Rear Brake Disc warping?

[al_roethlisberger]

Two topics:

 

First, an interesting twist on the rear-brake noise this weekend.... while riding down to Hollister, I heard the infamous rear-brake "groan" while actually travelling *forward*! ... at a very slow crawling-in-traffic pace. At first I thought it was coming from the front rotors, and it was cyclic... so I thought "did I warp them?". Then I recognized the "groan", tapped the rear brake... and it was gone

 

So I guess it's just an issue of "setting the pads" once they get cock-eyed. I had just used the brakes heavily a few moments before, so who knows.... it never happened again, and didn't affect braking. Just an odd noise.

 

 

Second, you didn't miss much at the "Rally". It wasn't much of a "Rally"... what is one anyway these days except somewhere to buy stuff it seems?? There were a TON of Harley's of course, must have been several hundred on Friday, and I think we counted 8 non-Harley bikes

 

But most were pretty cookie-cutter, and the real stand-outs were full-on customs that I wouldn't even call Harley's anyway... but very nice work none-the-less.

 

I tell ya though, I never saw soooo many people wearing skimpy leather and bikinis ... that.... well..... shouldn't. ...yuck.

 

...very loud bunch too. I don't know how they ride those bikes with pipes that loud. Anyway, we walked around for a couple hours, saw all the stereotypical product booths such as obligatory leather thongs and claw-kick-stands... then headed out to ride across to the coast, and back over Highway 9.

 

BTW, saw two bikes, a late 90's R1 and some bigger Ninja, being hauled up the mountain-side by wreckers. Totalled.... but I got the impression that no one was seriously hurt, just the bikes going down the hill.

 

al

[Guest marcialc]

Hey Al, I've been tapping the rear brake in the morning before starting the bike...and the "groan" has basically disappeared.

I say basically because it's still there, I hear it maybe once or twice during the day, but nowhere near as prevalent and loud as before.

I find it totally ironic that a modern bike with state of the art brakes will make these horrible sounding "groans" and my 1978 TR7 with first generation disc brakes makes no noise at all. <_<

 

...about the Rally, what did u expect??? it was after all, a Harley rally

I wonder what kind of booths you'd find at a Guzzi rally?

 

safe riding...

 

[Guest marcialc]

ok, had the rear disc replaced as a warranty item during the 1000 mile service. It's been a week now since the service and I'm happy to report that the "groan" has disappeared

 

I'm still tapping the rear break in the morning though as a precaution...so nice to hear nothing but the humm of the engine.

[Guest scott]

I've got over 3k miles on my LeMans, and my bike makes the exact same noise when I back it up! I thought it was just me. Recently, due to an oil leak that saturated the rear brake, the rear pads were replaced under warranty. The bike still makes the noise when backed. But, fortunately, I've never experienced any brake problems or surging of the brakes to indicate there is a warp in the disk.

[Guest marcialc]

ok, so last week I locked up my rear brakes and fishtailed whilst coming to a sudden screaching stop in order to save the lives of a pair of daydreaming nitwit pedestrians who crossed the street in an oblivious...lets stay totally engrossed in our own world....kinda state.

 

....ever since then, that horrible "groan" has re-emerged but this time it groans while moving....foward...at a slow speed (like 10-20mph)

[dlaing]

I had groaning rear brake durring the first few thousand miles. Lubricating the piston cylinders eliminated the problem. I had to replace the rear pads today with an EBC semi-metallic carbon pad set. The brembo pads were scored and starting crumble off a little. Total mileage on the rear brake pads 16,275 miles. They still had some depth left and could hav gone maybe another 5000 miles, but that would have been stretching it. For what it is worth, I consider myself a heavy front brake user and a light or seldom user of the rear brake. I also replaced one of the rear bearings today as it was showing some roughness of motion...Also tried a Continental Force 160/60 http://www.tiresunlimited.com/continental_...conti_force.htm I paid full retail, but you can get it for a lot less($89)! So far it seems about the same as the Pirelli Dragon Corsa 170/60 that it replaced. Both are pretty quick steering. Let me know if you want more feed back on the EBC and the "Cheap" Conti Force. They both need a little more breaking in, and to be tested for durability. But since I am chewing through tires every 5000 miles the Conti Force is looking like a bargain.

[dlaing]

correction, dragon gts, not dragon corsa.

[Guest Squashed Nose]

Gone off the subject a bit in the last few posts haven't we chaps?

 

I've had a problem with my rear brake since day 1. I took the bike back to the dealer after 2 days to get the fast idle to work and to get the rear brake sorted which was holding on (binding) whilst going forwards. It seems to be worse whilst down shifting through the gears. All they did was grease the back of the pads.

 

I've moaned about it at two services now (the bike has done 11000 miles in the last 7 months) and the problem is getting steadily worse. At the last service they had the temerity to suggest that it was my fault as I must be riding with my foot on the lever! It is binding so much now that the disc has scorched. A new rear master cylinder is on order (I have been waiting nearly three months for it to arrive!) and I will be demanding a new disc as well. I am pretty sure it is costing me dearly in fuel as well but I don't suppose they will refund me on warranty!

[dlaing]

Hey squashed,

if the master cylinder replacement does not fix the binding, you might look at your bearings. I noticed that if I pulled in my clutch so that I was free wheeling, and then did quick zigs and zags at about 10-20 mph, I found that something felt like it was rubbing, I suspect either the shaft u joints or the brake rubbing. Now that I know that the wheel bearing was the culprit, and that my disk pads were getting scored, I suspect the rubbing sensation was caused by the wheel bearing being less then perfect and the rear brakes rubbing durring lateral shifts(turns) of the bike. It was also probably rubbing durring acceleration and deacceleration, but was not as noticeable.

Did your dealer did try lubricating the master cylinder and the brake caliber before ordering the new master cylinder???

Cleaning the brake caliber pistons with extra fine steel wool can also work miracles.

Oh, and just to make sure I stray off the topic. Here is my report on the Contis and ECB carbons. The ECB stop the bike a little better than the Brembo. After a few hundred miles on the Conti Force I have reservations. They are great up to maybe 80 mph, gripping very well and feeling confident in the twisties but, above 80 mph then they do not feel very stable. I would say the Z rating is not earned.

[Guest Squashed Nose]

You could have a point with regard to the wheel bearing. I have noticed whilst wheeling the bike around that the brake tends to bind whilst straying off the vertical. Of course, during normal riding, there's no way I would hear it inside my helmet and with that glorious V twin rumble going on. Cheers geezer, I'll mention this to the dealer.

[Guest marcialc]

Ok, I think we might have solved the rear brake "groan" issue. Upon careful inspection of the rear brake pads, we found that the pad was worn almost to the metal. I was shocked to say the least, especially since the bike only has 4,000 miles on it.

 

Took the bike to the dealer to have them check the rear brake set-up. Their suspicion is that I might have been inadvertanlely riding the rear brake with the toe of my boot. We installed new EBC syntered pads (part# EBC FA47HH) and lowered/readjusted the rear brake lever.

 

Glad to report no more "groan" so far, knock on wood....and now I'm extremely conscious of my right foot placement, making sure that I'm not mistakenly touching the rear brake lever.

 

....however, we did notice that the rubber bushing on the rear stabilizer was worn and fried dealer is replacing under warranty.

 

Just when you think one problem is solved...