Swing arm play & stabilizers
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From: USA
Swing arm play & stabilizers
Replacinging the brake rotors, I happened to grab the swing arm and shove it side to side, and found I do have some play, and a nice clunk. OK, that would be worn bushings. Yippee, I'll add that to the list of things to do.
But, I'm a bit baffled by the swing arm mounting, and the claims of the various stabilizer makers on this. The swing arm is mounted to the frame, yet the various stabilizer kit makers insist it's actually mounted to the transmission. And to help thoroughly baffle me, most of the stabilizer kits join the swing arm to the transmission, not to the frame.
I don't get it.
I can understand how the rubber bushings in the joint where the swing arm mounts to the frame can cause deflection and handling problems. So I understand using different bearings and bushings here.
But I just do not understand the claims of the kits joining the swing arm to the transmission with a link help stabilize the swing arm. Or how the front motor mount affects swing arm deflection (these claims exist too).
But, I'm a bit baffled by the swing arm mounting, and the claims of the various stabilizer makers on this. The swing arm is mounted to the frame, yet the various stabilizer kit makers insist it's actually mounted to the transmission. And to help thoroughly baffle me, most of the stabilizer kits join the swing arm to the transmission, not to the frame.
I don't get it.
I can understand how the rubber bushings in the joint where the swing arm mounts to the frame can cause deflection and handling problems. So I understand using different bearings and bushings here.
But I just do not understand the claims of the kits joining the swing arm to the transmission with a link help stabilize the swing arm. Or how the front motor mount affects swing arm deflection (these claims exist too).
Last edited by foxtrapper; Apr 5, 2013 at 07:16 AM.
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From: Fla
That "L" bracket doesn't mount to the swing arm...
It mounts under the transmission, to the bolts holding the engine oil pan on. So, you're not joining the swing arm to the transmission, you're joining the engine/transmission to the frame.
The front motor mount is rubber also. With the swing arm/transmission/engine pretty much one solid unit that wobbles in the frame, the side to side stress on the rear tire causes the deflection. Which, in turn, creates a sort of ill alignment between the front and rear wheel. When that alignment sways to and fro, you feel that as the dreaded 'bagger wobble'.
It mounts under the transmission, to the bolts holding the engine oil pan on. So, you're not joining the swing arm to the transmission, you're joining the engine/transmission to the frame.
The front motor mount is rubber also. With the swing arm/transmission/engine pretty much one solid unit that wobbles in the frame, the side to side stress on the rear tire causes the deflection. Which, in turn, creates a sort of ill alignment between the front and rear wheel. When that alignment sways to and fro, you feel that as the dreaded 'bagger wobble'.
Last edited by Def Mute; Apr 5, 2013 at 10:20 AM.
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From: Mountain West, Big Sky Country
save your self some headaches, go with the complete Sta Bo kit, replace the swingarm internal bushing with Sta Bo's bearings, use the sta bo external bushings to tighten up the place in the stock harley donuts.
I did mine and it is solid and tracks like it is on rails. Call Kevin at Sta Bo and get the entire kit, you will be pleased
I did mine and it is solid and tracks like it is on rails. Call Kevin at Sta Bo and get the entire kit, you will be pleased
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From: Bedford UK
Before you do anything, read my thread on bagger wobble. It explains exactly what is going on and will remove your bafflement!
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From: Santa Cruz
If ya are replacing the bushings get one of the aftermarket poly sets and do the front motor mount poly too. Ya may not need a 3rd link setup with better mounts but it never hurts. Yes the swingarm pivot does rubber mount to the frame and transmission but it is also the rear drivetrain (engine/transmission) mount. The rubber swingarm mounts combined with the rubber front motor mount allows the engine/transmission/swingarm to pivot/move (in all planes) around the swingarm mount. Most of the 3rd links mount to the transmission and frame to prevent the horizontal pivot movement of the engine/transmission/swingarm.
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HDF Community Team
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From: USA
I've read the link, and others. I would have sworn at least one maker described joining the swingarm to the trany, but perhaps I misread or misremember.
The engineer in me is still rather befuddled. The swing arm is mounted on a shaft, and that shaft is mounted to the frame. Just like any other bike I've seen/had. The transmission rear mount hangs on that shaft, just like any other bike I've seen/had.
There is a difference. Almost every other bike I've seen/had has that shaft mounted rigidly into the frame, and the swingarm mounted rigidly to the shaft with metal bearings. There is no deflection as there is nothing elastic involved.
Harley has rubber bushings in the frame mounts of the shaft, to isolate vibration. This would certainly cause deflection under load. That's what rubber bushings do. As well degrade over time. So doing something about this rubber bushing in order to prevent the shaft from deflecting would seem like the proper fix to me.
But instead, many use a bracket to help hold the rear of the transmission in place side to side. OK. I'm not saying this won't work. In fact, it very much can. But it seems to me it's a rather backwards fix. Instead of fixing the bushing problem on the swingarm shaft, it attempts to fix the problem by getting the swingarm to grind against the transmission case instead. The bracket holds the transmission in place, and that in turn holds the swing arm in place side to side. It's a fix, of sorts, but at the expense of the transmission case.
It seems to me that fixing the swingarm bushing, while more tedious to do, is a far more proper fix to the problem than using a bracket that causes the swingarm to grind against the transmission case.
So go ahead, tell me what I'm seeing wrong. It wouldn't be the first time I totally missed something.
The engineer in me is still rather befuddled. The swing arm is mounted on a shaft, and that shaft is mounted to the frame. Just like any other bike I've seen/had. The transmission rear mount hangs on that shaft, just like any other bike I've seen/had.
There is a difference. Almost every other bike I've seen/had has that shaft mounted rigidly into the frame, and the swingarm mounted rigidly to the shaft with metal bearings. There is no deflection as there is nothing elastic involved.
Harley has rubber bushings in the frame mounts of the shaft, to isolate vibration. This would certainly cause deflection under load. That's what rubber bushings do. As well degrade over time. So doing something about this rubber bushing in order to prevent the shaft from deflecting would seem like the proper fix to me.
But instead, many use a bracket to help hold the rear of the transmission in place side to side. OK. I'm not saying this won't work. In fact, it very much can. But it seems to me it's a rather backwards fix. Instead of fixing the bushing problem on the swingarm shaft, it attempts to fix the problem by getting the swingarm to grind against the transmission case instead. The bracket holds the transmission in place, and that in turn holds the swing arm in place side to side. It's a fix, of sorts, but at the expense of the transmission case.
It seems to me that fixing the swingarm bushing, while more tedious to do, is a far more proper fix to the problem than using a bracket that causes the swingarm to grind against the transmission case.
So go ahead, tell me what I'm seeing wrong. It wouldn't be the first time I totally missed something.
Club Member
Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
The transmission rear mount hangs on that shaft, just like any other bike I've seen/had.
There is a difference. Almost every other bike I've seen/had has that shaft mounted rigidly into the frame, and the swingarm mounted rigidly to the shaft with metal bearings. There is no deflection as there is nothing elastic involved.
Harley has rubber bushings in the frame mounts of the shaft, to isolate vibration. This would certainly cause deflection under load. That's what rubber bushings do. As well degrade over time. So doing something about this rubber bushing in order to prevent the shaft from deflecting would seem like the proper fix to me.
Harley has rubber bushings in the frame mounts of the shaft, to isolate vibration. This would certainly cause deflection under load. That's what rubber bushings do. As well degrade over time. So doing something about this rubber bushing in order to prevent the shaft from deflecting would seem like the proper fix to me.
But instead, many use a bracket to help hold the rear of the transmission in place side to side. OK. I'm not saying this won't work. In fact, it very much can. But it seems to me it's a rather backwards fix. Instead of fixing the bushing problem on the swingarm shaft, it attempts to fix the problem by getting the swingarm to grind against the transmission case instead. The bracket holds the transmission in place, and that in turn holds the swing arm in place side to side. It's a fix, of sorts, but at the expense of the transmission case.
It seems to me that fixing the swingarm bushing, while more tedious to do, is a far more proper fix to the problem than using a bracket that causes the swingarm to grind against the transmission case.
So go ahead, tell me what I'm seeing wrong. It wouldn't be the first time I totally missed something.
It seems to me that fixing the swingarm bushing, while more tedious to do, is a far more proper fix to the problem than using a bracket that causes the swingarm to grind against the transmission case.
So go ahead, tell me what I'm seeing wrong. It wouldn't be the first time I totally missed something.
Some of the other solutions miss the point. There is a lot of misinformation on the internet about this (and a lot of other things too!) and also misleading claims by some of the makers of the 'cure'.
The stabilizer is part of Harley's original patent and it works. It is an elegant design when executed in full.