71 swingarm problem

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seaguy

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May 19, 2009
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Guys I need some advice about how to get my swing arm apart. The books I have don't do me any good. What I have is the cradle/swingarm out of the bike and the thin through bolt and end caps are removed. The center bolt that locks shaft to tube is out. The arm is real hard to move (swing) . Do I need to press the shaft out and if so push to left or right side? Any jig tricks for supporting? Big deepwell socket?
Rich
 
The spindle comes out on the right side. Are there threads inside the spindle on the right side? It's there to run a bolt in and pull the spindle out with it. Maybe they didn't put them in all of them.
 
The right side has a chamfered hole but no threads. left side is flush. It looks like a small pipe with one end chamfered or funnel shaped.
 
I've never seen a '71, but the standard spindle would have a 1/2-20 threaded hole in the right side. If you're lucky the spindle just slides right out. More stubborn spindles require a slide hammer fitted with a 1/2-20 bolt. If yours is not threaded I guess you'll have to drift it out from the left side. At the extreme end of unlucky, I've known people to bring the assembly to a machine shop with an arbor press.
 
Looks like either way I have to make something to do the job. Easiest to make a drift and push it out. I have a large press at work. That pipe could be a real bear to tap. Might be hard stuff. It must be rust/swelled to the bushings. I tried tapping on it with a rod and hammer but no joy. How could something thats usually worn out be so tight?
 
seaguy said:
Looks like either way I have to make something to do the job. Easiest to make a drift and push it out. I have a large press at work. That pipe could be a real bear to tap. Might be hard stuff. It must be rust/swelled to the bushings. I tried tapping on it with a rod and hammer but no joy. How could something thats usually worn out be so tight?
Click to expand...

If the swingarm moved arm at all with the center-bolt in then it must be hanging on the cradle, for the most part. As far as harness of the spindle goes, there have been some that are, and some that aint. If you flip the cradle on it's right side and support it around the hole it might be time to consider the 'Bigger Hammer Theory'.
 
The part that sticks is just a static steel on steel fit so you can imagine what that can look like after 35 or 40 years. The spindle should be a nice fit in the cradle after you're done. Oversized spindles are available if you have to ream out the cradle to clean it up.
 
Time to get out the penetrating oil too. The spindle will be rusted in and its surface will have huge pits - more like craters!
 
Hi Rich,
I just did mine last night. A 72 that's been sitting for many years. The spindle was in real tight. I suspect because someone had used grease in there rather than oil and it hadn't worn out as yet.

I soaked it up nicely with penetrating oil first. The bolt from the front Iso screws into the spindle nicely as the thread starts an inch or so in on mine. A few taps with a hammer and out she popped.

Cheers

Dave
 
Davo got it there.
Grease for some reason and a poor lube system in the first place even if oil is used seems to ensure they all seize. Contributes to bad handling complaints, as well.
Soak with plus gas for as long as possible.
Always lube with oil.
Consider a mod to ditch the little non-rotation screw, whilst you are there.
Stu.
 
bigstu said:
Davo got it there.
Grease for some reason and a poor lube system in the first place even if oil is used seems to ensure they all seize. Contributes to bad handling complaints, as well.
Soak with plus gas for as long as possible.
Always lube with oil.
Consider a mod to ditch the little non-rotation screw, whilst you are there.
Stu.
Click to expand...
What would I do there with that hole? Maybe weld a little patch over it?
 
I didn't do the mod. to my bike , so I can't help you. But I have been told alot of folk get rid of this screw because as the spindle siezes up the increased torque due to siezing is put on this little screw, and it shears off.
I am afraid I don't actually know the details of the mod.
Anybody else know?
Stu.
 
That swingarm spindle mod (Heinz-keigler or something like that) has been posted many times, try a search for it.

Bolt-on, under $100, plug-n-play, set it and forget it.
 
bigstu said:
I didn't do the mod. to my bike , so I can't help you. But I have been told alot of folk get rid of this screw because as the spindle siezes up the increased torque due to siezing is put on this little screw, and it shears off.
I am afraid I don't actually know the details of the mod.
Anybody else know?
Stu.
Click to expand...
Hi Stu,

The last thing these people want is for the spindle to be rotating in the cradle, if it is then they have a very large problem. The first and second things they don't want is for the spindle to be loose in the cradle and for any oil put in there to drain right out. The way it was designed originally does all three pretty good. The MKIII staked the spindle and capped the oil in for life. I don't think it worked out very well from what MKIII owners say. In fact, there's nothing good about the way the swingarm is attached to the cradle. I made a mod to my cradle for handling reasons that worked out pretty well. The spindle doesn't turn or wobble. Any machinist could make a part like it and weld it in. It needs to be reamed to fit after it's installed, but that's the only tricky issue.
71 swingarm problem
 
bpatton said:
71 swingarm problem
Click to expand...

Ok, sorry to hijack but I have to ask. Isn't the purpose of the heim joints to allow the engine and cradle to move up and down but not side to side? It seems that in this config that it can move front to back. I suppose a heim joint at the head steady will prevent any rocking but it still seems a little odd to have the lower facing that direction.
 
swooshdave said:
bpatton said:
71 swingarm problem
Click to expand...

Ok, sorry to hijack but I have to ask. Isn't the purpose of the heim joints to allow the engine and cradle to move up and down but not side to side? It seems that in this config that it can move front to back. I suppose a heim joint at the head steady will prevent any rocking but it still seems a little odd to have the lower facing that direction.
Click to expand...
Sorry to be obtuse, but I'm not clear on your question.
 
bpatton said:
Sorry to be obtuse, but I'm not clear on your question.
Click to expand...

It seems that the heim joints may be in the wrong orientation to allow the engine to move in the correct plane.
 
Hi Bob.
As I said, I didn't do a mod myself to my '74 MK2A, mainly coz at the time I did not know about one!
I made sure all was a nice sliding fit and put it together as standard.
I have heard of mods later and it does make sence to me that if the spindle seizes in the arm it will put a shearing force on the very small peg screw. I have chose for the moment to:-
a) Keep it well lubed with oil.
b) Keep my eye on the screw.

Have you got two anti-rotation screws there holding the arm in place? I am unsure of your mod. I am not that sure what the original looks like! I remember there is a small 1/4" ish peg screw central.

My eyes keep getting drawn to your rose joint modification there!
I think you must have convex sphered units inside the joints there, allowing each joint to rotate and change angle.
I think that is what swooshdave is meaning....without a ball rotation your assembly would not allow the correct movement, but I think with the ball movement it will.
How is your setup for vibration? Does the extra steady add more vibes?

Thanks for the info. from both.

Stu
 
Hi Stu,

The two bolts are in there to try to anchor the spindle to the cradle as much as to keep it from turning. They can become loose over time. I've seen some Commandos with quite a bit of play in the swingarm because of it.
Yeah, the rod-ends allow the cradle to move freely. The rose joint, called a heim over here, on the frame is a standard item. They have a wide range of motion. The one on the cradle is called an 'elastomeric" rod-end from Lords. They do everything a regular rod-end does but they are rubber so they have some cushion. This one is rated to deflect in tension or compression 20thou at 250lbs, it's a trade off against using a straight heim on both ends. It wasn't a comfort issue, I was afraid of breaking the frame. That's why there's a tube to spread the load to both sides.
 
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