How did you grind the frame for swingarm?

I just realized what I said might be confusing, so I made a visual. (I know, nerdy. haha)

Okay, here it is.



Let's pretend A and B are tubes (which the pivot area of a swingarm is obviouly. lol). The black lines represent the walls the tube are pressed or retained between, and the blue lines represent force. The amt of force isn't necessary to know for the idea I am explaining.

Now, imagine these tubes are 2" OD with a wall thickness of whatever.... 1/8th of an inch.

If forces are put on tube A the entire circumference of tube A on each end will evenly distribute the force, which will cause a very strong brace between the two black areas obviously.

Now, B is cut but the ends aren't really paralell to eachother. As you can see, the contact of the tube is at the bottom on both sides. The forces applied as the same, but the points that are initially absorbing the force are much smaller....

Obviously you can see why the arm having paralell ends on the pivot cylinder is important. :thumbup: Which one is going to crease, give way under force, bend, etc. sooner and easier? Yup, B.

Post edited by: twowheeledterror, at: 2006/02/22 18:58

Hi Guys, isnt the important part the sleeve that runs through the swingarm, with it being clamped between the swingarm pivots in the frame?
I would shorten the swing arm tube that the bearings are in as much as I could and then shorten the pivot tube that runs through the arm as it can be fitted in a lathe and machined true easier than the pivot of the frame and only grind the frame if more clearance was needed.
What do you recon?

I believe that the sleeve is the most important part and thats why I'm going to chose not to cut the pivot of the arm.
How soft is the metal of the frame? Will the pivot on the frame creat its own indentation for the sleeve?

Dave Sloan wrote:

Hi Guys, isnt the important part the sleeve that runs through the swingarm, with it being clamped between the swingarm pivots in the frame?
I would shorten the swing arm tube that the bearings are in as much as I could and then shorten the pivot tube that runs through the arm as it can be fitted in a lathe and machined true easier than the pivot of the frame and only grind the frame if more clearance was needed.
What do you recon?

I may be wrong on this, but I don't think he's looking forward to costs to have things machined.

Have you ever ground out the interior pivots on the frame?

As aformentioned it's a small cylinder put thru the frame and welded on.

Whats that mean? As long as you don't grind the weld away you will be fine shortening it.