Topic: how to fix swingarm bushes

[mazingerzeca]

Hello all.
I tried to extract the swingarm bushes of my bike (honda cb 125s) by myself, but I couldn't, so I went to a machine shop and they did it. I bought the new bushes, but one of them doesn't fit tight on the swingarm. Maybe the guy on the machine shop forced the swingarm hole a bit. The problem is, how do I fix the swingarm bush to get tight? I thought on putting some JP weld around it, but maybe it will be very soft, or maybe in the machine shop can be put something around the bush to make it fit tight? What would you do? Thank you.

this is the bush

[754]

Has that got rubber between the metal parts?

 2 things they can do, knurl the OD of the bushing (more money), or loctite it in if it is within .005.. way cheaper.

[mazingerzeca]

Yes, it's rubber. I will check the tolerance.

[Raul CB750K1]

In my CB350 I couldn't for the life of me get those bushes out. Not with a threaded rod, not with a bench vice, no way. As the rubber was not that bad I simply left the old ones in and got the new ones unused.

The key is to ask the machine shop how did they remove them. They should have used a press. If they drilled the bush out, bad news, they could have removed material from the swingarm.


In the other end of the swingarm, where the axle goes, I didn't mask the holes so some paint sprayed in. Well, needless to say, the bushings wouldn't come in. I had to sand all the paint out.


So, instead of JBWeld or Loctite, why don't you spray a couple of layers of black paint inside the hole? Chances are the bush will fit tighter afterwards and won't move from there.

[mazingerzeca]

They were taken using a press and heat; the hole seems to be intact. The paint to make it thicker seems a good idea. Somebody suggested me to put a layer from a coke can between the bush and the swingarm.

[Raul CB750K1]

They were taken using a press and heat; the hole seems to be intact. The paint to make it thicker seems a good idea. Somebody suggested me to put a layer from a coke can between the bush and the swingarm.

That would be a good idea. Actually I used it in a road bycicle whose seat stem slid in regardless of the pinch bolt tightening. A piece of aluminium sheet from a soda can and fixed. What you need is to shim that bush one way or another. It should go in using a hammer, but not too tight. Tight enought it won't move by itself.

[mystic_1]

Exactly how loose is it?

mystic_1

[mazingerzeca]

Exactly how loose is it?

mystic_1

I didn't measure it, but I tried the coke can trick around the bush and it gets thick.

[754]

Is this the swingarm PIVOT bushing,
or a shock mount bushing?

[mystic_1]

If the bushing just slides in the hole, but doesn't actually wiggle once it's in there, I'd say the paint or loctite ideas would work.  If the hole is any looser than that, I'd be concerned.

754:  These are shock mount bushings, based on the pic above.  Got a NOS set for my 750 hanging on my pegboard right now.

mystic_1

[754]

Well they looked like lower shock bushings to me, except the length seemed much longer than I remembered.

[mazingerzeca]

These are swingarm bushes from a cb 125s

[mazingerzeca]

I made the coke can trick, and it worked, it fits perfect tight. I had a problem with the other bush, because it doesn't enter completely, there is 1 mm left. I freezed the bushes, and it entered but there is 1 mm left. I think I won't bring the swingarm to the machine shop, because they would probably ruin the powdercoat paint on it, heating the piece and so on.

[mystic_1]

Glad the coke can trick worked for you.

What do you think is stopping the other bushing?  Is there some powdercoat on the inside of the hole perhaps?

mystic_1

[mazingerzeca]

Glad the coke can trick worked for you.

What do you think is stopping the other bushing?  Is there some powdercoat on the inside of the hole perhaps?

mystic_1

No, because I protected the inside of the swingarm. Maybe they are always too tight on the hole. I will post some pics of it.

[mystic_1]

When I replaced some on a 750 years ago they were a very tight fit indeed.  I whipped a press arrangement using my bench vise, a socket the same diameter as the bushing, and a wood block.  If you only have to press it in 1mm more, this should do the trick for you, so long as you're confident about the condition of the hole.

mystic_1

[mazingerzeca]

I used the vise grip to enter the bushing, but it doesn't enter anymore. There is 1,5 mm of the bushing out of the hole. I don't know how to enter it. I almost broke the vise. I think I will leave the bush that way, unless anybody gives me some advise for entering it.

[Raul CB750K1]

I used the vise grip to enter the bushing, but it doesn't enter anymore. There is 1,5 mm of the bushing out of the hole. I don't know how to enter it. I almost broke the vise. I think I will leave the bush that way, unless anybody gives me some advise for entering it.

Use a 8 mm high-tensile bolt with a few washers to press it in, or take it to the shop again so they can press it in. They shouldn't need to heat the swingarm up. You need a good vise for that; cheap chinese ones aren't up to the job, take it from me.

The other option is to press it out and use a thinner shim.

[754]

Get a piece of solid bar stoch that is at least the OD of the bush, or bigger.
 Put swingarm on block of wood, other side of the bushing hole down..


Then.... DRIVE 'ER   McGYVER...

[HondaMan]

In my CB350 I couldn't for the life of me get those bushes out. Not with a threaded rod, not with a bench vice, no way. As the rubber was not that bad I simply left the old ones in and got the new ones unused.

The key is to ask the machine shop how did they remove them. They should have used a press. If they drilled the bush out, bad news, they could have removed material from the swingarm.


In the other end of the swingarm, where the axle goes, I didn't mask the holes so some paint sprayed in. Well, needless to say, the bushings wouldn't come in. I had to sand all the paint out.


So, instead of JBWeld or Loctite, why don't you spray a couple of layers of black paint inside the hole? Chances are the bush will fit tighter afterwards and won't move from there.

Here's a hint, not really documented anywhere about the shock bushings: the holes are tapered. They go in and out better from one side. The CB750/500/550 arms go in & out to the inside.