Swingarm Pivot Bolts--- Machining, Metallurgy

[DohcBikes]

We are going to machine some 200x swinger pivot bolts.

What are they made of?

Anybody here made any before?

Will 304 stainless work? I'm a metal composition idiot, tell me why or why not.

What SHOULD I use?

I've seen a few failed attempts here... what went wrong?

Hoping to hear from Billy, H.J., El Camexican, DC, etc...

Any professional input would be greatly appreciated.

[oldskool83]

They were made of carbon steel. I use to have HRE make all me new bolts out of 304 SS. 316 is over kill and medical grade

[Dirtcrasher]

And some stainless never rusts.....

Just go to any metal selling place such as (Speedymetals.com) and they explain whether it's good for this or that as well as weld ability.

[fabiodriven]

Am I making this up in my head or did Ronny's stainless bolts start bending?

[Motorgidd]

I looked into this locally not too long ago but the machinist said it was a no-go because of the oval shape that is close to the head of the bolt, it wasn’t something their machines could do I guess. I have a good used 200x swinger bolt if you need dimensions.

[DohcBikes]

The machining is not an issue. Thanks for the offer on the bolt, I have a few to use.

Curious to fabio's concern of previously made ss bolts bending, can anyone substantiate or deny?

Thanks for the replies so far, I wanna get this right.

[86T3]

I also heard that ronnies SS bolts bent, i think Ben said raffa had problems with it. I'll get ahold of ben and have him comment. I know one company makes their front axle bolts out of chromemoly, probably overkill for a 200x.

[Mosh]

5 years on my HRR ss axle bolts..No issues Yet. I do not run a Swingarm bolt in mine, but My wifes trike does, but she does not jump a lot anymore.
Pretty sure there was a wreck that involved a bent bolt after the fact, but it did not snap.

Just keep in mind that when you make items of structural in nature, you open yourself up to any kind of liability or blame if said product fails.
In this day and age you could make them from indesctructatainium and still find someone that can overcome the durability, and still find a way to blame it on you.

[just ben]

Raffa did bend a stainless front axle. I'm not sure what grade it made out of. Solid round stainless is not rigid enough for axle but may be for a swingarm bolt since both sides are of the bolt are mounted solid. If I remember right Raffa bent the axle at tf 2011 going over a small jump but landed crooked on the front tire causing one fork to compress before the other. There is a video of the crash on YouTube and probably on here also.

[El Camexican]

In no particular order and from a fading memory…

I’m surprised to see Mosh has an SS axle. That would be the one place I’d be concerned to use SS as it is not all that hard and will bend with about the same force as a common steel rod of equal diameter. It is tough, but has a low yield strength. I once bent a high strength steel axle on a bike as it was too small in diameter for the width of the swing arm (19mm over a 12” span) The trick set-up back then was a vacuum heat treated hollow chromoly axle from PMFR in MN, but even they said my span was too much for a 19mm axle and that a 25mm was the min for that width. Fast forward to today and you see pipe axles and swing-arm pivots are the way to go. Strong as all heck, ridged and they weigh a fraction of a solid bar. So simple and cheap, yet so many years to figure out.

304 VS 316, I believe 304 is a little stronger that 316 and a lot cheaper, but 316 is the most corrosion resistant of all the common SS. Any SS will rust if contaminated with carbon steel (like if you grind carbon steel against it, or weld a piece to it, of even bend it on steel dies without protective paper) but even contaminated 304 will outlive the rest of the parts on any trike.

SS is hard to machine. I don’t know the proper terms, but in order to work it your tool speeds need to be decreased in comparison to carbon steel. I don’t recall what lathe work involves, but drilling requires a slower speed and a flatter bit tip. It likes to gall, so threading and such is best left to the experianced. You should use anti-seize on all SS threads if you ever want to take them apart.

If you are welding a carbon steel nut on your SS axle use 309 filler. Anything else will crack.

Unless the axles on this trike are prone to corrosion I would make your axle out of 4130 or 4140 steel and not even treat it (it distorts unless you use a vacuum system) and grease it every few years. It will last a long time.

[BOB MARLIN]

Any 300 series stainless is way to soft for that aplication. Its marine grade not medical grade. It won't rust but is not a whole lot harder than aluminum. 440 stainless is medical grade and can be heat treated to get very hard (scauples are made of this). I would think a mild steel or carbon steel that was machined and then "case" hardened to a depth of .030" would be perfect. That would bring it up to about 62RC , witch is very hard, great for bearings to ride on, but leaves it soft in the middle so it will resist cracking. This is the way a lot of car and truck axles are made.

[Mosh]

I’m surprised to see Mosh has an SS axle.

Well..... I have also been known to put tight plastic bags on my head..Just for fun.

Someone told me I would yank the foot pegs out of the engine on my 70's too doing this stuff.
But as mentioned..I am not the one to admire warning labels. I routinely spill Hot McDonalds coffee in my crotch, just to ease the numbness of everyday society..

[DohcBikes]

Just keep in mind that when you make items of structural in nature, you open yourself up to any kind of liability or blame if said product fails.
In this day and age you could make them from indesctructatainium and still find someone that can overcome the durability, and still find a way to blame it on you.

Yep, trying to keep that in mind during this process. Good to see that you've had some success with the ss axle bolts.

304 VS 316, I believe 304 is a little stronger that 316 and a lot cheaper, but 316 is the most corrosion resistant of all the common SS. Any SS will rust if contaminated with carbon steel (like if you grind carbon steel against it, or weld a piece to it, of even bend it on steel dies without protective paper) but even contaminated 304 will outlive the rest of the parts on any trike.

Great info thank you. Eric said something about using carbide to cut it...

SS is hard to machine. I don’t know the proper terms, but in order to work it your tool speeds need to be decreased in comparison to carbon steel. I don’t recall what lathe work involves, but drilling requires a slower speed and a flatter bit tip. It likes to gall, so threading and such is best left to the experianced. You should use anti-seize on all SS threads if you ever want to take them apart.

This was the first thing Eric said after he suggested the 304. He does a lot of gunsmith projects including threading barrels for suppressors and such. Watched him do one this morning, so cool to watch this stuff happen. I assume since he has the carbide to cut it that he has done some stainless, and I consider him more than qualified to handle the project.

Unless the axles on this trike are prone to corrosion I would make your axle out of 4130 or 4140 steel and not even treat it (it distorts unless you use a vacuum system) and grease it every few years. It will last a long time.

Not an axle, but a swing pivot bolt. I would however like to hear opinions on the comparison of wear and tear between the two. I'm thinking with the pivot bolt would receive much less shear load, and that the bearing wear would be considerably less as well. That being said, if SS aint strong enough, then it just aint strong enough. Judging by the jump pics Mosh has shared, 99% of sane people would have trouble snapping his axle bolt...

Any 300 series stainless is way to soft for that aplication. Its marine grade not medical grade. It won't rust but is not a whole lot harder than aluminum. 440 stainless is medical grade and can be heat treated to get very hard (scauples are made of this). I would think a mild steel or carbon steel that was machined and then "case" hardened to a depth of .030" would be perfect. That would bring it up to about 62RC , witch is very hard, great for bearings to ride on, but leaves it soft in the middle so it will resist cracking. This is the way a lot of car and truck axles are made.

Again, not an axle, but some excellent input as well. "way too soft" seems a little dramatic to me, but it might just be because this isn't what I wanted to hear... Anybody else think it's just not strong enough?

Let's keep in mind that your average 200xer isn't taking his ride over a whole lot of 'sweet jumps'...hawaiirider excluded of course.

More than likely I will go ahead and order a couple 304 rod blanks and have Eric make one, then maybe get one of the motocrossers that comes in to the shop to sign a waiver for a torture test ride, lol....

[toki]

Well..... I have also been known to put tight plastic bags on my head..Just for fun.

Someone told me I would yank the foot pegs out of the engine on my 70's too doing this stuff.
But as mentioned..I am not the one to admire warning labels. I routinely spill Hot McDonalds coffee in my crotch, just to ease the numbness of everyday society..

yup... i felt that was signature worthy lol.

[BOB MARLIN]

What I meant by way too soft. Is that it is way too soft. 304 stainless is about as hard as brass and is not well suited for anything that is holding the whole back end of your trike on. It will stretch, the threads wont be very strong, and if it gets stuck like a lot of them do, you wont be able to knock it out with a punch with out swedging it out and making a mess out of it. It MIGHT work just fine, but there is better options available that will even cost less and machine much better.

You don't have to use carbide to cut stainless, in fact high speed steel cutters work better. The problem with stainless is that it cuts like bubblegum and sticks to the cutter. The right coolant/lubricant and tool geometry is what is used to overcome this. High speed steel cutters have a sharper edge that create a smoother chip that with slide off the tool better so it doesn't load up. Believe me, I've been dealing with this stuff since I was 15, and I aint young.