Rotational Noise

[bobross]

Bike is a 1999 R1100S, with 41k miles.

Have recently notices a rotational noise when the bike is moving, rrrr---rrrr- rrrr-rrrr-rrrr- etc. Speeds up as I speed up, slows down as I slow down. Standing still and revving the engine, does not occur. The speeding up/slowing down matches the speed of the bike, and is not affected by what gear I am in, or whether I pull in the clutch or not.

If this was a car, I would be thinking universal joints in the driveline, maybe wheel bearings.

What would I look for on the BMW?

[ckcarr]

Tires

["A"]

Brake rotor?

[darkonaut]

tires or rotors yes

although, you do have bearings (front in the wheel, rear in the final drive) and universal joints

[bobross]

thanks for the replies. I will check these out. And report back.

[bobross]

I checked the tires. Called the dealer for the record on the work order when they were installed. the Pilot Road GTs have 12,000 miles on them. Probably about time for a new one.

Also looked at the rear brakes. The peep hole on the caliper shows the rotor, so the pads are ready for replacement if there is any pad left in there. Also, rear rotor is pretty grooved compared to the front rotors. When I turned the wheel it sounded rough. My guess is this is the source of the rotational sound.

I am looking for advice on aftermarket pads and rear rotor (if I replace it). OEM disc is over $300. Pads are $75 plus. I see various aftermarket discs from about $49 up. Kind of in line with what you pay for discs on a car. Parts fiche indicates organic pads for this model (1999).

[sgoodwin]

I run EBC sintered pads & consider them far superior to stock.

Here's a pile of rotors from ebay....sure there's a ton of other places to get them
https://www.ebay.com/sch/i.html?_odkw=bmw+r1100s&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xbmw+r1100 s+rear+brake+rotor.TRS0&_nkw=bmw+r1100s+rear+brake+rotor&_sacat=0

[Groceryrun]

The peep hole on the caliper shows the rotor, so the pads are ready for replacement if there is any pad left in there.

You have definitely found the source of the rrrr----rrrr----rrrr noise.
I find that the leading edge and the trailing edge of the rear brake pads do not wear evenly - If you can see thru the pad, it's past due.

If you like an organic pad for the rear , try the green Kevlar from Galfer.
The Galfer Green Kevlar (1532 ) produce a little less brake dust than the OEM BMW organic , and they feel like they stop the bike quicker . Only drawback is that they do not last that long.
I believe the correct model number is FD186G1532. ( Please make sure of the model number before purchasing. )
FD186 G1532

[tic105]

Here's a link to a post for a source I used for Brembo pads - best application IMO. At the time I got a full set (front & rear) for $76 USD.
They also have the rear Brembo disk for ~$90 USD.

Here's a good source for Brembo brake pads

[bobross]

I looked up the link for Carpimoto. They are, among other things, a Brembo dealer, located in Italy.

Ordered the rear disc for this bike, genuine Brembo part, made in Italy, for 76 Euro. ($88). A lot better than $315 from the BMW dealer! Arrived in 3-4 days. Stuck it on the wheel. Fits perfectly.

Also ordered pads, front and rear, 64 Euro, $74.

Seems like a good source for brake parts.

[bobross]

Bringing this back up.

Thought it was related to rear brake pads worn through and scoring the disc.

Replaced the pads. Replaced the disc. While I was at it, replaced the front pads too. In the process, busted a brake hose, so replaced the brake lines with SS. While the bodywork was off, replaced the air filter, fuel filter, and installed quick disconnect fuel line connections. Also, bought an AF-xied and put that in. also, replaced the cracked windshield.

Whew!

Took it out, after all that, rotational noise still there. thinking probably the tire all along. It has 12K miles on it and little tread. Time to go anyway. Hope that is it.

[Meeni]

While you have the wheels off for the tire change have the shop take a look at the wheel bearings on the front.

["A"]

Rotational noise are usually easy to diagnose, put bike on center stand and spin the wheels, one at a time.