Floating Brake Disc

[AdamWebber]

I just bought my fourth BMW. It's my first pre-servo ABS bike. It's a '96 R1100R with about 57k miles on it. It is in almost perfect condition. When I was backing it out of my garage the other day, there was a type of grinding sound. I thought that it may be the gear-drive for the speedometer but upon closer inspection, I found that the rotors are very loose and the grinding is ever-so-slight binding between the rotors and brake pads. There is a lot of left to right play in both rotors. Braking is fine. ABS is fine. I'm sure that this topic has been discussed in great detail before but since I am new to the site, I haven't viewed any.

Is it normal for the rotors to have a lot of play? My R1150R, K1200RS and R1200GS do not have problems like this. I have never had a Japanese bike do this. Should I worry? Is it worth replacing?

[omg1010]

Hello Adam,

the R1100R does have so-called floating discs hence it is normal that the discs have horizontal play. Nothing to worry about.

Brgds
Oliver

[CRazyCam]

Hi Adam.

Yeah, when I first got my R850R (1998 model, same brakes as your bike) I was surprised at the amount of "floating" that the floating discs did do.

AFAIK, they are supposed to be that way, certainly I have had no trouble with regard to brakes in the last 35,000 kilometres.

You're later motorbikes have semi-floating discs, because folk didn't like the occasional odd noise from fully floating discs when wheeling the bike around at low speed.

Relax and enjoy the bike.

regards,CrazyCam

[AdamWebber]

Thanks for the replies. I won't worry about the discs anymore.

[omg1010]

Hi Adam.

You're later motorbikes have semi-floating discs, because folk didn't like the occasional odd noise from fully floating discs when wheeling the bike around at low speed.

regards,CrazyCam

Objections your honor! The later 1150 models did NOT have have floating or semi-floating discs. Instead they have discs which are fixed to the wheels. I can judge because I have a R1150R front wheel in my R1100R. There is nothing floating or semi-floating.

Brgds
Oliver

[CRazyCam]

Fair enough, Oliver.

I don't have more modern BMW wheels close handy for examination.

I know that my Triumph has what they call semi-floating discs..... they look like they should "float" as in move about side to side, but they don't actually move.

There is a set of replacement "thimbles" to change the discs to full floating, which (I believe) racers use.

regards,CrazyCam