Brake Rotor Bobbin Replacement

[Santron]

I wish that I had read this before doing mine, as I paid full pop at my local BMW dealer for Bobbins that are, IMO, not a good fit.

 

http://www.myr1100rtp.netfirms.com/bobbins.htm

[DavidEBSmith]

Well, some might disagree with that website's conclusions. Some might argue that having the rotor more rigidly mounted to the wheel is a bad thing, because the rotors are supposed to move around and float which protects against warping. And some might argue that having steel bobbins is a bad thing because the stock aluminum bobbins will sacrifice themselves by wearing out first, whereas the harder steel bobbins will wear out the holes in the expensive rotors. But I wouldn't take any position on any of it because I wouldn't want to be thought of as being disagreeable or disputational or having an attitude.

[Santron]

..... But I wouldn't take any position on any of it because I wouldn't want to be thought of as being disagreeable or disputational or having an attitude.

 

Oh yeah, believe me...I got the snot beaten out of me here about those same issues on this very topic a few months ago on this site.... I present the website only as an alternative for informational purposes only.

[Stan Walker]

Well, some might disagree with that website's conclusions. Some might argue that having the rotor more rigidly mounted to the wheel is a bad thing, because the rotors are supposed to move around and float which protects against warping. And some might argue that having steel bobbins is a bad thing because the stock aluminum bobbins will sacrifice themselves by wearing out first, whereas the harder steel bobbins will wear out the holes in the expensive rotors. But I wouldn't take any position on any of it because I wouldn't want to be thought of as being disagreeable or disputational or having an attitude.

 

Hey David, some stranger is taking over your name and posting strange stuff on this site........

 

Stan

[smiller]

Now I could have gone down to my local BMW dealer and bought two sets of standard BMW bobbins but I didn't for two reasons.

 

The cost would have been the equivalent of $190.00 U.S.

The cost is around $80 mail order or about $100 at a dealer.

 

For some reason the BMW bobbins are made of aluminium alloy

Just because one doesn't understand the reason the bobbins are made out of alloy doesn't make it a bad reason.

 

 

I would hardly consider this info to be the definitive comment on the early floating rotor design. And FWIW I've read about more 1200RTs with warped rotors in the last few months than similar cases in the 1100RT in the last ten years.

 

Lastly, if you are having trouble fitting the BMW replacements it is more likely due to technique than anything else. I made the same mistake myself when I installed a set... do it in the wrong order and it's quite difficult (these things don't fit!), but do it in the right order and it's easy (oh wait a minute... they fit perfectly...)

[Santron]

The issue that I had with the BMW replacement Bibbins was that 1) They were $140 at my local dealer, and 2) They made no difference - the rotors had the same play on the carriers as the old bobbin set. I think that a set of Bobbins that are slightly oversized would have made the rotors fit in the carrier as snugly AS A NEW ROTOR WHICH DOES NOT HAVE ANY PLAY IN IT. I capitalize this because this was the main point of centention in the last thread on this topic that I participated it. Here goes...

[smiller]

They were $140 at my local dealer

 

That problem sounds more related to the dealer than the bobbins.

 

and 2) They made no difference - the rotors had the same play on the carriers as the old bobbin set.

 

Interesting. I've never heard of that happening before.

[Santron]

Yes, that is that part that I could not figure out either. My guess is that the play was perhaps in the notches in the carrier and rotor. I also measured the new bobbins versus the old ones with a micrometer and found no difference. I think that my case may have been an a strange one.

[Mark K]

The issue that I had with the BMW replacement Bibbins was that...they made no difference - the rotors had the same play on the carriers as the old bobbin set.

 

You're sure the old ones were........well, old? Also, you saying there was still rotational play, or play in and out? When I did mine, I offset them one hole to account for any possible wear on the carrier.

[SMD]

Aftermarket bobbins from Motobins.co.uk are supposed to be slightly oversized. At least on my bike, the rotors rattled like crazy before I replaced the bobbins. Now there is no rattle and the rotors still have a little side to side play. Plus, they're a little less expensive than OEM bobbins. I paid $79 USD including shipping.

[DavidEBSmith]

as snugly AS A NEW ROTOR WHICH DOES NOT HAVE ANY PLAY IN IT.

 

I have the advantage here of having two front wheels for my bike. (Not at the same time). One set of rotors on one wheel has always been loose and rattles like crazy, even with new bobbins. The other set of rotors on the other wheel have always been tight and barely move at all, with old or new bobbins. I had one rotor warp very badly on the wheel with the tight bobbins.

 

As has been said many times, side-to-side play is OK, rotational play is bad. I think some bikes happen to have looser rotors that rattle side-to-side and the owners (being neurotic BMW riders) take that as a sign of impending doom, or they're embarrassed at the harassment they get from Ducati riders for having a noisy, rattly bike.

 

Now, are you saying that after replacing the bobbins, you still had rotational play? That would suggest that the carrier was worn out, not the bobbins.

[Santron]

Yeah, not really sure that they were worn out. The rotors had a little side-to-side play, not much if any rotational play. I went to the dealer and looked at a set of new brake rotors and carrier, and they were TIGHT - no play whatsoever. I guess that is what I was expecting to get from the bobbin replacement and it didn't happen. Well, it did eventually but I got seriously flamed for what I did but I still stand behind my decision.

 

And yes, your description of the obsessive/neurotic BMW rider is me to a tee, hence the beating of this dead horse.