bushing suggestions? swing arm

[crazykart]

Working on the design for my swing arm now. I was thinking of using the brackets from steering spindles hooked to the back of my frame to mount the swing arm. Their 2 1/2" on the inside: http://www.bmikarts.com/Spindle-Bracket-_p_1336.html

I was wondering if anyone had any suggestions for some good bushings to fit somewhat snugly in that 2 1/2" spread. Hoping for as big an OD as possible so I can use as beefy a tube as possible in between to make sure everythings nice and strong.

Or if anyone has any other ideas on how to mount my swingarm, that would be greatly appreciated. I was thinking on using 3 total spindle brackets as the total spread of my swing arm will only be 16" from end to end, so one on each end, one in the middle should hold it.

 

[firemanjim]

Use a piece of 1.625" steel tube, .120" thick. That leaves you with an opening just perfect for a couple 1.375" x5/8" kart bearings. Use a quality sealed bearing, and put a tube between the bearing races....

 

[chancer]

Use a piece of 1.625" steel tube, .120" thick. That leaves you with an opening just perfect for a couple 1.375" x5/8" kart bearings. Use a quality sealed bearing, and put a tube between the bearing races....

Yep that is what I was thinking
Or something along the lines of this: At least the bearings and pipe sizes....
http://www.diygokarts.com/vb/showthread.php?t=28597 Like this but instead of the spindle bolt you have your swing arm.

 

[firemanjim]

I remember that thread....

 

[crazykart]

Wow, ya that sounds a LOT better lol. Sounds like less of a chance of it getting loose, or being sloppy. Thanks!

 

[Rickracer]

This is what I did on the swingarm for my trike build:

I haven't posted up the finished pics yet, cuz it's not finished, (still needs painting, I blew it all apart and painted the frame, but the tank and the engine shroud still need color). I drilled and tapped the bushing housings for grease fittings, so they should last a LONG time. I got the bushings from OMB Warehouse IIRC.

 

[crazykart]

So if I'm following this write up from the other thread right I need this:http://www.speedymetals.com/pc-3473-8242-1-58-od-x-120-wall-dom-steel-tube.aspx For the outer tube that the bearings will sit in. This for the inner pipe that will space the bearings:http://www.speedymetals.com/pc-3461-8242-1-38-od-x-120-wall-dom-steel-tube.aspx and 2 standard 5/8 bearings will fit perfectly. Then just sink a 5/8 grade 8 bolt through it to hold everything together, and bam I have my pivot point. Yes, no, maybe? Sorry I'm a 3rd shifter and its too early lol.

 

[chancer]

Yes those are the correct size pipes. I think it is important to mention again, cuz I did not make it totally clear in the beginning of that thread. You need a inner tube for the races in the center and the tiny spacers/ bushings outside the bearings, to keep pressure on the races. See post 12 pics 1 and 2. 1/2" gas pipe makes a good fit for the 5/8 bolt.
http://www.diygokarts.com/vb/showthread.php?t=28597&highlight=spindle+bearings

Happy 3rd shift.

 

[crazykart]

Ok so I'll also need a 7/8 .120 wall piece of pipe for the races of the inner bearings if im understanding this correctly.

a 1 5/8 that everything goes into, a 1 3/8 to correctly space the bearings to each end @ 1 3/8 long, a 7/8 /120 wall to equal the races of the inner bearings...@1 3/8 long I'm guessing, then two 1/8" long "spacers for in between the spindle brackets and entire bearing setup @ 7/8" .120 wall to sit on the inner races. The 5/8 bolt goes through the whole setup, that way the outer tube will spin on the bearings and the inner will basically stay still with the tension from the bracket and braces on the races (braces on the races, braces on the races... that just rolls off the tongue lol)

I won't be welding the bolt on the outside as I was going to weld either a 1/2" square piece of tube @ about 2" long to it so that I had more actual contact space between the tube/bearing setup and the frame of my swing arm.

I think I got ya though, sounds good and very sturdy actually, as well as easily serviced when needed. Also sounds like it would swing a lot easier with less possibility of binding. Thank you very much. I may just have to do this on the front suspension as well, hmmmm...

 

[crazykart]

O plus ya, I'm well awake now lol, but thanks!

 

[chancer]

Cool. Yes it sounds like you totally got it. I had a weak design idea originally for these as spindles, and Fireman Jim walked me through this final sturdy design. And steered me to the correct tube sizes. I am glad someone else is going to get good use out of it. Especially since it is so easily altered for a totally different use.

 

[shyflyguy]

Subscribed, and saved for my own front and rear suspension design!

 

[crazykart]

I'll be doing a full write up on this post expanding on chancer's (and firemanjim's final design!) beautifully written post (and of course giving full credit, and linking, well it's already linked lol) just giving a full step by step and including places to get each piece. I may possibly tap in a grease fitting depending on the bearings (but probably not, we'll see)

 

[crazykart]

Parts list, and where you can get each for a good price:

1 5/8" OD tube .120 wall thickness: http://www.speedymetals.com/pc-3473-8242-1-58-od-x-120-wall-dom-steel-tube.aspx

1 3/8" OD tube .120 wall thickness: http://www.speedymetals.com/pc-3461-8242-1-38-od-x-120-wall-dom-steel-tube.aspx

7/8" OD .120 wall thickness: http://www.speedymetals.com/p-3439-78-od-x-120-wall-dom-steel-tube.aspx

(remember you can also get all of these in STAINLESS STEEL! Though it is a LOT pricier!)

5/8" Grade 8 bolt (least I would use is a grade 8 lol. This I'm gpoing to have to measure as I would want the entire shoulder to be 2 1/2", but I'm guessing a 4" bolt) http://monsterfastener.com/item/hcs8-379

Spindle bracket 2 1/2" spread: http://www.bmikarts.com/Spindle-Bracket-_p_1336.html

5/8" nylock nut: http://www.marshallshardware.com/products/productList.aspx?uid=2-411-239-640&flt=1|5/8 (or bulk) http://www.fastenermart.com/html/NT128-6842.html

5/8" bearings: http://www.gokartsupply.com/bearings.htm (or very good ones) http://www.bmikarts.com/Ceramic-High-Speed-Wheel-Bearing-58-ID_p_1606.html (or cheapies) http://www.bmikarts.com/High-Speed-Wheel-Bearing-58-x-1-38_p_1609.html


Tools: Pipe cutter, welder, etc.

Difficulty, easy to moderate (with patience, measure 3 times, cut once! lol)

 

[firemanjim]

Another fine example of how this forum works. I showed him, he showed you.... Now you're showing every one.... !
This pivot housing can be adapted for many uses. Swing arms, J arms, A arms, motorcycle swing arms..... Any where you need to reduce friction. The outer housing can be as long as needed, as long as the inner race support coincides.....

 

[Poboy kartman]

BUT......after he showed you his.....you were embarrassed....JK....

 

[crazykart]

I would show you mine... but I'm pretty sure this might happen: https://www.youtube.com/watch?v=n2ZpsbGr7s8

 

[Poboy kartman]

Naw.....I rarely burst into flames looking at little things....

 

[crazykart]

I think over a certain length/weight though it may just be best to put an additional bearing in the middle. Say if you want to do this but 2' long, and have 300+ pounds on it, then you should probably measure it out to have a bearing at each end and one dead center to help balance the load.

 

[crazykart]

It might be rarely, but it can still happen! lol