concernedparent
New member
came back from a little ~15 mile jaunt around queens and when i got off the bike i saw this guy dancing around. common? anomaly? should i just tighten it and go on with my day? looks like it's just a frame bolt.
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76 R90/6 - Mystery Frame Bolt Loose
- Thread starter concernedparent
- Start date
Haven't this happen much. Makes sense to just inspect it and the area, tighten it, and see what happens over the next few rides. It appears to be a through bolt and because of the difficulty getting in there, the nut is likely welded to the inside of the frame. If it keeps loosening, I'd thoroughly clean the threads and use some blue Loctite to keep it from loosening.
RPGR90s
Member
Frame bolt
Better to re-torque it to the correct spec. and then check after another ride.
It's important because it holds the rear half of the bike together.
RPGR90s
came back from a little ~15 mile jaunt around queens and when i got off the bike i saw this guy dancing around. common? anomaly? should i just tighten it and go on with my day? looks like it's just a frame bolt.
Better to re-torque it to the correct spec. and then check after another ride.
It's important because it holds the rear half of the bike together.
RPGR90s
I would check every nut ad bolt
Surprising that things still look to be lined up and not bent. If I were the OP before I even pushed it out of the garage for another ride I would check every single nut, bolt, screw, clip and any other fasteners that might be loose. It makes me wonder who did what to it not to long ago and forgot to properly tighten those bolts, they both had a locking washer on them so someone missed a few basic items.
Surprising that things still look to be lined up and not bent. If I were the OP before I even pushed it out of the garage for another ride I would check every single nut, bolt, screw, clip and any other fasteners that might be loose. It makes me wonder who did what to it not to long ago and forgot to properly tighten those bolts, they both had a locking washer on them so someone missed a few basic items.
Gary -
I think that is an open unused hole. I have the same thing on my /7...nothing's been mounted there for all these years. To be honest, I don't even remember what that would be used for.
6322
Member
You know Kurt I wondered about those boltless holes as well. Being a hack guy, I know that we look for four good frame mounting points, two high and two low. I wonder if these may have been related to that? The most important things about the mounts is that they're spread out and that they're very solid. If you ran a heavy bolt/rod through these, that could tie the upper frame together for strength and provide a solid upper, rear sidecar mount. Just trying to make sense of German engineering...
Gary -
Technically, models after the /2 series are not designed for sidecar use. I think BMW might even have stated as such...the frame just isn't designed for those kinds of loads. People do it all the time, but there's the engineering! It would be nice to know what the open hole behind the battery cover is for. Here's my /7 right side...note that the battery cover even has a cutout for it. I noticed the there is a similar cutout on the left side cover where the handle mounts. I'm wondering if there might have been some consideration for a handle on the right side...maybe for people who ride on the left side of the road!
Technically, models after the /2 series are not designed for sidecar use. I think BMW might even have stated as such...the frame just isn't designed for those kinds of loads. People do it all the time, but there's the engineering! It would be nice to know what the open hole behind the battery cover is for. Here's my /7 right side...note that the battery cover even has a cutout for it. I noticed the there is a similar cutout on the left side cover where the handle mounts. I'm wondering if there might have been some consideration for a handle on the right side...maybe for people who ride on the left side of the road!
I guess we're getting off topic, but Snowbum talks about sidecar technical aspects on this page...see his section on Subframes. He mentions that the early Airheads didn't have enough side-to-side bracing. But it might be that with the proper additional bracing, then the loads can be introduced better into the frame. He's an experienced sidecar rider, so I suspect he knows what he's talking about. I've always wondered how the front end on a stock post 1969 Airhead can handle the diving loads with the hack attached. That's what I thought was brilliant with the leading link or Earles front end...when the brakes are used, the frame more or less squats rather than nose dives...better suspension if a chair is attached.
https://bmwmotorcycletech.info/sidecartech.htm
https://bmwmotorcycletech.info/sidecartech.htm
