Inboard swing arm bushings

[DucRedux]

Does anyone on the forum have experience in removing inboard bushings in a narrowcase frame? The frame in hand is a TS-200 frame circa early 60’s (it carried a 250 four speed engine). This “A-type” frame does not have pinch clamps for the pivot tube, but flanged bushings alone which are located in the lower frame cross tube. The pivot tube is held on by a through-bolt in the swing arm which has no bushings. I need guidance on bushing removal, for me or the machinist that may undertake the task. The bushings do not appear to be bronze since the metal is steel-like in color and is magnetic. What will it take to remove these possibly fused inserts?

My plans were to insert new bronze bushings, leave the frame as designed, or convert to a later “A-type” arrangement with a longer pivot tube, new welded-on outer frame brackets and substitute a swing arm that has integral bushings. Regardless of the first or second option, the inboard bushings need renewal since there is too much play. Will the bushings yield to pulling or being drifted out, or do they need cutting? What is a solution?

[Rick]

Those bushings will come out, they're probably some sort of sintered alloy, but if you feel inside you can feel the back of the bushing, so they're not driven into a blind counterbore- should be able to drive them out from the far side. There's nothing wrong with sawing an axial slot in the bushing to try and collapse it on itself- even a couple of slots that would allow a slice of it to be driven out would make the job easier. If you're careful you won't hit the frame with the blade, but a small nick won't do much harm- there's a lot of bearing surface between the bushing and the frame.
Converting to the later style bushing-in-swingarm arrangement would be a lot of work- the swingarm would need to be modified also, plus, there are guys like me who like the earlier models- I'd be glad to trade frames with you.
Replacing the bushings is the right repair, but, rather than hack up a nice frame, you could ream the existing bushings and have a slightly larger OD axle/pin made- that would require reaming the swingarm bores also, so you'd be making a modification that would be hard to undo, but much less destructive than converting to the later style arrangement.
Rick

[Jordan]

If it's possible to hammer out the bush from the other side of the tube, a simple tool helps - a thick washer, modified to be able to fit through the opposite bush. When flattened against the end of the bush you want to remove, it provides somewhere for a tube/drift to hit against with a hammer. The washer would be diameter nearly as big as the bush OD, and with sides made parallel, to just fit through the ID. Works well on widecase singles and V twins.

[DucRedux]

Thanks for the prompt replies and encouragement, Rick and Jordan. Think I’ll begin by filling the frame cross tube with penetrating fluid and plug it for a few days to get some lubrication by capillary action before any rough treatment. I initially tried a slap hammer bearing puller just to check resistance, but there was no visible movement in the bushings. Looking at some engineering tables, I saw that the coefficient of linear expansion between iron (the bushing?) and steel of the frame is favorable, possibly giving up to 2 ten-thousandths in. difference at 200F. This should help if I try heat excursions during lubrication and with final extraction.

I too would like to keep the frame as is, Rick. It simplifies the restoration and keeps an original item intact.

Jordan, do you mean bending the drift buffer washer over somehow, or just positioning internally along the internal perimeter of the bushing?

[Rick]

I wish I could 'unbreathe' some of the fumes that I've put into my lungs through the years- that penetrating oil will produce a smokey mess when you heat it up- when you can taste smoke you've probably done something foolish. If you plan to heat the bushings with a torch, I'd run that experiment before the penetrating oil.
Rick

[Rick]

Another thought- I don't know what sort of alloy the bushing is made of, so not sure how it will respond to welding, but lots of guys run a heavy weld bead around the inside of a tapered bearing race to remove it- when the weld bead contracts it shrinks the race- I've done it and it works great when you don't have any access to the back side of a race to drive it out.
I don't know what the bushing will do when you try to weld it- might just vaporize in a poof if it's a powdered metal, but if it's cast iron you should be able to do the weld bead shrink- if it doesn't shrink you probably won't be any worse off.
If the bushing seems to be weldable, you could probably weld a plug onto the face to make it easier to drive out.
I'd bet that a local welder would have experience with shrinking a race- might be the easiest way to get them out.
Rick

[Jordan]

Jordan, do you mean bending the drift buffer washer over somehow, or just positioning internally along the internal perimeter of the bushing?

Just position the washer flat against bush end, once it's between the 2 bushes.
That's assuming your arrangement is suitable.

[DucRedux]

The inboard swing arm bushings have been removed and they are strongly magnetic and stepped down on the inner length to accommodate the penetration of a grease fitting.

The procedure for removing them was 1) plug and fill the frame crosspiece with a 50-50 mix of automatic transmission fluid and acetone penetrant, 2) let sit for four days, 3) block up the frame securely with wood including a hole to receive the knock-out piece and pound with a drift on which the tip was ground to the “angle-of-attack” for a flush strike on the inside bushing perimeter.
This was the first time I used the homemade penetrant often mentioned in web articles and am very pleased with the outcome. On day two of soaking, I could clearly see the fluid weeping around the seam of the press fit. No heat needed.