanium for brake bolts, make sure you are using grade 5 titanium (6AL-4V) and that it is heat treated.  When properly heat treated titanium can surpass Metric grade 10.9 and SAE grade 8.  If you can find Ti beta alloys they get even stronger. The biggest advantage of titanium (other than weight and strength) is corrosion resistance.  Titanium is more corrosion resistant than stainless steel. Speeddog is right, you could use aluminum on several fasteners on the bike. A 7075-T6 aluminum bolt nears the strength of 304 stainless steel when used in that application. 

[krista]

Paging Chris @ CA Cycleworks...

There was a big "discussion" about this a couple years ago (can't remember which board exactly).  IIRC, they were talking specifically about caliper bolts.

Yeah, I give up. People whose "industry" or "engineering degree" is more accurate than my 25 years on motorcycles have proven to be closed minded and completely disregard the results of real world use. I use stainless steel bolts anywhere on my motorcycle where I have to replace them (and the bolt is available in SS). Lots of racers I know do, too. Never ever heard of anyone on a motorcycle having a SS bolt break. Stainless is too spongy to break... I have had nuts (that were finger tight) fall off, leaving SS bolts in shear mode. Even these didn't break. One of the stainless bolts from the tailsection left an interesting impression on the rear wheel on my 916 after falling out ... it happened at a race weekend.

And anywhere means just that, ANYWHERE. If I have to replace lame deformable OEM hardware, I get in SS replacements. I have used them in these instances: caliper mounts, fork and triple clamping screws, tail section mounts, sidestand plate screws, rearset mounts, shock mount bolts, rotor mount screws*, engine cover screws. I use grease to lubricate the threads on all fasteners to prevent them from seizing. Unless there is a location that has proven to loosen during use, I don't use loctite.

If you lose sleep when your bike has SS bolts, that's great -- just keep the hysteria out of motorcycle forums. And I promise not to go to your industry and say it's ok to use SS bolts. OK?

Even though I may seem as closed minded as the propeller-heads, I actually read their arguments, reasoning, and attempts to employ logic and then incorporate that into my reality. The propeller-heads don't like stainless hardware because they also love using solvents like simple green. The chlorides in solvents attack SS fasteners, impairing their strength. As opined above, I agree that nearly everything on a motorcycle is so engineered that it is never an issue. And now I ban the use of simple green on vehicles in my shop. It will etch engine surfaces or paint anyway, so beyond the remote chance of causing an SS bolt to fail, it's good practice anyway.

BTW, I have on more than one occasion had a "metric grade 10.9 or higher" bolt fail on my own personal motorcycles and will never, ever replace a standard fastener with a bolt that isn't stainless or OEM. If it needs to be 10.9, the factory will put it there. These bolts are too rigid and therefore brittle when vibrated by a Ducati engine.

One of the screws was a M6x25 on my 916's clip-on. I saw the head of the cap screw laying on the lift and took a while to find it. The other one was a M6x16 (or 20) that was on a 900 valve cover. Since it was forward cylinder exhaust side, the oil pouring out was a great direction finder for the broken screw.

I have spent a few thousand $ from this web page.

Chris

[motolocopat]

What Chris said