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Post by miker on Jan 26, 2007 14:42:29 GMT -5
I'm trying to decide if this swingarm is worn or not... I got it on ebay and its sitting loose on the bench.
Ok, the swingarm itself has bearings pressed into it. There's a short machined tube that goes thru the center of the bearings, and a longer pivot bolt that goes thru the center of the machined tube.
The bearings are solidly in the swingarm. The machined tube fits very closely inside the bearings, it turns easily but no side-to-side play. However, the pivot bolt has a small amount of side-to-side play inside the machined tube.
Does this matter? I would think that this would let the whole assembly move in relation to the frame (bad), but maybe when the pivot bolt is torqued it doesn't move???
miker
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Post by davedunsboro on Jan 27, 2007 9:13:16 GMT -5
Hi there, my opinion for what its worth (not much with the cost of inflation). There are supposed to be 2 cup style washers on either side of the bearings before the shaft goes thru then lock up the 2 nuts . There should be no play ! Only swing , good luck .
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Post by nvdezfox on Feb 21, 2007 23:09:41 GMT -5
miker - I see by the dates on your posting that it's been awhile, but I just finished this on my bike and thought I'd chime in.
I found I had approx. 1/4" side-to-side free movement at the rear wheel, and traced it back to freeplay in the swingarm pivot. This bike's been rode hard and put up wet, just about everything is worn out, so I figured it's probably just cheap crap plastic bushings or similar and set out to disassemble and replace the worn bits.
Savvy owners will be saying "the swingarm pivot bearings aren't cheap plastic - they're rollers" and that's true. Nonetheless, I decided to have a look.
Removal of the pivot shaft required some spirited work with a deadweight hammer, but wasn't as gruesome as described by others.
Fitting the unit to the vise, I observed that the play was between the pivot shaft and the machined tube, not between the tube and the bearings. I observed that the torque on the pivot shaft nuts seemed rather light on disassembly.
It appears that the Yamaha engineers designed it so that the machined tube carries the loads, not the pivot shaft. The machined tube locates into the frame and maintains a thrust clearance at each end using cup-washers as described by davedunsboro. If the pivot bolt torque isn't to spec, the thrust clearance allows the assembly to move axially on the pivot bolt, causing the play miker and I note. On assembly, I used the specs as listed on the SR500 spec page (58 ft/lb). I had play until the torque reached ~ 40 ft./lb and then it closed up. I think my machine had been ridden for some time with reduced torque causing the freeplay and additionally pounding a (slight) groove in the pivot shaft. I'd recommend checking the torque of the pivot shaft nuts periodically to avoid this issue.
Anyone else seeing the same thing?
--Mark
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Post by StewRoss on Feb 23, 2007 2:20:58 GMT -5
Hi, That is very common...one 'cheats' way to stop the freeplay instantly...well usually...is to undo the axle and rotate it about 90 degrees. That takes the 'worn' arear away from the pivot and eliminates the side to side play. That will last as a fix for a fair while as you save for a new shaft. They aren't that expensive as I recall. As you say the sleeve and bearings don't wear as much in my experience. SR  |
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Post by kentrex on Feb 23, 2007 5:25:51 GMT -5
Call me stoopid, but I just had a DOH! moment. I got my first SR in '80 and owned it for seven years. In that time I replaced the swingarm bearings at least three times. The first time they were definitely shot as I remember, Englands wet winter weather had got at them and they practically fell out of the housing.
But I had completely misunderstood the set up and didn't appreciate the importance of the inner tube / thrust washer set up and consequently probably didn't torque up the shaft nuts adequately, I certainly don't recall a figure of 40ft/lbs. This ignorance must have led to the early demise of the replacements.
Anyway, thanks to the knowledgeable folks on this site, SR ownership this time round should be a less frought experience!!
Ken
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Post by miker on Feb 23, 2007 10:28:56 GMT -5
Nvdezfox, thanks for posting - glad to have the confirmation.
miker
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