i think any nice steel stock would work. like you said, the origionals dont apear to be stainless.
theres more to heat treating carbon steels than just getting it red hot and fast cooling it. i wont pretend to know the intricate magic secrets of tempering. but id be worried about binding a bunch of stress into the structure of the steel and leaving it brittle and prone to cracking. especially with the kind of abuse its taking, i might focus on its ductility / hardness balance and if it wears out someday, make a new one. at least it didnt shatter catastrophically.
but im sure theres people on here whove made similar parts and im curious what theyll have to say.

 

I'm pretty sure that most average mild steel would only last a day or so in a high load bearing.

Intuition tells me that it def needs to be either a very hard or heat treated after machining.

 

try 4340 or 4130 steel, those are commonly used for structural parts that have to take abuse. could always use titanium for the extra baller status too...plus it's DUMB light. i remember the first time i held a piece, it was .75" round stock maybe 3' long, felt like balsa wood compared to steel.
i assume this will be in contact with grease inside the swingarm, from the bearings? cos another thing to think about is how it will hold up if it's exposed to the elements/road. u don't want to have to replace it all the time due to pitting/rusting

 

more than likely they were hardened to begin with, but you should be able to utilize tool steel or something similar. if you tell me what you have available i can get you the Rockwell's or Brinell's for that particular type.

 

4130 or 4340 seem way to soft imho, but I'm no expert, that's why I'm asking, I need to find someone who knows.

Was that a guess or do you know what inner races are usually made of?

 

Some p20 might work. You can test the hardness and then just get a comparable material.Or use like some A2 and then heat treat it. If you do heat treat after turning it will need to be a very stable steel that doesn't warp a lot unless you can finish grind it afterwards.

 

CK hit it. Tool steel FTW.

 

Youll have to excuse my ignorance, but what is tool steel? Is it a 1xxx series, or 4xxx series, or how do I identify it?


Can it be turned on a lathe? If not, how would I know what heat treating to get? Is there any way I can do this myself?



What is P20, or A2? I'm not familiar with this notation.

 

I'd save my friend a cutting head (hobby lathe?) and use 303 stainless. 303 is a little tougher than mild steel on hardness and is almost as corrosion-resistant as 304. It's regularly used for applications like this.

If that sleeve fits right, the only significant stress on it will be compression, and I can't see a situation where you would flatten a spacer made from even mild steel. Torsional stresses will be limited and there should be no shock loading or impact.

 

I just went out in the garage and hit the OE inner race with a file, it's VERY hard. Feels like glass at first, you've gotta really put some effort into it to scratch it much.

I'm not sure what tooling the guy would be using, he's my dad's friend, but he's an airline maintenance machinist, if he's doing it at work it's serious stuff, if it's at home I have no idea.


While riding, won't the rear wheel thrashing around hitting square edged bumps be impact load? This bike will get ridden hard in rocky terrain.

 

I'm not sure what tooling the guy would be using, he's my dad's friend, but he's an airline maintenance machinist, if he's doing it at work it's serious stuff, if it's at home I have no idea.

I'd ask him what to use, I bet he's more qualified than any of us to pick a metal.

While riding, won't the rear wheel thrashing around hitting square edged bumps be impact load? This bike will get ridden hard in rocky terrain.

No, not unless there's play at the joint. It wouldn't even be an instant load because of the bike's suspension. It takes serious impact loading to deform a part like that and even if it did deform, it doesn't sound like a catastrophic failure is possible at that location.

 

E52100. Bearing quality aircraft grade alloy steel and its not too expensive if you are just having bushings made from stock. You can get it at mcmaster.com.

You might also check into bushings already made unless you have some sort of funny requirement. If this buddy is going to be turning this stuff down he probably wont want anything over W1 general purpose tool steel.

 

I read this right after I finished looking through mcmaster-carr and found W1 tool steel. That E52100 looks good.

I'm having my dad ask the machinist tomorrow if he can work with that alloy. If not, I have to split the cases and drill the engine out to 17mm.


Thanks for the help guys, now I have to solve my bearing issue. :doh:

 

I was just thinking I misunderstood the question, is this a sleeve or a race?

 

The outer race is pressed into the swingarm and holds the needles, the inner race is basically a bushing, or sleeve, between the needles and the swinger pivot bolt.

I'm sure i'm describing this poorly....

 

I didn't realize it was in contact w/ the needles, yup on the tool steel

Sorry

 

Again... tool steel.

 

Would you choose tool steel over the E52100 alloy that shift posted? Is that also a type of tool steel?


Also, I'm still a little confused about the heat treating. Are you guys saying that even if I use a hard tool steel that I will still need to heat treat it? I have no way of grinding it after heat treating.


If this becomes way to difficult I can get around it by splitting the cases, boring out the motor mount to 17mm, and drilling the case mating surface for a larger dowel. (the 17mm bore would eat the whole dowel at the rear of the case halves.

In that case I could skip this step entirely and would only need to find a narrower bearing. which is turning out to be a total bitch btw.

 

making the pieces isn't the issue, its the grinding tools required to get your races to match your bearing surfaces that become the issue provided you can Heat treat the steel then temper the races to make them both strong and durable and once they are hardened and tempered, you can only shape them with grinding them, much too hard to cut on a lathe, yet trial and error always educates the builder. You could source a bearing company and see if they have what your looking for, have your inner and outer dimensions for outer race Dia. and inner bearing Dia for axle and you should be able to find a bearing and race to match your job. Such as Timken, Emerson, i'd bet you could find a bearing supply company in your town and take your dimensions and get something to work. Its a shot