Suspension pivot question for the experienced metal fab guys

[John in CR]

I need to fabricate a swingarm suspension pivot for a current build. I'm using a sealed bearing rear hub with a thick 14mm axle as a motor/pedal power combining jackshaft, and for what I believe a really good reasons, I want to make the rear swingarm pivot around the jackshaft axle. Here's a pic of what I have, but I don't like it, and I need advice.



The 14mm axle is threaded with 1mm threads, for which tap and die tools would have to be ordered, and I'd rather avoid the time and expense since this is supposed to be an easy economy build. The swingarm is made from 1/4" steel plate, and the motor along with a bolt on steel piece between the motor and tire will join the 2 arms.

I turned a nut with the lathe into the bushing in the pic, and I was just going to do a metal on greased metal pivot. The nuts, including that longer nut, have a bit of play on the axle, so I see that rapidly becoming a floppy loose pivot and maybe even start as one. The idea of a bushing that threads right onto the axle is now shit canned.

My metalwork experience is limited to a bit of poor welding and lots of grinding, plus a few hours getting to play with a lathe and milling machine, so I've never made anything like a pivot. I haven't even seen many pivots to know a good one vs a poor one. I have 12-15mm of axle to work with at the ends, and both ends are tapped with a threaded hole that looks to be 3 or 4mm and maybe 10mm deep.

My current thought is to turn the axle ends down to 12mm diameter to accept a bearing. If I can find bearings capable of side loads in that small size, then I can install a bolt just beyond the largest sprocket to draw the 2 arms of the swingarm tightly to the bearings. If I can't find such bearing, my next choice would be needle bearings and next roller bearings, and use a bolt with loctite in the axle end hole for a bearing retaining washer. In this latter case I'm unsure what prevents sideways movement through the bearings other than leaving a lip on one side of the arm when I cut the hole for the bearing. Is that one side sufficient?

Any better ideas, suggestions, pitfalls? I'm just looking for longevity and no squeaking with a pivot that has a primary force on it of the motor. If I double up the material of the arms to 1/2" at the pivot, should I just turn and polish the axle and swingarm holes for a metal on metal pivot with grease? Would it be far better to weld some ends onto the axle and fab up something with more like a 1" width and a plastic or rubber bushing like on motorcycle swingarms?

John

 

[John in CR]

I'm sorry, I should have just posted the problem and solution. I just got back from the bearing shop, which gave me my solution. They had small roller bearings they said could handle some side loading. I decided to go with 10mm ID to give me a sufficient lip on the axle to retain the inner race of the bearing. Then a bit of force pulling the 2 arms of the swingarm together will hold it in place. All I need to do tomorrow is turn the axle end down to accept the bearings, and make the holes in the swingarm to fit the bearing OD, leaving a retaining lip, and my swingarm pivot issue is permanently solved.

If I'm missing something please let me know, otherwise pics tomorrow.

John

 

[gwhy!]

I will be interested in see the pics on how you do this. I have been experimenting making a swing arm and I used rose joints as bearings

 

[John in CR]

I will be interested in see the pics on how you do this. I have been experimenting making a swing arm and I used rose joints as bearings

I like your solution too. Then I would have only needed to turn down my axle, and weld the rose joint to the swingarm. Mine may end up a bit cleaner but coming up with the 26mm hole for the OD of the bearings will take more metal work than a quick weld.

 

[Harold in CR]

What, exactly, is a Rose joint ?? That the same as a Heim Joint ??

 

[gwhy!]

What, exactly, is a Rose joint ?? That the same as a Heim Joint ??

Yes I think so.

 

[John in CR]

What, exactly, is a Rose joint ?? That the same as a Heim Joint ??

Google is your friend. Did you know their mission statement is "to organize the world's information and make it universally accessible and useful". To me that makes them the single best company on this planet, because the better Google gets the better the earth has a chance to become. Break the world down into say 5,000 groups of people with a common interest. That means if everyone has internet access that 1 million minds can easily work together with a common cause, and if Google does their job that they all have access to all of the pertinent info past and present. That can only make advancements to better this world accelerate...not just increase, but accelerate.

No doubt that Google will also add to the basic mission, "to facilitate the free communication of the inhabitants of our world", since once you organize the info and make it available, the next logical step is free communication. Now if we can just figure out how to marginalize the impact of the radical extreme minority that hurt people just for attention, then combined with the electric revolution, the world can quickly become a better place for all. A mass boycott of news organizations that sensationalize the bad may be the only way, however unlikely to pull off due to the flaw in human nature causing us to rubberneck as we pass a wreck.

 

[Harold in CR]

What are ya tryin to say, John ?? I figgered it wuz some local name, not a universal -world wide symbol

jest so's ya kno, I live in CENTRAL AMERICA, NOT England.

 

[John in CR]

Just sayin that Google has most answers. I didn't know what a rose joint was either, so I googled it. ES and Google are my most used websites for what I believe are very good reasons. I just figured you weren't yet used to going to google for answers. If I'm wrong I apologize, but hopefully my previous post turns at least one person into a googlemaniac.

BTW, I finished the pivots today. I want to do some grinder work and drill and tap the attachment to the swingarm itself before more pics. If it seems like my steel blade swingarm can act like a wet noodle laterally, then I'll remove a bunch of steel and replace it with balsa wood+fiberglass+epoxy for a lighter yet stronger and stiffer swingarm.... motor mount first though.

 

[olaf-lampe]

In some cases I like wikipedia better, because google doesn't filter out wrong informations. It's the same with forums where a lot of amateurs ( like me ) produce a lot of blurr above the hard facts. It means reading many useless pages online instead of reading a book from the tech. library to get to the same level of knowledge.

-Olaf

 

[Harold in CR]

I DO use Google search a lot. That was just a quick question, that I thought might get a much different answer.

I hope y'all realize that I DO appreciate every answer-comment that y'all post. This place is awesome, guys.

 

[amberwolf]

I have a number of possible ways to do this kind of thing, but they're all on sketches in various piles of paper from the past couple years of working out bike and trike designs. I'll have to dig them out and scan them in.

 

[John in CR]

I have a number of possible ways to do this kind of thing, but they're all on sketches in various piles of paper from the past couple years of working out bike and trike designs. I'll have to dig them out and scan them in.

Thanks, but please don't go to the trouble. It's a done deal. Pics this week once I get the motor mount and dropouts done.

John

 

[Dirt-E-Dan]

I've wondered this for a while, but how did you wind up in Costa Rica? I studied in San Jose for a month and I really love the country. I'm assuming that you're from the US? Just looking for tips on how to end up in a great place like that!

Daniel

 

[John in CR]

I've wondered this for a while, but how did you wind up in Costa Rica? I studied in San Jose for a month and I really love the country. I'm assuming that you're from the US? Just looking for tips on how to end up in a great place like that!

Daniel

Got on a plane and flew to Jamaica for a work related visit that turned into 18 months. I wanted something different., so I searched for a new place to live online, and the quote that caught me was "Of the developing countries, Costa Rica has the best quality of life." I came for a visit and moved the family shortly afterward. That was '97. I love it here.