‘98 r1200c. General question rear disc.

[flyingfrogs19]

I can hear this rattle a bit. Looked at sone videos of these being changed. It alarmed me. So I took the wheel off to look. It’s not broken at all. Just a bit loose side to side. I thought it was worse like the videos. And they are torching the two bolts cause of lock tight. And then the other three hex bolts would either come out or had to be drilled out. See video if this is just normal play in the disc. Thanks y’all. I did order a new one cause I thought this would cut into my caliper. 

[dirtrider]

On 8/14/2023 at 8:38 PM, flyingfrogs19 said:

I can hear this rattle a bit. Looked at sone videos of these being changed. It alarmed me. So I took the wheel off to look. It’s not broken at all. Just a bit loose side to side. I thought it was worse like the videos. And they are torching the two bolts cause of lock tight. And then the other three hex bolts would either come out or had to be drilled out. See video if this is just normal play in the disc. Thanks y’all. I did order a new one cause I thought this would cut into my caliper. 

71375267184__9B7E8297-714D-456A-A145-A5AB657AAD56.MOV

Morning   flyingfrogs19

 

The rear brake rotor on the 1200C does float, I can't find a spec on how much movement is too much but the usual complaint is a rear brake disk rattle when hitting bumps with no rear brake apply. If yours doesn't rattle then probably still OK.  

 

How much rotational movement does the disk have on the rivets?  This is the important thing, if the rotor has a lot of rotational movement then it can sheer the attaching rivets off under hard braking. How much rotation movement is too much, I really don't know, but you don't want to see a lot of rotational movement. 

 

I have (or used to have anyhow) a BMW service bulletin on the rear brake disk on the 1200C (or one of the 1200C variants anyhow), reason I am late posting on this. I looked & just can't seem to find that BMW service bulletin (they were in paper form back then).   

 

The bulletin was on the rear brake disk rattle issue (loose disk on the backing) I don't remember a lot (probably only read that bulletin when I got it then never again) but if memory serves me it seems that BMW acknowledged the rear rotor rattle but didn't offer any out-of-warranty help on their part. 

 

On your disk, & given no real spec that I can find, a little lateral disk displacement is not a big deal but more than just a "little" rotational movement would be a concern. 

[flyingfrogs19]

That was what I was thinking. At the moment I hear a bit but seems to be no harm. There is no play on the rotational just ever so slight on the side to side enough to give a slight sound. I heard this and while I was changing the rear pads. Btw unless I missed it in the manual taking off the rear tire and putting on the new pads would have been a whole lot easier than changing it while the tire was on. No way I say. There is no clearance. You hit the rim. The manual says to place tape on the rim so as not to scratch.  Anyway. I ground down that part of the pad to slip it past. Next time I’m just taking the shell off. I didn’t know the wheel was separate from the breaking system. Not like my big cruisers. Pretty cool.  Thanks for the heads up. oh and I meant to say this has only has 14,500 miles on it.  It is running great.  So the system parts are pretty new in mileage terms.  Disc is not worn out.  Thanks again.  

[flyingfrogs19]

Seems like I could just weld these rivets just enough to hold the shimmy shimmy.  Thoughts?

[dirtrider]

15 minutes ago, flyingfrogs19 said:

Seems like I could just weld these rivets just enough to hold the shimmy shimmy.  Thoughts?

Morning   flyingfrogs19

 

NO!, that rotor is supposed to float so you don't want to make it solid. Plus you don't want to compromise the rivet heat-treat or the rivets could fail (that would be BAD).

 

I never have tried it myself but I do know some 1200C riders used to use high temperature silicone to sort of glue under/around the rivet heads to try to remove the rear rotor rattle.  Probably worked for while but I don't know about long term. I just don't know many 1200C riders.

 

I don't do a lot of 1200C work (never have) so don't have a known cure for you.  You probably should try to find a dedicated 1200C forum (way different than the 1200 hexhead or 1200 camhead forum). I just don't do enough work on the old 1200C bikes to be more help to you on this issue.   The 1200C (+ variants) seem have a different following (cult-like even) than the other mainstream BWM boxers of their era.  

[flyingfrogs19]

Lol   Yes learning here.  thank you.  I figure most info (not all engine techs and specs) is similar.  I thought this was a hex head engine or box.   Anyway I hunt for a thread more exact I suppose, and I will not weld this.  Thank you for the information a great deal.  

[wbw6cos]

I remember reading about similar issues https://www.chromeheads.org/.  Use the search function.    I recall reading a few threads about people getting issues resolved through dealers past regular warranty, but that was many years ago.  I doubt that can be taken care of without paying for a new rotor.

 

 

[Hosstage]

6 hours ago, flyingfrogs19 said:

Seems like I could just weld these rivets just enough to hold the shimmy shimmy.  Thoughts?

That gave me heart palpitations.

Dr's response was correct, except he didn't use enough NOOOO!!

[flyingfrogs19]

Lolololol!   I got it!  I will weld.  Superrrrrrrrgluuuuuuuuuee!  Ill try some high temp silicone that was suggested; i like that idea.  Can't hurt anything.  I am having fun riding this thing in the 100+ Texas weather.  Everyday rider!  Love it.  Thanks again y'all!!!!