I'm replacing sprockets and chain on my M695. The upper rubbing block was looking a bit worn due to the 14T sprocket, so I bought a replacement. Figured I might as well freshen up the whole driveline while I'm at it. No good deed goes unpunished.
The rear bolt came out no problem. The front one is just spinning, so something is stripped. The bolts appear to be aluminum with some red thread sealant. WTF, why an aluminum bolt into a steel swingarm? Any good tips for removal of this bolt, short of major surgery??
I'm tempted to just run the existing rubbing block until the next chain, when maybe the swingarm will be coming off anyway for bearing service. I'm going back to a 15T front sprocket and +3 in the rear, so the wear rate should be decreased.
BK
If the bolt is just spinning, can you not just pull it out?
I'm about to replace the chain/sprockets on my bike as well, but haven't noticed a whole lot of wear on the rubbing block. If you go up 3 in the rear, would you be running a 51T?
It might help if you can apply some upward pressure on the head of the fastener while turning.
the bolt is aluminum so that it gets stripped before the threads on the swingarm (in theory, bolts are cheaper than swingarms). Its generally a good idea to put a hair dryer or (preferably) a heat gun on those bolts before removing them to loosen the loctite up, not doing that is probably at least part of what contributed to it getting stripped. There are a few methods of extracting bolts like this do a google search. I can imagine its gonna be difficult to get a drill in there though. Have fun!
Quote from: b. on March 11, 2009, 03:08:01 AM
If the bolt is just spinning, can you not just pull it out?
I'm about to replace the chain/sprockets on my bike as well, but haven't noticed a whole lot of wear on the rubbing block. If you go up 3 in the rear, would you be running a 51T?
I tried wedging a srewdriver under the rubbing block while turning the bolt - no dice.
Stock gearing on my M695 is 15/42 with 102 links, and I had been running 14/42 since early on. Rear is also raised a bit. I'm changing to 15/45 with 104 links. The larger front countersprocket will reduce wear on the rubbing block and the chain.
BK
Quote from: woodyracing on March 11, 2009, 04:56:24 AM
the bolt is aluminum so that it gets stripped before the threads on the swingarm (in theory, bolts are cheaper than swingarms). Its generally a good idea to put a hair dryer or (preferably) a heat gun on those bolts before removing them to loosen the loctite up, not doing that is probably at least part of what contributed to it getting stripped. There are a few methods of extracting bolts like this do a google search. I can imagine its gonna be difficult to get a drill in there though. Have fun!
Yeah, I think any type of drilling will require swingarm removal. All the other bolts (rubbing block, mud guard) came out without any issue. Heat gun would have been wise in retrospect.
BK
I messed with it some more, actually lots more, then I got suspicious of how easily the bolt was turning and even upward pressure resulted in no progress. I should have thought of this sooner, but pulling off the axle adjuster allowed me to peer into the swingarm with a flashlight. The threaded female doohicky pressed into the swingarm is spinning, so the aluminum bolt threads are not the problem. The doohicky is semmingly pressed in from the inside during manufacture, so I think this will probably require swingarm removal to resolve....at the next chain replacement.
BK
Good to know. Thanks for sharing, BK.
Quote from: BK_856er on March 11, 2009, 11:23:00 PM
I messed with it some more, actually lots more, then I got suspicious of how easily the bolt was turning and even upward pressure resulted in no progress. I should have thought of this sooner, but pulling off the axle adjuster allowed me to peer into the swingarm with a flashlight. The threaded female doohicky pressed into the swingarm is spinning, so the aluminum bolt threads are not the problem. The doohicky is semmingly pressed in from the inside during manufacture, so I think this will probably require swingarm removal to resolve....at the next chain replacement.
BK
the doohicky is called a riv-nut. they can spin, as you have found out.
you can try cutting the plastic block off so you can see the top of the nut, there may be a shoulder that is accessible. it may be possible to grab on to the shoulder with a pliers or slip a very thin screw driver or razor blade under the shoulder to hold it while you back the bolt out. if that still doesn't work you can just cut the bolt off and grind the shoulder away with a dremel and push it into through the hole.
if you get the bolt out without damaging the riv-nut you can tighten the nut up wit a longer bolt, a nut and some lubed washers. http://blogs.sun.com/chrisg/entry/tightening_a_rivnut (http://blogs.sun.com/chrisg/entry/tightening_a_rivnut)
otherwise you can replace the whole nut. mcmaster-carr sells them
(http://www.aimfasteners.com/sitebuildercontent/sitebuilderpictures/ribbed.jpg)
Quote from: aaronb on March 12, 2009, 07:13:08 PM
the doohicky is called a riv-nut. they can spin, as you have found out.
you can try cutting the plastic block off so you can see the top of the nut, there may be a shoulder that is accessible. it may be possible to grab on to the shoulder with a pliers or slip a very thin screw driver or razor blade under the shoulder to hold it while you back the bolt out. if that still doesn't work you can just cut the bolt off and grind the shoulder away with a dremel and push it into through the hole.
if you get the bolt out without damaging the riv-nut you can tighten the nut up wit a longer bolt, a nut and some lubed washers. http://blogs.sun.com/chrisg/entry/tightening_a_rivnut (http://blogs.sun.com/chrisg/entry/tightening_a_rivnut)
otherwise you can replace the whole nut. mcmaster-carr sells them
(http://www.aimfasteners.com/sitebuildercontent/sitebuilderpictures/ribbed.jpg)
Excellent! I knew there was a proper term for those things.
Hard to say for sure, but these look like they are pressed in from the inside, and the one in question is like 20 inches inside the swingarm with access from the rear only.
From your image it looks like these might have a shoulder at the top. Because I can't pry it up much at all, I wonder if I have just worn the knurled part where it contacts the thin metal swingarm. If I were to pound it up, maybe by going through the lower rubbing block hole (see pic) perhaps I could engage enough fresh knurl to hold the riv-nut in place while I back out the bolt. Hmmmm.
Here's a pic from the top (rear rubbing block hole):
(http://i43.tinypic.com/11sjcox.jpg)
...and inside the swingarm showing a riv-nut for the mudguard attachment:
(http://i41.tinypic.com/kdsrba.jpg)
...and a zoom of the same showing a squished riv-nut:
(http://i41.tinypic.com/29z6aoj.jpg)
...and waaaaay back you can see the forward upper rubbing block riv-nut and the lower rubbing block riv-nut:
(http://i40.tinypic.com/e0hd3s.jpg)
BK
They get installed from the outside, no inside access is necessary. And - get the steel ones, they'll last longer.
Quote from: Norm on March 12, 2009, 11:55:03 PM
They get installed from the outside, no inside access is necessary. And - get the steel ones, they'll last longer.
Now I understand: blind hole rivnut installed from the exterior. The rivnut gets pushed in, then a thin-wall section collapses as the install tool tightens the threads, thus pinching the swingarm sheetmetal and securing the rivnut. Looks like it'll need to be drilled out at some point. This cross-section clears things up for me and is consistent with my zoomed in pic:
(http://i43.tinypic.com/2zqsoli.jpg)
BK
If you have an aluminum one now, you can probably knock it out with a punch.
Quote from: Norm on March 13, 2009, 12:39:07 AM
If you have an aluminum one now, you can probably knock it out with a punch.
The rubbing block rivnuts look like they might not be aluminum, but I'll look into that. I'm going to save the new rubbing block for another day. Thanks to all for the good info!
BK
Try some penetrating oil on it, such as PB Blaster.
You can re-set the rivnut if you can get the bolt out.
I'm pretty sure they're steel.
Quote from: Speeddog on March 13, 2009, 09:24:38 AM
Try some penetrating oil on it, such as PB Blaster.
You can re-set the rivnut if you can get the bolt out.
I'm pretty sure they're steel.
I do believe that this particular rivnut is steel, so punching it out is probably not an option. Judging from the other bolts, corrosion is not the issue, but the heavy dose of loctite probably is. After it was already spinning I heated it with a heat gun until the plastic started to melt and then tried to remove the bolt while providing upward force under the rubbing block with a wedged screwdriver. No dice.
I think the next course of action will be to drill a small hole into the top flange of the rivnut and insert a pin to stake it in place and prevent rotation, hopefully allowing bolt removal and re-setting of the rivnut. Or maybe I could just notch the flange with a dremel cutting wheel and jam the rivnut steady with a screwdriver tip.
BK
here's a thought, if you can press down on the bolt head hard enough to keep the nut from spinning and tighten the bolt it may be enough to reset the riv-nut, then back the bolt out like normal
If you want to fix permanently with a very involved solution and, the swing arm and the rivnut are both made of steel (or both aluminum) you could also weld around the shoulder of the thing to lock it in place. I'm not certain re-crushing it to get it to seat without rotation will work. These things seem to fail very frequently when installed for the first time. But I'm not there looking at it ;)